WorldWideScience

Sample records for degrading image quality

  1. Digital image quality measurements by objective and subjective methods from series of parametrically degraded images

    Science.gov (United States)

    Tachó, Aura; Mitjà, Carles; Martínez, Bea; Escofet, Jaume; Ralló, Miquel

    2013-11-01

    Many digital image applications like digitization of cultural heritage for preservation purposes operate with compressed files in one or more image observing steps. For this kind of applications JPEG compression is one of the most widely used. Compression level, final file size and quality loss are parameters that must be managed optimally. Although this loss can be monitored by means of objective image quality measurements, the real challenge is to know how it can be related with the perceived image quality by observers. A pictorial image has been degraded by two different procedures. The first, applying different levels of low pass filtering by convolving the image with progressively broad Gauss kernels. The second, saving the original file to a series of JPEG compression levels. In both cases, the objective image quality measurement is done by analysis of the image power spectrum. In order to obtain a measure of the perceived image quality, both series of degraded images are displayed on a computer screen organized in random pairs. The observers are compelled to choose the best image of each pair. Finally, a ranking is established applying Thurstone scaling method. Results obtained by both measurements are compared between them and with other objective measurement method as the Slanted Edge Test.

  2. Radiation dose reduction without degrading image quality during computed tomography examinations: Dosimetry and quality control study

    Directory of Open Access Journals (Sweden)

    George Felix Acquah

    2014-08-01

    enough to produce acceptable level of image quality which leads to adequate diagnosis without unnecessary doses to patients.......................................................Cite this article as:Acquah GF, Schiestl B,Cofie AY, Nkansah JO. Radiation dose reduction without degrading image quality during computed tomography examinations: Dosimetry and quality control study. Int J Cancer Ther Oncol 2014; 2(3:02039.  DOI: 10.14319/ijcto.0203.9

  3. Medical Image Steganography: Study of Medical Image Quality Degradation when Embedding Data in the Frequency Domain

    Directory of Open Access Journals (Sweden)

    M.I.Khalil

    2017-02-01

    Full Text Available Steganography is the discipline of invisible communication by hiding the exchanged secret information (message in another digital information media (image, video or audio. The existence of the message is kept indiscernible in sense that no one, other than the intended recipient, suspects the existence of the message. The majority of steganography techniques are implemented either in spatial domain or in frequency domain of the digital images while the embedded information can be in the form of plain or cipher message. Medical image steganography is classified as a distinctive case of image steganography in such a way that both the image and the embedded information have special requirements such as achieving utmost clarity reading of the medical images and the embedded messages. There is a contention between the amount of hidden information and the caused detectable distortion of image. The current paper studies the degradation of the medical image when undergoes the steganography process in the frequency domain.

  4. Assessing pasture quality and degradation status using hyperspectral imaging: a case study from western Tibet

    Science.gov (United States)

    Lehnert, Lukas W.; Meyer, Hanna; Meyer, Nele; Reudenbach, Christoph; Bendix, Jörg

    2013-10-01

    Alpine grasslands on the Tibetan Plateau (TP) are suffering from pasture degradation induced by over-grazing, climate change and improper livestock management. Meanwhile, the status of pastures is largely unknown especially in poor accessible western parts on the TP. The aim of this case study was to assess the suitability of hyperspectral imaging to predict quality and amount of forage on the western TP. Therefore, 18 ground- based hyperspectral images taken along two transects on a winter pasture were used to estimate leaf chlorophyll content, photosynthetic-active vegetation cover (PV) and proportion of grasses. For calibration and validation purposes, chlorophyll content of 20 grass plants was measured in situ. From the images reference spectra of grass and non-grass species were collected. PV was assessed from similarity of images to mean vegetation spectra using spectral angle mapper and threshold classifications. A set of 48 previously published hyperspectral vegetation indices (VI) was used as predictors to estimate chlorophyll content and to discriminate grass and non-grass pixels. Separation into grass and non-grass species was performed using partial least squares (PLS) discriminant analysis and chlorophyll content was estimated with PLS regression. The accuracy of the models was assessed with leave-one-out cross validation and normalised root mean square errors (nRMSE) for chlorophyll and contingency matrices for grass classification and total PV separation. Highest error rates were observed for discrimination between vegetated and non-vegetated parts (Overall accuracy = 0.85), whilst accuracies of grass and non grass separation (Overall accuracy = 0.98) and chlorophyll estimation were higher (nRMSE = 10.7).

  5. Batteries: Imaging degradation

    Science.gov (United States)

    Shearing, Paul R.

    2016-11-01

    The degradation and failure of Li-ion batteries is strongly associated with electrode microstructure change upon (de)lithiation. Now, an operando X-ray tomography approach is shown to correlate changes in the microstructure of electrodes to cell performance, and thereby predict degradation pathways.

  6. Monopoly quality degradation in cable television

    OpenAIRE

    Crawford, Gregory S; Shum, Matthew

    2003-01-01

    Using an empirical framework derived from models of nonlinear pricing, we estimate the degree of quality degradation in cable television markets. We find lower bounds on quality degradation ranging from 11% to 45% of observed service qualities. Furthermore, cable operators in markets with local regulatory oversight tend to offer significantly higher quality products, and engage in less quality degradation. While prices are also higher in markets with local regulatory oversight, we find that c...

  7. Recovering of images degraded by atmosphere

    Science.gov (United States)

    Lin, Guang; Feng, Huajun; Xu, Zhihai; Li, Qi; Chen, Yueting

    2017-08-01

    Remote sensing images are seriously degraded by multiple scattering and bad weather. Through the analysis of the radiative transfer procedure in atmosphere, an image atmospheric degradation model considering the influence of atmospheric absorption multiple scattering and non-uniform distribution is proposed in this paper. Based on the proposed model, a novel recovering method is presented to eliminate atmospheric degradation. Mean-shift image segmentation and block-wise deconvolution are used to reduce time cost, retaining a good result. The recovering results indicate that the proposed method can significantly remove atmospheric degradation and effectively improve contrast compared with other removal methods. The results also illustrate that our method is suitable for various degraded remote sensing, including images with large field of view (FOV), images taken in side-glance situations, image degraded by atmospheric non-uniform distribution and images with various forms of clouds.

  8. Image Degradation in Microscopic Images: Avoidance, Artifacts, and Solutions.

    Science.gov (United States)

    Roels, Joris; Aelterman, Jan; De Vylder, Jonas; Lippens, Saskia; Luong, Hiêp Q; Guérin, Christopher J; Philips, Wilfried

    2016-01-01

    The goal of modern microscopy is to acquire high-quality image based data sets. A typical microscopy workflow is set up in order to address a specific biological question and involves different steps. The first step is to precisely define the biological question, in order to properly come to an experimental design for sample preparation and image acquisition. A better object representation allows biological users to draw more reliable scientific conclusions. Image restoration can manipulate the acquired data in an effort to reduce the impact of artifacts (spurious results) due to physical and technical limitations, resulting in a better representation of the object of interest. However, precise usage of these algorithms is necessary so as to avoid further artifacts that might influence the data analysis and bias the conclusions. It is essential to understand image acquisition, and how it introduces artifacts and degradations in the acquired data, so that their effects on subsequent analysis can be minimized. This paper provides an overview of the fundamental artifacts and degradations that affect many micrographs. We describe why artifacts appear, in what sense they impact overall image quality, and how to mitigate them by first improving the acquisition parameters and then applying proper image restoration techniques.

  9. Imaging Food Quality

    DEFF Research Database (Denmark)

    Møller, Flemming

    Imaging and spectroscopy have long been established methods for food quality control both in the laboratories and online. An ever increasing number of analytical techniques are being developed into imaging methods and existing imaging methods to contain spectral information. Images and especially...... spectral images contain large amounts of data which should be analysed appropriately by techniques combining structure and spectral information. This dissertation deals with how different types of food quality can be measured by imaging techniques, analysed with appropriate image analysis techniques...... and finally use the image data to predict or visualise food quality. A range of different food quality parameters was addressed, i.e. water distribution in bread throughout storage, time series analysis of chocolate milk stability, yoghurt glossiness, graininess and dullness and finally structure and meat...

  10. Image quality in mammography

    Energy Technology Data Exchange (ETDEWEB)

    Haus, A.G.; Doi, K.; Metz, C.E. Bernstein, J.

    1976-01-01

    In mammography, image quality is a function of the shape, size, and x-ray absorption properties of the anatomic part to be radiographed and of the lesion to be detected; it also depends on geometric unsharpness, and the resolution, characteristic curve and noise properties of the recording system. X-ray energy spectra, modulation transfer functions, Wiener spectra, characteristic and gradient curves, and radiographs of a breast phantom and of a resected breast specimen containing microcalcifications are used in a review of some current considerations of the factors, and the complex relationship among factors, that affect image quality in mammography. Image quality and patient radiation exposure in mammography are interrelated. An approach to the problem of evaluating the trade-off between diagnostic certainty and the cost or risk of performing a breast imaging procedure is discussed.

  11. Restoring Soil Quality to Mitigate Soil Degradation

    Directory of Open Access Journals (Sweden)

    Rattan Lal

    2015-05-01

    Full Text Available Feeding the world population, 7.3 billion in 2015 and projected to increase to 9.5 billion by 2050, necessitates an increase in agricultural production of ~70% between 2005 and 2050. Soil degradation, characterized by decline in quality and decrease in ecosystem goods and services, is a major constraint to achieving the required increase in agricultural production. Soil is a non-renewable resource on human time scales with its vulnerability to degradation depending on complex interactions between processes, factors and causes occurring at a range of spatial and temporal scales. Among the major soil degradation processes are accelerated erosion, depletion of the soil organic carbon (SOC pool and loss in biodiversity, loss of soil fertility and elemental imbalance, acidification and salinization. Soil degradation trends can be reversed by conversion to a restorative land use and adoption of recommended management practices. The strategy is to minimize soil erosion, create positive SOC and N budgets, enhance activity and species diversity of soil biota (micro, meso, and macro, and improve structural stability and pore geometry. Improving soil quality (i.e., increasing SOC pool, improving soil structure, enhancing soil fertility can reduce risks of soil degradation (physical, chemical, biological and ecological while improving the environment. Increasing the SOC pool to above the critical level (10 to 15 g/kg is essential to set-in-motion the restorative trends. Site-specific techniques of restoring soil quality include conservation agriculture, integrated nutrient management, continuous vegetative cover such as residue mulch and cover cropping, and controlled grazing at appropriate stocking rates. The strategy is to produce “more from less” by reducing losses and increasing soil, water, and nutrient use efficiency.

  12. Monopoly Quality Degradation and Regulation in Cable Television

    OpenAIRE

    Crawford, Gregory; Shum, Matthew

    2005-01-01

    Using an empirical framework based on the Mussa-Rosen model of monopoly quality choice, we calculate the degree of quality degradation in cable television markets and the impact of regulation on those choices. We find lower bounds of quality degradation ranging from 11 to 45 percent of offered service qualities. Furthermore, cable operators in markets with local regulatory oversight offer significantly higher quality, less degradation, and greater quality per dollar, despite higher prices.

  13. NIR hyperspectral imaging to evaluate degradation in captopril commercial tablets.

    Science.gov (United States)

    França, Leandro de Moura; Pimentel, Maria Fernanda; Simões, Simone da Silva; Grangeiro, Severino; Prats-Montalbán, José M; Ferrer, Alberto

    2016-07-01

    Pharmaceutical quality control is important for improving the effectiveness, purity and safety of drugs, as well as for the prevention or control of drug degradation. In the present work, near infrared hyperspectral images (HSI-NIR) of tablets with different expiration dates were employed to evaluate the degradation of captopril into captopril disulfide in different layers, on the top and on the bottom surfaces of the tablets. Multivariate curve resolution (MCR) models were used to extract the concentration distribution maps from the hyperspectral images. Afterward, multivariate image techniques were applied to the concentration distribution maps (CDMs), to extract features and build models relating the main characteristics of the images to their corresponding manufacturing dates. Resolution methods followed by extracting features were able to estimate the tablet manufacture date with a prediction error of 120days. The model developed could be useful to evaluate whether a sample shows a degradation pattern consistent with the date of manufacturing or to detect abnormal behaviors in the natural degradation process of the sample. The information provided by the HIS-NIR is important for the development of the process (QbD), looking inside the formulation, revealing the behavior of the active pharmaceutical ingredient (API) during the product's shelf life. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Text segmentation in degraded historical document images

    Directory of Open Access Journals (Sweden)

    A.S. Kavitha

    2016-07-01

    Full Text Available Text segmentation from degraded Historical Indus script images helps Optical Character Recognizer (OCR to achieve good recognition rates for Hindus scripts; however, it is challenging due to complex background in such images. In this paper, we present a new method for segmenting text and non-text in Indus documents based on the fact that text components are less cursive compared to non-text ones. To achieve this, we propose a new combination of Sobel and Laplacian for enhancing degraded low contrast pixels. Then the proposed method generates skeletons for text components in enhanced images to reduce computational burdens, which in turn helps in studying component structures efficiently. We propose to study the cursiveness of components based on branch information to remove false text components. The proposed method introduces the nearest neighbor criterion for grouping components in the same line, which results in clusters. Furthermore, the proposed method classifies these clusters into text and non-text cluster based on characteristics of text components. We evaluate the proposed method on a large dataset containing varieties of images. The results are compared with the existing methods to show that the proposed method is effective in terms of recall and precision.

  15. Predicting Visible Image Degradation by Colour Image Difference Formulae

    Institute of Scientific and Technical Information of China (English)

    Eriko Bando; Jon Y. Hardeberg; David Connah; Ivar Farup

    2004-01-01

    It carried out a CRT monitor based psychophysical experiment to investigate the quality of three colour image difference metrics, the CIEAE ab equation, the iCAM and the S-CIELAB metrics. Six original images were reproduced through six gamut mapping algorithms for the observer experiment. The result indicates that the colour image difference calculated by each metric does not directly relate to perceived image difference.

  16. An investigation of image compression on NIIRS rating degradation through automated image analysis

    Science.gov (United States)

    Chen, Hua-Mei; Blasch, Erik; Pham, Khanh; Wang, Zhonghai; Chen, Genshe

    2016-05-01

    The National Imagery Interpretability Rating Scale (NIIRS) is a subjective quantification of static image widely adopted by the Geographic Information System (GIS) community. Efforts have been made to relate NIIRS image quality to sensor parameters using the general image quality equations (GIQE), which make it possible to automatically predict the NIIRS rating of an image through automated image analysis. In this paper, we present an automated procedure to extract line edge profile based on which the NIIRS rating of a given image can be estimated through the GIQEs if the ground sampling distance (GSD) is known. Steps involved include straight edge detection, edge stripes determination, and edge intensity determination, among others. Next, we show how to employ GIQEs to estimate NIIRS degradation without knowing the ground truth GSD and investigate the effects of image compression on the degradation of an image's NIIRS rating. Specifically, we consider JPEG and JPEG2000 image compression standards. The extensive experimental results demonstrate the effect of image compression on the ground sampling distance and relative edge response, which are the major factors effecting NIIRS rating.

  17. Soil quality of a degraded urban area

    Science.gov (United States)

    Panico, Speranza; Memoli, Valeria; Maisto, Giulia; De Marco, Anna

    2017-04-01

    Human activities cause modifications of the soil characteristics, leading to a significant reduction of the soil fertility and quality. The aim of this study was to evaluate the relationships between microbial activity or biomass and chemical characteristics (i.e. heavy metal and organic matter contents) of a degraded urban soil. The study area is located in an urban park (about 10 ha, called Quarantena) near to the Fusaro Lake of Campi Flegrei (Southern Italy); the Park was established in 1953 to shelter animals coming from any place of the Planet and execute veterinary checks before their delivery to different European zoos. In 1997, the park was abandoned and nowadays in it a large amount of urban wastes accumulates. Surface soils (0-10 cm) were sampled at three points: two of them covered by Holm Oak specimens (P1 and P2) and one covered by herbaceous species, particularly legumes (P3). P1 was localized at the border of the park and next to a busy road; P2 at the centre of the Quarantena Park; P3 at a gap area near the Fusaro Lake. The results showed that the soil sampled at P1 showed the highest Cr and Ni concentrations; the soil sampled at P3 had high levels of Cu and Pb, exceeding the threshold values of 100 µg g-1 d.w. fixed by the Italian law for urban soils, probably due to boat traffic, fishing practice and agricultural activities; the soil sampled at P2 had intermediate values of metal concentrations but the highest amount of organic matter (more than 20% d.w.). Despite of metal contamination, P1 and P3 showed higher soil microbial biomass and activity as compared to P2. Therefore, at this site, the organic matter accumulation could be due to the scarce litter degradation. In conclusion, although the studied area was not too large, a wide heterogeneity of soil quality (in terms of the investigated chemical and biological characteristics) was detected, depending on the local human impact.

  18. WFC3 IR Image Quality

    Science.gov (United States)

    Dressel, Linda

    2009-07-01

    The IR imaging performance over the detector will be assessed periodically {every 4 months} in two passbands to check for image stability. The field around star 58 in the open cluster NGC188 is the chosen target because it is sufficiently dense to provide good sampling over the FOV while providing enough isolated stars to permit accurate PSF {point spread function} measurement. It is available year-round and used previously for ACS image quality assessment. The field is astrometric, and astrometric guide stars will be used, so that the plate scale and image orientation may also be determined if necessary {as in SMOV proposals 11437 and 11443}. Full frame images will be obtained at each of 4 POSTARG offset positions designed to improve sampling over the detector in F098M, F105W, and F160W. The PSFs will be sampled at 4 positions with subpixel shifts in filters F164N and F127M.This proposal is a periodic repeat {once every 4 months} of the visits in SMOV proposal 11437 {activity ID WFC3-24}. The data will be analyzed using the code and techniques described in ISR WFC3 2008-41 {Hartig}. Profiles of encircled energy will be monitored and presented in an ISR. If an update to the SIAF is needed, {V2,V3} locations of stars will be obtained from the Flight Ops Sensors and Calibrations group at GSFC, the {V2,V3} of the reference pixel and the orientation of the detector will be determined by the WFC3 group, and the Telescopes group will update and deliver the SIAF to the PRDB branch.The specific PSF metrics to be examined are encircled energy for aperture diameter 0.25, 0.37, and 0.60 arcsec, FWHM, and sharpness. {See ISR WFC3 2008-41 tables 2 and 3 and preceding text.} 20 stars distributed over the detector will be measured in each exposure for each filter. The mean, rms, and rms of the mean will be determined for each metric. The values determined from each of the 4 exposures per filter within a visit will be compared to each other to see to what extent they are affected

  19. WFC3 UVIS Image Quality

    Science.gov (United States)

    Dressel, Linda

    2009-07-01

    The UVIS imaging performance over the detector will be assessed periodically {every 4 months} in two passbands {F275W and F621M} to check for image stability. The field around star 58 in the open cluster NGC188 is the chosen target because it is sufficiently dense to provide good sampling over the FOV while providing enough isolated stars to permit accurate PSF {point spread function} measurement. It is available year-round and used previously for ACS image quality assessment. The field is astrometric, and astrometric guide stars will be used, so that the plate scale and image orientation may also be determined if necessary {as in SMOV proposals 11436 and 11442}. Full frame images will be obtained at each of 4 POSTARG offset positions designed to improve sampling over the detector.This proposal is a periodic repeat {once every 4 months} of visits similar to those in SMOV proposal 11436 {activity ID WFC3-23}. The data will be analyzed using the code and techniques described in ISR WFC3 2008-40 {Hartig}. Profiles of encircled energy will be monitored and presented in an ISR. If an update to the SIAF is needed, {V2,V3} locations of stars will be obtained from the Flight Ops Sensors and Calibrations group at GSFC, the {V2,V3} of the reference pixel and the orientation of the detector will be determined by the WFC3 group, and the Telescopes group will update and deliver the SIAF to the PRDB branch.The specific PSF metrics to be examined are encircled energy for aperture diameter 0.15, 0.20, 0.25, and 0.35 arcsec, FWHM, and sharpness. {See ISR WFC3 2008-40 tables 2 and 3 and preceding text.} about 20 stars distributed over the detector will be measured in each exposure for each filter. The mean, rms, and rms of the mean will be determined for each metric. The values determined from each of the 4 exposures per filter within a visit will be compared to each other to see to what extent they are affected by "breathing". Values will be compared from visit to visit, starting

  20. Image quality in context

    NARCIS (Netherlands)

    Besuijen, J.

    2008-01-01

    An analysis of the ergonomic quality of the current standards for the visual display quality leads to a number of recommendations for the development of new international standards: - Separation for different types of users, esp. display designers, purchasers, and end users, -Independence of display

  1. Analysis of Proposed Noise Detection & Removal Technique in Degraded Fingerprint Images

    Science.gov (United States)

    Hamid, Ainul Azura Abdul; Rahim, Mohd Shafry Mohd; Al-Mazyad, Abdulaziz S.; Saba, Tanzila

    2015-12-01

    The quality of fingerprint images is important to ensure good performance of fingerprint recognition since recognition process depends heavily on the quality of fingerprint images. Fingerprint images obtained from the acquisition phase are either contaminated with noise or degraded due to poor quality machines. Several factors such as scars, moist in scanner and many more noises affect the quality of the images during scanning process. This paper performed an analysis and compared noise removal techniques reported in the literature for fingerprint images. We also implemented histogram equalization, median filter, Fourier transform, unsharp mask and grayscale enhancement techniques. The quality of enhanced images is measured by peak signal to noise ratio (PSNR) calculation for analysis and comparisons.

  2. Does resolution really increase image quality?

    Science.gov (United States)

    Tisse, Christel-Loïc; Guichard, Frédéric; Cao, Frédéric

    2008-02-01

    A general trend in the CMOS image sensor market is for increasing resolution (by having a larger number of pixels) while keeping a small form factor by shrinking photosite size. This article discusses the impact of this trend on some of the main attributes of image quality. The first example is image sharpness. A smaller pitch theoretically allows a larger limiting resolution which is derived from the Modulation Transfer Function (MTF). But recent sensor technologies (1.75μm, and soon 1.45μm) with typical aperture f/2.8 are clearly reaching the size of the diffraction blur spot. A second example is the impact on pixel light sensitivity and image sensor noise. For photonic noise, the Signal-to-Noise-Ratio (SNR) is typically a decreasing function of the resolution. To evaluate whether shrinking pixel size could be beneficial to the image quality, the tradeoff between spatial resolution and light sensitivity is examined by comparing the image information capacity of sensors with varying pixel size. A theoretical analysis that takes into consideration measured and predictive models of pixel performance degradation and improvement associated with CMOS imager technology scaling, is presented. This analysis is completed by a benchmarking of recent commercial sensors with different pixel technologies.

  3. Reduced-reference image quality assessment using moment method

    Science.gov (United States)

    Yang, Diwei; Shen, Yuantong; Shen, Yongluo; Li, Hongwei

    2016-10-01

    Reduced-reference image quality assessment (RR IQA) aims to evaluate the perceptual quality of a distorted image through partial information of the corresponding reference image. In this paper, a novel RR IQA metric is proposed by using the moment method. We claim that the first and second moments of wavelet coefficients of natural images can have approximate and regular change that are disturbed by different types of distortions, and that this disturbance can be relevant to human perceptions of quality. We measure the difference of these statistical parameters between reference and distorted image to predict the visual quality degradation. The introduced IQA metric is suitable for implementation and has relatively low computational complexity. The experimental results on Laboratory for Image and Video Engineering (LIVE) and Tampere Image Database (TID) image databases indicate that the proposed metric has a good predictive performance.

  4. Digital Watermarking Method Warranting the Lower Limit of Image Quality of Watermarked Images

    Directory of Open Access Journals (Sweden)

    Iwata Motoi

    2010-01-01

    Full Text Available We propose a digital watermarking method warranting the lower limit of the image quality of watermarked images. The proposed method controls the degradation of a watermarked image by using a lower limit image. The lower limit image means the image of the worst quality that users can permit. The proposed method accepts any lower limit image and does not require it at extraction. Therefore lower limit images can be decided flexibly. In this paper, we introduce 2-dimensional human visual MTF model as an example of obtaining lower limit images. Also we use JPEG-compressed images of quality 75% and 50% as lower limit images. We investigate the performance of the proposed method by experiments. Moreover we compare the proposed method using three types of lower limit images with the existing method in view of the tradeoff between PSNR and the robustness against JPEG compression.

  5. Luminescence imaging of polymer solar cells: visualization of progressing degradation

    Energy Technology Data Exchange (ETDEWEB)

    Seeland, Marco; Roesch, Roland; Hoppe, Harald [Institute of Physics, Ilmenau University of Technology, Ilmenau (Germany)

    2011-07-01

    We apply luminescence imaging as tool for the non-destructive visualization of degradation processes within bulk heterojunction polymer solar cells. The imaging technique is based on luminescence detection with a highly sensitive silicon-ccd camera and is able to visualize the with time advancing degradation patterns of polymer solar cells. The devices investigated have been aged under defined conditions and were characterized periodically with current-voltage-sweeps. This allows determining the time evolution of the photovoltaic parameters and - in combination with the luminescence images - understanding differences in the observed degradation behaviour. The versatile usability of the method is demonstrated in a correlation between local reduction of lateral luminescence and a fast decrease of the short-circuit-current due to the loss of active area. Differences in the degradation of photovoltaic parameters under varied aging conditions are discussed.

  6. Image quality (IQ) guided multispectral image compression

    Science.gov (United States)

    Zheng, Yufeng; Chen, Genshe; Wang, Zhonghai; Blasch, Erik

    2016-05-01

    Image compression is necessary for data transportation, which saves both transferring time and storage space. In this paper, we focus on our discussion on lossy compression. There are many standard image formats and corresponding compression algorithms, for examples, JPEG (DCT -- discrete cosine transform), JPEG 2000 (DWT -- discrete wavelet transform), BPG (better portable graphics) and TIFF (LZW -- Lempel-Ziv-Welch). The image quality (IQ) of decompressed image will be measured by numerical metrics such as root mean square error (RMSE), peak signal-to-noise ratio (PSNR), and structural Similarity (SSIM) Index. Given an image and a specified IQ, we will investigate how to select a compression method and its parameters to achieve an expected compression. Our scenario consists of 3 steps. The first step is to compress a set of interested images by varying parameters and compute their IQs for each compression method. The second step is to create several regression models per compression method after analyzing the IQ-measurement versus compression-parameter from a number of compressed images. The third step is to compress the given image with the specified IQ using the selected compression method (JPEG, JPEG2000, BPG, or TIFF) according to the regressed models. The IQ may be specified by a compression ratio (e.g., 100), then we will select the compression method of the highest IQ (SSIM, or PSNR). Or the IQ may be specified by a IQ metric (e.g., SSIM = 0.8, or PSNR = 50), then we will select the compression method of the highest compression ratio. Our experiments tested on thermal (long-wave infrared) images (in gray scales) showed very promising results.

  7. A universal color image quality metric

    NARCIS (Netherlands)

    Toet, A.; Lucassen, M.P.

    2003-01-01

    We extend a recently introduced universal grayscale image quality index to a newly developed perceptually decorrelated color space. The resulting color image quality index quantifies the distortion of a processed color image relative to its original version. We evaluated the new color image quality

  8. Degradative encryption: An efficient way to protect SPIHT compressed images

    Science.gov (United States)

    Xiang, Tao; Qu, Jinyu; Yu, Chenyun; Fu, Xinwen

    2012-11-01

    Degradative encryption, a new selective image encryption paradigm, is proposed to encrypt only a small part of image data to make the detail blurred but keep the skeleton discernible. The efficiency is further optimized by combining compression and encryption. A format-compliant degradative encryption algorithm based on set partitioning in hierarchical trees (SPIHT) is then proposed, and the scheme is designed to work in progressive mode for gaining a tradeoff between efficiency and security. Extensive experiments are conducted to evaluate the strength and efficiency of the scheme, and it is found that less than 10% data need to be encrypted for a secure degradation. In security analysis, the scheme is verified to be immune to cryptographic attacks as well as those adversaries utilizing image processing techniques. The scheme can find its wide applications in online try-and-buy service on mobile devices, searchable multimedia encryption in cloud computing, etc.

  9. Groundtruth Generation and Document Image Degradation

    Science.gov (United States)

    2005-05-01

    the author in [32] uses this model to design a linear filtering scheme instead of generating synthetic images. The necessity and the work...TrueType specifications”, https://www.microsoft.com/ typography /specs/default.htm [28] Esko Ukkonen, “Algorithm for Approximate String Matching

  10. Quality assessment for online iris images

    CSIR Research Space (South Africa)

    Makinana, S

    2015-01-01

    Full Text Available Iris recognition systems have attracted much attention for their uniqueness, stability and reliability. However, performance of this system depends on quality of iris image. Therefore there is a need to select good quality images before features can...

  11. Optimization of Synthetic Aperture Image Quality

    DEFF Research Database (Denmark)

    Moshavegh, Ramin; Jensen, Jonas; Villagómez Hoyos, Carlos Armando

    2016-01-01

    Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameters...... effecting the image quality of SA is of great importance, and this paper proposes an advanced procedure for optimizing the parameters essential for acquiring an optimal image quality, while generating high resolution SA images. Optimization of the image quality is mainly performed based on measures...... such as F-number, number of emissions and the aperture size. They are considered to be the most contributing acquisition factors in the quality of the high resolution images in SA. Therefore, the performance of image quality is quantified in terms of full-width at half maximum (FWHM) and the cystic...

  12. Perceived image quality assessment for color images on mobile displays

    Science.gov (United States)

    Jang, Hyesung; Kim, Choon-Woo

    2015-01-01

    With increase in size and resolution of mobile displays and advances in embedded processors for image enhancement, perceived quality of images on mobile displays has been drastically improved. This paper presents a quantitative method to evaluate perceived image quality of color images on mobile displays. Three image quality attributes, colorfulness, contrast and brightness, are chosen to represent perceived image quality. Image quality assessment models are constructed based on results of human visual experiments. In this paper, three phase human visual experiments are designed to achieve credible outcomes while reducing time and resources needed for visual experiments. Values of parameters of image quality assessment models are estimated based on results from human visual experiments. Performances of different image quality assessment models are compared.

  13. Image degradation due to scattering effects in two-mirror telescopes

    Science.gov (United States)

    Harvey, James E.; Krywonos, Andrey; Peterson, Gary; Bruner, Marilyn

    2010-06-01

    Image degradation due to scattered radiation is a serious problem in many short-wavelength (x-ray and EUV) imaging systems. Most currently available image analysis codes require the scattering behavior [data on the bidirectional scattering distribution function (BSDF)] as input in order to calculate the image quality from such systems. Predicting image degradation due to scattering effects is typically quite computation-intensive. If using a conventional optical design and analysis code, each geometrically traced ray spawns hundreds of scattered rays randomly distributed and weighted according to the input BSDF. These scattered rays must then be traced through the system to the focal plane using nonsequential ray-tracing techniques. For multielement imaging systems even the scattered rays spawn more scattered rays at each additional surface encountered in the system. In this paper we describe a generalization of Peterson's analytical treatment of in-field stray light in multielement imaging systems. In particular, we remove the smooth-surface limitation that ignores the scattered-scattered radiation, which can be quite large for EUV wavelengths even for state-of-the-art optical surfaces. Predictions of image degradation for a two-mirror EUV telescope with the generalized Peterson model are then numerically validated with the much more computation-intensive ZEMAX® and ASAP® codes.

  14. Are Ventilation Filters Degrading Indoor Air Quality in California Classrooms?

    Energy Technology Data Exchange (ETDEWEB)

    Fisk, William J.; Destaillats, H.; Apte, M.G.; Destaillats,, Hugo; Fisk, Michael G. Apte and William J.

    2008-10-01

    Heating, ventilating, and cooling classrooms in California consume substantial electrical energy. Indoor air quality (IAQ) in classrooms affects studenthealth and performance. In addition to airborne pollutants that are emitted directly by indoor sources and those generated outdoors, secondary pollutants can be formed indoors by chemical reaction of ozone with other chemicals and materials. Filters are used in nearly all classroom heating, ventilation and air?conditioning (HVAC) systems to maintain energy-efficient HVAC performance and improve indoor air quality; however, recent evidence indicates that ozone reactions with filters may, in fact, be a source of secondary pollutants. This project quantitatively evaluated ozone deposition in HVAC filters and byproduct formation, and provided a preliminary assessment of the extent towhich filter systems are degrading indoor air quality. The preliminary information obtained will contribute to the design of subsequent research efforts and the identification of energy efficient solutions that improve indoor air quality in classrooms and the health and performance of students.

  15. Multiresolution Fusion of Remote Sensing Images Based on Resolution Degradation Model

    Institute of Scientific and Technical Information of China (English)

    LI Junli; SUN Jiabing; MAO Xi

    2005-01-01

    A new method based on resolution degradation model is proposed to improve both spatial and spectral quality of the synthetic images. Some ETM+ panchromatic and multispectral images are used to assess the new method. Its spatial and spectral effects are evaluated by qualitative and quantitative measures and the results are compared with those of IHS, PCA, Brovey, OWT(Orthogonal Wavelet Transform) and RWT(Redundant Wavelet Transform). The results show that the new method can keep almost the same spatial resolution as the panchromatic images, and the spectral effect of the new method is as good as those of wavelet-based methods.

  16. The new adaptive enhancement algorithm on the degraded color images

    Science.gov (United States)

    Xue, Rong Kun; He, Wei; Li, Yufeng

    2016-10-01

    Based on the scene characteristics of frequency distribution in the degraded color images, the MSRCR method and wavelet transform in the paper are introduced respectively to enhance color images and the advantages and disadvantages of them are analyzed combining with the experiment, then the combination of improved MSRCR method and wavelet transform are proposed to enhance color images, it uses wavelet to decompose color images in order to increase the coefficient of low-level details and reduce top-level details to highlight the scene information, meanwhile, the method of improved MSRCR is used to enhance the low-frequency components of degraded images processed by wavelet, then the adaptive equalization is carried on to further enhance images, finally, the enhanced color images are acquired with the reconstruction of all the coefficients brought by the wavelet transform. Through the evaluation of the experimental results and data analysis, it shows that the method proposed in the paper is better than the separate use of wavelet transform and MSRCR method.

  17. Assessing product image quality for online shopping

    Science.gov (United States)

    Goswami, Anjan; Chung, Sung H.; Chittar, Naren; Islam, Atiq

    2012-01-01

    Assessing product-image quality is important in the context of online shopping. A high quality image that conveys more information about a product can boost the buyer's confidence and can get more attention. However, the notion of image quality for product-images is not the same as that in other domains. The perception of quality of product-images depends not only on various photographic quality features but also on various high level features such as clarity of the foreground or goodness of the background etc. In this paper, we define a notion of product-image quality based on various such features. We conduct a crowd-sourced experiment to collect user judgments on thousands of eBay's images. We formulate a multi-class classification problem for modeling image quality by classifying images into good, fair and poor quality based on the guided perceptual notions from the judges. We also conduct experiments with regression using average crowd-sourced human judgments as target. We compute a pseudo-regression score with expected average of predicted classes and also compute a score from the regression technique. We design many experiments with various sampling and voting schemes with crowd-sourced data and construct various experimental image quality models. Most of our models have reasonable accuracies (greater or equal to 70%) on test data set. We observe that our computed image quality score has a high (0.66) rank correlation with average votes from the crowd sourced human judgments.

  18. Soil Quality Degradation in a Magnesite Mining Area

    Institute of Scientific and Technical Information of China (English)

    FU Sha-Sha; LI Pei-Jun; FENG Qian; LI Xiao-Jun; LI Peng; SUN Yue-Bing; CHEN Yang

    2011-01-01

    Fourteen soil properties in 17 sampling sites were analyzed to study the soil degradation in a magnesite mining area in Haicheng City, Northeast China. Such areas have hitherto received little attention. The current practices of magnesite mining in this area resulted in degradation of soil quality and specifically led to an increase in soil pH, the ratio of magnesium to calcium, bulk density,clay dispersibility, total magncsium and equivalent calcium carbonate and a decrease in surface soil porosity and available phosphorous.The soil quality in the areas affected by intensive nining activity was obviously worse than that of areas far away from the mine.Four factors were identified and “magnesium factor”, “pH factor” and “fertility factor”, involving 13 soil properties, explained 82% of the total variance in the entire data set. Discriminant analysis showed that the total magnesium, water-soluble calcium and available phosphorous were the most sensitive indicators for soil quality.

  19. Process perspective on image quality evaluation

    Science.gov (United States)

    Leisti, Tuomas; Halonen, Raisa; Kokkonen, Anna; Weckman, Hanna; Mettänen, Marja; Lensu, Lasse; Ritala, Risto; Oittinen, Pirkko; Nyman, Göte

    2008-01-01

    The psychological complexity of multivariate image quality evaluation makes it difficult to develop general image quality metrics. Quality evaluation includes several mental processes and ignoring these processes and the use of a few test images can lead to biased results. By using a qualitative/quantitative (Interpretation Based Quality, IBQ) methodology, we examined the process of pair-wise comparison in a setting, where the quality of the images printed by laser printer on different paper grades was evaluated. Test image consisted of a picture of a table covered with several objects. Three other images were also used, photographs of a woman, cityscape and countryside. In addition to the pair-wise comparisons, observers (N=10) were interviewed about the subjective quality attributes they used in making their quality decisions. An examination of the individual pair-wise comparisons revealed serious inconsistencies in observers' evaluations on the test image content, but not on other contexts. The qualitative analysis showed that this inconsistency was due to the observers' focus of attention. The lack of easily recognizable context in the test image may have contributed to this inconsistency. To obtain reliable knowledge of the effect of image context or attention on subjective image quality, a qualitative methodology is needed.

  20. Image quality, compression and segmentation in medicine.

    Science.gov (United States)

    Morgan, Pam; Frankish, Clive

    2002-12-01

    This review considers image quality in the context of the evolving technology of image compression, and the effects image compression has on perceived quality. The concepts of lossless, perceptually lossless, and diagnostically lossless but lossy compression are described, as well as the possibility of segmented images, combining lossy compression with perceptually lossless regions of interest. The different requirements for diagnostic and training images are also discussed. The lack of established methods for image quality evaluation is highlighted and available methods discussed in the light of the information that may be inferred from them. Confounding variables are also identified. Areas requiring further research are illustrated, including differences in perceptual quality requirements for different image modalities, image regions, diagnostic subtleties, and tasks. It is argued that existing tools for measuring image quality need to be refined and new methods developed. The ultimate aim should be the development of standards for image quality evaluation which take into consideration both the task requirements of the images and the acceptability of the images to the users.

  1. Hyperspectral Image Analysis of Food Quality

    DEFF Research Database (Denmark)

    Arngren, Morten

    Assessing the quality of food is a vital step in any food processing line to ensurethe best food quality and maximum profit for the farmer and food manufacturer.Traditional quality evaluation methods are often destructive and labourintensive procedures relying on wet chemistry or subjective human...... inspection.Near-infrared spectroscopy can address these issues by offering a fast and objectiveanalysis of the food quality. A natural extension to these single spectrumNIR systems is to include image information such that each pixel holds a NIRspectrum. This augmented image information offers several...... extensions to the analysis offood quality. This dissertation is concerned with hyperspectral image analysisused to assess the quality of single grain kernels. The focus is to highlight thebenefits and challenges of using hyperspectral imaging for food quality presentedin two research directions. Initially...

  2. Improving Quality of Service from TCP/IP Performance Degradation

    Directory of Open Access Journals (Sweden)

    Prof.N..Penchalaiah

    2011-02-01

    Full Text Available TCP is currently the dominate congestion control protocol for the Internet. However, as the Internet evolves into a high-speed wired-cum-wireless hybrid network, performance degradation problems of TCP have appeared, such as underutilizing high-speed links, regarding wireless loss as congestion signal, and unfairness among flows with different RTTs. In order to improve the quality of service for such highspeed hybrid networks, we propose a router-assisted congestion control protocol called Quick Flow Control Protocol (QFCP. The convergence of many traditional services over IPbased infrastructures drastically increases the amount of IP data traffic to be delivered to user clients, thus raising questions about the management of quality of service in such networks. Quality of service will be of primary importance in order to ensure right operation, and to face the occurrence of congestion conditions, due to bandwidth demandingmultimedia services. in this paper, shows that QFCP can significantly shorten flow completion time, fairly allocate bandwidth resource, and be robust to non-congestion related loss. Also we consider a possible scenarios in which multiple multimedia and control streams are conveyed over the same HAN, and study a possible solution for the implementation of an easily manageable QoS framework, that relies on a QoS router based on open source software.

  3. Image Signature Based Mean Square Error for Image Quality Assessment

    Institute of Scientific and Technical Information of China (English)

    CUI Ziguan; GAN Zongliang; TANG Guijin; LIU Feng; ZHU Xiuchang

    2015-01-01

    Motivated by the importance of Human visual system (HVS) in image processing, we propose a novel Image signature based mean square error (ISMSE) metric for full reference Image quality assessment (IQA). Efficient image signature based describer is used to predict visual saliency map of the reference image. The saliency map is incorporated into luminance diff erence between the reference and distorted images to obtain image quality score. The eff ect of luminance diff erence on visual quality with larger saliency value which is usually corresponding to foreground objects is highlighted. Experimental results on LIVE database release 2 show that by integrating the eff ects of image signature based saliency on luminance dif-ference, the proposed ISMSE metric outperforms several state-of-the-art HVS-based IQA metrics but with lower complexity.

  4. IMAGE QUALITY FORECASTING FOR SPACE OBJECTS

    Directory of Open Access Journals (Sweden)

    A. I. Altukhov

    2013-05-01

    Full Text Available The article deals with an approach to quality predicting of the space objects images, which can be used to plan optoelectronic systems of remote sensing satellites work programs. The proposed approach is based on evaluation of the optoelectronic equipment transfer properties and calculation of indexes images quality considering the influence of the orbital shooting conditions.

  5. Iris Image Quality Assessment for Biometric Application

    Directory of Open Access Journals (Sweden)

    U. M. Chaskar

    2012-05-01

    Full Text Available Image quality assessment plays an important role in the performance of biometric system involving iris images. Data quality assessment is a key issue in order to broaden the applicability of iris biometrics to unconstrained imaging conditions. In this paper, we have proposed the quality factors of individual iris images by assessing their prominent factors by their scores. The work has been carried out for the following databases: CASIA, UBIRIS, UPOL, MMU and our own created COEP Database using HIS 5000 HUVITZ Iris Camera. The comparison is also done with existing databases which in turn will act as a benchmark in increasing the efficiency of further processing.

  6. Sparse Representation-Based Image Quality Index With Adaptive Sub-Dictionaries.

    Science.gov (United States)

    Li, Leida; Cai, Hao; Zhang, Yabin; Lin, Weisi; Kot, Alex C; Sun, Xingming

    2016-08-01

    Distortions cause structural changes in digital images, leading to degraded visual quality. Dictionary-based sparse representation has been widely studied recently due to its ability to extract inherent image structures. Meantime, it can extract image features with slightly higher level semantics. Intuitively, sparse representation can be used for image quality assessment, because visible distortions can cause significant changes to the sparse features. In this paper, a new sparse representation-based image quality assessment model is proposed based on the construction of adaptive sub-dictionaries. An overcomplete dictionary trained from natural images is employed to capture the structure changes between the reference and distorted images by sparse feature extraction via adaptive sub-dictionary selection. Based on the observation that image sparse features are invariant to weak degradations and the perceived image quality is generally influenced by diverse issues, three auxiliary quality features are added, including gradient, color, and luminance information. The proposed method is not sensitive to training images, so a universal dictionary can be adopted for quality evaluation. Extensive experiments on five public image quality databases demonstrate that the proposed method produces the state-of-the-art results, and it delivers consistently well performances when tested in different image quality databases.

  7. The Degradation of Beam Quality in Large-Core Optical Fiber

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The degradation of beam quality in large-core fiber is investigated experimentally. It is found that the output beam quality factor M2 is a compound tanh function of the fiber lengths and misalignment launch results that the beam quality degraded faster.

  8. Three-dimensional imaging in degraded visual field

    Science.gov (United States)

    Oran, A.; Ozharar, S.; Ozdur, I.

    2016-04-01

    Imaging at degraded visual environments is one of the biggest challenges in today’s imaging technologies. Especially military and commercial rotary wing aviation is suffering from impaired visual field in sandy, dusty, marine and snowy environments. For example during landing the rotor churns up the particles and creates dense clouds of highly scattering medium, which limits the vision of the pilot and may result in an uncontrolled landing. The vision in such environments is limited because of the high ratio of scattered photons over the ballistic photons which have the image information. We propose to use optical spatial filtering (OSF) method in order to eliminate the scattered photons and only collect the ballistic photons at the receiver. OSF is widely used in microscopy, to the best of our knowledge this will be the first application of OSF for macroscopic imaging. Our experimental results show that most of the scattered photons are eliminated using the spatial filtering in a highly scattering impaired visual field. The results are compared with a standard broad area photo detector which shows the effectiveness of spatial filtering.

  9. Electrical Inspection Oriented Thermal Image Quality Assessment

    Science.gov (United States)

    Lin, Ying; Wang, Menglin; Gong, Xiaojin; Guo, Zhihong; Geng, Yujie; Bai, Demeng

    2017-01-01

    This paper presents an approach to access the quality of thermal images that are specially used in electrical inspection. In this application, no reference images are given for quality assessment. Therefore, we first analyze the characteristics for these thermal images. Then, four quantitative measurements, which are one-dimensional (1D) entropy, two-dimensional (2D) entropy, centrality, and No-Reference Structural Sharpness (NRSS), are investigated to measure the information content, the centrality for objects of interest, and the sharpness of images. Moreover, in order to provide a more intuitive measure for human operators, we assign each image with a discrete rate based on these quantitative measurements via the k-nearest neighbor (KNN) method. The proposed approach has been validated in a dataset composed of 2,336 images. Experiments show that our quality assessment results are consistent with subjective assessment.

  10. Digital radiography image quality: image processing and display.

    Science.gov (United States)

    Krupinski, Elizabeth A; Williams, Mark B; Andriole, Katherine; Strauss, Keith J; Applegate, Kimberly; Wyatt, Margaret; Bjork, Sandra; Seibert, J Anthony

    2007-06-01

    This article on digital radiography image processing and display is the second of two articles written as part of an intersociety effort to establish image quality standards for digital and computed radiography. The topic of the other paper is digital radiography image acquisition. The articles were developed collaboratively by the ACR, the American Association of Physicists in Medicine, and the Society for Imaging Informatics in Medicine. Increasingly, medical imaging and patient information are being managed using digital data during acquisition, transmission, storage, display, interpretation, and consultation. The management of data during each of these operations may have an impact on the quality of patient care. These articles describe what is known to improve image quality for digital and computed radiography and to make recommendations on optimal acquisition, processing, and display. The practice of digital radiography is a rapidly evolving technology that will require timely revision of any guidelines and standards.

  11. Image quality evaluation of linear plastic scintillating fiber array detector for X-ray imaging

    Institute of Scientific and Technical Information of China (English)

    Mohammad Mehdi NASSERI; MA Qing-Li; YIN Ze-Jie

    2004-01-01

    It is important to assess image quality, in order to ensure that the imaging system is performing optimally and also identify the weak points in an imaging system. Three parameters mostly leading to image degradation are contrast, spatial resolution and noise. There is always a trade-off between spatial resolution and signal to noise ratio,but in scintillating fiber array detectors spatial resolution is not as important as signal to noise ratio, so we paid more attention to contrast and SNR of the system. By using GEANT4 Monte Carlo detector simulation toolkit, some effective parameters of the linear plastic scintillating fiber (PSF) array as an imaging detector were investigated. Finally we show that it is possible to use this kind of detector to take CT and DR (Digital Radiography) image under certain conditions.

  12. Imaging through turbid media via sparse representation: imaging quality comparison of three projection matrices

    Science.gov (United States)

    Shao, Xiaopeng; Li, Huijuan; Wu, Tengfei; Dai, Weijia; Bi, Xiangli

    2015-05-01

    The incident light will be scattered away due to the inhomogeneity of the refractive index in many materials which will greatly reduce the imaging depth and degrade the imaging quality. Many exciting methods have been presented in recent years for solving this problem and realizing imaging through a highly scattering medium, such as the wavefront modulation technique and reconstruction technique. The imaging method based on compressed sensing (CS) theory can decrease the computational complexity because it doesn't require the whole speckle pattern to realize reconstruction. One of the key premises of this method is that the object is sparse or can be sparse representation. However, choosing a proper projection matrix is very important to the imaging quality. In this paper, we analyzed that the transmission matrix (TM) of a scattering medium obeys circular Gaussian distribution, which makes it possible that a scattering medium can be used as the measurement matrix in the CS theory. In order to verify the performance of this method, a whole optical system is simulated. Various projection matrices are introduced to make the object sparse, including the fast Fourier transform (FFT) basis, the discrete cosine transform (DCT) basis and the discrete wavelet transform (DWT) basis, the imaging performances of each of which are compared comprehensively. Simulation results show that for most targets, applying the discrete wavelet transform basis will obtain an image in good quality. This work can be applied to biomedical imaging and used to develop real-time imaging through highly scattering media.

  13. Image quality dependence on image processing software in computed radiography

    Directory of Open Access Journals (Sweden)

    Lourens Jochemus Strauss

    2012-06-01

    Full Text Available Background. Image post-processing gives computed radiography (CR a considerable advantage over film-screen systems. After digitisation of information from CR plates, data are routinely processed using manufacturer-specific software. Agfa CR readers use MUSICA software, and an upgrade with significantly different image appearance was recently released: MUSICA2. Aim. This study quantitatively compares the image quality of images acquired without post-processing (flatfield with images processed using these two software packages. Methods. Four aspects of image quality were evaluated. An aluminium step-wedge was imaged using constant mA at tube voltages varying from 40 to 117kV. Signal-to-noise ratios (SNRs and contrast-to-noise Ratios (CNRs were calculated from all steps. Contrast variation with object size was evaluated with visual assessment of images of a Perspex contrast-detail phantom, and an image quality figure (IQF was calculated. Resolution was assessed using modulation transfer functions (MTFs. Results. SNRs for MUSICA2 were generally higher than the other two methods. The CNRs were comparable between the two software versions, although MUSICA2 had slightly higher values at lower kV. The flatfield CNR values were better than those for the processed images. All images showed a decrease in CNRs with tube voltage. The contrast-detail measurements showed that both MUSICA programmes improved the contrast of smaller objects. MUSICA2 was found to give the lowest (best IQF; MTF measurements confirmed this, with values at 3.5 lp/mm of 10% for MUSICA2, 8% for MUSICA and 5% for flatfield. Conclusion. Both MUSICA software packages produced images with better contrast resolution than unprocessed images. MUSICA2 has slightly improved image quality than MUSICA.

  14. Image Quality Meter Using Compression

    Directory of Open Access Journals (Sweden)

    Muhammad Ibrar-Ul-Haque

    2016-01-01

    Full Text Available This paper proposed a new technique to compressed image blockiness/blurriness in frequency domain through edge detection method by applying Fourier transform. In image processing, boundaries are characterized by edges and thus, edges are the problems of fundamental importance. The edges have to be identified and computed thoroughly in order to retrieve the complete illustration of the image. Our novel edge detection scheme for blockiness and blurriness shows improvement of 60 and 100 blocks for high frequency components respectively than any other detection technique.

  15. Enhancement of Video Images Degraded by Turbid Water

    Science.gov (United States)

    1986-12-01

    I o o i^ipipP^^iW^ NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS ENHANCEMENT OF VIDEO IMAGES DEGRADED BY TURBID WATER by Jorge A...OUTPUT ARRAY » « • DOL = I.IHG DO M - 1 .IM6Y SALIDA (L.M) = 0 END DO END DO c c c c c c c TYPE «/OUTPUT ARRAY INITIALIZED’ CALL riCHECK...MM((J-1)»16>+1 IXX=LL+IX-1 IYY =MM+IY-1 SALIDA (IXX.IYY) = SALIDA (IXX.IYY>+INTE(IX.IY) TYPEMXX AND IYY =>’.IXX.IYY 50 ^&&J^i£aJ^^ ’» 100 c

  16. A comprehensive study on the relationship between image quality and imaging dose in low-dose cone beam CT

    CERN Document Server

    Yan, Hao; Jia, Xun; Jiang, Steve B

    2011-01-01

    While compressed sensing (CS) based reconstructions have been developed for low-dose CBCT, a clear understanding on the relationship between the image quality and imaging dose at low dose levels is needed. In this paper, we qualitatively investigate this subject in a comprehensive manner with extensive experimental and simulation studies. The basic idea is to plot image quality and imaging dose together as functions of number of projections and mAs per projection over the whole clinically relevant range. A clear understanding on the tradeoff between image quality and dose can be achieved and optimal low-dose CBCT scan protocols can be developed for various imaging tasks in IGRT. Main findings of this work include: 1) Under the CS framework, image quality has little degradation over a large dose range, and the degradation becomes evident when the dose < 100 total mAs. A dose < 40 total mAs leads to a dramatic image degradation. Optimal low-dose CBCT scan protocols likely fall in the dose range of 40-100 ...

  17. Legume-Cereal Intercropping Improves Forage Yield, Quality and Degradability.

    Directory of Open Access Journals (Sweden)

    Jie Zhang

    Full Text Available Intercropping legume with cereal is an extensively applied planting pattern in crop cultivation. However, forage potential and the degradability of harvested mixtures from intercropping system remain unclear. To investigate the feasibility of applying an intercropping system as a forage supply source to ruminants, two consecutive experiments (experiments 1 and 2 involving a field cultivation trial and a subsequent in vivo degradable experiment were conducted to determine the forage production performance and the ruminally degradable characteristics of a harvested mixture from an alfalfa/corn-rye intercropping system. In experiment 1, the intercropping system was established by alternating alfalfa and corn or rye with a row ratio of 5:2. Dry matter (DM and nutrient yields were determined. In experiment 2, forages harvested from the different treatments were used as feedstuff to identify nutrient degradation kinetics and distribution of components between the rapidly degradable (a, potentially degradable (b and the degradation rate constant (c of 'b' fraction by in sacco method in Small-Tail Han wether Sheep. The intercropping system of alfalfa and corn-rye provided higher forage production performance with net increases of 9.52% and 34.81% in DM yield, 42.13% and 16.74% in crude protein (CP yield, 25.94% and 69.99% in degradable DM yield, and 16.96% and 5.50% in degradable CP yield than rotation and alfalfa sole cropping systems, respectively. In addition, the harvest mixture from intercropping system also had greater 'a' fraction, 'b' fraction, 'c' values, and effective degradability (E value of DM and CP than corn or rye hay harvested from rotation system. After 48-h exposure to rumen microbes, intercropping harvest materials were degraded to a higher extent than separately degraded crop stems from the sole system as indicated by visual microscopic examination with more tissues disappeared. Thus, the intercropping of alfalfa and corn

  18. Legume-Cereal Intercropping Improves Forage Yield, Quality and Degradability.

    Science.gov (United States)

    Zhang, Jie; Yin, Binjie; Xie, Yuhuai; Li, Jing; Yang, Zaibin; Zhang, Guiguo

    2015-01-01

    Intercropping legume with cereal is an extensively applied planting pattern in crop cultivation. However, forage potential and the degradability of harvested mixtures from intercropping system remain unclear. To investigate the feasibility of applying an intercropping system as a forage supply source to ruminants, two consecutive experiments (experiments 1 and 2) involving a field cultivation trial and a subsequent in vivo degradable experiment were conducted to determine the forage production performance and the ruminally degradable characteristics of a harvested mixture from an alfalfa/corn-rye intercropping system. In experiment 1, the intercropping system was established by alternating alfalfa and corn or rye with a row ratio of 5:2. Dry matter (DM) and nutrient yields were determined. In experiment 2, forages harvested from the different treatments were used as feedstuff to identify nutrient degradation kinetics and distribution of components between the rapidly degradable (a), potentially degradable (b) and the degradation rate constant (c) of 'b' fraction by in sacco method in Small-Tail Han wether Sheep. The intercropping system of alfalfa and corn-rye provided higher forage production performance with net increases of 9.52% and 34.81% in DM yield, 42.13% and 16.74% in crude protein (CP) yield, 25.94% and 69.99% in degradable DM yield, and 16.96% and 5.50% in degradable CP yield than rotation and alfalfa sole cropping systems, respectively. In addition, the harvest mixture from intercropping system also had greater 'a' fraction, 'b' fraction, 'c' values, and effective degradability (E value) of DM and CP than corn or rye hay harvested from rotation system. After 48-h exposure to rumen microbes, intercropping harvest materials were degraded to a higher extent than separately degraded crop stems from the sole system as indicated by visual microscopic examination with more tissues disappeared. Thus, the intercropping of alfalfa and corn-rye exhibited a greater

  19. Perceptual Depth Quality in Distorted Stereoscopic Images.

    Science.gov (United States)

    Wang, Jiheng; Wang, Shiqi; Ma, Kede; Wang, Zhou

    2017-03-01

    Subjective and objective measurement of the perceptual quality of depth information in symmetrically and asymmetrically distorted stereoscopic images is a fundamentally important issue in stereoscopic 3D imaging that has not been deeply investigated. Here, we first carry out a subjective test following the traditional absolute category rating protocol widely used in general image quality assessment research. We find this approach problematic, because monocular cues and the spatial quality of images have strong impact on the depth quality scores given by subjects, making it difficult to single out the actual contributions of stereoscopic cues in depth perception. To overcome this problem, we carry out a novel subjective study where depth effect is synthesized at different depth levels before various types and levels of symmetric and asymmetric distortions are applied. Instead of following the traditional approach, we ask subjects to identify and label depth polarizations, and a depth perception difficulty index (DPDI) is developed based on the percentage of correct and incorrect subject judgements. We find this approach highly effective at quantifying depth perception induced by stereo cues and observe a number of interesting effects regarding image content dependency, distortion-type dependence, and the impact of symmetric versus asymmetric distortions. Furthermore, we propose a novel computational model for DPDI prediction. Our results show that the proposed model, without explicitly identifying image distortion types, leads to highly promising DPDI prediction performance. We believe that these are useful steps toward building a comprehensive understanding on 3D quality-of-experience of stereoscopic images.

  20. Improvement of the image quality of random phase--free holography using an iterative method

    CERN Document Server

    Shimobaba, Tomoyoshi; Endo, Yutaka; Hirayama, Ryuji; Hiyama, Daisuke; Hasegawa, Satoki; Nagahama, Yuki; Sano, Marie; Oikawa, Minoru; Sugie, Takashige; Ito, Tomoyoshi

    2015-01-01

    Our proposed method of random phase-free holography using virtual convergence light can obtain large reconstructed images exceeding the size of the hologram, without the assistance of random phase. The reconstructed images have low-speckle noise in the amplitude and phase-only holograms (kinoforms); however, in low-resolution holograms, we obtain a degraded image quality compared to the original image. We propose an iterative random phase-free method with virtual convergence light to address this problem.

  1. Automated marker tracking using noisy X-ray images degraded by the treatment beam

    Energy Technology Data Exchange (ETDEWEB)

    Wisotzky, E. [Fraunhofer Institute for Production Systems and Design Technology (IPK), Berlin (Germany); German Cancer Research Center (DKFZ), Heidelberg (Germany); Fast, M.F.; Nill, S. [The Royal Marsden NHS Foundation Trust, London (United Kingdom). Joint Dept. of Physics; Oelfke, U. [The Royal Marsden NHS Foundation Trust, London (United Kingdom). Joint Dept. of Physics; German Cancer Research Center (DKFZ), Heidelberg (Germany)

    2015-09-01

    This study demonstrates the feasibility of automated marker tracking for the real-time detection of intrafractional target motion using noisy kilovoltage (kV) X-ray images degraded by the megavoltage (MV) treatment beam. The authors previously introduced the in-line imaging geometry, in which the flat-panel detector (FPD) is mounted directly underneath the treatment head of the linear accelerator. They found that the 121 kVp image quality was severely compromised by the 6 MV beam passing through the FPD at the same time. Specific MV-induced artefacts present a considerable challenge for automated marker detection algorithms. For this study, the authors developed a new imaging geometry by re-positioning the FPD and the X-ray tube. This improved the contrast-to-noise-ratio between 40% and 72% at the 1.2 mAs/image exposure setting. The increase in image quality clearly facilitates the quick and stable detection of motion with the aid of a template matching algorithm. The setup was tested with an anthropomorphic lung phantom (including an artificial lung tumour). In the tumour one or three Calypso {sup registered} beacons were embedded to achieve better contrast during MV radiation. For a single beacon, image acquisition and automated marker detection typically took around 76±6 ms. The success rate was found to be highly dependent on imaging dose and gantry angle. To eliminate possible false detections, the authors implemented a training phase prior to treatment beam irradiation and also introduced speed limits for motion between subsequent images.

  2. Sources of image degradation in fundamental and harmonic ultrasound imaging using nonlinear, full-wave simulations.

    Science.gov (United States)

    Pinton, Gianmarco F; Trahey, Gregg E; Dahl, Jeremy J

    2011-04-01

    A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain (FDTD). This numerical method is used to simulate propagation of a diagnostic ultrasound pulse through a measured representation of the human abdomen with heterogeneities in speed of sound, attenuation, density, and nonlinearity. Conventional delay-andsum beamforming is used to generate point spread functions (PSF) that display the effects of these heterogeneities. For the particular imaging configuration that is modeled, these PSFs reveal that the primary source of degradation in fundamental imaging is reverberation from near-field structures. Reverberation clutter in the harmonic PSF is 26 dB higher than the fundamental PSF. An artificial medium with uniform velocity but unchanged impedance characteristics indicates that for the fundamental PSF, the primary source of degradation is phase aberration. An ultrasound image is created in silico using the same physical and algorithmic process used in an ultrasound scanner: a series of pulses are transmitted through heterogeneous scattering tissue and the received echoes are used in a delay-and-sum beamforming algorithm to generate images. These beamformed images are compared with images obtained from convolution of the PSF with a scatterer field to demonstrate that a very large portion of the PSF must be used to accurately represent the clutter observed in conventional imaging. © 2011 IEEE

  3. NOVEL IMAGE-DEPENDENT QUALITY ASSESSMENT MEASURES

    OpenAIRE

    Asaad Noori Hashim; Zahir M. Hussain

    2014-01-01

    The image is a 2D signal whose pixels are highly correlated in a 2D manner. Hence, using pixel by pixel error what we called previously Mean-Square Error, (MSE) is not an efficient way to compare two similar images (e.g., an original image and a compressed version of it). Due to this correlation, image comparison needs a correlative quality measure. It is clear that correlation between two signals gives an idea about the relation between samples of the two signals. Generally speaking, correla...

  4. Computational imaging from non-uniform degradation of staggered TDI thermal infrared imager.

    Science.gov (United States)

    Sun, Tao; Liu, Jian Guo; Shi, Yan; Chen, Wangli; Qin, Qianqing; Zhang, Zijian

    2015-09-21

    For the Time Delay Integration (TDI) staggered line-scanning thermal infrared imager, a Computational Imaging (CI) approach is developed to achieve higher spatial resolution images. After a thorough analysis of the causes of non-uniform image displacement and degradation for multi-channel staggered TDI arrays, the study aims to approach one-dimensional (1D) sub-pixel displacement estimation and superposition of images from time-division multiplexing scanning lines. Under the assumption that a thermal image is 2D piecewise C(2) smooth, a sparse-and-smooth deconvolution algorithm with L1-norm regularization terms combining the first and second order derivative operators is proposed to restore high frequency components and to suppress aliasing simultaneously. It is theoretically and experimentally demonstrated, with simulation and airborne thermal infrared images, that this is a state-of-the-art practical CI method to reconstruct clear images with higher frequency components from raw thermal images that are subject to instantaneous distortion and blurring.

  5. High-Resolution Ultrasound Imaging Using Model-Bases Iterative Reconstruction For Canister Degradation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Chatzidakis, Stylianos [ORNL; Jarrell, Joshua J [ORNL; Scaglione, John M [ORNL

    2017-01-01

    The inspection of the dry storage canisters that house spent nuclear fuel is an important issue facing the nuclear industry; currently, there are limited options available to provide for even minimal inspections. An issue of concern is stress corrosion cracking (SCC) in austenitic stainless steel canisters. SCC is difficult to predict and exhibits small crack opening displacements on the order of 15 30 m. Nondestructive examination (NDE) of such microscopic cracks is especially challenging, and it may be possible to miss SCC during inspections. The coarse grain microstructure at the heat affected zone reduces the achievable sensitivity of conventional ultrasound techniques. At Oak Ridge National Laboratory, a tomographic approach is under development to improve SCC detection using ultrasound guided waves and model-based iterative reconstruction (MBIR). Ultrasound-guided waves propagate parallel to the physical boundaries of the surface and allow for rapid inspection of a large area from a single probe location. MBIR is a novel, effective probabilistic imaging tool that offers higher precision and better image quality than current reconstruction techniques. This paper analyzes the canister environment, stainless steel microstructure, and SCC characteristics. The end goal is to demonstrate the feasibility of an NDE system based on ultrasonic guided waves and MBIR for canister degradation and to produce radar-like images of the canister surface with significantly improved image quality. The proposed methodology can potentially reduce human radiation exposure, result in lower operational costs, and provide a methodology that can be used to verify canister integrity in-situ during extended storage

  6. SIMPLE QUALITY ASSESSMENT FOR BINARY IMAGES

    Institute of Scientific and Technical Information of China (English)

    Zhang Chun'e; Qiu Zhengding

    2007-01-01

    Usually image assessment methods could be classified into two categories: subjective assessments and objective ones. The latter are judged by the correlation coefficient with subjective quality measurement MOS (Mean Opinion Score). This paper presents an objective quality assessment algorithm special for binary images. In the algorithm, noise energy is measured by Euclidean distance between noises and signals and the structural effects caused by noise are described by Euler number change. The assessment on image quality is calculated quantitatively in terms of PSNR (Peak Signal to Noise Ratio). Our experiments show that the results of the algorithm are highly correlative with subjective MOS and the algorithm is more simple and computational saving than traditional objective assessment methods.

  7. Subjective matters: from image quality to image psychology

    Science.gov (United States)

    Fedorovskaya, Elena A.; De Ridder, Huib

    2013-03-01

    From the advent of digital imaging through several decades of studies, the human vision research community systematically focused on perceived image quality and digital artifacts due to resolution, compression, gamma, dynamic range, capture and reproduction noise, blur, etc., to help overcome existing technological challenges and shortcomings. Technological advances made digital images and digital multimedia nearly flawless in quality, and ubiquitous and pervasive in usage, provide us with the exciting but at the same time demanding possibility to turn to the domain of human experience including higher psychological functions, such as cognition, emotion, awareness, social interaction, consciousness and Self. In this paper we will outline the evolution of human centered multidisciplinary studies related to imaging and propose steps and potential foci of future research.

  8. No-Reference Image Quality Assessment for ZY3 Imagery in Urban Areas Using Statistical Model

    Science.gov (United States)

    Zhang, Y.; Cui, W. H.; Yang, F.; Wu, Z. C.

    2016-06-01

    More and more high-spatial resolution satellite images are produced with the improvement of satellite technology. However, the quality of images is not always satisfactory for application. Due to the impact of complicated atmospheric conditions and complex radiation transmission process in imaging process the images often suffer deterioration. In order to assess the quality of remote sensing images over urban areas, we proposed a general purpose image quality assessment methods based on feature extraction and machine learning. We use two types of features in multi scales. One is from the shape of histogram the other is from the natural scene statistics based on Generalized Gaussian distribution (GGD). A 20-D feature vector for each scale is extracted and is assumed to capture the RS image quality degradation characteristics. We use SVM to learn to predict image quality scores from these features. In order to do the evaluation, we construct a median scale dataset for training and testing with subjects taking part in to give the human opinions of degraded images. We use ZY3 satellite images over Wuhan area (a city in China) to conduct experiments. Experimental results show the correlation of the predicted scores and the subjective perceptions.

  9. Quantification of image quality using information theory.

    Science.gov (United States)

    Niimi, Takanaga; Maeda, Hisatoshi; Ikeda, Mitsuru; Imai, Kuniharu

    2011-12-01

    Aims of present study were to examine usefulness of information theory in visual assessment of image quality. We applied first order approximation of the Shannon's information theory to compute information losses (IL). Images of a contrast-detail mammography (CDMAM) phantom were acquired with computed radiographies for various radiation doses. Information content was defined as the entropy Σp( i )log(1/p ( i )), in which detection probabilities p ( i ) were calculated from distribution of detection rate of the CDMAM. IL was defined as the difference between information content and information obtained. IL decreased with increases in the disk diameters (P information losses (TIL), were closely correlated with the image quality figures (r = 0.985). TIL was dependent on the distribution of image reading ability of each examinee, even when average reading ratio was the same in the group. TIL was shown to be sensitive to the observers' distribution of image readings and was expected to improve the evaluation of image quality.

  10. [Effects of aerosol optical thickness on the optical remote sensing imaging quality].

    Science.gov (United States)

    Hu, Xin-Li; Gu, Xing-Fa; Yu, Tao; Zhang, Zhou-Wei; Li, Juan; Luan, Hai-Jun

    2014-03-01

    In recent years, due to changes in atmospheric environment, atmospheric aerosol affection on optical sensor imaging quality is increasingly considered by the load developed departments. Space-based remote sensing system imaging process, atmospheric aerosol makes optical sensor imaging quality deterioration. Atmospheric medium causing image degradation is mainly forward light scattering effect caused by the aerosol turbid medium. Based on the turbid medium radiation transfer equation, the point spread function models were derived contained aerosol optical properties of atmosphere in order to analyze and evaluate the atmospheric blurring effect on optical sensor imaging system. It was found that atmospheric aerosol medium have effect on not only energy decay of atmospheric transmittance, but also the degradation of image quality due to the scattering effect. Increase of atmospheric aerosol optical thickness makes aerosol scattering intensity enhanced, variation of aerosol optical thickness is also strongly influences the point spread function of the spatial distribution. it is because the degradation of aerosol in spatial domain, which reduces the quality of remote sensing image, in particularly reduction of the sharpness of image. Meanwhile, it would provide a method to optimize and improve simulation of atmospheric chain.

  11. Identification of water quality degradation hotspots in developing countries by applying large scale water quality modelling

    Science.gov (United States)

    Malsy, Marcus; Reder, Klara; Flörke, Martina

    2014-05-01

    regions, and across sectors demand for an integrated approach to assess main causes of water quality degradation.

  12. REQUIREMENTS FOR IMAGE QUALITY OF EMERGENCY SPACECRAFTS

    Directory of Open Access Journals (Sweden)

    A. I. Altukhov

    2015-05-01

    Full Text Available The paper deals with the method for formation of quality requirements to the images of emergency spacecrafts. The images are obtained by means of remote sensing of near-earth space orbital deployment in the visible range. of electromagnetic radiation. The method is based on a joint taking into account conditions of space survey, characteristics of surveillance equipment, main design features of the observed spacecrafts and orbital inspection tasks. Method. Quality score is the predicted linear resolution image that gives the possibility to create a complete view of pictorial properties of the space image obtained by electro-optical system from the observing satellite. Formulation of requirements to the numerical value of this indicator is proposed to perform based on the properties of remote sensing system, forming images in the conditions of outer space, and the properties of the observed emergency spacecraft: dimensions, platform construction of the satellite, on-board equipment placement. For method implementation the authors have developed a predictive model of requirements to a linear resolution for images of emergency spacecrafts, making it possible to select the intervals of space shooting and get the satellite images required for quality interpretation. Main results. To verify the proposed model functionality we have carried out calculations of the numerical values for the linear resolution of the image, ensuring the successful task of determining the gross structural damage of the spacecrafts and identifying changes in their spatial orientation. As input data were used with dimensions and geometric primitives corresponding to the shape of deemed inspected spacecrafts: Resurs-P", "Canopus-B", "Electro-L". Numerical values of the linear resolution images have been obtained, ensuring the successful task solution for determining the gross structural damage of spacecrafts.

  13. Color Image Quality in Presentation Software

    Directory of Open Access Journals (Sweden)

    María S. Millán

    2008-11-01

    Full Text Available The color image quality of presentation programs is evaluated and measured using S-CIELAB and CIEDE2000 color difference formulae. A color digital image in its original format is compared with the same image already imported by the program and introduced as a part of a slide. Two widely used presentation programs—Microsoft PowerPoint 2004 for Mac and Apple's Keynote 3.0.2—are evaluated in this work.

  14. X-ray image quality in radiography

    Energy Technology Data Exchange (ETDEWEB)

    Borcke, E.

    1987-01-01

    A proposal is worked out to express X-ray image quality by means of a meaningful and practically useful numerical system. Attenuations have been selected in such a manner that whole numbers of quality value figures ranging from -10 to +60 result in meaningful associations with radiological indications. Individual parameters are incorporated into the resulting values. A test body for determining information sensitivity figures is described that is practical easy built and inexpensive; its most important feature, however, is that it is reproducible and permits international comparisons. This test body provides a direct linking with the quality value figures.

  15. Image quality in digital radiographic systems

    Directory of Open Access Journals (Sweden)

    Almeida Solange Maria de

    2003-01-01

    Full Text Available The aim of the present study was to evaluate the image quality of four direct digital radiographic systems. Radiographs were made of the maxillary central incisor and mandibular left molar regions of a dry skull, and an aluminum step-wedge. The X-ray generator operated at 10 mA, 60 and 70 kVp, and images were acquired with 3, 5, 8, 12, 24 and 48 exposure pulses. Six well-trained observers classified the images by means of scores from 1 to 3. Collected data were submitted to nonparametric statistical analysis using Fisher's exact test. Statistical analysis showed significant differences (p<0.01 in image quality with the four systems. Based on the results, it was possible to conclude that: 1 all of the digital systems presented good performance in producing acceptable images for diagnosis, if the exposures of the step-wedge and the maxillary central incisor region were made at 5 pulses, as well as at 8 pulses for the mandibular left molar region, selecting 60 or 70kVp; 2 higher percentages of acceptable images were obtained with the administration of lower radiation doses in CCD-sensors (charge-coupled device; 3 the Storage Phosphor systems produced acceptable images at a large range of exposure settings, that included low, intermediate and high radiation doses.

  16. Quality metric in matched Laplacian of Gaussian response domain for blind adaptive optics image deconvolution

    Science.gov (United States)

    Guo, Shiping; Zhang, Rongzhi; Yang, Yikang; Xu, Rong; Liu, Changhai; Li, Jisheng

    2016-04-01

    Adaptive optics (AO) in conjunction with subsequent postprocessing techniques have obviously improved the resolution of turbulence-degraded images in ground-based astronomical observations or artificial space objects detection and identification. However, important tasks involved in AO image postprocessing, such as frame selection, stopping iterative deconvolution, and algorithm comparison, commonly need manual intervention and cannot be performed automatically due to a lack of widely agreed on image quality metrics. In this work, based on the Laplacian of Gaussian (LoG) local contrast feature detection operator, we propose a LoG domain matching operation to perceive effective and universal image quality statistics. Further, we extract two no-reference quality assessment indices in the matched LoG domain that can be used for a variety of postprocessing tasks. Three typical space object images with distinct structural features are tested to verify the consistency of the proposed metric with perceptual image quality through subjective evaluation.

  17. Ultrasound Image Quality Assessment: A framework for evaluation of clinical image quality

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Pedersen, Mads Møller; Nikolov, Svetoslav Ivanov

    2010-01-01

    Improvement of ultrasound images should be guided by their diagnostic value. Evaluation of clinical image quality is generally performed subjectively, because objective criteria have not yet been fully developed and accepted for the evaluation of clinical image quality. Based on recommendation 500...... from the International Telecommunication Union - Radiocommunication (ITU-R) for such subjective quality assessment, this work presents equipment and a methodology for clinical image quality evaluation for guiding the development of new and improved imaging. The system is based on a BK-Medical 2202 Pro......Focus scanner equipped with a UA2227 research interface, connected to a PC through X64-CL Express camera link. Data acquisition features subject data recording, loading/saving of exact scanner settings (for later experiment reproducibility), free access to all system parameters for beamformation...

  18. Image Quality Indicator for Infrared Inspections

    Science.gov (United States)

    Burke, Eric

    2011-01-01

    The quality of images generated during an infrared thermal inspection depends on many system variables, settings, and parameters to include the focal length setting of the IR camera lens. If any relevant parameter is incorrect or sub-optimal, the resulting IR images will usually exhibit inherent unsharpness and lack of resolution. Traditional reference standards and image quality indicators (IQIs) are made of representative hardware samples and contain representative flaws of concern. These standards are used to verify that representative flaws can be detected with the current IR system settings. However, these traditional standards do not enable the operator to quantify the quality limitations of the resulting images, i.e. determine the inherent maximum image sensitivity and image resolution. As a result, the operator does not have the ability to optimize the IR inspection system prior to data acquisition. The innovative IQI described here eliminates this limitation and enables the operator to objectively quantify and optimize the relevant variables of the IR inspection system, resulting in enhanced image quality with consistency and repeatability in the inspection application. The IR IQI consists of various copper foil features of known sizes that are printed on a dielectric non-conductive board. The significant difference in thermal conductivity between the two materials ensures that each appears with a distinct grayscale or brightness in the resulting IR image. Therefore, the IR image of the IQI exhibits high contrast between the copper features and the underlying dielectric board, which is required to detect the edges of the various copper features. The copper features consist of individual elements of various shapes and sizes, or of element-pairs of known shapes and sizes and with known spacing between the elements creating the pair. For example, filled copper circles with various diameters can be used as individual elements to quantify the image sensitivity

  19. Simulation of High Quality Ultrasound Imaging

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Kortbek, Jacob; Nikolov, Svetoslav Ivanov

    2010-01-01

    This paper investigates if the influence on image quality using physical transducers can be simulated with an sufficient accuracy to reveal system performance. The influence is investigated in a comparative study between Synthetic Aperture Sequential Beamformation (SASB) and Dynamic Receive Focus...

  20. Detection of image quality metamers based on the metric for unified image quality

    Science.gov (United States)

    Miyata, Kimiyoshi; Tsumura, Norimichi

    2012-01-01

    In this paper, we introduce a concept of the image quality metamerism as an expanded version of the metamerism defined in the color science. The concept is used to unify different image quality attributes, and applied to introduce a metric showing the degree of image quality metamerism to analyze a cultural property. Our global goal is to build a metric to evaluate total quality of images acquired by different imaging systems and observed under different viewing conditions. As the basic step to the global goal, the metric is consisted of color, spectral and texture information in this research, and applied to detect image quality metamers to investigate the cultural property. The property investigated is the oldest extant version of folding screen paintings that depict the thriving city of Kyoto designated as a nationally important cultural property in Japan. Gold colored areas painted by using high granularity colorants compared with other color areas in the property are evaluated based on the metric, then the metric is visualized as a map showing the possibility of the image quality metamer to the reference pixel.

  1. Patient dose and image quality from mega-voltage cone beam computed tomography imaging.

    Science.gov (United States)

    Gayou, Olivier; Parda, David S; Johnson, Mark; Miften, Moyed

    2007-02-01

    The evolution of ever more conformal radiation delivery techniques makes the subject of accurate localization of increasing importance in radiotherapy. Several systems can be utilized including kilo-voltage and mega-voltage cone-beam computed tomography (MV-CBCT), CT on rail or helical tomography. One of the attractive aspects of mega-voltage cone-beam CT is that it uses the therapy beam along with an electronic portal imaging device to image the patient prior to the delivery of treatment. However, the use of a photon beam energy in the mega-voltage range for volumetric imaging degrades the image quality and increases the patient radiation dose. To optimize image quality and patient dose in MV-CBCT imaging procedures, a series of dose measurements in cylindrical and anthropomorphic phantoms using an ionization chamber, radiographic films, and thermoluminescent dosimeters was performed. Furthermore, the dependence of the contrast to noise ratio and spatial resolution of the image upon the dose delivered for a 20-cm-diam cylindrical phantom was evaluated. Depending on the anatomical site and patient thickness, we found that the minimum dose deposited in the irradiated volume was 5-9 cGy and the maximum dose was between 9 and 17 cGy for our clinical MV-CBCT imaging protocols. Results also demonstrated that for high contrast areas such as bony anatomy, low doses are sufficient for image registration and visualization of the three-dimensional boundaries between soft tissue and bony structures. However, as the difference in tissue density decreased, the dose required to identify soft tissue boundaries increased. Finally, the dose delivered by MV-CBCT was simulated using a treatment planning system (TPS), thereby allowing the incorporation of MV-CBCT dose in the treatment planning process. The TPS-calculated doses agreed well with measurements for a wide range of imaging protocols.

  2. Blind image quality assessment via deep learning.

    Science.gov (United States)

    Hou, Weilong; Gao, Xinbo; Tao, Dacheng; Li, Xuelong

    2015-06-01

    This paper investigates how to blindly evaluate the visual quality of an image by learning rules from linguistic descriptions. Extensive psychological evidence shows that humans prefer to conduct evaluations qualitatively rather than numerically. The qualitative evaluations are then converted into the numerical scores to fairly benchmark objective image quality assessment (IQA) metrics. Recently, lots of learning-based IQA models are proposed by analyzing the mapping from the images to numerical ratings. However, the learnt mapping can hardly be accurate enough because some information has been lost in such an irreversible conversion from the linguistic descriptions to numerical scores. In this paper, we propose a blind IQA model, which learns qualitative evaluations directly and outputs numerical scores for general utilization and fair comparison. Images are represented by natural scene statistics features. A discriminative deep model is trained to classify the features into five grades, corresponding to five explicit mental concepts, i.e., excellent, good, fair, poor, and bad. A newly designed quality pooling is then applied to convert the qualitative labels into scores. The classification framework is not only much more natural than the regression-based models, but also robust to the small sample size problem. Thorough experiments are conducted on popular databases to verify the model's effectiveness, efficiency, and robustness.

  3. Similar Reference Image Quality Assessment: A New Database and A Trial with Local Feature Matching

    Science.gov (United States)

    Lu, Qingbo; Zhou, Wengang; Li, Houqiang

    2016-12-01

    Conventionally, the reference image for image quality assessment (IQA) is completely available (full-reference IQA) or unavailable (no-reference IQA). Even for reduced-reference IQA, the features that are used to predict image quality are still extracted from the pristine reference image. However, the pristine reference image is always unavailable in many real scenarios. In contrast, it is convenient to obtain a number of similar reference images via retrieval from the Internet. These similar reference images may share similar contents and scenes with the image to be assessed. In this paper, we attempt to discuss the image quality assessment problem from the view of similar images, i.e. similar reference IQA. Although the similar reference images share similar contents with the degraded image, the difference between them still cannot be ignored. Therefore, we propose an IQA framework based on local feature matching, which can help to identify the similar regions and structures. Then the IQA features are computed only from these similar regions to predict the final image quality score. Besides, since there is no IQA databases for the similar reference IQA problem, we establish a novel IQA database that consists of 272 images from four scenes. The experiments demonstrate that the performance of our scheme goes beyond state-of-the-art no-reference IQA methods and some full-reference IQA algorithms.

  4. The Influence of Spectral Wavelength on the Quality of Pansharpened Image Simulated Using Hyperspectral Data

    Science.gov (United States)

    Matsuoka, M.

    2012-07-01

    Preservation of the spectral characteristics in multispectral images is important in the development of pansharpening methods because it affects the accuracy of subsequent applications, such as visual interpretation, land cover classification, and change detection. The combinations of the spectral properties (observation wavelength and width of spectral bands) of multispectral and panchromatic images affect both the spatial and spectral quality of pansharpened images. Therefore, the clarification of the relations between spectral bands and quality of pansharpened image is important for improving our understanding of pansharpening methods, and for developing better schemes for image fusion. This study investigated the influence of the spectral waveband of panchromatic images on the image quality of multispectral (MS) images using simulated images produced from hyperspectral data. Panchromatic images with different spectral band position and multispectral images with degraded spatial resolution were generated from airborne visible/infrared imaging spectrometer (AVIRIS) images and pansharpened using seven methods: additive wavelet intensity, additive wavelet principal component, generalized Laplacian pyramid with spectral distortion minimization, generalized intensity-huesaturation (GIHS) transform, GIHS adaptive, Gram-Schmidt spectral sharpening, and block-based synthetic variable ratio. The pansharpened near-infrared band was visually and statistically compared with the non-degraded image. Wide variation in quality was identified visually within and between methods depending on the spectral wavelengths of the panchromatic images. Quantitative evaluations using three frequently used indices, the correlation coefficient, erreur relative globale adimensionnelle de synthèse (ERGAS), and the Q index, showed the individual behaviors of the pansharpening methods in terms of the spectral similarity in panchromatic and near-infrared, though all methods had similar qualities

  5. Image quality assessment metrics by using directional projection

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Objective image quality mcasure, which is a fundamental and challenging job in image processing, evaluates the image quality consistently with human perception automatically. On the assumption that any image distortion could be modeled as the difference between the directional projection-based maps of reference and distortion images, wc propose a new objective quality assessment method based on directional projection for full reference model. Experimental results show that the proposed metrics are well consistent with the subjective quality score.

  6. Image quality evaluation of light field photography

    Science.gov (United States)

    Fu, Qiang; Zhou, Zhiliang; Yuan, Yan; Xiangli, Bin

    2011-01-01

    Light field photography captures 4D radiance information of a scene. Digital refocusing and digital correction of aberrations could be done after the photograph is taken. However, capturing 4D light field is costly and tradeoffs between different image quality metrics should be made and evaluated. This paper explores the effects of light field photography on image quality by quantitatively evaluating some basic criteria for an imaging system. A simulation approach was first developed by ray-tracing a designed light field camera. A standard testing chart followed by ISO 12233 was provided as the input scene. A sequence of light field raw images were acquired and processed by light field rendering methods afterwards. Through-focus visual resolution and MTF were calculated and analyzed. As a comparison, the same tests were taken for the same main lens system as the results of conventional photography. An experimental light field system was built up and its performance was tested. This work helps better understanding the pros and cons of light field photography in contrast with conventional imaging methods and perceiving the way to optimize the joint digital-optical design of the system.

  7. Objective assessment of image quality VI: imaging in radiation therapy

    Science.gov (United States)

    Barrett, Harrison H.; Kupinski, Matthew A.; Müeller, Stefan; Halpern, Howard J.; Morris, John C., III; Dwyer, Roisin

    2013-11-01

    Earlier work on objective assessment of image quality (OAIQ) focused largely on estimation or classification tasks in which the desired outcome of imaging is accurate diagnosis. This paper develops a general framework for assessing imaging quality on the basis of therapeutic outcomes rather than diagnostic performance. By analogy to receiver operating characteristic (ROC) curves and their variants as used in diagnostic OAIQ, the method proposed here utilizes the therapy operating characteristic or TOC curves, which are plots of the probability of tumor control versus the probability of normal-tissue complications as the overall dose level of a radiotherapy treatment is varied. The proposed figure of merit is the area under the TOC curve, denoted AUTOC. This paper reviews an earlier exposition of the theory of TOC and AUTOC, which was specific to the assessment of image-segmentation algorithms, and extends it to other applications of imaging in external-beam radiation treatment as well as in treatment with internal radioactive sources. For each application, a methodology for computing the TOC is presented. A key difference between ROC and TOC is that the latter can be defined for a single patient rather than a population of patients.

  8. Dried fruits quality assessment by hyperspectral imaging

    Science.gov (United States)

    Serranti, Silvia; Gargiulo, Aldo; Bonifazi, Giuseppe

    2012-05-01

    Dried fruits products present different market values according to their quality. Such a quality is usually quantified in terms of freshness of the products, as well as presence of contaminants (pieces of shell, husk, and small stones), defects, mould and decays. The combination of these parameters, in terms of relative presence, represent a fundamental set of attributes conditioning dried fruits humans-senses-detectable-attributes (visual appearance, organolectic properties, etc.) and their overall quality in terms of marketable products. Sorting-selection strategies exist but sometimes they fail when a higher degree of detection is required especially if addressed to discriminate between dried fruits of relatively small dimensions and when aiming to perform an "early detection" of pathogen agents responsible of future moulds and decays development. Surface characteristics of dried fruits can be investigated by hyperspectral imaging (HSI). In this paper, specific and "ad hoc" applications addressed to propose quality detection logics, adopting a hyperspectral imaging (HSI) based approach, are described, compared and critically evaluated. Reflectance spectra of selected dried fruits (hazelnuts) of different quality and characterized by the presence of different contaminants and defects have been acquired by a laboratory device equipped with two HSI systems working in two different spectral ranges: visible-near infrared field (400-1000 nm) and near infrared field (1000-1700 nm). The spectra have been processed and results evaluated adopting both a simple and fast wavelength band ratio approach and a more sophisticated classification logic based on principal component (PCA) analysis.

  9. Automated Quality Assurance Applied to Mammographic Imaging

    Directory of Open Access Journals (Sweden)

    Anne Davis

    2002-07-01

    Full Text Available Quality control in mammography is based upon subjective interpretation of the image quality of a test phantom. In order to suppress subjectivity due to the human observer, automated computer analysis of the Leeds TOR(MAM test phantom is investigated. Texture analysis via grey-level co-occurrence matrices is used to detect structures in the test object. Scoring of the substructures in the phantom is based on grey-level differences between regions and information from grey-level co-occurrence matrices. The results from scoring groups of particles within the phantom are presented.

  10. Image quality and dose differences caused by vendor-specific image processing of neonatal radiographs

    Energy Technology Data Exchange (ETDEWEB)

    Sensakovic, William F.; O' Dell, M.C.; Letter, Haley; Kohler, Nathan; Rop, Baiywo; Cook, Jane; Logsdon, Gregory; Varich, Laura [Florida Hospital, Imaging Administration, Orlando, FL (United States)

    2016-10-15

    Image processing plays an important role in optimizing image quality and radiation dose in projection radiography. Unfortunately commercial algorithms are black boxes that are often left at or near vendor default settings rather than being optimized. We hypothesize that different commercial image-processing systems, when left at or near default settings, create significant differences in image quality. We further hypothesize that image-quality differences can be exploited to produce images of equivalent quality but lower radiation dose. We used a portable radiography system to acquire images on a neonatal chest phantom and recorded the entrance surface air kerma (ESAK). We applied two image-processing systems (Optima XR220amx, by GE Healthcare, Waukesha, WI; and MUSICA{sup 2} by Agfa HealthCare, Mortsel, Belgium) to the images. Seven observers (attending pediatric radiologists and radiology residents) independently assessed image quality using two methods: rating and matching. Image-quality ratings were independently assessed by each observer on a 10-point scale. Matching consisted of each observer matching GE-processed images and Agfa-processed images with equivalent image quality. A total of 210 rating tasks and 42 matching tasks were performed and effective dose was estimated. Median Agfa-processed image-quality ratings were higher than GE-processed ratings. Non-diagnostic ratings were seen over a wider range of doses for GE-processed images than for Agfa-processed images. During matching tasks, observers matched image quality between GE-processed images and Agfa-processed images acquired at a lower effective dose (11 ± 9 μSv; P < 0.0001). Image-processing methods significantly impact perceived image quality. These image-quality differences can be exploited to alter protocols and produce images of equivalent image quality but lower doses. Those purchasing projection radiography systems or third-party image-processing software should be aware that image

  11. Does Elite Sport Degrade Sleep Quality? A Systematic Review.

    Science.gov (United States)

    Gupta, Luke; Morgan, Kevin; Gilchrist, Sarah

    2017-07-01

    Information on sleep quality and insomnia symptomatology among elite athletes remains poorly systematised in the sports science and medicine literature. The extent to which performance in elite sport represents a risk for chronic insomnia is unknown. The purpose of this systematic review was to profile the objective and experienced characteristics of sleep among elite athletes, and to consider relationships between elite sport and insomnia symptomatology. Studies relating to sleep involving participants described on a pre-defined continuum of 'eliteness' were located through a systematic search of four research databases: SPORTDiscus, PubMed, Science Direct and Google Scholar, up to April 2016. Once extracted, studies were categorised as (1) those mainly describing sleep structure/patterns, (2) those mainly describing sleep quality and insomnia symptomatology and (3) those exploring associations between aspects of elite sport and sleep outcomes. The search returned 1676 records. Following screening against set criteria, a total of 37 studies were identified. The quality of evidence reviewed was generally low. Pooled sleep quality data revealed high levels of sleep complaints in elite athletes. Three risk factors for sleep disturbance were broadly identified: (1) training, (2) travel and (3) competition. While acknowledging the limited number of high-quality evidence reviewed, athletes show a high overall prevalence of insomnia symptoms characterised by longer sleep latencies, greater sleep fragmentation, non-restorative sleep, and excessive daytime fatigue. These symptoms show marked inter-sport differences. Two underlying mechanisms are implicated in the mediation of sport-related insomnia symptoms: pre-sleep cognitive arousal and sleep restriction.

  12. Imaging the intracellular degradation of biodegradable polymer nanoparticles

    Directory of Open Access Journals (Sweden)

    Anne-Kathrin Barthel

    2014-10-01

    Full Text Available In recent years, the development of smart drug delivery systems based on biodegradable polymeric nanoparticles has become of great interest. Drug-loaded nanoparticles can be introduced into the cell interior via endocytotic processes followed by the slow release of the drug due to degradation of the nanoparticle. In this work, poly(L-lactic acid (PLLA was chosen as the biodegradable polymer. Although common degradation of PLLA has been studied in various biological environments, intracellular degradation processes have been examined only to a very limited extent. PLLA nanoparticles with an average diameter of approximately 120 nm were decorated with magnetite nanocrystals and introduced into mesenchymal stem cells (MSCs. The release of the magnetite particles from the surface of the PLLA nanoparticles during the intracellular residence was monitored by transmission electron microscopy (TEM over a period of 14 days. It was demonstrated by the release of the magnetite nanocrystals from the PLLA surface that the PLLA nanoparticles do in fact undergo degradation within the cell. Furthermore, even after 14 days of residence, the PLLA nanoparticles were found in the MSCs. Additionally, the ultrastructural TEM examinations yield insight into the long term intercellular fate of these nanoparticles. From the statistical analysis of ultrastructural details (e.g., number of detached magnetite crystals, and the number of nanoparticles in one endosome, we demonstrate the importance of TEM studies for such applications in addition to fluorescence studies (flow cytometry and confocal laser scanning microscopy.

  13. Low Quality Image Retrieval System For Generic Databases

    Directory of Open Access Journals (Sweden)

    W.A.D.N. Wijesekera

    2015-08-01

    Full Text Available Abstract Content Based Image Retrieval CBIR systems have become the trend in image retrieval technologies as the index or notation based image retrieval algorithms give less efficient results in high usage of images. These CBIR systems are mostly developed considering the availability of high or normal quality images. High availability of low quality images in databases due to usage of different quality equipment to capture images and different environmental conditions the photos are being captured has opened up a new path in image retrieval research area. The algorithms which are developed for low quality image based image retrieval are only a few and have been performed only for specific domains. Low quality image based image retrieval algorithm on a generic database with a considerable accuracy level for different industries is an area which remains unsolved. Through this study an algorithm has been developed to achieve above mentioned gaps. By using images with inappropriate brightness and compressed images as low quality images the proposed algorithm is tested on a generic database which includes many categories of data instead of using a specific domain. The new algorithm developed gives better precision and recall values when they are clustered into the most appropriate number of clusters which changes according to the level of quality of the image. As the quality of the image decreases the accuracy of the algorithm also tends to be reduced a space for further improvement.

  14. A Medical Image Watermarking Technique for Embedding EPR and Its Quality Assessment Using No-Reference Metrics

    Directory of Open Access Journals (Sweden)

    Rupinder Kaur

    2013-01-01

    Full Text Available Digital watermarking can be used as an important tool for the security and copyright protection of digital multimedia content. The present paper explores its applications as a quality indicator of a watermarked medical image when subjected to intentional (noise, cropping, alteration or unintentional (compression, transmission or filtering operations. The watermark also carries EPR data along with a binary mark (used for quality assessment. The binary mark is used as a No-Reference (NR quality metrics that blindly estimates the quality of an image without the need of original image. It is a semi-fragile watermark which degrades at around the same rate as the original image and thus gives an indication of the quality degradation of the host image at the receiving end. In the proposed method, the original image is divided into two parts- ROI and non-ROI. ROI is an area that contains diagnostically important information and must be processed without any distortion. The binary mark and EPR are embedded into the DCT domain of Non-ROI. Embedding EPR within a medical image reduces storage and transmission overheads and no additional file has to be sent along with an image. The watermark (binary mark and EPR is extracted from non-ROI part at the receiving end and a measure of degradation of binary mark is used to estimate the quality of the original image. The performance of the proposed method is evaluated by calculating MSE and PSNR of original and extracted mark.

  15. Influence of partial k-space filling on the quality of magnetic resonance images*

    Science.gov (United States)

    Jornada, Tiago da Silva; Murata, Camila Hitomi; Medeiros, Regina Bitelli

    2016-01-01

    Objective To study the influence that the scan percentage tool used in partial k-space acquisition has on the quality of images obtained with magnetic resonance imaging equipment. Materials and Methods A Philips 1.5 T magnetic resonance imaging scanner was used in order to obtain phantom images for quality control tests and images of the knee of an adult male. Results There were no significant variations in the uniformity and signal-to-noise ratios with the phantom images. However, analysis of the high-contrast spatial resolution revealed significant degradation when scan percentages of 70% and 85% were used in the acquisition of T1- and T2-weighted images, respectively. There was significant degradation when a scan percentage of 25% was used in T1- and T2-weighted in vivo images (p ≤ 0.01 for both). Conclusion The use of tools that limit the k-space is not recommended without knowledge of their effect on image quality. PMID:27403015

  16. Does Elite Sport Degrade Sleep Quality? A Systematic Review

    OpenAIRE

    Gupta, Luke; Morgan, Kevin; Gilchrist, Sarah

    2016-01-01

    Background Information on sleep quality and insomnia symptomatology among elite athletes remains poorly systematised in the sports science and medicine literature. The extent to which performance in elite sport represents a risk for chronic insomnia is unknown. Objectives The purpose of this systematic review was to profile the objective and experienced characteristics of sleep among elite athletes, and to consider relationships between elite sport and insomnia symptomatology. Methods Studies...

  17. Modelling the Cost and Quality of Preservation Imaging and Archiving

    DEFF Research Database (Denmark)

    Kejser, Ulla Bøgvad

    2009-01-01

    in the OAIS Reference Model. The cost model divides the OAIS functions in a hierarchy of cost critical activities and measurable components, which are implemented as formulas in a spreadsheet. So far the model has only been completed for activities relating to preservation planning and digital migrations......, fire and other risks. In this PhD thesis it is examined how one may evaluate the long‐term costs and benefits to cultural heritage institutions of different preservation strategies for digital copies. The investigated alternatives are preserving the copies in a digital repository, and printing...... the files out on microfilm and preserving them in a non‐digital repository. In order to obtain empirical data and to understand the decisive cost factors in preservation copying, a case study was set up in which degrading sheet‐film negatives were digitised. Requirements for image quality and metadata were...

  18. Image analysis for dental bone quality assessment using CBCT imaging

    Science.gov (United States)

    Suprijanto; Epsilawati, L.; Hajarini, M. S.; Juliastuti, E.; Susanti, H.

    2016-03-01

    Cone beam computerized tomography (CBCT) is one of X-ray imaging modalities that are applied in dentistry. Its modality can visualize the oral region in 3D and in a high resolution. CBCT jaw image has potential information for the assessment of bone quality that often used for pre-operative implant planning. We propose comparison method based on normalized histogram (NH) on the region of inter-dental septum and premolar teeth. Furthermore, the NH characteristic from normal and abnormal bone condition are compared and analyzed. Four test parameters are proposed, i.e. the difference between teeth and bone average intensity (s), the ratio between bone and teeth average intensity (n) of NH, the difference between teeth and bone peak value (Δp) of NH, and the ratio between teeth and bone of NH range (r). The results showed that n, s, and Δp have potential to be the classification parameters of dental calcium density.

  19. Image Quality Stability of Whole-body Diffusion Weighted Imaging

    Institute of Scientific and Technical Information of China (English)

    Yun-bin Chen; Chun-miao Hu; Jing Zhong; Fei Sun

    2009-01-01

    To assess the reproducibility of whole-body diffusion weighted imaging (WB-DWI) technique in healthy volunteers under normal breathing with background body signal suppression. Methods WB-DWI was performed on 32 healthy volunteers twice within two-week period using short TI inversion-recovery diffusion-weighted echo-planar imaging sequence and built-in body coil. The volunteers were scanned across six stations continuously covering the entire body from the head to the feet under normal breathing. The bone apparent diffusion coefficient (ADC) and exponential ADC (eADC) of regions of interest (ROIs) were measured. We analyzed correlation of the results using paired-t-test to assess the reproducibility of the WB-DWl technique.Results We were successful in collecting and analyzing data of 64 WB-DWI images. There was no significant difference in bone ADC and eADC of 824 ROIs between the paired observers and paired scans (P>0.05). Most of the images from all stations were of diagnostic quality.Conclusion The measurements of bone ADC and eADC have good reproducibility. WB-DWI technique under normal breathing with background body signal suppression is adequate.

  20. Finger vein image quality evaluation using support vector machines

    Science.gov (United States)

    Yang, Lu; Yang, Gongping; Yin, Yilong; Xiao, Rongyang

    2013-02-01

    In an automatic finger-vein recognition system, finger-vein image quality is significant for segmentation, enhancement, and matching processes. In this paper, we propose a finger-vein image quality evaluation method using support vector machines (SVMs). We extract three features including the gradient, image contrast, and information capacity from the input image. An SVM model is built on the training images with annotated quality labels (i.e., high/low) and then applied to unseen images for quality evaluation. To resolve the class-imbalance problem in the training data, we perform oversampling for the minority class with random-synthetic minority oversampling technique. Cross-validation is also employed to verify the reliability and stability of the learned model. Our experimental results show the effectiveness of our method in evaluating the quality of finger-vein images, and by discarding low-quality images detected by our method, the overall finger-vein recognition performance is considerably improved.

  1. Fingerprint matching algorithm for poor quality images

    Directory of Open Access Journals (Sweden)

    Vedpal Singh

    2015-04-01

    Full Text Available The main aim of this study is to establish an efficient platform for fingerprint matching for low-quality images. Generally, fingerprint matching approaches use the minutiae points for authentication. However, it is not such a reliable authentication method for low-quality images. To overcome this problem, the current study proposes a fingerprint matching methodology based on normalised cross-correlation, which would improve the performance and reduce the miscalculations during authentication. It would decrease the computational complexities. The error rate of the proposed method is 5.4%, which is less than the two-dimensional (2D dynamic programming (DP error rate of 5.6%, while Lee's method produces 5.9% and the combined method has 6.1% error rate. Genuine accept rate at 1% false accept rate is 89.3% but at 0.1% value it is 96.7%, which is higher. The outcome of this study suggests that the proposed methodology has a low error rate with minimum computational effort as compared with existing methods such as Lee's method and 2D DP and the combined method.

  2. Sources of Image Degradation in Fundamental and Harmonic Ultrasound Imaging: A Nonlinear, Full-Wave, Simulation Study

    Science.gov (United States)

    Pinton, Gianmarco F.; Trahey, Gregg E.; Dahl, Jeremy J.

    2011-01-01

    A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain (FDTD). This numerical method is used to simulate propagation of a diagnostic ultrasound pulse through a measured representation of the human abdomen with heterogeneities in speed of sound, attenuation, density, and nonlinearity. Conventional delay-and-sum beamforming is used to generate point spread functions (PSF) that display the effects of these heterogeneities. For the particular imaging configuration that is modeled, these PSFs reveal that the primary source of degradation in fundamental imaging is due to reverberation from near-field structures. Compared to fundamental imaging, reverberation clutter in harmonic imaging is 27.1 dB lower. Simulated tissue with uniform velocity but unchanged impedance characteristics indicates that for fundamental imaging, the primary source of degradation is phase aberration. PMID:21507753

  3. Erratum: Sources of Image Degradation in Fundamental and Harmonic Ultrasound Imaging: A Nonlinear, Full-Wave, Simulation Study

    Science.gov (United States)

    Pinton, Gianmarco F.; Trahey, Gregg E.; Dahl, Jeremy J.

    2015-01-01

    A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences in the time domain. This numerical method is used to simulate propagation of a diagnostic ultrasound pulse through a measured representation of the human abdomen with heterogeneities in speed of sound, attenuation, density, and nonlinearity. Conventional delay-and-sum beamforming is used to generate point spread functions (PSFs) that display the effects of these heterogeneities. For the particular imaging configuration that is modeled, these PSFs reveal that the primary source of degradation in fundamental imaging is due to reverberation from near-field structures. Compared with fundamental imaging, reverberation clutter in harmonic imaging is 27.1 dB lower. Simulated tissue with uniform velocity but unchanged impedance characteristics indicates that for harmonic imaging, the primary source of degradation is phase aberration. PMID:21693410

  4. A method for the evaluation of image quality according to the recognition effectiveness of objects in the optical remote sensing image using machine learning algorithm.

    Directory of Open Access Journals (Sweden)

    Tao Yuan

    Full Text Available Objective and effective image quality assessment (IQA is directly related to the application of optical remote sensing images (ORSI. In this study, a new IQA method of standardizing the target object recognition rate (ORR is presented to reflect quality. First, several quality degradation treatments with high-resolution ORSIs are implemented to model the ORSIs obtained in different imaging conditions; then, a machine learning algorithm is adopted for recognition experiments on a chosen target object to obtain ORRs; finally, a comparison with commonly used IQA indicators was performed to reveal their applicability and limitations. The results showed that the ORR of the original ORSI was calculated to be up to 81.95%, whereas the ORR ratios of the quality-degraded images to the original images were 65.52%, 64.58%, 71.21%, and 73.11%. The results show that these data can more accurately reflect the advantages and disadvantages of different images in object identification and information extraction when compared with conventional digital image assessment indexes. By recognizing the difference in image quality from the application effect perspective, using a machine learning algorithm to extract regional gray scale features of typical objects in the image for analysis, and quantitatively assessing quality of ORSI according to the difference, this method provides a new approach for objective ORSI assessment.

  5. [The quality of the roentgen image--a recommendation for quantifying image quality].

    Science.gov (United States)

    Borcke, E

    1987-01-01

    A proposal is worked out to express x-ray image quality by means of a meaningful and practically useful numerical system. Attennations have been selected in such a manner that whole numbers of Quality Value figures ranging from -10 to +60 result in meaningful associations with radiological indications. Individual parameters are incorporated into the resulting values. A test body for determining Information Sensitivity figures is described that is practical easy built and inexpensive; its most important feature, however, is that it is reproducible and permits international comparisons. This test body provides a direct linking with the Quality Value figures.

  6. Content based no-reference image quality metrics

    OpenAIRE

    Marini,, A.C.

    2012-01-01

    Images are playing a more and more important role in sharing, expressing, mining and exchanging information in our daily lives. Now we can all easily capture and share images anywhere and anytime. Since digital images are subject to a wide variety of distortions during acquisition, processing, compression, storage, transmission and reproduction; it becomes necessary to assess the Image Quality. In this thesis, starting from an organized overview of available Image Quality Assessment methods, ...

  7. Near-infrared fluorescence imaging for noninvasive trafficking of scaffold degradation.

    Science.gov (United States)

    Kim, Soon Hee; Lee, Jeong Heon; Hyun, Hoon; Ashitate, Yoshitomo; Park, Gwangli; Robichaud, Kyle; Lunsford, Elaine; Lee, Sang Jin; Khang, Gilson; Choi, Hak Soo

    2013-01-01

    Biodegradable scaffolds could revolutionize tissue engineering and regenerative medicine; however, in vivo matrix degradation and tissue ingrowth processes are not fully understood. Currently a large number of samples and animals are required to track biodegradation of implanted scaffolds, and such nonconsecutive single-time-point information from various batches result in inaccurate conclusions. To overcome this limitation, we developed functional biodegradable scaffolds by employing invisible near-infrared fluorescence and followed their degradation behaviors in vitro and in vivo. Using optical fluorescence imaging, the degradation could be quantified in real-time, while tissue ingrowth was tracked by measuring vascularization using magnetic resonance imaging in the same animal over a month. Moreover, we optimized the in vitro process of enzyme-based biodegradation to predict implanted scaffold behaviors in vivo, which was closely related to the site of inoculation. This combined multimodal imaging will benefit tissue engineers by saving time, reducing animal numbers, and offering more accurate conclusions.

  8. Electro- and photoluminescence imaging as fast screening technique of the layer uniformity and device degradation in planar perovskite solar cells

    Science.gov (United States)

    Soufiani, Arman Mahboubi; Tayebjee, Murad J. Y.; Meyer, Steffen; Ho-Baillie, Anita; Sung Yun, Jae; MacQueen, Rowan W.; Spiccia, Leone; Green, Martin A.; Hameiri, Ziv

    2016-07-01

    In this study, we provide insights into planar structure methylammonium lead triiodide (MAPbI3) perovskite solar cells (PSCs) using electroluminescence and photoluminescence imaging techniques. We demonstrate the strength of these techniques in screening relatively large area PSCs, correlating the solar cell electrical parameters to the images and visualizing the features which contribute to the variation of the parameters extracted from current density-voltage characterizations. It is further used to investigate one of the major concerns about perovskite solar cells, their long term stability and aging. Upon storage under dark in dry glovebox condition for more than two months, the major parameter found to have deteriorated in electrical performance measurements was the fill factor; this was elucidated via electroluminescence image comparisons which revealed that the contacts' quality degrades. Interestingly, by deploying electroluminescence imaging, the significance of having a pin-hole free active layer is demonstrated. Pin-holes can grow over time and can cause degradation of the active layer surrounding them.

  9. Supervised restoration of degraded medical images using multiple-point geostatistics.

    Science.gov (United States)

    Pham, Tuan D

    2012-06-01

    Reducing noise in medical images has been an important issue of research and development for medical diagnosis, patient treatment, and validation of biomedical hypotheses. Noise inherently exists in medical and biological images due to the acquisition and transmission in any imaging devices. Being different from image enhancement, the purpose of image restoration is the process of removing noise from a degraded image in order to recover as much as possible its original version. This paper presents a statistically supervised approach for medical image restoration using the concept of multiple-point geostatistics. Experimental results have shown the effectiveness of the proposed technique which has potential as a new methodology for medical and biological image processing.

  10. Quality Prediction of Asymmetrically Distorted Stereoscopic 3D Images.

    Science.gov (United States)

    Wang, Jiheng; Rehman, Abdul; Zeng, Kai; Wang, Shiqi; Wang, Zhou

    2015-11-01

    Objective quality assessment of distorted stereoscopic images is a challenging problem, especially when the distortions in the left and right views are asymmetric. Existing studies suggest that simply averaging the quality of the left and right views well predicts the quality of symmetrically distorted stereoscopic images, but generates substantial prediction bias when applied to asymmetrically distorted stereoscopic images. In this paper, we first build a database that contains both single-view and symmetrically and asymmetrically distorted stereoscopic images. We then carry out a subjective test, where we find that the quality prediction bias of the asymmetrically distorted images could lean toward opposite directions (overestimate or underestimate), depending on the distortion types and levels. Our subjective test also suggests that eye dominance effect does not have strong impact on the visual quality decisions of stereoscopic images. Furthermore, we develop an information content and divisive normalization-based pooling scheme that improves upon structural similarity in estimating the quality of single-view images. Finally, we propose a binocular rivalry-inspired multi-scale model to predict the quality of stereoscopic images from that of the single-view images. Our results show that the proposed model, without explicitly identifying image distortion types, successfully eliminates the prediction bias, leading to significantly improved quality prediction of the stereoscopic images.

  11. Using short-wave infrared imaging for fruit quality evaluation

    Science.gov (United States)

    Zhang, Dong; Lee, Dah-Jye; Desai, Alok

    2013-12-01

    Quality evaluation of agricultural and food products is important for processing, inventory control, and marketing. Fruit size and surface quality are two important quality factors for high-quality fruit such as Medjool dates. Fruit size is usually measured by length that can be done easily by simple image processing techniques. Surface quality evaluation on the other hand requires more complicated design, both in image acquisition and image processing. Skin delamination is considered a major factor that affects fruit quality and its value. This paper presents an efficient histogram analysis and image processing technique that is designed specifically for real-time surface quality evaluation of Medjool dates. This approach, based on short-wave infrared imaging, provides excellent image contrast between the fruit surface and delaminated skin, which allows significant simplification of image processing algorithm and reduction of computational power requirements. The proposed quality grading method requires very simple training procedure to obtain a gray scale image histogram for each quality level. Using histogram comparison, each date is assigned to one of the four quality levels and an optimal threshold is calculated for segmenting skin delamination areas from the fruit surface. The percentage of the fruit surface that has skin delamination can then be calculated for quality evaluation. This method has been implemented and used for commercial production and proven to be efficient and accurate.

  12. Quality Improvement of Liver Ultrasound Images Using Fuzzy Techniques

    Science.gov (United States)

    Bayani, Azadeh; Langarizadeh, Mostafa; Radmard, Amir Reza; Nejad, Ahmadreza Farzaneh

    2016-01-01

    Background: Liver ultrasound images are so common and are applied so often to diagnose diffuse liver diseases like fatty liver. However, the low quality of such images makes it difficult to analyze them and diagnose diseases. The purpose of this study, therefore, is to improve the contrast and quality of liver ultrasound images. Methods: In this study, a number of image contrast enhancement algorithms which are based on fuzzy logic were applied to liver ultrasound images - in which the view of kidney is observable - using Matlab2013b to improve the image contrast and quality which has a fuzzy definition; just like image contrast improvement algorithms using a fuzzy intensification operator, contrast improvement algorithms applying fuzzy image histogram hyperbolization, and contrast improvement algorithms by fuzzy IF-THEN rules. Results: With the measurement of Mean Squared Error and Peak Signal to Noise Ratio obtained from different images, fuzzy methods provided better results, and their implementation - compared with histogram equalization method - led both to the improvement of contrast and visual quality of images and to the improvement of liver segmentation algorithms results in images. Conclusion: Comparison of the four algorithms revealed the power of fuzzy logic in improving image contrast compared with traditional image processing algorithms. Moreover, contrast improvement algorithm based on a fuzzy intensification operator was selected as the strongest algorithm considering the measured indicators. This method can also be used in future studies on other ultrasound images for quality improvement and other image processing and analysis applications. PMID:28077898

  13. Quality Improvement of Liver Ultrasound Images Using Fuzzy Techniques.

    Science.gov (United States)

    Bayani, Azadeh; Langarizadeh, Mostafa; Radmard, Amir Reza; Nejad, Ahmadreza Farzaneh

    2016-12-01

    Liver ultrasound images are so common and are applied so often to diagnose diffuse liver diseases like fatty liver. However, the low quality of such images makes it difficult to analyze them and diagnose diseases. The purpose of this study, therefore, is to improve the contrast and quality of liver ultrasound images. In this study, a number of image contrast enhancement algorithms which are based on fuzzy logic were applied to liver ultrasound images - in which the view of kidney is observable - using Matlab2013b to improve the image contrast and quality which has a fuzzy definition; just like image contrast improvement algorithms using a fuzzy intensification operator, contrast improvement algorithms applying fuzzy image histogram hyperbolization, and contrast improvement algorithms by fuzzy IF-THEN rules. With the measurement of Mean Squared Error and Peak Signal to Noise Ratio obtained from different images, fuzzy methods provided better results, and their implementation - compared with histogram equalization method - led both to the improvement of contrast and visual quality of images and to the improvement of liver segmentation algorithms results in images. Comparison of the four algorithms revealed the power of fuzzy logic in improving image contrast compared with traditional image processing algorithms. Moreover, contrast improvement algorithm based on a fuzzy intensification operator was selected as the strongest algorithm considering the measured indicators. This method can also be used in future studies on other ultrasound images for quality improvement and other image processing and analysis applications.

  14. Practical guidelines for radiographers to improve computed radiography image quality.

    Science.gov (United States)

    Pongnapang, N

    2005-10-01

    Computed Radiography (CR) has become a major digital imaging modality in a modern radiological department. CR system changes workflow from the conventional way of using film/screen by employing photostimulable phosphor plate technology. This results in the changing perspectives of technical, artefacts and quality control issues in radiology departments. Guidelines for better image quality in digital medical enterprise include professional guidelines for users and the quality control programme specifically designed to serve the best quality of clinical images. Radiographers who understand technological shift of the CR from conventional method can employ optimization of CR images. Proper anatomic collimation and exposure techniques for each radiographic projection are crucial steps in producing quality digital images. Matching image processing with specific anatomy is also important factor that radiographers should realise. Successful shift from conventional to fully digitised radiology department requires skilful radiographers who utilise the technology and a successful quality control program from teamwork in the department.

  15. Learning to rank for blind image quality assessment.

    Science.gov (United States)

    Gao, Fei; Tao, Dacheng; Gao, Xinbo; Li, Xuelong

    2015-10-01

    Blind image quality assessment (BIQA) aims to predict perceptual image quality scores without access to reference images. State-of-the-art BIQA methods typically require subjects to score a large number of images to train a robust model. However, subjective quality scores are imprecise, biased, and inconsistent, and it is challenging to obtain a large-scale database, or to extend existing databases, because of the inconvenience of collecting images, training the subjects, conducting subjective experiments, and realigning human quality evaluations. To combat these limitations, this paper explores and exploits preference image pairs (PIPs) such as the quality of image Ia is better than that of image Ib for training a robust BIQA model. The preference label, representing the relative quality of two images, is generally precise and consistent, and is not sensitive to image content, distortion type, or subject identity; such PIPs can be generated at a very low cost. The proposed BIQA method is one of learning to rank. We first formulate the problem of learning the mapping from the image features to the preference label as one of classification. In particular, we investigate the utilization of a multiple kernel learning algorithm based on group lasso to provide a solution. A simple but effective strategy to estimate perceptual image quality scores is then presented. Experiments show that the proposed BIQA method is highly effective and achieves a performance comparable with that of state-of-the-art BIQA algorithms. Moreover, the proposed method can be easily extended to new distortion categories.

  16. Food quality assessment by NIR hyperspectral imaging

    Science.gov (United States)

    Whitworth, Martin B.; Millar, Samuel J.; Chau, Astor

    2010-04-01

    Near infrared reflectance (NIR) spectroscopy is well established in the food industry for rapid compositional analysis of bulk samples. NIR hyperspectral imaging provides new opportunities to measure the spatial distribution of components such as moisture and fat, and to identify and measure specific regions of composite samples. An NIR hyperspectral imaging system has been constructed for food research applications, incorporating a SWIR camera with a cooled 14 bit HgCdTe detector and N25E spectrograph (Specim Ltd, Finland). Samples are scanned in a pushbroom mode using a motorised stage. The system has a spectral resolution of 256 pixels covering a range of 970-2500 nm and a spatial resolution of 320 pixels covering a swathe adjustable from 8 to 300 mm. Images are acquired at a rate of up to 100 lines s-1, enabling samples to be scanned within a few seconds. Data are captured using SpectralCube software (Specim) and analysed using ENVI and IDL (ITT Visual Information Solutions). Several food applications are presented. The strength of individual absorbance bands enables the distribution of particular components to be assessed. Examples are shown for detection of added gluten in wheat flour and to study the effect of processing conditions on fat distribution in chips/French fries. More detailed quantitative calibrations have been developed to study evolution of the moisture distribution in baguettes during storage at different humidities, to assess freshness of fish using measurements of whole cod and fillets, and for prediction of beef quality by identification and separate measurement of lean and fat regions.

  17. An image quality analysis of ANVIS-6 night vision goggles

    OpenAIRE

    Abel, Derek H.

    1994-01-01

    This study was undertaken in an effort to relate ANVIS-6 Night Vision Goggle image quality to user performance. The purpose was to determine which of five image quality metrics best related to performance tasks. The image quality metrics examined Modulation Transfer Function Area (MTFA), Integrated Contrast Sensitivity (leS), Square Root Integral (SQRI), Resolution, and Signal-to-Noise Ratio (SNR). The performance tasks were detection and recognition of targets under various le...

  18. Measuring Fingerprint Image Quality Using the Fourier Spectrum

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The fingerprint image quality has a significant effect on the performance of automatic fingerprint identification system. A method for measure of fingerprint image quality based on Fourier spectrum is proposed. First the band frequency which corresponds to the global average period of ridge is searched. Then the quality score of the fingerprint image is computed by measuring relative magnitude of the band frequency components. The method is verified to have good performance by experiments.

  19. Quantitative image quality evaluation for cardiac CT reconstructions

    Science.gov (United States)

    Tseng, Hsin-Wu; Fan, Jiahua; Kupinski, Matthew A.; Balhorn, William; Okerlund, Darin R.

    2016-03-01

    Maintaining image quality in the presence of motion is always desirable and challenging in clinical Cardiac CT imaging. Different image-reconstruction algorithms are available on current commercial CT systems that attempt to achieve this goal. It is widely accepted that image-quality assessment should be task-based and involve specific tasks, observers, and associated figures of merits. In this work, we developed an observer model that performed the task of estimating the percentage of plaque in a vessel from CT images. We compared task performance of Cardiac CT image data reconstructed using a conventional FBP reconstruction algorithm and the SnapShot Freeze (SSF) algorithm, each at default and optimal reconstruction cardiac phases. The purpose of this work is to design an approach for quantitative image-quality evaluation of temporal resolution for Cardiac CT systems. To simulate heart motion, a moving coronary type phantom synchronized with an ECG signal was used. Three different percentage plaques embedded in a 3 mm vessel phantom were imaged multiple times under motion free, 60 bpm, and 80 bpm heart rates. Static (motion free) images of this phantom were taken as reference images for image template generation. Independent ROIs from the 60 bpm and 80 bpm images were generated by vessel tracking. The observer performed estimation tasks using these ROIs. Ensemble mean square error (EMSE) was used as the figure of merit. Results suggest that the quality of SSF images is superior to the quality of FBP images in higher heart-rate scans.

  20. Corroborating the Land Use Change as Primary Determinant of Air Quality Degradation in a Concentric City

    Directory of Open Access Journals (Sweden)

    Ariva Sugandi Permana

    2015-05-01

    Full Text Available Bandung City is characterized by concentric land use pattern as found in many naturally grown cities. It radiates from mixed commercial areas in the center to low density residential areas in the periphery. This pattern generates significant traffic volume towards city center. The gener-ated traffic releases emissions and degrades urban air quality since fossil fuel is predominantly used by vehicles in Bandung. In the absence of air polluting industries as well as construction and demolition activities, traffic load generated by land use changes is the only major contribu-tor to air quality degradation in the city. The land use change can therefore be seen as primary determinant of air pollution in Bandung. This study analyses land use changes and its impacts on traffic pattern and air quality. Multivariate correlation between traffic load and land use changes is employed as tool to substantiate the proposition. Relationships between the degree of chang-es in land use, as reflected in traffic loads, and the quantity of two principal air pollutants, namely SO2 and HC are also established to validate the argument. The result of analysis sub-stantiates the correlation between land use changes and air quality degradation.

  1. Effects of post-mortem and physical degradation on RNA integrity and quality

    Directory of Open Access Journals (Sweden)

    Monika Sidova

    2015-09-01

    Full Text Available The precision and reliability of quantitative nucleic acid analysis depends on the quality of the sample analyzed and the integrity of the nucleic acids. The integrity of RNA is currently primarily assessed by the analysis of ribosomal RNA, which is the by far dominant species. The extrapolation of these results to mRNAs and microRNAs, which are structurally quite different, is questionable. Here we show that ribosomal and some nucleolar and mitochondrial RNAs, are highly resistant to naturally occurring post-mortem degradation, while mRNAs, although showing substantial internal variability, are generally much more prone to nucleolytic degradation. In contrast, all types of RNA show the same sensitivity to heat. Using qPCR assays targeting different regions of mRNA molecules, we find no support for 5′ or 3′ preferentiality upon post-mortem degradation.

  2. Analysis of thermal degradation of organic light-emitting diodes with infrared imaging and impedance spectroscopy.

    Science.gov (United States)

    Kwak, Kiyeol; Cho, Kyoungah; Kim, Sangsig

    2013-12-02

    We propose a route to examine the thermal degradation of organic light-emitting diodes (OLEDs) with infrared (IR) imaging and impedance spectroscopy. Four different OLEDs with tris (8-hydroxyquinolinato) aluminum are prepared in this study for the analysis of thermal degradation. Our comparison of the thermal and electrical characteristics of these OLEDs reveals that the real-time temperatures of these OLEDs obtained from the IR images clearly correlate with the electrical properties and lifetimes. The OLED with poor electrical properties shows a fairly high temperature during the operation and a considerably short lifetime. Based on the correlation of the real-time temperature and the performance of the OLEDs, the impedance results suggest different thermal degradation mechanisms for each of the OLEDs. The analysis method suggested in this study will be helpful in developing OLEDs with higher efficiency and longer lifetime.

  3. Image quality and dose differences caused by vendor-specific image processing of neonatal radiographs.

    Science.gov (United States)

    Sensakovic, William F; O'Dell, M Cody; Letter, Haley; Kohler, Nathan; Rop, Baiywo; Cook, Jane; Logsdon, Gregory; Varich, Laura

    2016-10-01

    Image processing plays an important role in optimizing image quality and radiation dose in projection radiography. Unfortunately commercial algorithms are black boxes that are often left at or near vendor default settings rather than being optimized. We hypothesize that different commercial image-processing systems, when left at or near default settings, create significant differences in image quality. We further hypothesize that image-quality differences can be exploited to produce images of equivalent quality but lower radiation dose. We used a portable radiography system to acquire images on a neonatal chest phantom and recorded the entrance surface air kerma (ESAK). We applied two image-processing systems (Optima XR220amx, by GE Healthcare, Waukesha, WI; and MUSICA(2) by Agfa HealthCare, Mortsel, Belgium) to the images. Seven observers (attending pediatric radiologists and radiology residents) independently assessed image quality using two methods: rating and matching. Image-quality ratings were independently assessed by each observer on a 10-point scale. Matching consisted of each observer matching GE-processed images and Agfa-processed images with equivalent image quality. A total of 210 rating tasks and 42 matching tasks were performed and effective dose was estimated. Median Agfa-processed image-quality ratings were higher than GE-processed ratings. Non-diagnostic ratings were seen over a wider range of doses for GE-processed images than for Agfa-processed images. During matching tasks, observers matched image quality between GE-processed images and Agfa-processed images acquired at a lower effective dose (11 ± 9 μSv; P < 0.0001). Image-processing methods significantly impact perceived image quality. These image-quality differences can be exploited to alter protocols and produce images of equivalent image quality but lower doses. Those purchasing projection radiography systems or third-party image-processing software should be aware that image

  4. Objective and Subjective Assessment of Digital Pathology Image Quality

    Directory of Open Access Journals (Sweden)

    Prarthana Shrestha

    2015-03-01

    Full Text Available The quality of an image produced by the Whole Slide Imaging (WSI scanners is of critical importance for using the image in clinical diagnosis. Therefore, it is very important to monitor and ensure the quality of images. Since subjective image quality assessments by pathologists are very time-consuming, expensive and difficult to reproduce, we propose a method for objective assessment based on clinically relevant and perceptual image parameters: sharpness, contrast, brightness, uniform illumination and color separation; derived from a survey of pathologists. We developed techniques to quantify the parameters based on content-dependent absolute pixel performance and to manipulate the parameters in a predefined range resulting in images with content-independent relative quality measures. The method does not require a prior reference model. A subjective assessment of the image quality is performed involving 69 pathologists and 372 images (including 12 optimal quality images and their distorted versions per parameter at 6 different levels. To address the inter-reader variability, a representative rating is determined as a one-tailed 95% confidence interval of the mean rating. The results of the subjective assessment support the validity of the proposed objective image quality assessment method to model the readers’ perception of image quality. The subjective assessment also provides thresholds for determining the acceptable level of objective quality per parameter. The images for both the subjective and objective quality assessment are based on the HercepTestTM slides scanned by the Philips Ultra Fast Scanners, developed at Philips Digital Pathology Solutions. However, the method is applicable also to other types of slides and scanners.

  5. Gold Core Mesoporous Organosilica Shell Degradable Nanoparticles for Two-Photon Imaging and Gemcitabine Monophosphate Delivery

    KAUST Repository

    Rhamani, Saher

    2017-09-12

    The synthesis of gold core degradable mesoporous organosilica shell nanoparticles is described. The nanopaticles were very efficient for two-photon luminescence imaging of cancer cells and for in vitro gemcitabine monophosphate delivery, allowing promising theranostic applications in the nanomedicine field.

  6. Enzymatically Degradable Hybrid Organic-Inorganic Bridged Silsesquioxane Nanoparticles for In-Vitro Imaging

    KAUST Repository

    Fatieiev, Yevhen

    2015-06-30

    Non-aggregated dense bridged silsesquioxane (BS) nanoparticles based on nature-inspired oxamide bridges are shown to degrade in simulated biological media upon cleavage with endopeptidase. Fluorescent BS nanoprobes with incorporated fluorescein dyes were applied for in-vitro imaging in cancer cells.

  7. A New Approach for Enhancing the Quality of Medical Computerized Tomography Images

    Directory of Open Access Journals (Sweden)

    Mutaz Al-Frejat

    2016-05-01

    Full Text Available Computerized tomography (CT images contribute immensely to medical research and diagnosis. However, due to degradative factors such as noise, low contrast, and blurring, CT images tend to be a degraded representation of the actual body or part under investigation. To reduce the risk of imprecise diagnosis associated with poor-quality CT images, this paper presents a new technique designed to enhance the quality of medical CT images. The main objective is to improve the appearance of CT images in order to obtain better visual interpretation and analysis, which is expected to ease the diagnosis process. The proposed technique involves applying a median filter to remove noise from the CT images and then using a Laplacian filter to enhance the edges and the contrast in the images. Also, as CT images suffer from low contrast, a Contrast Limited Adaptive Histogram Equalization transform is also applied to solve this problem. The main strength of this transform is its modest computational requirements, ease of application, and excellent results for most images. According to a subjective assessment by a group of radiologists, the proposed technique resulted in excellent enhancement, including that of the contrast and the edges of medical CT images. From a medical perspective, the proposed technique was able to clarify the arteries, tissues, and lung nodules in the CT images. In addition, blurred nodules in chest CT images were enhanced effectively. Therefore the proposed technique can help radiologists to better detect lung nodules and can also assist in diagnosing the presence of tumours and in the detection of abnormal growths.

  8. Mitigation of signal quality degradation induced by PMD using synchronous modulation

    Institute of Scientific and Technical Information of China (English)

    Li Huo(霍力); Yanfu Yang(杨彦甫); Caiyun Lou(娄采云); Hejun Yao(姚和军); Xiaomin Song(宋晓旻); Yizhi Gao(高以智)

    2004-01-01

    In-line synchronous modulation as a way of mitigating the signal quality degradation induced by polar ization mode dispersion(PMD)was experimentally studied using 10-Gb/s return to zero signal.Bit error rate of the degraded signal and the synchronously modulated signal under the differential group delay(DGD)values of 10,20,34,and 70 ps was measured and compared.The experimental results showed that in-line synchronous modulation is useful to mitigate the signal quality degeneration induced by PMD.1-dB power penalty reduction was obtained even when the PMD was as high as 70% of the bit interval.The limitation of method is also discussed.

  9. Quality assurance in digital dental imaging: a systematic review.

    Science.gov (United States)

    Metsälä, Eija; Henner, Anja; Ekholm, Marja

    2014-07-01

    Doses induced by individual dental examinations are low. However, dental radiography accounts for nearly one third of the total number of radiological examinations in the European Union. Therefore, special attention is needed with regard to radiation protection. In order to lower patient doses, the staff performing dental examinations must have competence in imaging as well as in radiation protection issues. This paper presents a systematic review about the core competencies needed by the healthcare staff in performing digital dental radiological imaging quality assurance. The following databases were searched: Pubmed, Cinahl, Pro Quest and IEEXplore digital library. Also volumes of some dental imaging journals and doctoral theses of the Finnish universities educating dentists were searched. The search was performed using both MeSH terms and keywords using the option 'search all text'. The original keywords were: dental imaging, digital, x-ray, panoramic, quality, assurance, competence, competency, skills, knowledge, radiographer, radiologist technician, dentist, oral hygienist, radiation protection and their Finnish synonyms. Core competencies needed by the healthcare staff performing digital dental radiological imaging quality assurance described in the selected studies were: management of dental imaging equipment, competence in image quality and factors associated with it, dose optimization and quality assurance. In the future there will be higher doses in dental imaging due to increasing use of CBCT and digital imaging. The staff performing dental imaging must have competence in dental imaging quality assurance issues found in this review. They also have to practice ethical radiation safety culture in clinical practice.

  10. Water quality degradation effects on freshwater availability: Impacts to human activities

    Science.gov (United States)

    Peters, N.E.; Meybeck, Michel

    2000-01-01

    The quality of freshwater at any point on the landscape reflects the combined effects of many processes along water pathways. Human activities on all spatial scales affect both water quality and quantity. Alteration of the landscape and associated vegetation has not only changed the water balance, but typically has altered processes that control water quality. Effects of human activities on a small scale are relevant to an entire drainage basin. Furthermore, local, regional, and global differences in climate and water flow are considerable, causing varying effects of human activities on land and water quality and quantity, depending on location within a watershed, geology, biology, physiographic characteristics, and climate. These natural characteristics also greatly control human activities, which will, in turn, modify (or affect) the natural composition of water. One of the most important issues for effective resource management is recognition of cyclical and cascading effects of human activities on the water quality and quantity along hydrologic pathways. The degradation of water quality in one part of a watershed can have negative effects on users downstream. Everyone lives downstream of the effects of some human activity. An extremely important factor is that substances added to the atmosphere, land, and water generally have relatively long time scales for removal or clean up. The nature of the substance, including its affinity for adhering to soil and its ability to be transformed, affects the mobility and the time scale for removal of the substance. Policy alone will not solve many of the degradation issues, but a combination of policy, education, scientific knowledge, planning, and enforcement of applicable laws can provide mechanisms for slowing the rate of degradation and provide human and environmental protection. Such an integrated approach is needed to effectively manage land and water resources.

  11. Research on a novel restoration algorithm of turbulence-degraded images with alternant iterations

    Institute of Scientific and Technical Information of China (English)

    Liu Chunsheng; Hong Hanyu; Zhang Tianxu

    2006-01-01

    A new restoration algorithm based on double loops and alternant iterations is proposed to restore the object image effectively from a few frames of turbulence-degraded images. Based on the double loops, the iterative relations for estimating the turbulent point spread function PSF and object image alternately are derived. The restoration experiments have been made on computers, showing that the proposed algorithm can obtain the optimal estimations of the object and the point spread function, with the feasibility and practicality of the proposed algorithm being convincing.

  12. The study of surgical image quality evaluation system by subjective quality factor method

    Science.gov (United States)

    Zhang, Jian J.; Xuan, Jason R.; Yang, Xirong; Yu, Honggang; Koullick, Edouard

    2016-03-01

    GreenLightTM procedure is an effective and economical way of treatment of benign prostate hyperplasia (BPH); there are almost a million of patients treated with GreenLightTM worldwide. During the surgical procedure, the surgeon or physician will rely on the monitoring video system to survey and confirm the surgical progress. There are a few obstructions that could greatly affect the image quality of the monitoring video, like laser glare by the tissue and body fluid, air bubbles and debris generated by tissue evaporation, and bleeding, just to name a few. In order to improve the physician's visual experience of a laser surgical procedure, the system performance parameter related to image quality needs to be well defined. However, since image quality is the integrated set of perceptions of the overall degree of excellence of an image, or in other words, image quality is the perceptually weighted combination of significant attributes (contrast, graininess …) of an image when considered in its marketplace or application, there is no standard definition on overall image or video quality especially for the no-reference case (without a standard chart as reference). In this study, Subjective Quality Factor (SQF) and acutance are used for no-reference image quality evaluation. Basic image quality parameters, like sharpness, color accuracy, size of obstruction and transmission of obstruction, are used as subparameter to define the rating scale for image quality evaluation or comparison. Sample image groups were evaluated by human observers according to the rating scale. Surveys of physician groups were also conducted with lab generated sample videos. The study shows that human subjective perception is a trustworthy way of image quality evaluation. More systematic investigation on the relationship between video quality and image quality of each frame will be conducted as a future study.

  13. Image quality influences the assessment of left ventricular function

    DEFF Research Database (Denmark)

    Grossgasteiger, Manuel; Hien, Maximilian D; Graser, Bastian;

    2014-01-01

    divided by the total endocardial border. These ratings were used to generate groups of poor (0%-40%), fair (41%-70%), and good (71%-100%) image quality. The ejection fraction (EF), end-diastolic volume, and end-systolic volume were analyzed by the Simpson method of disks (biplane and monoplane), eyeball......Objectives: Transesophageal echocardiography has become a standard tool for eval uating left ventricular function during cardiac surgery. However, the image quality varies widely between patients and examinations. The aim of this study was to investigate the influence of the image quality on 5...... commonly used 2-dimensional methods. Methods: Transesophageal real-time 3-dimensional echocardiography (3DE) served as a reference. Left ventricular function was evaluated in 63 patients with sufficient real-time 3DE image quality. The image quality was rated using the ratio of the visualized border...

  14. Image quality assessment for CT used on small animals

    Energy Technology Data Exchange (ETDEWEB)

    Cisneros, Isabela Paredes, E-mail: iparedesc@unal.edu.co; Agulles-Pedrós, Luis, E-mail: lagullesp@unal.edu.co [Universidad Nacional de Colombia, Departamento de Física, Grupo de Física Médica (Colombia)

    2016-07-07

    Image acquisition on a CT scanner is nowadays necessary in almost any kind of medical study. Its purpose, to produce anatomical images with the best achievable quality, implies the highest diagnostic radiation exposure to patients. Image quality can be measured quantitatively based on parameters such as noise, uniformity and resolution. This measure allows the determination of optimal parameters of operation for the scanner in order to get the best diagnostic image. A human Phillips CT scanner is the first one minded for veterinary-use exclusively in Colombia. The aim of this study was to measure the CT image quality parameters using an acrylic phantom and then, using the computational tool MATLAB, determine these parameters as a function of current value and window of visualization, in order to reduce dose delivery by keeping the appropriate image quality.

  15. Image quality assessment for CT used on small animals

    Science.gov (United States)

    Cisneros, Isabela Paredes; Agulles-Pedrós, Luis

    2016-07-01

    Image acquisition on a CT scanner is nowadays necessary in almost any kind of medical study. Its purpose, to produce anatomical images with the best achievable quality, implies the highest diagnostic radiation exposure to patients. Image quality can be measured quantitatively based on parameters such as noise, uniformity and resolution. This measure allows the determination of optimal parameters of operation for the scanner in order to get the best diagnostic image. A human Phillips CT scanner is the first one minded for veterinary-use exclusively in Colombia. The aim of this study was to measure the CT image quality parameters using an acrylic phantom and then, using the computational tool MatLab, determine these parameters as a function of current value and window of visualization, in order to reduce dose delivery by keeping the appropriate image quality.

  16. Practical guidelines for radiographers to improve computed radiography image quality

    OpenAIRE

    Pongnapang, N

    2005-01-01

    Computed Radiography (CR) has become a major digital imaging modality in a modern radiological department. CR system changes workflow from the conventional way of using film/screen by employing photostimulable phosphor plate technology. This results in the changing perspectives of technical, artefacts and quality control issues in radiology departments. Guidelines for better image quality in digital medical enterprise include professional guidelines for users and the quality control programme...

  17. Adaptive multi-sample-based photoacoustic tomography with imaging quality optimization

    Institute of Scientific and Technical Information of China (English)

    Yuxin Wang; Jie Yuan; Sidan Du; Xiaojun Liu; Guan Xu; Xueding Wang

    2015-01-01

    The energy of light exposed on human skin is compulsively limited for safety reasons which affects the power of photoacoustic (PA) signal and its signal-to-noise ratio (SNR) level.Thus,the final reconstructed PA image quality is degraded.This Letter proposes an adaptive multi-sample-based approach to enhance the SNR of PA signals and in addition,detailed information in rebuilt PA images that used to be buried in the noise can be distinguished.Both ex vivo and in vivo experiments are conducted to validate the effectiveness of our proposed method which provides its potential value in clinical trials.

  18. A new assessment method for image fusion quality

    Science.gov (United States)

    Li, Liu; Jiang, Wanying; Li, Jing; Yuchi, Ming; Ding, Mingyue; Zhang, Xuming

    2013-03-01

    Image fusion quality assessment plays a critically important role in the field of medical imaging. To evaluate image fusion quality effectively, a lot of assessment methods have been proposed. Examples include mutual information (MI), root mean square error (RMSE), and universal image quality index (UIQI). These image fusion assessment methods could not reflect the human visual inspection effectively. To address this problem, we have proposed a novel image fusion assessment method which combines the nonsubsampled contourlet transform (NSCT) with the regional mutual information in this paper. In this proposed method, the source medical images are firstly decomposed into different levels by the NSCT. Then the maximum NSCT coefficients of the decomposed directional images at each level are obtained to compute the regional mutual information (RMI). Finally, multi-channel RMI is computed by the weighted sum of the obtained RMI values at the various levels of NSCT. The advantage of the proposed method lies in the fact that the NSCT can represent image information using multidirections and multi-scales and therefore it conforms to the multi-channel characteristic of human visual system, leading to its outstanding image assessment performance. The experimental results using CT and MRI images demonstrate that the proposed assessment method outperforms such assessment methods as MI and UIQI based measure in evaluating image fusion quality and it can provide consistent results with human visual assessment.

  19. Standardizing Quality Assessment of Fused Remotely Sensed Images

    Science.gov (United States)

    Pohl, C.; Moellmann, J.; Fries, K.

    2017-09-01

    The multitude of available operational remote sensing satellites led to the development of many image fusion techniques to provide high spatial, spectral and temporal resolution images. The comparison of different techniques is necessary to obtain an optimized image for the different applications of remote sensing. There are two approaches in assessing image quality: 1. Quantitatively by visual interpretation and 2. Quantitatively using image quality indices. However an objective comparison is difficult due to the fact that a visual assessment is always subject and a quantitative assessment is done by different criteria. Depending on the criteria and indices the result varies. Therefore it is necessary to standardize both processes (qualitative and quantitative assessment) in order to allow an objective image fusion quality evaluation. Various studies have been conducted at the University of Osnabrueck (UOS) to establish a standardized process to objectively compare fused image quality. First established image fusion quality assessment protocols, i.e. Quality with No Reference (QNR) and Khan's protocol, were compared on varies fusion experiments. Second the process of visual quality assessment was structured and standardized with the aim to provide an evaluation protocol. This manuscript reports on the results of the comparison and provides recommendations for future research.

  20. Image processing system performance prediction and product quality evaluation

    Science.gov (United States)

    Stein, E. K.; Hammill, H. B. (Principal Investigator)

    1976-01-01

    The author has identified the following significant results. A new technique for image processing system performance prediction and product quality evaluation was developed. It was entirely objective, quantitative, and general, and should prove useful in system design and quality control. The technique and its application to determination of quality control procedures for the Earth Resources Technology Satellite NASA Data Processing Facility are described.

  1. Effect of image quality on calcification detection in digital mammography.

    Science.gov (United States)

    Warren, Lucy M; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M; Wallis, Matthew G; Chakraborty, Dev P; Dance, David R; Bosmans, Hilde; Young, Kenneth C

    2012-06-01

    This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC (AFROC) area decreased from

  2. Degradation decomposition of the perceived quality of speech signals on the basis of a perceptual modeling approach

    NARCIS (Netherlands)

    Beerends, J.G.; Busz, B.; Oudshoorn, P.; Vugt, J. van; Ahmed, K.; Niamut, O.

    2007-01-01

    The authors discuss the way we perceive the quality of a speech signal and how different degradations contribute to the overall perceived speech (listening) quality. More specifically, ITU-T Recommendation P.862 (perceptual evaluation of speech quality-PESQ), which provides a perceptual modeling app

  3. Degradation decomposition of the perceived quality of speech signals on the basis of a perceptual modeling approach

    NARCIS (Netherlands)

    Beerends, J.G.; Busz, B.; Oudshoorn, P.; Vugt, J. van; Ahmed, K.; Niamut, O.

    2007-01-01

    The authors discuss the way we perceive the quality of a speech signal and how different degradations contribute to the overall perceived speech (listening) quality. More specifically, ITU-T Recommendation P.862 (perceptual evaluation of speech quality-PESQ), which provides a perceptual modeling

  4. Automated quality assessment in three-dimensional breast ultrasound images.

    Science.gov (United States)

    Schwaab, Julia; Diez, Yago; Oliver, Arnau; Martí, Robert; van Zelst, Jan; Gubern-Mérida, Albert; Mourri, Ahmed Bensouda; Gregori, Johannes; Günther, Matthias

    2016-04-01

    Automated three-dimensional breast ultrasound (ABUS) is a valuable adjunct to x-ray mammography for breast cancer screening of women with dense breasts. High image quality is essential for proper diagnostics and computer-aided detection. We propose an automated image quality assessment system for ABUS images that detects artifacts at the time of acquisition. Therefore, we study three aspects that can corrupt ABUS images: the nipple position relative to the rest of the breast, the shadow caused by the nipple, and the shape of the breast contour on the image. Image processing and machine learning algorithms are combined to detect these artifacts based on 368 clinical ABUS images that have been rated manually by two experienced clinicians. At a specificity of 0.99, 55% of the images that were rated as low quality are detected by the proposed algorithms. The areas under the ROC curves of the single classifiers are 0.99 for the nipple position, 0.84 for the nipple shadow, and 0.89 for the breast contour shape. The proposed algorithms work fast and reliably, which makes them adequate for online evaluation of image quality during acquisition. The presented concept may be extended to further image modalities and quality aspects.

  5. Soil Degradation and Soil Quality in Western Europe: Current Situation and Future Perspectives

    Directory of Open Access Journals (Sweden)

    Iñigo Virto

    2014-12-01

    Full Text Available The extent and causes of chemical, physical and biological degradation of soil, and of soil loss, vary greatly in different countries in Western Europe. The objective of this review paper is to examine these issues and also strategies for soil protection and future perspectives for soil quality evaluation, in light of present legislation aimed at soil protection. Agriculture and forestry are the main causes of many of the above problems, especially physical degradation, erosion and organic matter loss. Land take and soil sealing have increased in recent decades, further enhancing the problems. In agricultural land, conservation farming, organic farming and other soil-friendly practices have been seen to have site-specific effects, depending on the soil characteristics and the particular types of land use and land users. No single soil management strategy is suitable for all regions, soil types and soil uses. Except for soil contamination, specific legislation for soil protection is lacking in Western Europe. The Thematic Strategy for Soil Protection in the European Union has produced valuable information and has encouraged the development of networks and databases. However, soil degradation is addressed only indirectly in environmental policies and through the Common Agricultural Policy of the European Union, which promotes farming practices that support soil conservation. Despite these efforts, there remains a need for soil monitoring networks and decision-support systems aimed at optimization of soil quality in the region. The pressure on European soils will continue in the future, and a clearly defined regulatory framework is needed.

  6. Quality control of ER synthesized proteins: an exposed thiol group as a three-way switch mediating assembly, retention and degradation.

    Science.gov (United States)

    Fra, A M; Fagioli, C; Finazzi, D; Sitia, R; Alberini, C M

    1993-01-01

    Plasma cells secrete IgM only in the polymeric form: the C-terminal cysteine of the mu heavy chain (Cys575) is responsible for both intracellular retention and assembly of IgM subunits. Polymerization is not quantitative, and part of IgM is degraded intracellularly. Neither chloroquine nor brefeldin A (BFA) inhibits degradation, suggesting that this process occurs in a pre-Golgi compartment. Degradation of IgM assembly intermediates requires Cys575: the monomeric IgMala575 mutant is stable also when endoplasmic reticulum (ER) to Golgi transport is blocked by BFA. Addition of the 20 C-terminal residues of mu to the lysosomal protease cathepsin D is sufficient to induce pre-Golgi retention and degradation of the chimeric protein: the small amounts of molecules which exit from the ER are mostly covalent dimers. By contrast, when retained by the KDEL sequence, cathepsin D is stable in the ER, indicating that retention is not sufficient to cause degradation. Replacing the C-terminal cysteine with serine restores transport through the Golgi. As all chimeric cathepsin D constructs display comparable protease activity in vitro, their different fates are not determined by gross alterations in folding. Thus, also out of its normal context, the mu chain Cys575 plays a crucial role in quality control, mediating assembly, retention and degradation. Images PMID:8223484

  7. Determinants of image quality of rotational angiography for on-line assessment of frame geometry after transcatheter aortic valve implantation.

    Science.gov (United States)

    Rodríguez-Olivares, Ramón; El Faquir, Nahid; Rahhab, Zouhair; Maugenest, Anne-Marie; Van Mieghem, Nicolas M; Schultz, Carl; Lauritsch, Guenter; de Jaegere, Peter P T

    2016-07-01

    To study the determinants of image quality of rotational angiography using dedicated research prototype software for motion compensation without rapid ventricular pacing after the implantation of four commercially available catheter-based valves. Prospective observational study including 179 consecutive patients who underwent transcatheter aortic valve implantation (TAVI) with either the Medtronic CoreValve (MCS), Edward-SAPIEN Valve (ESV), Boston Sadra Lotus (BSL) or Saint-Jude Portico Valve (SJP) in whom rotational angiography (R-angio) with motion compensation 3D image reconstruction was performed. Image quality was evaluated from grade 1 (excellent image quality) to grade 5 (strongly degraded). Distinction was made between good (grades 1, 2) and poor image quality (grades 3-5). Clinical (gender, body mass index, Agatston score, heart rate and rhythm, artifacts), procedural (valve type) and technical variables (isocentricity) were related with the image quality assessment. Image quality was good in 128 (72 %) and poor in 51 (28 %) patients. By univariable analysis only valve type (BSL) and the presence of an artefact negatively affected image quality. By multivariate analysis (in which BMI was forced into the model) BSL valve (Odds 3.5, 95 % CI [1.3-9.6], p = 0.02), presence of an artifact (Odds 2.5, 95 % CI [1.2-5.4], p = 0.02) and BMI (Odds 1.1, 95 % CI [1.0-1.2], p = 0.04) were independent predictors of poor image quality. Rotational angiography with motion compensation 3D image reconstruction using a dedicated research prototype software offers good image quality for the evaluation of frame geometry after TAVI in the majority of patients. Valve type, presence of artifacts and higher BMI negatively affect image quality.

  8. Quality assessment of video image capture systems

    Science.gov (United States)

    Rowberg, Alan H.; Lian, Jing

    1991-05-01

    As Picture Archiving and Communication System (PACS) technology has matured, video image capture has become a common way of capturing digital images from many modalities. While digital interfaces, such as those which use the ACR/NEMA standard, will become more common in the future, and are preferred because of the accuracy of image transfer, video image capture will be the dominant method in the short term, and may continue to be used for some time because of the low cost and high speed often associated with such devices. A series of digital phantoms has been developed for display on either a CT9800 or Hilite Advantage scanner. The phantom images have been stored on magnetic tape in the standard tape archive format used by General Electric, so that the images may be loaded onto the scanner at any time. These images are then captured using a commercial video image capture board in a PC/286 computer, where the images are not only to be displayed, but also analyzed with the use of an automated process implemented in a computer program on the same PC. Results of the analyses are saved, together with the data and time of image acquisition, so that the results can be displayed graphically, as trend plots.

  9. Rebounding process of moulding sands-thermal degradation of bentonite binding qualities

    Directory of Open Access Journals (Sweden)

    R. Dańko

    2010-01-01

    Full Text Available Problems related to a gradual degradation of binding qualities of montmorillonite, the main component of foundry bentonites, are presented in the paper. This degradation is caused by high temperatures originated from liquid metal influencing moulding sands. Laboratory measurements of an active binding agent content in classic moulding sands prepared with two types of bentonite and subjected to a controlled heating to high temperatures – were performed. These laboratory examinations were compared to industrial tests, in which a temperature distribution was being determined in several places in the thickness of the casting ingot mould for 24 hours from the moment of pouring liquid metal. On the basis of the performed examinations, the method allowing to determine optimal additions in the rebounding process of the tested bentonites was developed.

  10. Image quality of a mobile display under different illuminations.

    Science.gov (United States)

    Lin, Po-Hung; Kuo, Wen-Hung

    2011-08-01

    This study constructed the image quality models for a small mobile display under different ambient illumination levels using Group Method and Data Handling (GMDH) and described the relationship between perceived image quality and physical measurements. 33 college students took part in this experiment and were asked to evaluate the image quality under 1500 lux (typical indoor office illumination) and 7000 lux (simulated outdoor environment) in Stage One and Stage Two, respectively. In each stage, the participants had to evaluate 21 images. 17 sets of the data as a training set were used to build the model and four sets of the data as a testing set were used to verify the model. The results indicated that the effects of luminance, contrast, correlated color temperature (CCT), and resolution were significant on perceived image quality under 1500 lux. However, color temperature was not a significant physical characteristic, and an interaction between luminance and contrast was found below 7000 lux. From the results of the experiment, it is considered that the outdoor environment (7000 lux) is not suitable for using mobile displays. Finally, once a valid image quality model is built, the subjective image quality can be established when the measurements of significant physical characteristics are provided. The results of subjective ratings can also be provided for mobile display manufacturers to improve the product quality so that their products can meet customers' requirements.

  11. Image and Video Quality Assessment Using Neural Network and SVM

    Institute of Scientific and Technical Information of China (English)

    DING Wenrui; TONG Yubing; ZHANG Qishan; YANG Dongkai

    2008-01-01

    An image and video quality assessment method was developed using neural network and support vector machines (SVM) with the peak signal to noise ratio (PSNR) and the structure similarity indexes used to describe image quality. The neural network was used to obtain the mapping functions between the objec-tive quality assessment indexes and subjective quality assessment. The SVM was used to classify the im-ages into different types which were accessed using different mapping functions. Video quality was as-sessed based on the quality of each frame in the video sequence with various weights to describe motion and scene changes in the video. The number of isolated points in the correlations of the image and video subjective and objective quality assessments was reduced by this method. Simulation results show that the method accurately accesses image quality. The monotonicity of the method for images is 6.94% higher than with the PSNR method, and the root mean square error is at least 35.90% higher than with the PSNR.

  12. Performance comparison of different graylevel image fusion schemes through a universal image quality index

    NARCIS (Netherlands)

    Toet, A.; Hogervorst, M.A.

    2003-01-01

    We applied a recently introduced universal image quality index Q that quantifies the distortion of a processed image relative to its original version, to assess the performance of different graylevel image fusion schemes. The method is as follows. First, we adopt an original test image as the refere

  13. Soil Quality Assessment Strategies for Evaluating Soil Degradation in Northern Ethiopia

    Directory of Open Access Journals (Sweden)

    Gebreyesus Brhane Tesfahunegn

    2014-01-01

    Full Text Available Soil quality (SQ degradation continues to challenge sustainable development throughout the world. One reason is that degradation indicators such as soil quality index (SQI are neither well documented nor used to evaluate current land use and soil management systems (LUSMS. The objective was to assess and identify an effective SQ indicator dataset from among 25 soil measurements, appropriate scoring functions for each indicator and an efficient SQ indexing method to evaluate soil degradation across the LUSMS in the Mai-Negus catchment of northern Ethiopia. Eight LUSMS selected for soil sampling and analysis included (i natural forest (LS1, (ii plantation of protected area, (iii grazed land, (iv teff (Eragrostis tef-faba bean (Vicia faba rotation, (v teff-wheat (Triticum vulgare/barley (Hordeum vulgare rotation, (vi teff monocropping, (vii maize (Zea mays monocropping, and (viii uncultivated marginal land (LS8. Four principal components explained almost 88% of the variability among the LUSMS. LS1 had the highest mean SQI (0.931 using the scoring functions and principal component analysis (PCA dataset selection, while the lowest SQI (0.458 was measured for LS8. Mean SQI values for LS1 and LS8 using expert opinion dataset selection method were 0.874 and 0.406, respectively. Finally, a sensitivity analysis (S used to compare PCA and expert opinion dataset selection procedures for various scoring functions ranged from 1.70 for unscreened-SQI to 2.63 for PCA-SQI. Therefore, this study concludes that a PCA-based SQI would be the best way to distinguish among LUSMS since it appears more sensitive to disturbances and management practices and could thus help prevent further SQ degradation.

  14. Meat quality evaluation by hyperspectral imaging technique: an overview.

    Science.gov (United States)

    Elmasry, Gamal; Barbin, Douglas F; Sun, Da-Wen; Allen, Paul

    2012-01-01

    During the last two decades, a number of methods have been developed to objectively measure meat quality attributes. Hyperspectral imaging technique as one of these methods has been regarded as a smart and promising analytical tool for analyses conducted in research and industries. Recently there has been a renewed interest in using hyperspectral imaging in quality evaluation of different food products. The main inducement for developing the hyperspectral imaging system is to integrate both spectroscopy and imaging techniques in one system to make direct identification of different components and their spatial distribution in the tested product. By combining spatial and spectral details together, hyperspectral imaging has proved to be a promising technology for objective meat quality evaluation. The literature presented in this paper clearly reveals that hyperspectral imaging approaches have a huge potential for gaining rapid information about the chemical structure and related physical properties of all types of meat. In addition to its ability for effectively quantifying and characterizing quality attributes of some important visual features of meat such as color, quality grade, marbling, maturity, and texture, it is able to measure multiple chemical constituents simultaneously without monotonous sample preparation. Although this technology has not yet been sufficiently exploited in meat process and quality assessment, its potential is promising. Developing a quality evaluation system based on hyperspectral imaging technology to assess the meat quality parameters and to ensure its authentication would bring economical benefits to the meat industry by increasing consumer confidence in the quality of the meat products. This paper provides a detailed overview of the recently developed approaches and latest research efforts exerted in hyperspectral imaging technology developed for evaluating the quality of different meat products and the possibility of its widespread

  15. Total Variation Based Perceptual Image Quality Assessment Modeling

    Directory of Open Access Journals (Sweden)

    Yadong Wu

    2014-01-01

    Full Text Available Visual quality measure is one of the fundamental and important issues to numerous applications of image and video processing. In this paper, based on the assumption that human visual system is sensitive to image structures (edges and image local luminance (light stimulation, we propose a new perceptual image quality assessment (PIQA measure based on total variation (TV model (TVPIQA in spatial domain. The proposed measure compares TVs between a distorted image and its reference image to represent the loss of image structural information. Because of the good performance of TV model in describing edges, the proposed TVPIQA measure can illustrate image structure information very well. In addition, the energy of enclosed regions in a difference image between the reference image and its distorted image is used to measure the missing luminance information which is sensitive to human visual system. Finally, we validate the performance of TVPIQA measure with Cornell-A57, IVC, TID2008, and CSIQ databases and show that TVPIQA measure outperforms recent state-of-the-art image quality assessment measures.

  16. Biofilm increases permeate quality by organic carbon degradation in low pressure ultrafiltration.

    Science.gov (United States)

    Chomiak, A; Traber, J; Morgenroth, E; Derlon, N

    2015-11-15

    We investigated the influence of biofouling of ultrafiltration membranes on the removal of organic model foulants and ultimately on the quality of permeate. Gravity Driven Membrane ultrafiltration (GDM) membrane systems were operated with modified river water during five weeks without control of the biofilm formation. Three GDM systems were studied: two systems with biofilms exposed to (A) variable or (B) constant load of organic foulants, and (C) one system operated without biofilm and exposed to constant foulant loading. Biodegradable dextran or non-biodegradable polystyrene sulfonate model foulants were tested. Substrate biodegradability was confirmed by Size Exclusion Chromatography (SEC) and by degradation batch tests (D). The GDM systems (A) and (B) were fed with pre-filtered river water supplemented with dextran (Dex) of 1, 150 or 2000 kDa, or polystyrene sulfonate (PSS) of 1 or 80 kDa at concentrations of 2-3.5 mgC L(-1). In exp. (C) the feed water consisted of deionized water with 25 mgC L(-1) of either PSS 1, 80 kDa or Dex 2000 kDa. The biofilm formation on UF membrane surfaces controlled the foulant permeation and thus the permeate quality. Biofilms exposed to continuous foulant loading (exp. B) degraded low molecular weight (LMW) biodegradable foulants (1 kDa Dex), which improved the permeate quality. For high molecular weight (HMW) substrates (150, 2000 kDa Dex), the improvement of the permeate quality was observed after 7 days of biofilm formation, and resulted from the foulant hydrolysis followed by degradation. For non-biodegradable foulants, an improvement of 20% of the retention was observed for the polystyrene (1, 80 kDa PSS) due to the presence of biofilms on membrane surfaces. For variable foulant loading (exp. A) the biofilms hydrolysed the large biodegradable foulants but did not degraded them fully, which resulted a deterioration of the permeate quality (except for the LMW dextran (1 kDa) that was fully degraded). Overall, the "biofilm

  17. Method and tool for generating and managing image quality allocations through the design and development process

    Science.gov (United States)

    Sparks, Andrew W.; Olson, Craig; Theisen, Michael J.; Addiego, Chris J.; Hutchins, Tiffany G.; Goodman, Timothy D.

    2016-05-01

    Performance models for infrared imaging systems require image quality parameters; optical design engineers need image quality design goals; systems engineers develop image quality allocations to test imaging systems against. It is a challenge to maintain consistency and traceability amongst the various expressions of image quality. We present a method and parametric tool for generating and managing expressions of image quality during the system modeling, requirements specification, design, and testing phases of an imaging system design and development project.

  18. SEGMENTATION AND QUALITY ANALYSIS OF LONG RANGE CAPTURED IRIS IMAGE

    Directory of Open Access Journals (Sweden)

    Anand Deshpande

    2016-05-01

    Full Text Available The iris segmentation plays a major role in an iris recognition system to increase the performance of the system. This paper proposes a novel method for segmentation of iris images to extract the iris part of long range captured eye image and an approach to select best iris frame from the iris polar image sequences by analyzing the quality of iris polar images. The quality of iris image is determined by the frequency components present in the iris polar images. The experiments are carried out on CASIA-long range captured iris image sequences. The proposed segmentation method is compared with Hough transform based segmentation and it has been determined that the proposed method gives higher accuracy for segmentation than Hough transform.

  19. Brain imaging with synthetic MR in children: clinical quality assessment

    Energy Technology Data Exchange (ETDEWEB)

    Betts, Aaron M.; Serai, Suraj [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Leach, James L.; Jones, Blaise V. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); University of Cincinnati College of Medicine, Cincinnati, OH (United States); Zhang, Bin [Cincinnati Children' s Hospital Medical Center, Biostatistics and Epidemiology, Cincinnati, OH (United States)

    2016-10-15

    Synthetic magnetic resonance imaging is a quantitative imaging technique that measures inherent T1-relaxation, T2-relaxation, and proton density. These inherent tissue properties allow synthesis of various imaging sequences from a single acquisition. Clinical use of synthetic MR imaging has been described in adult populations. However, use of synthetic MR imaging has not been previously reported in children. The purpose of this study is to report our assessment of diagnostic image quality using synthetic MR imaging in children. Synthetic MR acquisition was obtained in a sample of children undergoing brain MR imaging. Image quality assessments were performed on conventional and synthetic T1-weighted, T2-weighted, and FLAIR images. Standardized linear measurements were performed on conventional and synthetic T2 images. Estimates of patient age based upon myelination patterns were also performed. Conventional and synthetic MR images were evaluated on 30 children. Using a 4-point assessment scale, conventional imaging performed better than synthetic imaging for T1-weighted, T2-weighted, and FLAIR images. When the assessment was simplified to a dichotomized scale, the conventional and synthetic T1-weighted and T2-weighted images performed similarly. However, the superiority of conventional FLAIR images persisted in the dichotomized assessment. There were no statistically significant differences between linear measurements made on T2-weighted images. Estimates of patient age based upon pattern of myelination were also similar between conventional and synthetic techniques. Synthetic MR imaging may be acceptable for clinical use in children. However, users should be aware of current limitations that could impact clinical utility in the software version used in this study. (orig.)

  20. Assessment of CT image quality using a Bayesian approach

    Science.gov (United States)

    Reginatto, M.; Anton, M.; Elster, C.

    2017-08-01

    One of the most promising approaches for evaluating CT image quality is task-specific quality assessment. This involves a simplified version of a clinical task, e.g. deciding whether an image belongs to the class of images that contain the signature of a lesion or not. Task-specific quality assessment can be done by model observers, which are mathematical procedures that carry out the classification task. The most widely used figure of merit for CT image quality is the area under the ROC curve (AUC), a quantity which characterizes the performance of a given model observer. In order to estimate AUC from a finite sample of images, different approaches from classical statistics have been suggested. The goal of this paper is to introduce task-specific quality assessment of CT images to metrology and to propose a novel Bayesian estimation of AUC for the channelized Hotelling observer (CHO) applied to the task of detecting a lesion at a known image location. It is assumed that signal-present and signal-absent images follow multivariate normal distributions with the same covariance matrix. The Bayesian approach results in a posterior distribution for the AUC of the CHO which provides in addition a complete characterization of the uncertainty of this figure of merit. The approach is illustrated by its application to both simulated and experimental data.

  1. Quality Evaluation and Nonuniform Compression of Geometrically Distorted Images Using the Quadtree Distortion Map

    Directory of Open Access Journals (Sweden)

    Cristina Costa

    2004-09-01

    Full Text Available The paper presents an analysis of the effects of lossy compression algorithms applied to images affected by geometrical distortion. It will be shown that the encoding-decoding process results in a nonhomogeneous image degradation in the geometrically corrected image, due to the different amount of information associated to each pixel. A distortion measure named quadtree distortion map (QDM able to quantify this aspect is proposed. Furthermore, QDM is exploited to achieve adaptive compression of geometrically distorted pictures, in order to ensure a uniform quality on the final image. Tests are performed using JPEG and JPEG2000 coding standards in order to quantitatively and qualitatively assess the performance of the proposed method.

  2. Evaluating Picture Quality of Image Plates in Digital CR Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Byung Joon [Dept. of Radiological Tecnology, Choonhae College of Health Science, Ulsan (Korea, Republic of); Ji Tae Jeong [Dept. of Radiological Science, Kaya University, Kimhae (Korea, Republic of)

    2011-12-15

    Lab effectively supplemented the effects of outside radiation on image plates in the process of image acquisition of CR (computed radiography) systems and conducted for effective utilization in the case of clinical application. For this, Lab classified the storage places and time periods of image plates and compared and analyzed the differences between small dark spots. Lab also assessed the concentration distribution within the boundaries of images. Lab compared and measured the number of dark spots in a light room and a dark room depending on the storage places of image plates and found that dark spots slightly increased in an image plate when stored in a light room on the first and second days. Dark spots increased in proportion to the length of time stored. In the case of the image plate stored in a dark room, the number of dark spots remarkably decreased. With regard to picture quality as related to the location of image plates, the damage to picture quality could be reduced by locating regions of interest in the center. With regard to differences in sharpness following changes in the thickness of subjects, fewer scatter rays occurred and sharpness improved by reducing the thickness of subjects as much as possible. To get medical images of excellent quality, image plates should be managed effectively and it is desirable to keep images plates in dark iron plate boxes and not to expose them to outside radiation for a long time.

  3. Spectral CT in patients with small HCC: investigation of image quality and diagnostic accuracy

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Peijie; Gao, Jianbo [The First Affiliated Hospital of Zhengzhou University, The Department of Radiology, Zhengzhou, Henan Province (China); Lin, Xiao Zhu; Chen, Kemin [Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai (China)

    2012-10-15

    To assess image quality and diagnostic accuracy of monochromatic imaging from spectral CT in patients with small HCC ({<=}3 cm). Twenty-seven patients with 31 HCC underwent spectral CT to generate conventional 140-kVp polychromatic images (group A) and monochromatic images with energy levels from 40 to 140 keV (group B) during the late arterial phase (LAP) and the portal venous phase (PVP). Two-sample t tests compared the tumour-to-liver contrast-to-noise ratio (CNR) and mean image noise. Lesion detection for LAP, reader confidence and readers' subjective evaluations of image quality were recorded. Highest CNRs in group B were distributed at 40, 50 and 70 keV. Higher CNR values and lesion conspicuity scores (LCS) were obtained in group B than in group A (CNR 3.36 {+-} 2.07 vs. 1.47 {+-} 0.89 in LAP; 2.29 {+-} 2.26 vs. 1.58 {+-} 1.75 in PVP; LCS 2.82, 2.84, 2.63 and 2.53 at 40-70 keV, respectively, vs. 1.95) (P < 0.001). Lowest image noise for group B was at 70 keV, resulting in higher image quality than that in group A (4.70 vs. 4.07; P < 0.001). Monochromatic energy levels of 40-70 keV can increase detectability in small HCC and this increase might not result in image quality degradation. (orig.)

  4. The Image Quality Translator – A Way to Support Specification of Imaging Requirements

    DEFF Research Database (Denmark)

    Kejser, Ulla Bøgvad; Bech, Mogens

    2015-01-01

    Archives, libraries, and museums run numerous imaging projects to digitize physical works and collections of cultural heritage. This study presents a tool called the 'Image Quality Translator' that is being designed at the Royal Library to support the planning of digitization projects and to make...... the process of specifying and controlling imaging requirements more efficient. The tool seeks to translate between the language used by collection managers and curators to express needs for image quality, and the more technical terms and metrics used by imaging experts and photographers to express...... the requirements for the performance of imaging systems....

  5. Digital radiography: image quality and radiation dose.

    Science.gov (United States)

    Seibert, J Anthony

    2008-11-01

    Digital radiography devices, rapidly replacing analog screen-film detectors, are now common in diagnostic radiological imaging, where implementation has been accelerated by the commodity status of electronic imaging and display systems. The shift from narrow latitude, fixed-speed screen-film detectors to wide latitude, variable-speed digital detectors has created a flexible imaging system that can easily result in overexposures to the patient without the knowledge of the operator, thus potentially increasing the radiation burden of the patient population from radiographic examinations. In addition, image processing can be inappropriately applied causing inconsistent or artifactual appearance of anatomy, which can lead to misdiagnosis. On the other hand, many advantages can be obtained from the variable-speed digital detector, such as an ability to lower dose in many examinations, image post-processing for disease-specific conditions, display flexibility to change the appearance of the image and aid the physician in making a differential diagnosis, and easy access to digital images. An understanding of digital radiography is necessary to minimize the possibility of overexposures and inconsistent results, and to achieve the principle of as low as reasonably achievable (ALARA) for the safe and effective care of all patients. Thus many issues must be considered for optimal implementation of digital radiography, as reviewed in this article.

  6. Perceived no reference image quality measurement for chromatic aberration

    Science.gov (United States)

    Lamb, Anupama B.; Khambete, Madhuri

    2016-03-01

    Today there is need for no reference (NR) objective perceived image quality measurement techniques as conducting subjective experiments and making reference image available is a very difficult task. Very few NR perceived image quality measurement algorithms are available for color distortions like chromatic aberration (CA), color quantization with dither, and color saturation. We proposed NR image quality assessment (NR-IQA) algorithms for images distorted with CA. CA is mostly observed in images taken with digital cameras, having higher sensor resolution with inexpensive lenses. We compared our metric performance with two state-of-the-art NR blur techniques, one full reference IQA technique and three general-purpose NR-IQA techniques, although they are not tailored for CA. We used a CA dataset in the TID-2013 color image database to evaluate performance. Proposed algorithms give comparable performance with state-of-the-art techniques in terms of performance parameters and outperform them in terms of monotonicity and computational complexity. We have also discovered that the proposed CA algorithm best predicts perceived image quality of images distorted with realistic CA.

  7. Optimisation of patient protection and image quality in diagnostic ...

    African Journals Online (AJOL)

    Optimisation of patient protection and image quality in diagnostic radiology. ... The study leads to the introduction of the concept of plan- do-check-act on QC results ... (QA) programme and continues to collect data for establishment of DRL's.

  8. Multivariate image analysis for quality inspection in fish feed production

    DEFF Research Database (Denmark)

    Ljungqvist, Martin Georg

    , or synthesised chemically. Common for both types is that they are relatively expensive in comparison to the other feed ingredients. This thesis investigates multi-variate data collection for visual inspection and optimisation of industrial production in the fish feed industry. Quality parameters focused on here...... are: pellet size, type and concentration level of astaxanthin in pellet coating, as well as astaxanthin type detected in salmonid fish. Methods used are three different devices for multi- and hyper-spectral imaging, together with shape analysis and multi-variate statistical analysis. The results...... of the work demonstrate a high potential of image analysis and spectral imaging for assessing the product quality of fish feed pellets, astaxanthin and fish meat. We show how image analysis can be used to inspect the pellet size, and how spectral imaging can be used to inspect the surface quality...

  9. Dosimetry and image quality assessment in a direct radiography system

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Bruno Beraldo; Paixao, Lucas; Nogueira, Maria do Socorro, E-mail: boliveira.mg@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Oliveira, Marcio Alves de [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Fac. de Medicina. Dept. de Anatomia e Imagem; Teixeira, Maria Helena Araujo [Clinica Dra. Maria Helena Araujo Teixeira, Belo Horizonte, MG (Brazil)

    2014-11-15

    Objective: to evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms. Materials and methods: Irradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms. Results: considering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values. Conclusion: the present study contributes to verify the equipment conformity as regards dose values and image quality. (author)

  10. Web-based psychometric evaluation of image quality

    Science.gov (United States)

    Sprow, Iris; Baranczuk, Zofia; Stamm, Tobias; Zolliker, Peter

    2009-01-01

    The measurement of image quality requires the judgement by the human visual system. This paper describes a psycho-visual test technique that uses the internet as a test platform to identify image quality in a more time-effective manner, comparing the visual response data with the results from the same test in a lab-based environment and estimate the usefulness of the internet as a platform for scaling studies.

  11. Effect of degrading yellow oxo-biodegradable low-density polyethylene films to water quality

    Science.gov (United States)

    Requejo, B. A.; Pajarito, B. B.

    2017-05-01

    Polyethylene (PE) contributes largely to plastic wastes that are disposed in aquatic environment as a consequence of its widespread use. In this study, yellow oxo-biodegradable low-density PE films were immersed in deionized water at 50°C for 49 days. Indicators of water quality: pH, oxidation-reduction potential, turbidity, and total dissolved solids (TDS), were monitored at regular intervals. It was observed that pH initially rises and then slowly decreases with time, oxidation-reduction potential decreases then slowly increases with time, turbidity rises above the control at varied rates, and TDS increases abruptly and rises at a hindered rate. Moreover, the films potentially leach out lead chromate. The results imply that degrading oxo-biodegradable LDPE films results to significant reduction of water quality.

  12. Bio-degradable highly fluorescent conjugated polymer nanoparticles for bio-medical imaging applications.

    Science.gov (United States)

    Repenko, Tatjana; Rix, Anne; Ludwanowski, Simon; Go, Dennis; Kiessling, Fabian; Lederle, Wiltrud; Kuehne, Alexander J C

    2017-09-07

    Conjugated polymer nanoparticles exhibit strong fluorescence and have been applied for biological fluorescence imaging in cell culture and in small animals. However, conjugated polymer particles are hydrophobic and often chemically inert materials with diameters ranging from below 50 nm to several microns. As such, conjugated polymer nanoparticles cannot be excreted through the renal system. This drawback has prevented their application for clinical bio-medical imaging. Here, we present fully conjugated polymer nanoparticles based on imidazole units. These nanoparticles can be bio-degraded by activated macrophages. Reactive oxygen species induce scission of the conjugated polymer backbone at the imidazole unit, leading to complete decomposition of the particles into soluble low molecular weight fragments. Furthermore, the nanoparticles can be surface functionalized for directed targeting. The approach opens a wide range of opportunities for conjugated polymer particles in the fields of medical imaging, drug-delivery, and theranostics.Conjugated polymer nanoparticles have been applied for biological fluorescence imaging in cell culture and in small animals, but cannot readily be excreted through the renal system. Here the authors show fully conjugated polymer nanoparticles based on imidazole units that can be bio-degraded by activated macrophages.

  13. MATLAB-based Applications for Image Processing and Image Quality Assessment – Part II: Experimental Results

    Directory of Open Access Journals (Sweden)

    L. Krasula

    2012-04-01

    Full Text Available The paper provides an overview of some possible usage of the software described in the Part I. It contains the real examples of image quality improvement, distortion simulations, objective and subjective quality assessment and other ways of image processing that can be obtained by the individual applications.

  14. Image Quality Modeling and Optimization for Non-Conventional Aperture Imaging Systems

    Science.gov (United States)

    Salvaggio, Philip S.

    The majority of image quality studies have been performed on systems with conventional aperture functions. These systems have straightforward aperture designs and well-understood behavior. Image quality for these systems can be predicted by the General Image Quality Equation (GIQE). However, in order to continue pushing the boundaries of imaging, more control over the point spread function of an imaging system may be necessary. This requires modifications in the pupil plane of a system, causing a departure from the realm of most image quality studies. Examples include sparse apertures, synthetic apertures, coded apertures and phase elements. This work will focus on sparse aperture telescopes and the image quality issues associated with them, however, the methods presented will be applicable to other non-conventional aperture systems. In this research, an approach for modeling the image quality of non-conventional aperture systems will be introduced. While the modeling approach is based in previous work, a novel validation study will be performed, which accounts for the effects of both broadband illumination and wavefront error. One of the key image quality challenges for sparse apertures is post-processing ringing artifacts. These artifacts have been observed in modeled data, but a validation study will be performed to observe them in measured data and to compare them to model predictions. Once validated, the modeling approach will be used to perform a small set of design studies for sparse aperture systems, including spectral bandpass selection and aperture layout optimization.

  15. A Methodology for Anatomic Ultrasound Image Diagnostic Quality Assessment

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Lange, Theis; Brandt, Andreas Hjelm

    2017-01-01

    is valuable in the continuing process of method optimization and guided development of new imaging methods. It includes a three phased study plan covering from initial prototype development to clinical assessment. Recommendations to the clinical assessment protocol, software, and statistical analysis......This paper discusses methods for assessment of ultrasound image quality based on our experiences with evaluating new methods for anatomic imaging. It presents a methodology to ensure a fair assessment between competing imaging methods using clinically relevant evaluations. The methodology...... to properly reveal the clinical value. The paper exemplifies the methodology using recent studies of Synthetic Aperture Sequential Beamforming tissue harmonic imaging....

  16. ANALYSIS OF THE EFFECTS OF IMAGE QUALITY ON DIGITAL MAP GENERATION FROM SATELLITE IMAGES

    Directory of Open Access Journals (Sweden)

    H. Kim

    2012-07-01

    Full Text Available High resolution satellite images are widely used to produce and update a digital map since they became widely available. It is well known that the accuracy of digital map produced from satellite images is decided largely by the accuracy of geometric modelling. However digital maps are made by a series of photogrammetric workflow. Therefore the accuracy of digital maps are also affected by the quality of satellite images, such as image interpretability. For satellite images, parameters such as Modulation Transfer Function(MTF, Signal to Noise Ratio(SNR and Ground Sampling Distance(GSD are used to present images quality. Our previous research stressed that such quality parameters may not represent the quality of image products such as digital maps and that parameters for image interpretability such as Ground Resolved Distance(GRD and National Imagery Interpretability Rating Scale(NIIRS need to be considered. In this study, we analyzed the effects of the image quality on accuracy of digital maps produced by satellite images. QuickBird, IKONOS and KOMPSAT-2 imagery were used to analyze as they have similar GSDs. We measured various image quality parameters mentioned above from these images. Then we produced digital maps from the images using a digital photogrammetric workstation. We analyzed the accuracy of the digital maps in terms of their location accuracy and their level of details. Then we compared the correlation between various image quality parameters and the accuracy of digital maps. The results of this study showed that GRD and NIIRS were more critical for map production then GSD, MTF or SNR.

  17. Age estimation under changes in image quality: An experimental study

    NARCIS (Netherlands)

    Alnajar, F.; Gevers, T.; Karaoglu, S.

    2015-01-01

    In this paper, we investigate the influence of image quality on the performance of aging features. Age estimation systems used or designed a number of aging features to capture the aging cues from the face such as skin texture and wrinkles. These aging cues are sensitive to small changes in the imag

  18. Chemometrics in multispectral imaging for quality inspection of postharvest products

    NARCIS (Netherlands)

    Noordam, Jan Corstiaan

    2005-01-01

    This thesis describes different novel chemometric techniques applied to multispectral images for quality inspection on agricultural food products. These images do not only have a huge number of spectral bands which makes training set selection a challenging task, they also contain classes with small

  19. A review of image quality assessment methods with application to computational photography

    Science.gov (United States)

    Maître, Henri

    2015-12-01

    Image quality assessment has been of major importance for several domains of the industry of image as for instance restoration or communication and coding. New application fields are opening today with the increase of embedded power in the camera and the emergence of computational photography: automatic tuning, image selection, image fusion, image data-base building, etc. We review the literature of image quality evaluation. We pay attention to the very different underlying hypotheses and results of the existing methods to approach the problem. We explain why they differ and for which applications they may be beneficial. We also underline their limits, especially for a possible use in the novel domain of computational photography. Being developed to address different objectives, they propose answers on different aspects, which make them sometimes complementary. However, they all remain limited in their capability to challenge the human expert, the said or unsaid ultimate goal. We consider the methods which are based on retrieving the parameters of a signal, mostly in spectral analysis; then we explore the more global methods to qualify the image quality in terms of noticeable defects or degradation as popular in the compression domain; in a third field the image acquisition process is considered as a channel between the source and the receiver, allowing to use the tools of the information theory and to qualify the system in terms of entropy and information capacity. However, these different approaches hardly attack the most difficult part of the task which is to measure the quality of the photography in terms of aesthetic properties. To help in addressing this problem, in between Philosophy, Biology and Psychology, we propose a brief review of the literature which addresses the problematic of qualifying Beauty, present the attempts to adapt these concepts to visual patterns and initiate a reflection on what could be done in the field of photography.

  20. A feature-enriched completely blind image quality evaluator.

    Science.gov (United States)

    Lin Zhang; Lei Zhang; Bovik, Alan C

    2015-08-01

    Existing blind image quality assessment (BIQA) methods are mostly opinion-aware. They learn regression models from training images with associated human subjective scores to predict the perceptual quality of test images. Such opinion-aware methods, however, require a large amount of training samples with associated human subjective scores and of a variety of distortion types. The BIQA models learned by opinion-aware methods often have weak generalization capability, hereby limiting their usability in practice. By comparison, opinion-unaware methods do not need human subjective scores for training, and thus have greater potential for good generalization capability. Unfortunately, thus far no opinion-unaware BIQA method has shown consistently better quality prediction accuracy than the opinion-aware methods. Here, we aim to develop an opinion-unaware BIQA method that can compete with, and perhaps outperform, the existing opinion-aware methods. By integrating the features of natural image statistics derived from multiple cues, we learn a multivariate Gaussian model of image patches from a collection of pristine natural images. Using the learned multivariate Gaussian model, a Bhattacharyya-like distance is used to measure the quality of each image patch, and then an overall quality score is obtained by average pooling. The proposed BIQA method does not need any distorted sample images nor subjective quality scores for training, yet extensive experiments demonstrate its superior quality-prediction performance to the state-of-the-art opinion-aware BIQA methods. The MATLAB source code of our algorithm is publicly available at www.comp.polyu.edu.hk/~cslzhang/IQA/ILNIQE/ILNIQE.htm.

  1. Beef quality parameters estimation using ultrasound and color images

    OpenAIRE

    Nunes, Jose Luis; Piquerez, Martín; Pujadas, Leonardo; Armstrong,Eileen; Alicia FERNÁNDEZ; Lecumberry, Federico

    2015-01-01

    Background Beef quality measurement is a complex task with high economic impact. There is high interest in obtaining an automatic quality parameters estimation in live cattle or post mortem. In this paper we set out to obtain beef quality estimates from the analysis of ultrasound (in vivo) and color images (post mortem), with the measurement of various parameters related to tenderness and amount of meat: rib eye area, percentage of intramuscular fat and backfat thickness or subcutaneous fat. ...

  2. Beef quality parameters estimation using ultrasound and color images

    OpenAIRE

    Nunes, Jose Luis; Piquerez, Mart?n; Pujadas, Leonardo; Armstrong,Eileen; Fern?ndez, Alicia; Lecumberry, Federico

    2015-01-01

    Background Beef quality measurement is a complex task with high economic impact. There is high interest in obtaining an automatic quality parameters estimation in live cattle or post mortem. In this paper we set out to obtain beef quality estimates from the analysis of ultrasound (in vivo) and color images (post mortem), with the measurement of various parameters related to tenderness and amount of meat: rib eye area, percentage of intramuscular fat and backfat thickness or subcutaneous fat. ...

  3. Learning Sparse Representation for Objective Image Retargeting Quality Assessment.

    Science.gov (United States)

    Jiang, Qiuping; Shao, Feng; Lin, Weisi; Jiang, Gangyi

    2017-04-13

    The goal of image retargeting is to adapt source images to target displays with different sizes and aspect ratios. Different retargeting operators create different retargeted images, and a key problem is to evaluate the performance of each retargeting operator. Subjective evaluation is most reliable, but it is cumbersome and labor-consuming, and more importantly, it is hard to be embedded into online optimization systems. This paper focuses on exploring the effectiveness of sparse representation for objective image retargeting quality assessment. The principle idea is to extract distortion sensitive features from one image (e.g., retargeted image) and further investigate how many of these features are preserved or changed in another one (e.g., source image) to measure the perceptual similarity between them. To create a compact and robust feature representation, we learn two overcomplete dictionaries to represent the distortion sensitive features of an image. Features including local geometric structure and global context information are both addressed in the proposed framework. The intrinsic discriminative power of sparse representation is then exploited to measure the similarity between the source and retargeted images. Finally, individual quality scores are fused into an overall quality by a typical regression method. Experimental results on several databases have demonstrated the superiority of the proposed method.

  4. Optimized Plane Wave Imaging for Fast and High-Quality Ultrasound Imaging

    DEFF Research Database (Denmark)

    Jensen, Jonas; Stuart, Matthias Bo; Jensen, Jørgen Arendt

    2016-01-01

    This paper presents a method for optimizing parameters affecting the image quality in plane wave imaging. More specifically, the number of emissions and steering angles is optimized to attain the best images with the highest frame rate possible. The method is applied to a specific problem, where ...

  5. Quality assessment of butter cookies applying multispectral imaging

    DEFF Research Database (Denmark)

    Stenby Andresen, Mette; Dissing, Bjørn Skovlund; Løje, Hanne

    2013-01-01

    A method for characterization of butter cookie quality by assessing the surface browning and water content using multispectral images is presented. Based on evaluations of the browning of butter cookies, cookies were manually divided into groups. From this categorization, reference values were...... in a forced convection electrically heated oven. In addition to the browning score, a model for predicting the average water content based on the same images is presented. This shows how multispectral images of butter cookies may be used for the assessment of different quality parameters. Statistical analysis...

  6. [Image quality from direct radiological magnification (author's transl)].

    Science.gov (United States)

    Franken, T; Borcke, E

    1980-03-01

    An assessment of image quality from a direct radiological magnification method with a microfocus was carried out. It was found that direct magnification has advantages for the magnification of thin objects (5 cm. thickness). Because of the marked radiation scarrer in thick objects an improvement in picture quality is not possible. Scatter, despite the Groedel effect, is too large. Optimum results are obtained with a microfocus tube using universal screens. Comparable image quality is not possible with high intensification screens. High definition screens are not suitable for magnification. Dose measurements revealed unexpectedly low levels, particularly for thin objects. The reasons for this were examined and are described.

  7. Image quality and radiation dose in cardiac imaging

    NARCIS (Netherlands)

    Dijk, van Joris David

    2016-01-01

    Coronary artery disease is a major cause of death accounting for 8% of all deaths in the Netherlands. This disease can be detected in an early stage by cardiac imaging. However, this detection comes at the price of a relatively high radiation dose which is potentially harmful for the patient. Despit

  8. Image quality and radiation dose in cardiac imaging

    NARCIS (Netherlands)

    van Dijk, Joris David

    2016-01-01

    Coronary artery disease is a major cause of death accounting for 8% of all deaths in the Netherlands. This disease can be detected in an early stage by cardiac imaging. However, this detection comes at the price of a relatively high radiation dose which is potentially harmful for the patient.

  9. Standardization of Image Quality Analysis – ISO 19264

    DEFF Research Database (Denmark)

    Kejser, Ulla Bøgvad; Wüller, Dietmar

    2016-01-01

    There are a variety of image quality analysis tools available for the archiving world, which are based on different test charts and analysis algorithms. ISO has formed a working group in 2012 to harmonize these approaches and create a standard way of analyzing the image quality for archiving...... systems. This has resulted in three documents that have been or are going to be published soon. ISO 19262 defines the terms used in the area of image capture to unify the language. ISO 19263 describes the workflow issues and provides detailed information on how the measurements are done. Last...... but not least ISO 19264 describes the measurements in detail and provides aims and tolerance levels for the different aspects. This paper will present the new ISO 19264 technical specification to analyze image quality based on a single capture of a multi-pattern test chart, and discuss the reasoning behind its...

  10. Standardization of Image Quality Analysis – ISO 19264

    DEFF Research Database (Denmark)

    Kejser, Ulla Bøgvad; Wüller, Dietmar

    2016-01-01

    There are a variety of image quality analysis tools available for the archiving world, which are based on different test charts and analysis algorithms. ISO has formed a working group in 2012 to harmonize these approaches and create a standard way of analyzing the image quality for archiving...... systems. This has resulted in three documents that have been or are going to be published soon. ISO 19262 defines the terms used in the area of image capture to unify the language. ISO 19263 describes the workflow issues and provides detailed information on how the measurements are done. Last...... but not least ISO 19264 describes the measurements in detail and provides aims and tolerance levels for the different aspects. This paper will present the new ISO 19264 technical specification to analyze image quality based on a single capture of a multi-pattern test chart, and discuss the reasoning behind its...

  11. Surface Investigation of Photo-Degraded Wood by Colour Monitoring, Infrared Spectroscopy, and Hyperspectral Imaging

    Directory of Open Access Journals (Sweden)

    Giorgia Agresti

    2013-01-01

    Full Text Available The aim of this investigation is to study the changes occurring on the surface of poplar wood exposed to artificial irradiation in a Solar Box. Colour changes were monitored with a reflectance spectrophotometer. Surface chemical modifications were evaluated by measuring the infrared spectra. Hyperspectral imaging was also applied to study the surface wood changes in the visible-near infrared and the short wave infrared wavelength ranges. The data obtained from the different techniques were compared to find the possible correlations in order to evaluate the applicability of the Hyperspectral imaging to investigate wood modifications in a non-invasive modality. The study of colour changes showed an important variation due to photo-irradiation which is the greatest change occurring within the first 24 hours. Infrared spectroscopy revealed that lignin degrades mainly in the first 48 hours. Concerning Hyperspectral imaging, the spectral features in the visible-near infrared range are mainly linked to the spectral shape, whereas in the short wave infrared cellulose and lignin affect shape and reflectance levels. The proposed approach showed that a correlation can be established between colour variation and wood degradation in the visible-near infrared range; furthermore in the short wave infrared region surface chemical changes can be assessed.

  12. Effects of image compression and degradation on an automatic diabetic retinopathy screening algorithm

    Science.gov (United States)

    Agurto, C.; Barriga, S.; Murray, V.; Pattichis, M.; Soliz, P.

    2010-03-01

    Diabetic retinopathy (DR) is one of the leading causes of blindness among adult Americans. Automatic methods for detection of the disease have been developed in recent years, most of them addressing the segmentation of bright and red lesions. In this paper we present an automatic DR screening system that does approach the problem through the segmentation of features. The algorithm determines non-diseased retinal images from those with pathology based on textural features obtained using multiscale Amplitude Modulation-Frequency Modulation (AM-FM) decompositions. The decomposition is represented as features that are the inputs to a classifier. The algorithm achieves 0.88 area under the ROC curve (AROC) for a set of 280 images from the MESSIDOR database. The algorithm is then used to analyze the effects of image compression and degradation, which will be present in most actual clinical or screening environments. Results show that the algorithm is insensitive to illumination variations, but high rates of compression and large blurring effects degrade its performance.

  13. Benchmarking the performance of fixed-image receptor digital radiographic systems part 1: a novel method for image quality analysis.

    Science.gov (United States)

    Lee, Kam L; Ireland, Timothy A; Bernardo, Michael

    2016-06-01

    This is the first part of a two-part study in benchmarking the performance of fixed digital radiographic general X-ray systems. This paper concentrates on reporting findings related to quantitative analysis techniques used to establish comparative image quality metrics. A systematic technical comparison of the evaluated systems is presented in part two of this study. A novel quantitative image quality analysis method is presented with technical considerations addressed for peer review. The novel method was applied to seven general radiographic systems with four different makes of radiographic image receptor (12 image receptors in total). For the System Modulation Transfer Function (sMTF), the use of grid was found to reduce veiling glare and decrease roll-off. The major contributor in sMTF degradation was found to be focal spot blurring. For the System Normalised Noise Power Spectrum (sNNPS), it was found that all systems examined had similar sNNPS responses. A mathematical model is presented to explain how the use of stationary grid may cause a difference between horizontal and vertical sNNPS responses.

  14. Image quality improvement for underground radar by block migration method

    Science.gov (United States)

    Ho, Gwangsu; Kawanaka, Akira; Takagi, Mikio

    1993-11-01

    Techniques have been developed which have been imaging optically opaque regions using an electromagnetic wave radar in order to estimate the location of the objects in those regions. One important application of these techniques is the detection of buried pipes and cables. In the case of underground radar, its image quality often becomes low because the nature of the soil is not uniform and an electromagnetic wave is attenuated in soil. Hence, the method which improves the quality of the radar images is required. In this paper, we point out that the quality of underground images can be improved significantly by means of the block migration method. In this method LOT (Lapped Orthogonal Transform) was applied. LOT is a new block transform method in which basis functions overlap in adjacent blocks, and it has a fast computation algorithm. In addition to above, we propose a method of estimating dielectric constant in soil using the processed images. The result of applying the block migration method to the underground radar images are presented. It points out the good capability for the image quality improvement and the application of LOT can improve the influence by blocking and the processing time. Also the dielectric constant in each block can be estimated accurately.

  15. Quantifying Image Quality Improvement Using Elevated Acoustic Output in B-Mode Harmonic Imaging.

    Science.gov (United States)

    Deng, Yufeng; Palmeri, Mark L; Rouze, Ned C; Trahey, Gregg E; Haystead, Clare M; Nightingale, Kathryn R

    2017-10-01

    Tissue harmonic imaging has been widely used in abdominal imaging because of its significant reduction in acoustic noise compared with fundamental imaging. However, tissue harmonic imaging can be limited by both signal-to-noise ratio and penetration depth during clinical imaging, resulting in decreased diagnostic utility. A logical approach would be to increase the source pressure, but the in situ pressures used in diagnostic ultrasound are subject to a de facto upper limit based on the U.S. Food and Drug Administration guideline for the mechanical index (tissues without gas bodies, but would only be justified if there were a concurrent improvement in image quality and diagnostic utility. This work evaluates image quality differences between normal and elevated acoustic output hepatic harmonic imaging using a transmit frequency of 1.8 MHz. The results indicate that harmonic imaging using elevated acoustic output leads to modest improvements (3%-7%) in contrast-to-noise ratio of hypo-echoic hepatic vessels and increases in imaging penetration depth on the order of 4 mm per mechanical index increase of 0.1 for a given focal depth. Difficult-to-image patients who suffer from poor ultrasound image quality exhibited larger improvements than easy-to-image study participants. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  16. Impairment-Factor-Based Audiovisual Quality Model for IPTV: Influence of Video Resolution, Degradation Type, and Content Type

    Directory of Open Access Journals (Sweden)

    Garcia MN

    2011-01-01

    Full Text Available This paper presents an audiovisual quality model for IPTV services. The model estimates the audiovisual quality of standard and high definition video as perceived by the user. The model is developed for applications such as network planning and packet-layer quality monitoring. It mainly covers audio and video compression artifacts and impairments due to packet loss. The quality tests conducted for model development demonstrate a mutual influence of the perceived audio and video quality, and the predominance of the video quality for the overall audiovisual quality. The balance between audio quality and video quality, however, depends on the content, the video format, and the audio degradation type. The proposed model is based on impairment factors which quantify the quality-impact of the different degradations. The impairment factors are computed from parameters extracted from the bitstream or packet headers. For high definition video, the model predictions show a correlation with unknown subjective ratings of 95%. For comparison, we have developed a more classical audiovisual quality model which is based on the audio and video qualities and their interaction. Both quality- and impairment-factor-based models are further refined by taking the content-type into account. At last, the different model variants are compared with modeling approaches described in the literature.

  17. Characterization of the image quality in neutron radioscopy

    Science.gov (United States)

    Brunner, J.; Engelhardt, M.; Frei, G.; Gildemeister, A.; Lehmann, E.; Hillenbach, A.; Schillinger, B.

    2005-04-01

    Neutron radioscopy, or dynamic neutron radiography, is a non-destructive testing method, which has made big steps in the last years. Depending on the neutron flux, the object and the detector, for single events a time resolution down to a few milliseconds is possible. In the case of repetitive processes the object can be synchronized with the detector and better statistics in the image can be reached by adding radiographies of the same phase with a time resolution down to 100 μs. By stepwise delaying the trigger signal a radiography movie can be composed. Radiography images of a combustion engine and an injection nozzle were evaluated quantitatively by different methods trying to characterize the image quality of an imaging system. The main factors which influence the image quality are listed and discussed.

  18. Automated Selection of Uniform Regions for CT Image Quality Detection

    CERN Document Server

    Naeemi, Maitham D; Roychodhury, Sohini

    2016-01-01

    CT images are widely used in pathology detection and follow-up treatment procedures. Accurate identification of pathological features requires diagnostic quality CT images with minimal noise and artifact variation. In this work, a novel Fourier-transform based metric for image quality (IQ) estimation is presented that correlates to additive CT image noise. In the proposed method, two windowed CT image subset regions are analyzed together to identify the extent of variation in the corresponding Fourier-domain spectrum. The two square windows are chosen such that their center pixels coincide and one window is a subset of the other. The Fourier-domain spectral difference between these two sub-sampled windows is then used to isolate spatial regions-of-interest (ROI) with low signal variation (ROI-LV) and high signal variation (ROI-HV), respectively. Finally, the spatial variance ($var$), standard deviation ($std$), coefficient of variance ($cov$) and the fraction of abdominal ROI pixels in ROI-LV ($\

  19. Design and analysis of algorithms for enhancing the quality and the resolution of Dubai Sat-1 images

    Science.gov (United States)

    Al-Mansoori, Saeed

    2011-11-01

    DubaiSat-1 (DS1) captures multispectral images with 5-meter resolution using three visible bands red (420 to 510 nm), green (510 to 580 nm), blue (600 to 720 nm) and one near-IR band (760 to 890 nm). It also has a panchromatic channel with 2.5-meter resolution (420 to 720 nm). [1] Under certain conditions, degradation in quality might occur over DS1 captured images. The aim of this project is to enhance the quality of the image in terms of resolution, sharpness and color quality. It is well known that the enhancement procedure is a very difficult task due to the significant noise increase resulted from any sharpening action. Moreover, sometimes the color of the captured images might become saturated, thus some areas will be given false coloring (i.e., some colors will be presented as gray instead of their original colors).

  20. Image quality in double- and triple-intensity ghost imaging with classical partially polarized light

    CERN Document Server

    Kellock, Henri; Shirai, Tomohiro; Friberg, Ari T

    2012-01-01

    Classical ghost imaging is a correlation-imaging technique in which the image of the object is found through intensity correlations of light. We analyze three different quality parameters, namely the visibility, the signal-to-noise ratio (SNR), and the contrast-to-noise ratio (CNR), to assess the performance of double- and triple-intensity correlation-imaging setups. The source is a random partially polarized beam of light obeying Gaussian statistics and the image quality is evaluated as a function of the degree of polarization (DoP). We show that the visibility improves when the DoP and the order of imaging increase, while the SNR behaves oppositely. The CNR is for the most part independent of DoP and the imaging order. The results are important for the development of new imaging devices using partially polarized light.

  1. Learning Receptive Fields and Quality Lookups for Blind Quality Assessment of Stereoscopic Images.

    Science.gov (United States)

    Shao, Feng; Lin, Weisi; Wang, Shanshan; Jiang, Gangyi; Yu, Mei; Dai, Qionghai

    2016-03-01

    Blind quality assessment of 3D images encounters more new challenges than its 2D counterparts. In this paper, we propose a blind quality assessment for stereoscopic images by learning the characteristics of receptive fields (RFs) from perspective of dictionary learning, and constructing quality lookups to replace human opinion scores without performance loss. The important feature of the proposed method is that we do not need a large set of samples of distorted stereoscopic images and the corresponding human opinion scores to learn a regression model. To be more specific, in the training phase, we learn local RFs (LRFs) and global RFs (GRFs) from the reference and distorted stereoscopic images, respectively, and construct their corresponding local quality lookups (LQLs) and global quality lookups (GQLs). In the testing phase, blind quality pooling can be easily achieved by searching optimal GRF and LRF indexes from the learnt LQLs and GQLs, and the quality score is obtained by combining the LRF and GRF indexes together. Experimental results on three publicly 3D image quality assessment databases demonstrate that in comparison with the existing methods, the devised algorithm achieves high consistent alignment with subjective assessment.

  2. Artifacts and image degradation in MRI. Application to the exploration of the motor system. Les artefacts et la degradation de l'image en I. R. M. Application a l'exploration de l'appareil locomoteur

    Energy Technology Data Exchange (ETDEWEB)

    Gagey, N.; Duvauferier, R.; Lucas, C.; Korvin, B. de; Bernard, A.M.; Ramee, A. (Centre Hospitalier Regional Fontenoy, 35 - Rennes (FR))

    1989-01-01

    MRI is a relatively new examination technique. The basic semiology is now well known, but MRI artifacts still deserve description, since they may degrade the images or produce appearances leading to misinterpretation. This text will deal with the major artifacts caused by metallic bodies, chemical shift, motion, aliasing and partial volume. A number of causes of image degradation will then be studied, including signal decay as well as calibration and centering problems. This article has an essentially practical goal since it points out the misleading images and, more importantly, the ways of avoiding these pitfalls.

  3. Toward the development of an image quality tool for active millimeter wave imaging systems

    Science.gov (United States)

    Barber, Jeffrey; Weatherall, James C.; Greca, Joseph; Smith, Barry T.

    2015-05-01

    Preliminary design considerations for an image quality tool to complement millimeter wave imaging systems are presented. The tool is planned for use in confirming operating parameters; confirmation of continuity for imaging component design changes, and analysis of new components and detection algorithms. Potential embodiments of an image quality tool may contain materials that mimic human skin in order to provide a realistic signal return for testing, which may also help reduce or eliminate the need for mock passengers for developmental testing. Two candidate materials, a dielectric liquid and an iron-loaded epoxy, have been identified and reflection measurements have been performed using laboratory systems in the range 18 - 40 GHz. Results show good agreement with both laboratory and literature data on human skin, particularly in the range of operation of two commercially available millimeter wave imaging systems. Issues related to the practical use of liquids and magnetic materials for image quality tools are discussed.

  4. Perceptual image quality in normalized LOG domain for Adaptive Optics image post-processing

    Science.gov (United States)

    Guo, Shiping; Zhang, Rongzhi; Li, Jisheng; Zou, Jianhua; Liu, Changhai; Gao, Weizhe

    2015-08-01

    Adaptive Optics together with subsequent post-processing techniques obviously improve the resolution of turbulencedegraded images in ground-based space objects detection and identification. The most common method for frame selection and stopping iteration in post-processing has always been subjective viewing of the images due to a lack of widely agreed-upon objective quality metric. Full reference metrics are not applicable for assessing the field data, no-reference metrics tend to perform poor sensitivity for Adaptive Optics images. In the present work, based on the Laplacian of Gaussian (LOG) local contrast feature, a nonlinear normalization is applied to transform the input image into a normalized LOG domain; a quantitative index is then extracted in this domain to assess the perceptual image quality. Experiments show this no-reference quality index is highly consistent with the subjective evaluation of input images for different blur degree and different iteration number.

  5. Image quality of mixed convolution kernel in thoracic computed tomography.

    Science.gov (United States)

    Neubauer, Jakob; Spira, Eva Maria; Strube, Juliane; Langer, Mathias; Voss, Christian; Kotter, Elmar

    2016-11-01

    The mixed convolution kernel alters his properties geographically according to the depicted organ structure, especially for the lung. Therefore, we compared the image quality of the mixed convolution kernel to standard soft and hard kernel reconstructions for different organ structures in thoracic computed tomography (CT) images.Our Ethics Committee approved this prospective study. In total, 31 patients who underwent contrast-enhanced thoracic CT studies were included after informed consent. Axial reconstructions were performed with hard, soft, and mixed convolution kernel. Three independent and blinded observers rated the image quality according to the European Guidelines for Quality Criteria of Thoracic CT for 13 organ structures. The observers rated the depiction of the structures in all reconstructions on a 5-point Likert scale. Statistical analysis was performed with the Friedman Test and post hoc analysis with the Wilcoxon rank-sum test.Compared to the soft convolution kernel, the mixed convolution kernel was rated with a higher image quality for lung parenchyma, segmental bronchi, and the border between the pleura and the thoracic wall (P kernel, the mixed convolution kernel was rated with a higher image quality for aorta, anterior mediastinal structures, paratracheal soft tissue, hilar lymph nodes, esophagus, pleuromediastinal border, large and medium sized pulmonary vessels and abdomen (P kernel cannot fully substitute the standard CT reconstructions. Hard and soft convolution kernel reconstructions still seem to be mandatory for thoracic CT.

  6. Fast vector quantization algorithm preserving color image quality

    Science.gov (United States)

    Charrier, Christophe; Cherifi, Hocine

    1998-04-01

    In the color image compression field, it is well known by researchers that the information is statistically redundant. This redundancy is a handicap in terms of dictionary construction time. A way to counterbalance this time consuming effect is to reduce the redundancy within the original image while keeping the image quality. One can extract a random sample of the initial training set on which one constructs the codebook whose quality is equal to the quality of the codebook generated from the entire training set. We applied this idea in the color vector quantization (VQ) compression scheme context. We propose an algorithm to reduce the complexity of the standard LBG technique. We searched for a measure of relevance of each block from the entire training set. Under the assumption that the measure of relevance is a independent random variable, we applied the Kolmogorov statistical test to define the smallest size of a random sample, and then the sample itself. Finally, from blocks associated to each measure of relevance of the random sample, we compute the standard LBG algorithm to construct the codebook. Psychophysics and statistical measures of image quality allow us to find the best measure of relevance to reduce the training set while preserving the image quality and decreasing the computational cost.

  7. Land-based salmon aquacultures change the quality and bacterial degradation of riverine dissolved organic matter

    Science.gov (United States)

    Kamjunke, Norbert; Nimptsch, Jorge; Harir, Mourad; Herzsprung, Peter; Schmitt-Kopplin, Philippe; Neu, Thomas R.; Graeber, Daniel; Osorio, Sebastian; Valenzuela, Jose; Carlos Reyes, Juan; Woelfl, Stefan; Hertkorn, Norbert

    2017-03-01

    Aquacultures are of great economic importance worldwide but pollute pristine headwater streams, lakes, and estuaries. However, there are no in-depth studies of the consequences of aquacultures on dissolved organic matter (DOM) composition and structure. We performed a detailed molecular level characterization of aquaculture DOM quality and its bacterial degradation using four salmon aquacultures in Chile. Fluorescence measurements, ultrahigh-resolution mass spectrometry, and nuclear magnetic resonance spectroscopy of the DOM revealed specific and extensive molecular alterations caused by aquacultures. Aquacultures released large quantities of readily bioavailable metabolites (primarily carbohydrates and peptides/proteins, and lipids), causing the organic matter downstream of all the investigated aquacultures to deviate strongly from the highly processed, polydisperse and molecularly heterogeneous DOM found in pristine rivers. However, the upstream individual catchment DOM signatures remained distinguishable at the downstream sites. The benthic algal biovolume decreased and the bacterial biovolume and production increased downstream of the aquacultures, shifting stream ecosystems to a more heterotrophic state and thus impairing the ecosystem health. The bacterial DOM degradation rates explain the attenuation of aquaculture DOM within the subsequent stream reaches. This knowledge may aid the development of improved waste processing facilities and may help to define emission thresholds to protect sensitive stream ecosystems.

  8. Body image and quality of life in a Spanish population

    Directory of Open Access Journals (Sweden)

    Ignacio Jáuregui Lobera

    2011-01-01

    Full Text Available Ignacio Jáuregui Lobera1, Patricia Bolaños Ríos21Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain; 2Behavior Science Institute, Seville, SpainPurpose: The aim of the current study was to analyze the psychometric properties, factor structure, and internal consistency of the Spanish version of the Body Image Quality of Life Inventory (BIQLI-SP as well as its test–retest reliability. Further objectives were to analyze different relationships with key dimensions of psychosocial functioning (ie, self-esteem, presence of psychopathological symptoms, eating and body image-related problems, and perceived stress and to evaluate differences in body image quality of life due to gender.Patients and methods: The sample comprised 417 students without any psychiatric history, recruited from the Pablo de Olavide University and the University of Seville. There were 140 men (33.57% and 277 women (66.43%, and the mean age was 21.62 years (standard deviation = 5.12. After obtaining informed consent from all participants, the following questionnaires were administered: BIQLI, Eating Disorder Inventory-2 (EDI-2, Perceived Stress Questionnaire (PSQ, Self-Esteem Scale (SES, and Symptom Checklist-90-Revised (SCL-90-R.Results: The BIQLI-SP shows adequate psychometric properties, and it may be useful to determine the body image quality of life in different physical conditions. A more positive body image quality of life is associated with better self-esteem, better psychological wellbeing, and fewer eating-related dysfunctional attitudes, this being more evident among women.Conclusion: The BIQLI-SP may be useful to determine the body image quality of life in different contexts with regard to dermatology, cosmetic and reconstructive surgery, and endocrinology, among others. In these fields of study, a new trend has emerged to assess body image-related quality of life.Keywords: body appreciation, wellbeing, self-esteem, social

  9. Characterization of Organic Solar Cell Devices and their Interfaces under Degradation: Imaging, Electrical and Mechanical Methods

    DEFF Research Database (Denmark)

    Corazza, Michael

    techniques were also employed in order to study the effect of degradation on the device structure and its interfaces. This was done by exploiting different techniques that measured different properties of the device: mechanical, imaging, and electrical. Mechanical characterization of roll-to-roll processed....... Finally, imaging of cross sections of an ITO-free roll-to-roll processed device was performed successfully using transmission electron microscopy. The cross sections were prepared both with focused-ion-beam and ultramicrotomy, which gave the possibility for effectively comparing these two techniques...... energy is one of the answers for renewable energy. In this thesis, the research has been conducted on polymer solar cells. In particular, the thesis deals with the extensive study of device lifetime, characterized with several methods: from bare benchmarking of the lifetimes, to more advanced...

  10. Neurophysiological assessment of perceived image quality using steady-state visual evoked potentials

    Science.gov (United States)

    Bosse, Sebastian; Acqualagna, Laura; Porbadnigk, Anne K.; Curio, Gabriel; Müller, Klaus-Robert; Blankertz, Benjamin; Wiegand, Thomas

    2015-09-01

    An approach to the neural measurement of perceived image quality using electroencephalography (EEG) is presented. 6 different images were tested on 6 different distortion levels. The distortions were introduced by a hybrid video encoder. The presented study consists of two parts: In a first part, subjects were asked to evaluate the quality of the test stimuli behaviorally during a conventional psychophysical test using a degradation category rating procedure. In a second part, subjects were presented undistorted and distorted texture images in a periodically alternating fashion at a fixed frequency. This alternating presentation elicits so called steady-state visual evoked potentials (SSVEP) as a brain response that can be measured on the scalp. The amplitude of modulations in the brain signals is significantly and strongly negatively correlated with the magnitude of visual impairment reported by the subjects. This neurophysiological approach to image quality assessment may potentially lead to a more objective evaluation, as behavioral approaches suffer from drawbacks such as biases, inter-subject variances and limitations to test duration.

  11. Real-time computer treatment of THz passive device images with the high image quality

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Trofimov, Vladislav V.

    2012-06-01

    We demonstrate real-time computer code improving significantly the quality of images captured by the passive THz imaging system. The code is not only designed for a THz passive device: it can be applied to any kind of such devices and active THz imaging systems as well. We applied our code for computer processing of images captured by four passive THz imaging devices manufactured by different companies. It should be stressed that computer processing of images produced by different companies requires using the different spatial filters usually. The performance of current version of the computer code is greater than one image per second for a THz image having more than 5000 pixels and 24 bit number representation. Processing of THz single image produces about 20 images simultaneously corresponding to various spatial filters. The computer code allows increasing the number of pixels for processed images without noticeable reduction of image quality. The performance of the computer code can be increased many times using parallel algorithms for processing the image. We develop original spatial filters which allow one to see objects with sizes less than 2 cm. The imagery is produced by passive THz imaging devices which captured the images of objects hidden under opaque clothes. For images with high noise we develop an approach which results in suppression of the noise after using the computer processing and we obtain the good quality image. With the aim of illustrating the efficiency of the developed approach we demonstrate the detection of the liquid explosive, ordinary explosive, knife, pistol, metal plate, CD, ceramics, chocolate and other objects hidden under opaque clothes. The results demonstrate the high efficiency of our approach for the detection of hidden objects and they are a very promising solution for the security problem.

  12. An approach for quantitative image quality analysis for CT

    Science.gov (United States)

    Rahimi, Amir; Cochran, Joe; Mooney, Doug; Regensburger, Joe

    2016-03-01

    An objective and standardized approach to assess image quality of Compute Tomography (CT) systems is required in a wide variety of imaging processes to identify CT systems appropriate for a given application. We present an overview of the framework we have developed to help standardize and to objectively assess CT image quality for different models of CT scanners used for security applications. Within this framework, we have developed methods to quantitatively measure metrics that should correlate with feature identification, detection accuracy and precision, and image registration capabilities of CT machines and to identify strengths and weaknesses in different CT imaging technologies in transportation security. To that end we have designed, developed and constructed phantoms that allow for systematic and repeatable measurements of roughly 88 image quality metrics, representing modulation transfer function, noise equivalent quanta, noise power spectra, slice sensitivity profiles, streak artifacts, CT number uniformity, CT number consistency, object length accuracy, CT number path length consistency, and object registration. Furthermore, we have developed a sophisticated MATLAB based image analysis tool kit to analyze CT generated images of phantoms and report these metrics in a format that is standardized across the considered models of CT scanners, allowing for comparative image quality analysis within a CT model or between different CT models. In addition, we have developed a modified sparse principal component analysis (SPCA) method to generate a modified set of PCA components as compared to the standard principal component analysis (PCA) with sparse loadings in conjunction with Hotelling T2 statistical analysis method to compare, qualify, and detect faults in the tested systems.

  13. Body image quality of life in eating disorders

    Directory of Open Access Journals (Sweden)

    Ignacio Jáuregui Lobera

    2011-03-01

    Full Text Available Ignacio Jáuregui Lobera1, Patricia Bolaños Ríos21Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain; 2Behavior Sciences Institute, Seville, SpainPurpose: The objective was to examine how body image affects quality of life in an eating-disorder (ED clinical sample, a non-ED clinical sample, and a nonclinical sample. We hypothesized that ED patients would show the worst body image quality of life. We also hypothesized that body image quality of life would have a stronger negative association with specific ED-related variables than with other psychological and psychopathological variables, mainly among ED patients. On the basis of previous studies, the influence of gender on the results was explored, too.Patients and methods: The final sample comprised 70 ED patients (mean age 22.65 ± 7.76 years; 59 women and 11 men; 106 were patients with other psychiatric disorders (mean age 28.20 ± 6.52; 67 women and 39 men, and 135 were university students (mean age 21.57 ± 2.58; 81 women and 54 men, with no psychiatric history. After having obtained informed consent, the following questionnaires were administered: Body Image Quality of Life Inventory-Spanish version (BIQLI-SP, Eating Disorders Inventory-2 (EDI-2, Perceived Stress Questionnaire (PSQ, Self-Esteem Scale (SES, and Symptom Checklist-90-Revised (SCL-90-R.Results: The ED patients' ratings on the BIQLI-SP were the lowest and negatively scored (BIQLI-SP means: +20.18, +5.14, and —6.18, in the student group, the non-ED patient group, and the ED group, respectively. The effect of body image on quality of life was more negative in the ED group in all items of the BIQLI-SP. Body image quality of life was negatively associated with specific ED-related variables, more than with other psychological and psychopathological variables, but not especially among ED patients.Conclusion: Body image quality of life was affected not only by specific pathologies related to body

  14. Exploratory survey of image quality on CR digital mammography imaging systems in Mexico.

    Science.gov (United States)

    Gaona, E; Rivera, T; Arreola, M; Franco, J; Molina, N; Alvarez, B; Azorín, C G; Casian, G

    2014-01-01

    The purpose of this study was to assess the current status of image quality and dose in computed radiographic digital mammography (CRDM) systems. Studies included CRDM systems of various models and manufacturers which dose and image quality comparisons were performed. Due to the recent rise in the use of digital radiographic systems in Mexico, CRDM systems are rapidly replacing conventional film-screen systems without any regard to quality control or image quality standards. Study was conducted in 65 mammography facilities which use CRDM systems in the Mexico City and surrounding States. The systems were tested as used clinically. This means that the dose and beam qualities were selected using the automatic beam selection and photo-timed features. All systems surveyed generate laser film hardcopies for the radiologist to read on a scope or mammographic high luminance light box. It was found that 51 of CRDM systems presented a variety of image artefacts and non-uniformities arising from inadequate acquisition and processing, as well as from the laser printer itself. Undisciplined alteration of image processing settings by the technologist was found to be a serious prevalent problem in 42 facilities. Only four of them showed an image QC program which is periodically monitored by a medical physicist. The Average Glandular Dose (AGD) in the surveyed systems was estimated to have a mean value of 2.4 mGy. To improve image quality in mammography and make more efficient screening mammographic in early detection of breast cancer is required new legislation.

  15. Image-Processing Techniques for the Creation of Presentation-Quality Astronomical Images

    CERN Document Server

    Rector, T A; Frattare, L M; English, J; Puuohau-Pummill, K

    2004-01-01

    The quality of modern astronomical data, the power of modern computers and the agility of current image-processing software enable the creation of high-quality images in a purely digital form. The combination of these technological advancements has created a new ability to make color astronomical images. And in many ways it has led to a new philosophy towards how to create them. A practical guide is presented on how to generate astronomical images from research data with powerful image-processing programs. These programs use a layering metaphor that allows for an unlimited number of astronomical datasets to be combined in any desired color scheme, creating an immense parameter space to be explored using an iterative approach. Several examples of image creation are presented. A philosophy is also presented on how to use color and composition to create images that simultaneously highlight scientific detail and are aesthetically appealing. This philosophy is necessary because most datasets do not correspond to t...

  16. Dose and diagnostic image quality in digital tomosynthesis imaging of facial bones in pediatrics

    Science.gov (United States)

    King, J. M.; Hickling, S.; Elbakri, I. A.; Reed, M.; Wrogemann, J.

    2011-03-01

    The purpose of this study was to evaluate the use of digital tomosynthesis (DT) for pediatric facial bone imaging. We compared the eye lens dose and diagnostic image quality of DT facial bone exams relative to digital radiography (DR) and computed tomography (CT), and investigated whether we could modify our current DT imaging protocol to reduce patient dose while maintaining sufficient diagnostic image quality. We measured the dose to the eye lens for all three modalities using high-sensitivity thermoluminescent dosimeters (TLDs) and an anthropomorphic skull phantom. To assess the diagnostic image quality of DT compared to the corresponding DR and CT images, we performed an observer study where the visibility of anatomical structures in the DT phantom images were rated on a four-point scale. We then acquired DT images at lower doses and had radiologists indicate whether the visibility of each structure was adequate for diagnostic purposes. For typical facial bone exams, we measured eye lens doses of 0.1-0.4 mGy for DR, 0.3-3.7 mGy for DT, and 26 mGy for CT. In general, facial bone structures were visualized better with DT then DR, and the majority of structures were visualized well enough to avoid the need for CT. DT imaging provides high quality diagnostic images of the facial bones while delivering significantly lower doses to the lens of the eye compared to CT. In addition, we found that by adjusting the imaging parameters, the DT effective dose can be reduced by up to 50% while maintaining sufficient image quality.

  17. A new method to evaluate imaging quality of CCD cameras

    Institute of Scientific and Technical Information of China (English)

    LI Wen-juan; DU Hai-hui; DAI Jing-min; CHEN Ying-hang

    2005-01-01

    In order to evaluate the imaging quality of CCD cameras fully and rapidly,the minimum resolvable contrast (MRC) is presented in this paper and the system of measuring MRC is constructed as well,in which two integrating spheres are proposed to illuminate two sides of the target respectively.The variable contrast can be obtained by regulating the luminance of integrating spheres. Experimental results indicate that the error of measuring luminance is within ±0.3 cd/m2,MRC rises with the increase of the spatial frequency.The experimental results show that the method proposed is an effective approach to evaluate the imaging quality of CCD cameras.

  18. Radiation dose and image quality for paediatric interventional cardiology

    Energy Technology Data Exchange (ETDEWEB)

    Vano, E [Radiology Department, Medicine School, Complutense University and San Carlos University Hospital, 28040 Madrid (Spain); Ubeda, C [Clinical Sciences Department, Faculty of the Science of Health, Tarapaca University, 18 de Septiembre 2222, Arica (Chile); Leyton, F [Institute of Public Health of Chile, Marathon 1000, Nunoa, Santiago (Chile); Miranda, P [Hemodynamic Department, Cardiovascular Service, Luis Calvo Mackenna Hospital, Avenida Antonio Varas 360, Providencia, Santiago (Chile)], E-mail: eliseov@med.ucm.es

    2008-08-07

    Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 {mu}Gy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 {mu}Gy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

  19. Radiation dose and image quality for paediatric interventional cardiology

    Science.gov (United States)

    Vano, E.; Ubeda, C.; Leyton, F.; Miranda, P.

    2008-08-01

    Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 µGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 µGy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

  20. Presence capture cameras - a new challenge to the image quality

    Science.gov (United States)

    Peltoketo, Veli-Tapani

    2016-04-01

    Commercial presence capture cameras are coming to the markets and a new era of visual entertainment starts to get its shape. Since the true presence capturing is still a very new technology, the real technical solutions are just passed a prototyping phase and they vary a lot. Presence capture cameras have still the same quality issues to tackle as previous phases of digital imaging but also numerous new ones. This work concentrates to the quality challenges of presence capture cameras. A camera system which can record 3D audio-visual reality as it is has to have several camera modules, several microphones and especially technology which can synchronize output of several sources to a seamless and smooth virtual reality experience. Several traditional quality features are still valid in presence capture cameras. Features like color fidelity, noise removal, resolution and dynamic range create the base of virtual reality stream quality. However, co-operation of several cameras brings a new dimension for these quality factors. Also new quality features can be validated. For example, how the camera streams should be stitched together with 3D experience without noticeable errors and how to validate the stitching? The work describes quality factors which are still valid in the presence capture cameras and defines the importance of those. Moreover, new challenges of presence capture cameras are investigated in image and video quality point of view. The work contains considerations how well current measurement methods can be used in presence capture cameras.

  1. Achieving quality in cardiovascular imaging: proceedings from the American College of Cardiology-Duke University Medical Center Think Tank on Quality in Cardiovascular Imaging.

    Science.gov (United States)

    Douglas, Pamela; Iskandrian, Ami E; Krumholz, Harlan M; Gillam, Linda; Hendel, Robert; Jollis, James; Peterson, Eric; Chen, Jersey; Masoudi, Frederick; Mohler, Emile; McNamara, Robert L; Patel, Manesh R; Spertus, John

    2006-11-21

    Cardiovascular imaging has enjoyed both rapid technological advances and sustained growth, yet less attention has been focused on quality than in other areas of cardiovascular medicine. To address this deficit, representatives from cardiovascular imaging societies, private payers, government agencies, the medical imaging industry, and experts in quality measurement met, and this report provides an overview of the discussions. A consensus definition of quality in imaging and a convergence of opinion on quality measures across imaging modalities was achieved and are intended to be the start of a process culminating in the development, dissemination, and adoption of quality measures for all cardiovascular imaging modalities.

  2. Factors that affect print quality in thermal dye transfer imaging

    Science.gov (United States)

    Harrison, Daniel J. P.; McInerney, Elizabeth

    1995-04-01

    Thermal dye transfer (TDT) imaging has established itself as the state- of-the-art process for high quality, continuous tone, nonimpact printing. Imaging quality from this process rivals conventional silver halide photography and exceeds other nonimpact printing technologies. Because this output appears to be virtually indistinguishable from photographic prints, there has been an expectation that all the quality attributes of silver halide photography are embodied in a TDT print. However, there are many significant differences that affect output quality between these two technologies. These differences are primarily in color gamut, print artifacts, Dmin, grain/sharpness, and image stability. The range of colors reproducible by a color, hard copy device, known as its color gamut, is dictated primarily by the image- forming dyes used by the device. The size and shape of a device's gamut is controlled by the spectral density distributions of these image forming dyes, the Dmin of the receiver base, the Dmax of each dye, the amount of light scatter, and the spectral distribution of the viewing illuminant. The spectral density distributions of dyes also have an impact on illuminant sensitivity, which is a predictor of how much the color balance of a print will change with a change in illuminant. By determining and then using characteristic curves for various image- forming dyes, we have been able to calculate and compare the color gamuts and illuminant sensitivity of TDT imaging with other technologies (color monitor and silver halide photography, for example). The differences we have found can have a significant impact on output quality, depending upon the application. Compared to conventional photography, thermal dye transfer prints have traditionally had inferior light stability and resistance to damage from fingerprints. In addition, thermal dye transfer prints have been aggressively attacked by plasticized polyvinyl chloride sheets and folders commonly found in

  3. Image quality in CT: From physical measurements to model observers.

    OpenAIRE

    2015-01-01

    Evaluation of image quality (IQ) in Computed Tomography (CT) is important to ensure that diagnostic questions are correctly answered, whilst keeping radiation dose to the patient as low as is reasonably possible. The assessment of individual aspects of IQ is already a key component of routine quality control of medical x-ray devices. These values together with standard dose indicators can be used to give rise to 'figures of merit' (FOM) to characterise the dose efficiency of the CT scanners o...

  4. Local Imaging of Optoelectronic Properties and Film Degradation in Polymer/Fullerene Solar Cells with Electrostatic Force Microscopy

    Science.gov (United States)

    Cox, Phillip Alexander

    With power conversion efficiencies on the rise, organic photovoltaics (OPVs) hold promise as a next-generation thin-film solar technology. However, both device performance and stability are inextricably linked to local film structure. Methods capable of probing nanoscale electronic properties as a function of film structure are thus a crucial component of the rational design of efficient and robust devices. This dissertation describes the use of three scanning probe methods for studying local charge generation and photodegradation in polymer/fullerene solar cells. First, we show that time-resolved electrostatic force microscopy (trEFM) is capable of resolving local photocurrent from sub-bandgap excitation down to attoampere level currents, a result unattainable by traditional contact-mode methods. We find that the local charging rates measured with trEFM are proportional to external quantum efficiency (EQE) measurements made on completed devices, making trEFM images equivalent to local EQE maps across the entire solar spectrum. For both phase-segregated and well-mixed MDMO-PPV:PCBM film morphologies, we show that the local distribution of photocurrent is invariant to excitation wavelength, providing local evidence for the controversial result that the probability of generating separated charge carriers does not depend on whether excitons are formed at the singlet state or charge transfer state. Next, we describe how local dissipation imaging can be performed with commercially-available frequency-modulated electrostatic force microscopy (FM-EFM) and show that dissipation maps are highly sensitive to photo-oxidative effects in organic semiconductors. We show that photo-oxidation induced changes in cantilever energy dissipation are proportional to device performance losses. We further develop dissipation imaging by implementing ringdown imaging, which directly measures the quality factor of the cantilever, enabling quantitative dissipation mapping. Using organic

  5. CCD Astrophotography High-Quality Imaging from the Suburbs

    CERN Document Server

    Stuart, Adam

    2006-01-01

    This is a reference book for amateur astronomers who have become interested in CCD imaging. Those glorious astronomical images found in astronomy magazines might seem out of reach to newcomers to CCD imaging, but this is not the case. Great pictures are attainable with modest equipment. Adam Stuart’s many beautiful images, reproduced in this book, attest to the quality of – initially – a beginner’s efforts. Chilled-chip astronomical CCD-cameras and software are also wonderful tools for cutting through seemingly impenetrable light-pollution. CCD Astrophotography from the Suburbs describes one man’s successful approach to the problem of getting high-quality astronomical images under some of the most light-polluted conditions. Here is a complete and thoroughly tested program that will help every CCD-beginner to work towards digital imaging of the highest quality. It is equally useful to astronomers who have perfect observing conditions, as to those who have to observe from light-polluted city skies.

  6. Degradation of water quality: the case of plain west of Annaba (northeast Algeria

    Directory of Open Access Journals (Sweden)

    Attoui Badra

    2016-12-01

    Full Text Available In the world, the water quality is undergoing deterioration due to urban and industrial wastes, and intensive use of chemical fertilizers in agriculture. Unfortunately, as in most countries of the world, Algeria is experiencing a severe crisis of its environment apart from the problem of depletion of water resources. The plain west of Annaba is particularly subjected to a general industrial pollution. The pollution problem in this region has really started to become worrying not earlier than in 1980, when the economic crisis has led some industrial units to sacrifice the “Environment” criterion for the benefit of the production. We were particularly interested in this work in waters of the superficial aquifer and wadis like Boudjemaa, Bouhdid, Sidi Harb, and Forcha whose waters are most often used to irrigate the surrounding agricultural land. Comparison of analytical results from two periods – 2006–2016 for the: EC, pH, Ca2+, Mg2+, Cl−, NO2 and 2006–2010 for the: Fe, Cr, Cu2+, Pb+ show a degradation of water quality in this region, which represents a very vulnerable area with a risk to pollution of groundwater.

  7. Quench-Induced Degradation of the Quality Factor in Superconducting Resonators

    CERN Document Server

    Checchin, M; Romanenko, A; Grassellino, A; Sergatskov, D A; Posen, S; Melnychuk, O; Zasadzinski, J F

    2016-01-01

    Quench of superconducting radio-frequency cavities frequently leads to the lowered quality factor Q0, which had been attributed to the additional trapped magnetic flux. Here we demonstrate that the origin of this magnetic flux is purely extrinsic to the cavity by showing no extra dissipation (unchanged Q0) after quenching in zero magnetic field, which allows us to rule out intrinsic mechanisms of flux trapping such as generation of thermal currents or trapping of the rf field. We also show the clear relation of dissipation introduced by quenching to the orientation of the applied magnetic field and the possibility to fully recover the quality factor by requenching in the compensated field. We discover that for larger values of the ambient field, the Q-factor degradation may become irreversible by this technique, likely due to the outward flux migration beyond the normal zone opening during quench. Our findings are of special practical importance for accelerators based on low- and medium-beta accelerating stru...

  8. Analysis and Comparison of Objective Methods for Image Quality Assessment

    Directory of Open Access Journals (Sweden)

    P. S. Babkin

    2014-01-01

    Full Text Available The purpose of this work is research and modification of the reference objective methods for image quality assessment. The ultimate goal is to obtain a modification of formal assessments that more closely corresponds to the subjective expert estimates (MOS.In considering the formal reference objective methods for image quality assessment we used the results of other authors, which offer results and comparative analyzes of the most effective algorithms. Based on these investigations we have chosen two of the most successful algorithm for which was made a further analysis in the MATLAB 7.8 R 2009 a (PQS and MSSSIM. The publication focuses on the features of the algorithms, which have great importance in practical implementation, but are insufficiently covered in the publications by other authors.In the implemented modification of the algorithm PQS boundary detector Kirsch was replaced by the boundary detector Canny. Further experiments were carried out according to the method of the ITU-R VT.500-13 (01/2012 using monochrome images treated with different types of filters (should be emphasized that an objective assessment of image quality PQS is applicable only to monochrome images. Images were obtained with a thermal imaging surveillance system. The experimental results proved the effectiveness of this modification.In the specialized literature in the field of formal to evaluation methods pictures, this type of modification was not mentioned.The method described in the publication can be applied to various practical implementations of digital image processing.Advisability and effectiveness of using the modified method of PQS to assess the structural differences between the images are shown in the article and this will be used in solving the problems of identification and automatic control.

  9. Pitch and image quality in computed tomography; Pitch et qualite d'image en tomodensitometrie

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, B.; Le Marec, E.; Pharaboz, C. [Hopital d' Instruction des Armees Begin, 94 - Saint-Mande (France); Le Bruno, B. [Siemens SA, 92 - Saint-Denis (France)

    1999-10-01

    Pitch is a specific parameter in helical computed tomography. Once the definition of the pitch and its situation in parameters obtaining the image have been resumed, we propose to evaluate theoretic and experimental influence of the pitch on image quality. Best indications of pitch values greater than 1.0 are discussed. (author)

  10. IMPROVING THE QUALITY OF NEAR-INFRARED IMAGING OF IN VIVOBLOOD VESSELS USING IMAGE FUSION METHODS

    DEFF Research Database (Denmark)

    Jensen, Andreas Kryger; Savarimuthu, Thiusius Rajeeth; Sørensen, Anders Stengaard

    2009-01-01

    We investigate methods for improving the visual quality of in vivo images of blood vessels in the human forearm. Using a near-infrared light source and a dual CCD chip camera system capable of capturing images at visual and nearinfrared spectra, we evaluate three fusion methods in terms of their ...

  11. Registration accuracy and quality of real-life images.

    Directory of Open Access Journals (Sweden)

    Wei-Yen Hsu

    Full Text Available BACKGROUND: A common registration problem for the application of consumer device is to align all the acquired image sequences into a complete scene. Image alignment requires a registration algorithm that will compensate as much as possible for geometric variability among images. However, images captured views from a real scene usually produce different distortions. Some are derived from the optic characteristics of image sensors, and others are caused by the specific scenes and objects. METHODOLOGY/PRINCIPAL FINDINGS: An image registration algorithm considering the perspective projection is proposed for the application of consumer devices in this study. It exploits a multiresolution wavelet-based method to extract significant features. An analytic differential approach is then proposed to achieve fast convergence of point matching. Finally, the registration accuracy is further refined to obtain subpixel precision by a feature-based modified Levenberg-Marquardt method. Due to its feature-based and nonlinear characteristic, it converges considerably faster than most other methods. In addition, vignette compensation and color difference adjustment are also performed to further improve the quality of registration results. CONCLUSIONS/SIGNIFICANCE: The performance of the proposed method is evaluated by testing the synthetic and real images acquired by a hand-held digital still camera and in comparison with two registration techniques in terms of the squared sum of intensity differences (SSD and correlation coefficient (CC. The results indicate that the proposed method is promising in registration accuracy and quality, which are statistically significantly better than other two approaches.

  12. A Methodology for Anatomic Ultrasound Image Diagnostic Quality Assessment.

    Science.gov (United States)

    Hemmsen, Martin Christian; Lange, Theis; Brandt, Andreas Hjelm; Nielsen, Michael Bachmann; Jensen, Jorgen Arendt

    2017-01-01

    This paper discusses the methods for the assessment of ultrasound image quality based on our experiences with evaluating new methods for anatomic imaging. It presents a methodology to ensure a fair assessment between competing imaging methods using clinically relevant evaluations. The methodology is valuable in the continuing process of method optimization and guided development of new imaging methods. It includes a three phased study plan covering from initial prototype development to clinical assessment. Recommendations to the clinical assessment protocol, software, and statistical analysis are presented. Earlier uses of the methodology has shown that it ensures validity of the assessment, as it separates the influences between developer, investigator, and assessor once a research protocol has been established. This separation reduces confounding influences on the result from the developer to properly reveal the clinical value. This paper exemplifies the methodology using recent studies of synthetic aperture sequential beamforming tissue harmonic imaging.

  13. Image quality and high contrast improvements on VLT/NACO

    CERN Document Server

    Girard, Julien H V; Mawet, Dimitri; Kasper, Markus; Zins, Gérard; Neichel, Benoît; Kolb, Johann; Christiaens, Valentin; Tourneboeuf, Martin; 10.1117/12.925660

    2012-01-01

    NACO is the famous and versatile diffraction limited NIR imager and spectrograph with which ESO celebrated 10 years of Adaptive Optics at the VLT. Since two years a substantial effort has been put in to understanding and fixing issues that directly affect the image quality and the high contrast performances of the instrument. Experiments to compensate the non-common-path aberrations and recover the highest possible Strehl ratios have been carried out successfully and a plan is hereafter described to perform such measurements regularly. The drift associated to pupil tracking since 2007 was fixed in October 2011. NACO is therefore even better suited for high contrast imaging and can be used with coronagraphic masks in the image plane. Some contrast measurements are shown and discussed. The work accomplished on NACO will serve as reference for the next generation instruments on the VLT, especially those working at the diffraction limit and making use of angular differential imaging (i.e. SPHERE, VISIR, possibly ...

  14. Multispectral Imaging of Meat Quality - Color and Texture

    DEFF Research Database (Denmark)

    Trinderup, Camilla Himmelstrup

    of meat quality parameters, especially with regards to meat color and texture. Several image modalities have been applied, all considering multi- or hyper spectral imaging. The work demonstrates the use of computer vision systems for meat color measurements. The color is assessed by suitable...... transformations to the CIELAB color space, the common color space within food science. The results show that meat color assessment with a multispectral imaging is a great alternative to the traditional colorimeter, i.e. the vision system meets some of the limitations that the colorimeter possesses. To mention one......, it is possible to assess color of very complicated structures, such as salamis, with a vision system. More importantly though, the vision system embraces the complicated scattering properties of meat. The images can also lead to other analyses, e.g. image texture analysis relating to the structure of the meat...

  15. Quality measures for HRR alignment based ISAR imaging algorithms

    CSIR Research Space (South Africa)

    Janse van Rensburg, V

    2013-05-01

    Full Text Available Some Inverse Synthetic Aperture Radar (ISAR) algorithms form the image in a two-step process of range alignment and phase conjugation. This paper discusses a comprehensive set of measures used to quantify the quality of range alignment, with the aim...

  16. Simultaneous analysis and quality assurance for diffusion tensor imaging.

    Directory of Open Access Journals (Sweden)

    Carolyn B Lauzon

    Full Text Available Diffusion tensor imaging (DTI enables non-invasive, cyto-architectural mapping of in vivo tissue microarchitecture through voxel-wise mathematical modeling of multiple magnetic resonance imaging (MRI acquisitions, each differently sensitized to water diffusion. DTI computations are fundamentally estimation processes and are sensitive to noise and artifacts. Despite widespread adoption in the neuroimaging community, maintaining consistent DTI data quality remains challenging given the propensity for patient motion, artifacts associated with fast imaging techniques, and the possibility of hardware changes/failures. Furthermore, the quantity of data acquired per voxel, the non-linear estimation process, and numerous potential use cases complicate traditional visual data inspection approaches. Currently, quality inspection of DTI data has relied on visual inspection and individual processing in DTI analysis software programs (e.g. DTIPrep, DTI-studio. However, recent advances in applied statistical methods have yielded several different metrics to assess noise level, artifact propensity, quality of tensor fit, variance of estimated measures, and bias in estimated measures. To date, these metrics have been largely studied in isolation. Herein, we select complementary metrics for integration into an automatic DTI analysis and quality assurance pipeline. The pipeline completes in 24 hours, stores statistical outputs, and produces a graphical summary quality analysis (QA report. We assess the utility of this streamlined approach for empirical quality assessment on 608 DTI datasets from pediatric neuroimaging studies. The efficiency and accuracy of quality analysis using the proposed pipeline is compared with quality analysis based on visual inspection. The unified pipeline is found to save a statistically significant amount of time (over 70% while improving the consistency of QA between a DTI expert and a pool of research associates. Projection of QA

  17. Simultaneous analysis and quality assurance for diffusion tensor imaging.

    Science.gov (United States)

    Lauzon, Carolyn B; Asman, Andrew J; Esparza, Michael L; Burns, Scott S; Fan, Qiuyun; Gao, Yurui; Anderson, Adam W; Davis, Nicole; Cutting, Laurie E; Landman, Bennett A

    2013-01-01

    Diffusion tensor imaging (DTI) enables non-invasive, cyto-architectural mapping of in vivo tissue microarchitecture through voxel-wise mathematical modeling of multiple magnetic resonance imaging (MRI) acquisitions, each differently sensitized to water diffusion. DTI computations are fundamentally estimation processes and are sensitive to noise and artifacts. Despite widespread adoption in the neuroimaging community, maintaining consistent DTI data quality remains challenging given the propensity for patient motion, artifacts associated with fast imaging techniques, and the possibility of hardware changes/failures. Furthermore, the quantity of data acquired per voxel, the non-linear estimation process, and numerous potential use cases complicate traditional visual data inspection approaches. Currently, quality inspection of DTI data has relied on visual inspection and individual processing in DTI analysis software programs (e.g. DTIPrep, DTI-studio). However, recent advances in applied statistical methods have yielded several different metrics to assess noise level, artifact propensity, quality of tensor fit, variance of estimated measures, and bias in estimated measures. To date, these metrics have been largely studied in isolation. Herein, we select complementary metrics for integration into an automatic DTI analysis and quality assurance pipeline. The pipeline completes in 24 hours, stores statistical outputs, and produces a graphical summary quality analysis (QA) report. We assess the utility of this streamlined approach for empirical quality assessment on 608 DTI datasets from pediatric neuroimaging studies. The efficiency and accuracy of quality analysis using the proposed pipeline is compared with quality analysis based on visual inspection. The unified pipeline is found to save a statistically significant amount of time (over 70%) while improving the consistency of QA between a DTI expert and a pool of research associates. Projection of QA metrics to a low

  18. Thermoluminescence dosimetry in quality imaging in CR mammography systems

    Energy Technology Data Exchange (ETDEWEB)

    Gaona, E.; Franco E, J.G. [UAM-Xochimilco, 04960 Mexico D.F. (Mexico); Azorin N, J. [UAM-Iztapalapa, 09340 Mexico D.F. (Mexico); Diaz G, J.A.I. [CICATA, Unidad Legaria, Av. Legaria 694, 11599 mexico D.F. (Mexico); Arreola, M. [Department of Radiology, Shands Hospital at UF, PO Box 100374, Gainesville, FL 32610-0374 (United States)

    2006-07-01

    The aim of this work is to estimate the average glandular dose with Thermoluminescence Dosimetry (TLD) and comparison with quality imaging in CR mammography. For measuring dose, FDA and ACR use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, Full Field Digital Mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one CR mammography system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium fluoro halide. We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated x-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose that overcomes 3.0 mGy and it doesn't improve the image quality and dose to the breast will be excessive. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement. (Author)

  19. Thermoluminescence dosimetry in quality imaging in CR mammography systems

    Energy Technology Data Exchange (ETDEWEB)

    Gaona, E.; Franco E, J.G. [UAM-Xochimilco, 04960 Mexico D.F. (Mexico); Azorin N, J. [UAM-Iztapalapa, 09340 Mexico D.F. (Mexico); Diaz G, J.A.I. [CICATA, Unidad Legaria, Av. Legaria 694, 11599 mexico D.F. (Mexico); Arreola, M. [Department of Radiology, Shands Hospital at UF, PO Box 100374, Gainesville, FL 32610-0374 (United States)

    2006-07-01

    The aim of this work is to estimate the average glandular dose with Thermoluminescence Dosimetry (TLD) and comparison with quality imaging in CR mammography. For measuring dose, FDA and ACR use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, Full Field Digital Mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one CR mammography system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium fluoro halide. We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated x-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose that overcomes 3.0 mGy and it doesn't improve the image quality and dose to the breast will be excessive. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement. (Author)

  20. Postmortem proteome degradation profiles of longissimus muscle in Yorkshire and Duroc pigs and their relationship with pork quality traits

    NARCIS (Netherlands)

    te Pas, M.F.W.; Jansen, J; Broekman, K.C.J.A.; Reimert, H.; Heuven, H.C.M.

    2009-01-01

    doi:10.1016/j.meatsci.2009.08.030 Copyright © 2009 Elsevier Ltd All rights reserved. Postmortem proteome degradation profiles of longissimus muscle in Yorkshire and Duroc pigs and their relationship with pork quality traits Marinus F.W. te Pasa, , , Jaap Jansena, Konrad C.J.A. Broekmanb, Henny Reime

  1. Simultaneous Objective Measurements Of Dose And Image Quality In Mammography

    Science.gov (United States)

    Pochon, Y.; Depeursinge, Ch.; Hessler, Ch.; Raimondi, S.; Valley, J.-F.

    1982-12-01

    The performance of a radiological system can be evaluated on the one hand by an objective determination of the quality of the produced image and, on the other hand, by the dose delivered to the patient. In order to measure these two factors in a single exposure a Kodak breast phantom has been modified so as to simulate the breast absorption. The dose distribution is measured with thermoluminescent detectors. By consideration of a theoretical model of the X-ray imaging in mammography, a single quality factor is computed from the contrast, the spatial resolution and the noise measured on the phantom image. We present results obtained in various working conditions, i.e. variable X-ray tube voltages, use of different screen-film combinations, use of a grid.

  2. A NEW IMAGE QUALITY ASSESSMENT BASED ON HVS

    Institute of Scientific and Technical Information of China (English)

    Du Juan; Yu Yinglin; Xie Shengli

    2005-01-01

    This letter proposes a new kind of image quality philosophy-Modulate Quality based on Fixation Points (MQFP) based on Human Visual System (HVS) model. Dissimilar to the former HVS-based quality assessment, the new measure emphasizes particularly on modeling the jumping phenomenon of human sight instead of modeling the visual perception of human.In other words, to model the HVS using fixation points and stay-frequency instead of Contrast Sensitive Function (CSF) etc. which models the visual perception of HVS. The experiment on various frequency-distortion images indicates that the new measure is correlated with the subjective judgment more than the former HVS-based measure and is a robust measure.

  3. Image simulation and a model of noise power spectra across a range of mammographic beam qualities

    Energy Technology Data Exchange (ETDEWEB)

    Mackenzie, Alistair, E-mail: alistairmackenzie@nhs.net; Dance, David R.; Young, Kenneth C. [National Coordinating Centre for the Physics of Mammography, Royal Surrey County Hospital, Guildford GU2 7XX, United Kingdom and Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Diaz, Oliver [Centre for Vision, Speech and Signal Processing, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom and Computer Vision and Robotics Research Institute, University of Girona, Girona 17071 (Spain)

    2014-12-15

    Purpose: The aim of this work is to create a model to predict the noise power spectra (NPS) for a range of mammographic radiographic factors. The noise model was necessary to degrade images acquired on one system to match the image quality of different systems for a range of beam qualities. Methods: Five detectors and x-ray systems [Hologic Selenia (ASEh), Carestream computed radiography CR900 (CRc), GE Essential (CSI), Carestream NIP (NIPc), and Siemens Inspiration (ASEs)] were characterized for this study. The signal transfer property was measured as the pixel value against absorbed energy per unit area (E) at a reference beam quality of 28 kV, Mo/Mo or 29 kV, W/Rh with 45 mm polymethyl methacrylate (PMMA) at the tube head. The contributions of the three noise sources (electronic, quantum, and structure) to the NPS were calculated by fitting a quadratic at each spatial frequency of the NPS against E. A quantum noise correction factor which was dependent on beam quality was quantified using a set of images acquired over a range of radiographic factors with different thicknesses of PMMA. The noise model was tested for images acquired at 26 kV, Mo/Mo with 20 mm PMMA and 34 kV, Mo/Rh with 70 mm PMMA for three detectors (ASEh, CRc, and CSI) over a range of exposures. The NPS were modeled with and without the noise correction factor and compared with the measured NPS. A previous method for adapting an image to appear as if acquired on a different system was modified to allow the reference beam quality to be different from the beam quality of the image. The method was validated by adapting the ASEh flat field images with two thicknesses of PMMA (20 and 70 mm) to appear with the imaging characteristics of the CSI and CRc systems. Results: The quantum noise correction factor rises with higher beam qualities, except for CR systems at high spatial frequencies, where a flat response was found against mean photon energy. This is due to the dominance of secondary quantum noise

  4. Face Image Quality and its Improvement in a Face Detection System

    DEFF Research Database (Denmark)

    Kamal, Nasrollahi; Moeslund, Thomas B.

    2008-01-01

    When a person passes by a surveillance camera a sequence of images is obtained. Most of these images are redundant and usually keeping some of them which have better quality is sufficient. So before performing any analysis on the face of a person, the face at the first step needs to be detected....... In the second step the quality of the different face images needs to be evaluated. Finally, after choosing the best image(s) based on this quality assessment, in the third step, if this image(s) is not satisfying a predefined set of measures for good quality images, its quality should be improved. In this work...

  5. Image quality specification and maintenance for airborne SAR

    Science.gov (United States)

    Clinard, Mark S.

    2004-08-01

    Specification, verification, and maintenance of image quality over the lifecycle of an operational airborne SAR begin with the specification for the system itself. Verification of image quality-oriented specification compliance can be enhanced by including a specification requirement that a vendor provide appropriate imagery at the various phases of the system life cycle. The nature and content of the imagery appropriate for each stage of the process depends on the nature of the test, the economics of collection, and the availability of techniques to extract the desired information from the data. At the earliest lifecycle stages, Concept and Technology Development (CTD) and System Development and Demonstration (SDD), the test set could include simulated imagery to demonstrate the mathematical and engineering concepts being implemented thus allowing demonstration of compliance, in part, through simulation. For Initial Operational Test and Evaluation (IOT&E), imagery collected from precisely instrumented test ranges and targets of opportunity consisting of a priori or a posteriori ground-truthed cultural and natural features are of value to the analysis of product quality compliance. Regular monitoring of image quality is possible using operational imagery and automated metrics; more precise measurements can be performed with imagery of instrumented scenes, when available. A survey of image quality measurement techniques is presented along with a discussion of the challenges of managing an airborne SAR program with the scarce resources of time, money, and ground-truthed data. Recommendations are provided that should allow an improvement in the product quality specification and maintenance process with a minimal increase in resource demands on the customer, the vendor, the operational personnel, and the asset itself.

  6. Improving the Image Quality of Synthetic Transmit Aperture Ultrasound Images - Achieving Real-Time In-Vivo Imaging

    DEFF Research Database (Denmark)

    Gammelmark, Kim

    2004-01-01

    to increase the SNR, which employs multi-element subapertures and linearly frequency modulated (FM) signals at each emission. The subaperture is applied to emulate a high power spherical wave transmitted by a virtual point source positioned behind the subaperture, and the linear FM signal replaces...... in-vivo experiments, showed, that TMS imaging can increase the SNR by as much as 17 dB compared to the traditional imaging techniques, which improves the in-vivo image quality to a highly competitive level. An in-vivo evaluation of convex array TMS imaging for abdominal imaging applications...

  7. Image Segmentation for Food Quality Evaluation Using Computer Vision System

    Directory of Open Access Journals (Sweden)

    Nandhini. P

    2014-02-01

    Full Text Available Quality evaluation is an important factor in food processing industries using the computer vision system where human inspection systems provide high variability. In many countries food processing industries aims at producing defect free food materials to the consumers. Human evaluation techniques suffer from high labour costs, inconsistency and variability. Thus this paper provides various steps for identifying defects in the food material using the computer vision systems. Various steps in computer vision system are image acquisition, Preprocessing, image segmentation, feature identification and classification. The proposed framework provides the comparison of various filters where the hybrid median filter was selected as the filter with the high PSNR value and is used in preprocessing. Image segmentation techniques such as Colour based binary Image segmentation, Particle swarm optimization are compared and image segmentation parameters such as accuracy, sensitivity , specificity are calculated and found that colour based binary image segmentation is well suited for food quality evaluation. Finally this paper provides an efficient method for identifying the defected parts in food materials.

  8. Investigation of grid performance using simple image quality tests

    Directory of Open Access Journals (Sweden)

    Dogan Bor

    2016-01-01

    Full Text Available Antiscatter grids improve the X-ray image contrast at a cost of patient radiation doses. The choice of appropriate grid or its removal requires a good knowledge of grid characteristics, especially for pediatric digital imaging. The aim of this work is to understand the relation between grid performance parameters and some numerical image quality metrics for digital radiological examinations. The grid parameters such as bucky factor (BF, selectivity (Σ, Contrast improvement factor (CIF, and signal-to-noise improvement factor (SIF were determined following the measurements of primary, scatter, and total radiations with a digital fluoroscopic system for the thicknesses of 5, 10, 15, 20, and 25 cm polymethyl methacrylate blocks at the tube voltages of 70, 90, and 120 kVp. Image contrast for low- and high-contrast objects and high-contrast spatial resolution were measured with simple phantoms using the same scatter thicknesses and tube voltages. BF and SIF values were also calculated from the images obtained with and without grids. The correlation coefficients between BF values obtained using two approaches (grid parameters and image quality metrics were in good agreement. Proposed approach provides a quick and practical way of estimating grid performance for different digital fluoroscopic examinations.

  9. Image quality assessment using the dead leaves target: experience with the latest approach and further investigations

    Science.gov (United States)

    Artmann, Uwe

    2015-02-01

    The so-called texture loss is a critical parameter in the objective image quality assessment of todays cameras. Especially cameras build in mobile phones show significant loss of low contrast, fine details which are hard to describe using standard resolution measurement procedures. The combination of very small form factor and high pixel count leads to a high demand of noise reduction in the signal-processing pipeline of these cameras. Different work groups within ISO and IEEE are investigating methods to describe the texture loss with an objective method. The so-called dead leaves pattern has been used for quite a while in this context. Image Engineering presented a new intrinsic approach at the Electronic Imaging Conference 2014, which promises to solve the open issue of the original approach, which could be influenced by noise and artifacts. In this paper, we present our experience with the new approach for a large set of different imaging devices. We show, that some sharpening algorithm found in todays cameras can significantly influence the Spatial Frequency Response based on the Dead Leaves structure (SFRDeadLeaves) results and therefore make an objective evaluation of the perceived image quality even harder. For an objective comparison of cameras, the resulting SFR needs to be reduced to a small set of numbers, ideally a single number. The observed sharpening algorithms lead to much better numerical results, while the image quality already degrades due to strong sharpening. So the measured, high SFRDeadLeaves result is not wrong, as it reflects the artificially enhanced SFR, but the numerical result cannot be used as the only number to describe the image quality. We propose to combine the SFRDeadLeaves measurement with other SFR measurement procedures as described in ISO12233:2014. Based on the three different SFR functions using the dead leaves pattern, sinusoidal Siemens Stars and slanted edges, it is possible to obtain a much better description if the

  10. Correlation of bone quality in radiographic images with clinical bone quality classification

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Woo; Huh, Kyung Hoe; Kim, Jeong Hwa; Yi, Won Jin; Heo, Min Suk; Lee, Sam Sun; Choi, Soon Chul [Seoul National University, Seoul (Korea, Republic of); Park, Kwan Soo [Inje University, Seoul (Korea, Republic of)

    2006-03-15

    To investigate the validity of digital image processing on panoramic radiographs in estimating bone quality before endosseous dental implant installation by correlating bone quality in radiographic images with clinical bone quality classification. An experienced surgeon assessed and classified bone quality for implant sites with tactile sensation at the time of implant placement. Including fractal dimension eighteen morphologic features of trabecular pattern were examined in each anatomical sites on panoramic radiographs. Finally bone quality of 67 implant sites were evaluated in 42 patients. Pearson correlation analysis showed that three morphologic parameters had weak linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.276, -0.280, and -0.289, respectively (p<0.05). And other three morphologic parameters had obvious linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.346, -0.488, and -0.343 respectively (p<0.05). Fractal dimension also had a linear correlating with clinical bone quality classification with correlation coefficients -0.506 significantly (P<0.05). This study suggests that fractal and morphometric analysis using digital panoramic radiographs can be used to evaluate bone quality for implant recipient sites.

  11. Full-Reference Image Quality Assessment with Linear Combination of Genetically Selected Quality Measures.

    Directory of Open Access Journals (Sweden)

    Mariusz Oszust

    Full Text Available Information carried by an image can be distorted due to different image processing steps introduced by different electronic means of storage and communication. Therefore, development of algorithms which can automatically assess a quality of the image in a way that is consistent with human evaluation is important. In this paper, an approach to image quality assessment (IQA is proposed in which the quality of a given image is evaluated jointly by several IQA approaches. At first, in order to obtain such joint models, an optimisation problem of IQA measures aggregation is defined, where a weighted sum of their outputs, i.e., objective scores, is used as the aggregation operator. Then, the weight of each measure is considered as a decision variable in a problem of minimisation of root mean square error between obtained objective scores and subjective scores. Subjective scores reflect ground-truth and involve evaluation of images by human observers. The optimisation problem is solved using a genetic algorithm, which also selects suitable measures used in aggregation. Obtained multimeasures are evaluated on four largest widely used image benchmarks and compared against state-of-the-art full-reference IQA approaches. Results of comparison reveal that the proposed approach outperforms other competing measures.

  12. Monitoring chemical degradation of thermally cycled glass-fibre composites using hyperspectral imaging

    Science.gov (United States)

    Papadakis, V. M.; Müller, B.; Hagenbeek, M.; Sinke, J.; Groves, R. M.

    2016-04-01

    Nowadays, the application of glass-fibre composites in light-weight structures is growing. Although mechanical characterizations of those structures are commonly performed in testing, chemical changes of materials under stresses have not yet been well documented. In the present work coupon tests and Hyperspectral Imaging (HSI) have been used to categorise possible chemical changes of glass-fibre reinforced polymers (GFRP) which are currently used in the aircraft industry. HSI is a hybrid technique that combines spectroscopy with imaging. It is able to detect chemical degradation of surfaces and has already been successfully applied in a wide range of fields including astronomy, remote sensing, cultural heritage and medical sciences. GFRP specimens were exposed to two different thermal loading conditions. One thermal loading condition was a continuous thermal exposure at 120°C for 24h, 48 h and 96h, i.e. ageing at a constant temperature. The other thermal loading condition was thermal cycling with three different numbers of cycles (4000, 8000, 12000) and two temperature ranges (0°C to 120°C and -25°C to 95°C). The effects of both conditions were measured using both HSI and interlaminar shear (ILSS) tests. No significant changes of the physical properties of the thermally cycled GFRP specimens were detected using interlaminar shear strength tests and optical microscopy. However, when using HIS, differences of the surface conditions were detected. The results showed that the different thermal loading conditions could be successfully clustered in different colours, using the HSI linear unmixing technique. Each different thermal loading condition showed a different chemical degradation level on its surface which was indicated using different colours.

  13. Online hyperspectral imaging system for evaluating quality of agricultural products

    Science.gov (United States)

    Mo, Changyeun; Kim, Giyoung; Lim, Jongguk

    2017-06-01

    The consumption of fresh-cut agricultural produce in Korea has been growing. The browning of fresh-cut vegetables that occurs during storage and foreign substances such as worms and slugs are some of the main causes of consumers' concerns with respect to safety and hygiene. The purpose of this study is to develop an on-line system for evaluating quality of agricultural products using hyperspectral imaging technology. The online evaluation system with single visible-near infrared hyperspectral camera in the range of 400 nm to 1000 nm that can assess quality of both surfaces of agricultural products such as fresh-cut lettuce was designed. Algorithms to detect browning surface were developed for this system. The optimal wavebands for discriminating between browning and sound lettuce as well as between browning lettuce and the conveyor belt were investigated using the correlation analysis and the one-way analysis of variance method. The imaging algorithms to discriminate the browning lettuces were developed using the optimal wavebands. The ratio image (RI) algorithm of the 533 nm and 697 nm images (RI533/697) for abaxial surface lettuce and the ratio image algorithm (RI533/697) and subtraction image (SI) algorithm (SI538-697) for adaxial surface lettuce had the highest classification accuracies. The classification accuracy of browning and sound lettuce was 100.0% and above 96.0%, respectively, for the both surfaces. The overall results show that the online hyperspectral imaging system could potentially be used to assess quality of agricultural products.

  14. Achieving Quality in Cardiovascular Imaging II: proceedings from the Second American College of Cardiology -- Duke University Medical Center Think Tank on Quality in Cardiovascular Imaging.

    Science.gov (United States)

    Douglas, Pamela S; Chen, Jersey; Gillam, Linda; Hendel, Robert; Hundley, W Gregory; Masoudi, Frederick; Patel, Manesh R; Peterson, Eric

    2009-02-01

    Despite rapid technologic advances and sustained growth, less attention has been focused on quality in imaging than in other areas of cardiovascular medicine. To address this deficit, representatives from cardiovascular imaging societies, private payers, government agencies, the medical imaging industry, and experts in quality measurement met in the second Quality in Cardiovascular Imaging Think Tank. The participants endorsed the previous consensus definition of quality in imaging and proposed quality measures. Additional areas of needed effort included data standardization and structured reporting, appropriateness criteria, imaging registries, laboratory accreditation, partnership development, and imaging research. The second American College of Cardiology-Duke University Think Tank continued the process of the development, dissemination, and adoption of quality improvement initiatives for all cardiovascular imaging modalities.

  15. Development of profession and quality in radiography with focus on evaluation criteria and image quality of chest x-rays

    DEFF Research Database (Denmark)

    Debess, Jeanne; Thomsen, Henrik; Conradsen, Jacob

    2011-01-01

    Learning Objectives: Learning Objectives: To improve quality of chest xrays by Education Conferences for radiographers and evaluation of image quality. Background: Introduction of digital imaging technology and picture archiving and communication system (PACS) has changed the workflow in the x......-ray department including evaluation of image quality and feedback from radiologist to radiographer. Imaging Findings or Procedure Details: Procedure Details: Data for evaluation of image quality was collected by questionnaires aimed at: anatomy, image-focusing, image-collimation, exposure and body habitus...... collection were found. Evaluation results from anatomy, image-focusing, image-collimation and exposure from first data collection shows variations from 7 % to 37 % between evaluation at primary monitor by the radiographers and diagnostic monitor by the radiologist. In relation to anatomy, the quality...

  16. Improvement of material decomposition and image quality in dual-energy radiography by reducing image noise

    Science.gov (United States)

    Lee, D.; Kim, Y.-s.; Choi, S.; Lee, H.; Choi, S.; Jo, B. D.; Jeon, P.-H.; Kim, H.; Kim, D.; Kim, H.; Kim, H.-J.

    2016-08-01

    Although digital radiography has been widely used for screening human anatomical structures in clinical situations, it has several limitations due to anatomical overlapping. To resolve this problem, dual-energy imaging techniques, which provide a method for decomposing overlying anatomical structures, have been suggested as alternative imaging techniques. Previous studies have reported several dual-energy techniques, each resulting in different image qualities. In this study, we compared three dual-energy techniques: simple log subtraction (SLS), simple smoothing of a high-energy image (SSH), and anti-correlated noise reduction (ACNR) with respect to material thickness quantification and image quality. To evaluate dual-energy radiography, we conducted Monte Carlo simulation and experimental phantom studies. The Geant 4 Application for Tomographic Emission (GATE) v 6.0 and tungsten anode spectral model using interpolation polynomials (TASMIP) codes were used for simulation studies and digital radiography, and human chest phantoms were used for experimental studies. The results of the simulation study showed improved image contrast-to-noise ratio (CNR) and coefficient of variation (COV) values and bone thickness estimation accuracy by applying the ACNR and SSH methods. Furthermore, the chest phantom images showed better image quality with the SSH and ACNR methods compared to the SLS method. In particular, the bone texture characteristics were well-described by applying the SSH and ACNR methods. In conclusion, the SSH and ACNR methods improved the accuracy of material quantification and image quality in dual-energy radiography compared to SLS. Our results can contribute to better diagnostic capabilities of dual-energy images and accurate material quantification in various clinical situations.

  17. Using Degraded Music Quality to Encourage a Health Improving Walking Pace: BeatClearWalker

    Directory of Open Access Journals (Sweden)

    Andreas Komninos

    2015-08-01

    Full Text Available Meeting the target of 8000 steps/day, as recommended by many national governments and health authorities, can provide considerable physical and mental health benefits and is seen as a key target for reducing obesity levels and improving public health. However, to optimize the health benefits, walking should be performed at a “moderate” intensity. While there are numerous mobile fitness applications that monitor distance walked, none directly support walking at this cadence nor has there been any research into live feedback for walking cadence. We present a smartphone fitness application to help users learn how to walk at a moderate cadence and maintain that cadence. We apply real-time audio effects that diminish the audio quality of music when the target walking cadence is not being reached. This provides an immersive and intuitive application that can easily be integrated into everyday life as allows users to walk while listening to their own music and encourages eyes-free interaction. In this paper, we introduce our approach, design, initial lab evaluation and a controlled outdoor study. Results show that using music degradation decreases the number of below-cadence steps, that users felt they worked harder with our player and would use it while exercise walking.

  18. 3D-MAD: A Full Reference Stereoscopic Image Quality Estimator Based on Binocular Lightness and Contrast Perception.

    Science.gov (United States)

    Zhang, Yi; Chandler, Damon M

    2015-11-01

    Algorithms for a stereoscopic image quality assessment (IQA) aim to estimate the qualities of 3D images in a manner that agrees with human judgments. The modern stereoscopic IQA algorithms often apply 2D IQA algorithms on stereoscopic views, disparity maps, and/or cyclopean images, to yield an overall quality estimate based on the properties of the human visual system. This paper presents an extension of our previous 2D most apparent distortion (MAD) algorithm to a 3D version (3D-MAD) to evaluate 3D image quality. The 3D-MAD operates via two main stages, which estimate perceived quality degradation due to 1) distortion of the monocular views and 2) distortion of the cyclopean view. In the first stage, the conventional MAD algorithm is applied on the two monocular views, and then the combined binocular quality is estimated via a weighted sum of the two estimates, where the weights are determined based on a block-based contrast measure. In the second stage, intermediate maps corresponding to the lightness distance and the pixel-based contrast are generated based on a multipathway contrast gain-control model. Then, the cyclopean view quality is estimated by measuring the statistical-difference-based features obtained from the reference stereopair and the distorted stereopair, respectively. Finally, the estimates obtained from the two stages are combined to yield an overall quality score of the stereoscopic image. Tests on various 3D image quality databases demonstrate that our algorithm significantly improves upon many other state-of-the-art 2D/3D IQA algorithms.

  19. COATLI: an all-sky robotic optical imager with 0.3 arcsec image quality

    CERN Document Server

    Watson, Alan M; Núñez, Luis C Álvarez; Ángeles, Fernando; Becerra-Godínez, Rosa L; Chapa, Oscar; Farah, Alejandro S; Fuentes-Fernández, Jorge; Figueroa, Liliana; Lebre, Rosalía Langarica; Quirós, Fernando; Román-Zúñiga, Carlos G; Ruíz-Diáz-Soto, Jaime; Tejada, Carlos G; Tinoco, Silvio J

    2016-01-01

    COATLI will provide 0.3 arcsec FWHM images from 550 to 900 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited fast-guiding imager. Since the telescope is small, fast guiding will provide diffraction-limited image quality over a field of at least 1 arcmin and with coverage of a large fraction of the sky, even in relatively poor seeing. The COATLI telescope will be installed at the at the Observatorio Astron\\'omico Nacional in Sierra San Pedro M\\'artir, M\\'exico, during 2016 and the diffraction-limited imager will follow in 2017.

  20. Observer detection of image degradation caused by irreversible data compression processes

    Science.gov (United States)

    Chen, Ji; Flynn, Michael J.; Gross, Barry; Spizarny, David

    1991-05-01

    Irreversible data compression methods have been proposed to reduce the data storage and communication requirements of digital imaging systems. In general, the error produced by compression increases as an algorithm''s compression ratio is increased. We have studied the relationship between compression ratios and the detection of induced error using radiologic observers. The nature of the errors was characterized by calculating the power spectrum of the difference image. In contrast with studies designed to test whether detected errors alter diagnostic decisions, this study was designed to test whether observers could detect the induced error. A paired-film observer study was designed to test whether induced errors were detected. The study was conducted with chest radiographs selected and ranked for subtle evidence of interstitial disease, pulmonary nodules, or pneumothoraces. Images were digitized at 86 microns (4K X 5K) and 2K X 2K regions were extracted. A full-frame discrete cosine transform method was used to compress images at ratios varying between 6:1 and 60:1. The decompressed images were reprinted next to the original images in a randomized order with a laser film printer. The use of a film digitizer and a film printer which can reproduce all of the contrast and detail in the original radiograph makes the results of this study insensitive to instrument performance and primarily dependent on radiographic image quality. The results of this study define conditions for which errors associated with irreversible compression cannot be detected by radiologic observers. The results indicate that an observer can detect the errors introduced by this compression algorithm for compression ratios of 10:1 (1.2 bits/pixel) or higher.

  1. Effect of catchment land use and soil type on the concentration, quality, and bacterial degradation of riverine dissolved organic matter

    DEFF Research Database (Denmark)

    Autio, Iida; Soinne, Helena; Helin, Janne;

    2016-01-01

    of dissolved organic carbon, nitrogen, and phosphorus (DOC, DON, and DOP, respectively), and was linked to DOM quality. Soil type was more important than land use in determining the concentration and quality of riverine DOM. On average, 5–9 % of the DOC and 45 % of the DON were degraded by the bacterial......We studied the effects of catchment characteristics (soil type and land use) on the concentration and quality of dissolved organic matter (DOM) in river water and on the bacterial degradation of terrestrial DOM. The share of organic soil was the strongest predictor of high concentrations...... communities within 2–3 months. Simultaneously, the proportion of humic-like compounds in the DOM pool increased. Bioavailable DON accounted for approximately one-third of the total bioavailable dissolved nitrogen, and thus, terrestrial DON can markedly contribute to the coastal plankton dynamics and support...

  2. Metal artifact reduction and image quality evaluation of lumbar spine CT images using metal sinogram segmentation.

    Science.gov (United States)

    Kaewlek, Titipong; Koolpiruck, Diew; Thongvigitmanee, Saowapak; Mongkolsuk, Manus; Thammakittiphan, Sastrawut; Tritrakarn, Siri-on; Chiewvit, Pipat

    2015-01-01

    Metal artifacts often appear in the images of computed tomography (CT) imaging. In the case of lumbar spine CT images, artifacts disturb the images of critical organs. These artifacts can affect the diagnosis, treatment, and follow up care of the patient. One approach to metal artifact reduction is the sinogram completion method. A mixed-variable thresholding (MixVT) technique to identify the suitable metal sinogram is proposed. This technique consists of four steps: 1) identify the metal objects in the image by using k-mean clustering with the soft cluster assignment, 2) transform the image by separating it into two sinograms, one of which is the sinogram of the metal object, with the surrounding tissue shown in the second sinogram. The boundary of the metal sinogram is then found by the MixVT technique, 3) estimate the new value of the missing data in the metal sinogram by linear interpolation from the surrounding tissue sinogram, 4) reconstruct a modified sinogram by using filtered back-projection and complete the image by adding back the image of the metal object into the reconstructed image to form the complete image. The quantitative and clinical image quality evaluation of our proposed technique demonstrated a significant improvement in image clarity and detail, which enhances the effectiveness of diagnosis and treatment.

  3. TL dosimetry for quality control of CR mammography imaging systems

    Science.gov (United States)

    Gaona, E.; Nieto, J. A.; Góngora, J. A. I. D.; Arreola, M.; Enríquez, J. G. F.

    The aim of this work is to estimate the average glandular dose with thermoluminescent (TL) dosimetry and comparison with quality imaging in computed radiography (CR) mammography. For a measuring dose, the Food and Drug Administration (FDA) and the American College of Radiology (ACR) use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, full field digital mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium flourohalideE We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated X-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose greater than 3.0 mGy without demonstrating improved image quality. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement for X-rays with a HVL (0.35-0.38 mmAl) and kVp (24-26) used in quality control procedures with ACR Mammography Accreditation Phantom.

  4. Comparison-based Image Quality Assessment for Selecting Image Restoration Parameters.

    Science.gov (United States)

    Liang, Haoyi; Weller, Daniel

    2016-08-19

    Image quality assessment (IQA) is traditionally classified into full-reference (FR) IQA, reduced-reference (RR) IQA, and no-reference (NR) IQA according to the amount of information required from the original image. Although NRIQA and RR-IQA are widely used in practical applications, room for improvement still remains because of the lack of the reference image. Inspired by the fact that in many applications, such as parameter selection for image restoration algorithms, a series of distorted images are available, the authors propose a novel comparison-based image quality assessment (C-IQA) framework. The new comparison-based framework parallels FRIQA by requiring two input images, and resembles NR-IQA by not using the original image. As a result, the new comparisonbased approach has more application scenarios than FR-IQA does, and takes greater advantage of the accessible information than the traditional single-input NR-IQA does. Further, C-IQA is compared with other state-of-the-art NR-IQA methods and another RR-IQA method on two widely used IQA databases. Experimental results show that C-IQA outperforms the other methods for parameter selection, and the parameter trimming framework combined with C-IQA saves the computation of iterative image reconstruction up to 80%.

  5. Quantifying the influence of Bessel beams on image quality in optical coherence tomography.

    Science.gov (United States)

    Curatolo, Andrea; Munro, Peter R T; Lorenser, Dirk; Sreekumar, Parvathy; Singe, C Christian; Kennedy, Brendan F; Sampson, David D

    2016-03-24

    Light scattered by turbid tissue is known to degrade optical coherence tomography (OCT) image contrast progressively with depth. Bessel beams have been proposed as an alternative to Gaussian beams to image deeper into turbid tissue. However, studies of turbid tissue comparing the image quality for different beam types are lacking. We present such a study, using numerically simulated beams and experimental OCT images formed by Bessel or Gaussian beams illuminating phantoms with optical properties spanning a range typical of soft tissue. We demonstrate that, for a given scattering parameter, the higher the scattering anisotropy the lower the OCT contrast, regardless of the beam type. When focusing both beams at the same depth in the sample, we show that, at focus and for equal input power and resolution, imaging with the Gaussian beam suffers less reduction of contrast. This suggests that, whilst Bessel beams offer extended depth of field in a single depth scan, for low numerical aperture (NA 0.95), superior contrast (by up to ~40%) may be obtained over an extended depth range by a Gaussian beam combined with dynamic focusing.

  6. ASSESMENT OF THE INFLUENCE OF UAV IMAGE QUALITY ON THE ORTHOPHOTO PRODUCTION

    Directory of Open Access Journals (Sweden)

    D. Wierzbicki

    2015-08-01

    Full Text Available Over the past years a noticeable increase of interest in using Unmanned Aerial Vehicles (UAV for acquiring low altitude images has been observed. This method creates new possibilities of using geodata captured from low altitudes to generate large scale orthophotos. Because of comparatively low costs, UAV aerial surveying systems find many applications in photogrammetry and remote sensing. One of the most significant problems with automation of processing of image data acquired with this method is its low accuracy. This paper presents the following stages of acquisition and processing of images collected in various weather and lighting conditions: aerotriangulation, generating of Digital Terrain Models (DTMs, orthorectification and mosaicking. In the research a compact, non-metric camera, mounted on a fuselage powered by an electric motor was used. The tested area covered flat, agricultural and woodland terrains. Aerotriangulation and point cloud accuracy as well as generated digital terrain model and mosaic exactness were examined. Dense multiple image matching was used as a benchmark. The processing and analysis were carried out with INPHO UASMaster programme. Based on performed accuracy analysis it was stated that images acquired in poor weather conditions (cloudy, precipitation degrade the final quality and accuracy of a photogrammetric product by an average of 25%.

  7. Characterization of image quality and image-guidance performance of a preclinical microirradiator

    Energy Technology Data Exchange (ETDEWEB)

    Clarkson, R.; Lindsay, P. E.; Ansell, S.; Wilson, G.; Jelveh, S.; Hill, R. P.; Jaffray, D. A. [Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 1A1 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada) and Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5S 1A1 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 1A1 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5S 1A1 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 1A1 (Canada)

    2011-02-15

    Purpose: To assess image quality and image-guidance capabilities of a cone-beam CT based small-animal image-guided irradiation unit (micro-IGRT). Methods: A micro-IGRT system has been developed in collaboration with the authors' laboratory as a means to study the radiobiological effects of conformal radiation dose distributions in small animals. The system, the X-Rad 225Cx, consists of a 225 kVp x-ray tube and a flat-panel amorphous silicon detector mounted on a rotational C-arm gantry and is capable of both fluoroscopic x-ray and cone-beam CT imaging, as well as image-guided placement of the radiation beams. Image quality (voxel noise, modulation transfer, CT number accuracy, and geometric accuracy characteristics) was assessed using water cylinder and micro-CT test phantoms. Image guidance was tested by analyzing the dose delivered to radiochromic films fixed to BB's through the end-to-end process of imaging, targeting the center of the BB, and irradiation of the film/BB in order to compare the offset between the center of the field and the center of the BB. Image quality and geometric studies were repeated over a 5-7 month period to assess stability. Results: CT numbers reported were found to be linear (R{sup 2}{>=}0.998) and the noise for images of homogeneous water phantom was 30 HU at imaging doses of approximately 1 cGy (to water). The presampled MTF at 50% and 10% reached 0.64 and 1.35 mm{sup -1}, respectively. Targeting accuracy by means of film irradiations was shown to have a mean displacement error of [{Delta}x,{Delta}y,{Delta}z]=[-0.12,-0.05,-0.02] mm, with standard deviations of [0.02, 0.20, 0.17] mm. The system has proven to be stable over time, with both the image quality and image-guidance performance being reproducible for the duration of the studies. Conclusions: The micro-IGRT unit provides soft-tissue imaging of small-animal anatomy at acceptable imaging doses ({<=}1 cGy). The geometric accuracy and targeting systems permit dose

  8. METHOD OF IMAGE QUALITY ENHANCEMENT FOR SPACE OBJECTS

    Directory of Open Access Journals (Sweden)

    D. S. Korshunov

    2014-07-01

    Full Text Available The paper deals with an approach for image quality improvement of the space objects in the visible range of electromagnetic wave spectrum. The proposed method is based on the joint taking into account of both the motion velocity of the space supervisory apparatus and a space object observed in the near-earth space when the time of photo-detector exposure is chosen. The timing of exposure is carried out by light-signal characteristics, which determines the optimal value of the charge package formed in the charge-coupled device being irradiated. Thus, the parameters of onboard observation equipment can be selected, which provides space images suitable for interpretation. The linear resolving capacity is used as quality indicator for space images, giving a complete picture for the image contrast and geometric properties of the object on the photo. Observation scenario modeling of the space object, done by sputnik-inspector, has shown the possibility of increasing the linear resolution up to10% - 20% or up to 40% - 50% depending on the non-complanarity angle at the movement along orbits. The proposed approach to the increase of photographs quality provides getting sharp and highcontrast images of space objects by the optical-electronic equipment of the space-based remote sensing. The usage of these images makes it possible to detect in time the space technology failures, which are the result of its exploitation in the nearearth space. The proposed method can be also applied at the stage of space systems design for optical-electronic surveillance in computer models used for facilities assessment of the shooting equipment information tract.

  9. Eye Model for Inspecting the Image Quality of IOLs

    Institute of Scientific and Technical Information of China (English)

    Zhenping Huang; Renfeng Xu; Chunyan Xue; Yong Wu; Huachun Wang; Degao Zhao

    2007-01-01

    Purpose: To inspect and compare the image quality of an aspheric intraocular lens (IQ, Alcon) with those of conventional monofocal silicone and acrylic intraocular lens and multifocal intraocular lens (Array).Methods: The IOLs were tested in the eye model, which was designed to be optically equivalent to the theoretical eye model. The eye model is a combination of a spherical photographic lens with 35 mm focal length (IOL put in a water cell) and a charge coupled device (CCD) camera. The images constructed by the lenses are observed on a monitor of personal computer and the contrasts of the images are analyzed by using commercial image processing software. SHARP value is used to measure and estimate image definition.Results: The images constructed by changing the diameter of aperture stop and IOL. Observed by this eye model, the image definition of aspheric intraocular lens (IQ, Alcon) is better than others.Discussion: The proposed eye model is useful for testing functional vision and for inspecting the differences of intraocular lens.

  10. Quality assessment of butter cookies applying multispectral imaging

    Science.gov (United States)

    Andresen, Mette S; Dissing, Bjørn S; Løje, Hanne

    2013-01-01

    A method for characterization of butter cookie quality by assessing the surface browning and water content using multispectral images is presented. Based on evaluations of the browning of butter cookies, cookies were manually divided into groups. From this categorization, reference values were calculated for a statistical prediction model correlating multispectral images with a browning score. The browning score is calculated as a function of oven temperature and baking time. It is presented as a quadratic response surface. The investigated process window was the intervals 4–16 min and 160–200°C in a forced convection electrically heated oven. In addition to the browning score, a model for predicting the average water content based on the same images is presented. This shows how multispectral images of butter cookies may be used for the assessment of different quality parameters. Statistical analysis showed that the most significant wavelengths for browning predictions were in the interval 400–700 nm and the wavelengths significant for water prediction were primarily located in the near-infrared spectrum. The water prediction model was found to correctly estimate the average water content with an absolute error of 0.22%. From the images it was also possible to follow the browning and drying propagation from the cookie edge toward the center. PMID:24804036

  11. Spread spectrum image watermarking based on perceptual quality metric.

    Science.gov (United States)

    Zhang, Fan; Liu, Wenyu; Lin, Weisi; Ngan, King Ngi

    2011-11-01

    Efficient image watermarking calls for full exploitation of the perceptual distortion constraint. Second-order statistics of visual stimuli are regarded as critical features for perception. This paper proposes a second-order statistics (SOS)-based image quality metric, which considers the texture masking effect and the contrast sensitivity in Karhunen-Loève transform domain. Compared with the state-of-the-art metrics, the quality prediction by SOS better correlates with several subjectively rated image databases, in which the images are impaired by the typical coding and watermarking artifacts. With the explicit metric definition, spread spectrum watermarking is posed as an optimization problem: we search for a watermark to minimize the distortion of the watermarked image and to maximize the correlation between the watermark pattern and the spread spectrum carrier. The simple metric guarantees the optimal watermark a closed-form solution and a fast implementation. The experiments show that the proposed watermarking scheme can take full advantage of the distortion constraint and improve the robustness in return.

  12. Amendments and mulches improve the biological quality of soils degraded by mining activities in SE Spain

    Science.gov (United States)

    Luna Ramos, Lourdes; Miralles Mellado, Isabel; Hernández Fernández, María Teresa; García Izquierdo, Carlos; Solé Benet, Albert

    2014-05-01

    Mining and quarrying activities generate negative visual impacts in the landscape and a loss of environmental quality. Substrate properties at the end of mining are in general not suitable for plant growth, even native ones. In an experimental soil restoration in limestone quarries from Sierra de Gádor (Almería), SE Spain, the effect of organic amendment (sewage sludge, compost from the organic fraction of domestic waste or non-amendment) combined or not with two different kind of mulches (fine gravel, chopped forest residue) was tested by triplicate in 5 x 5 m plots with the aim to improve soil/substrate properties and to reduce evaporation and erosion. In each experimental plot 75 native plants (Stipa tenacissima, Anthyllis terniflora and Anthyllis cytisoides) were planted. Effects of adding organic amendments and mulches on some soil microbiological and biochemical parameters (microbial biomass carbon, basal respiration and different enzymatic activities, such as dehydrogenase, phosphatase, β-glucosidase and urease) were analyzed 5 years after the start of the experiment. Vegetation growth was also monitored. The two-way ANOVA, using as factors amendment and mulch, showed a significant positive influence of organic amendments on microbial biomass (Cmic), basal respiration and some enzymatic activities related to the cycles of C and N. The highest values of these parameters were obtained with compost. The influence of the mulch factor and its interactions with the amendment factor on the measured variables did not follow a clear trend with respect the measured parameters. Mulching did not improved significantly (pcontrol, but it is remarkable that the mulch type "forest chopped residue" had a negative effect on vegetation growth. The addition of organic amendments, especially compost from the organic fraction of domestic wastes, is beneficial to restore degraded or man-made soils from quarrying areas because they stimulate microbial growth and activity

  13. The Importance of Store Image and Retail Service Quality in Private Brand Image-Building

    Directory of Open Access Journals (Sweden)

    Adi Alić

    2017-03-01

    Full Text Available Objective: The purpose of this research is to highlight the role which store image and retail service quality can play in private brand image-building in the context of an emerging market in South-Eastern Europe (i.e. Bosnia and Herzegovina. We propose to address this issue by seeking answers to the following questions: (1 Does a ‘halo effect’ take place between the store image and the private brand image? (2 How does consumer’s evaluation of the quality of the service delivered by a retailer affect the image of its private brand? Research Design & Methods: Data were collected through a field survey via the store-intercept method. The sample consisted of 699 customers of two large retail chains. The data were analysed using the Structural Equation Modelling technique. Findings: The findings of the present study suggest that store image and retail service quality are important factors in the formation of the image of product-branded products. Implications & Recommendations: This study offers some important insights for retailers who intend to develop their private brand. First, the image transfer from store brand to private brand suggests that retailers should consider the introduction of a private brand as a brand extension, with their stores as the parent brand. Second, we recommend that retailers put more emphasis on quality improvement initiatives related to the store environment attributes. Contribution & Value Added: This study enhances the discussion on the phenomenon of private branding by analysing the store-level factors which underpin the formation of private brand image in the context of less developed European markets.

  14. Vibration factors impact analysis on aerial film camera imaging quality

    Science.gov (United States)

    Xie, Jun; Han, Wei; Xu, Zhonglin; Tan, Haifeng; Yang, Mingquan

    2017-08-01

    Aerial film camera can acquire ground target image information advantageous, but meanwhile the change of aircraft attitude, the film features and the work of camera inside system could result in a vibration which could depress the image quality greatly. This paper presented a design basis of vibration mitigation stabilized platform based on the vibration characteristic of the aerial film camera and indicated the application analysis that stabilized platform could support aerial camera to realize the shoot demand of multi-angle and large scale. According to the technique characteristics of stabilized platform, the development direction are high precision, more agility, miniaturization and low power.

  15. Free-breathing motion-corrected late-gadolinium-enhancement imaging improves image quality in children.

    Science.gov (United States)

    Olivieri, Laura; Cross, Russell; O'Brien, Kendall J; Xue, Hui; Kellman, Peter; Hansen, Michael S

    2016-06-01

    The value of late-gadolinium-enhancement (LGE) imaging in the diagnosis and management of pediatric and congenital heart disease is clear; however current acquisition techniques are susceptible to error and artifacts when performed in children because of children's higher heart rates, higher prevalence of sinus arrhythmia, and inability to breath-hold. Commonly used techniques in pediatric LGE imaging include breath-held segmented FLASH (segFLASH) and steady-state free precession-based (segSSFP) imaging. More recently, single-shot SSFP techniques with respiratory motion-corrected averaging have emerged. This study tested and compared single-shot free-breathing LGE techniques with standard segmented breath-held techniques in children undergoing LGE imaging. Thirty-two consecutive children underwent clinically indicated late-enhancement imaging using intravenous gadobutrol 0.15 mmol/kg. Breath-held segSSFP, breath-held segFLASH, and free-breathing single-shot SSFP LGE sequences were performed in consecutive series in each child. Two blinded reviewers evaluated the quality of the images and rated them on a scale of 1-5 (1 = poor, 5 = superior) based on blood pool-myocardial definition, presence of cardiac motion, presence of respiratory motion artifacts, and image acquisition artifact. We used analysis of variance (ANOVA) to compare groups. Patients ranged in age from 9 months to 18 years, with a mean +/- standard deviation (SD) of 13.3 +/- 4.8 years. R-R interval at the time of acquisition ranged 366-1,265 milliseconds (ms) (47-164 beats per minute [bpm]), mean +/- SD of 843+/-231 ms (72+/-21 bpm). Mean +/- SD quality ratings for long-axis imaging for segFLASH, segSSFP and single-shot SSFP were 3.1+/-0.9, 3.4+/-0.9 and 4.0+/-0.9, respectively (P quality ratings for short-axis imaging for segFLASH, segSSFP and single-shot SSFP were 3.4+/-1, 3.8+/-0.9 and 4.3+/-0.7, respectively (P quality ratings than standard breath-held techniques. Use of free

  16. A virtual image chain for perceived image quality of medical display

    Science.gov (United States)

    Marchessoux, Cédric; Jung, Jürgen

    2006-03-01

    This paper describes a virtual image chain for medical display (project VICTOR: granted in the 5th framework program by European commission). The chain starts from raw data of an image digitizer (CR, DR) or synthetic patterns and covers image enhancement (MUSICA by Agfa) and both display possibilities, hardcopy (film on viewing box) and softcopy (monitor). Key feature of the chain is a complete image wise approach. A first prototype is implemented in an object-oriented software platform. The display chain consists of several modules. Raw images are either taken from scanners (CR-DR) or from a pattern generator, in which characteristics of DR- CR systems are introduced by their MTF and their dose-dependent Poisson noise. The image undergoes image enhancement and comes to display. For soft display, color and monochrome monitors are used in the simulation. The image is down-sampled. The non-linear response of a color monitor is taken into account by the GOG or S-curve model, whereas the Standard Gray-Scale-Display-Function (DICOM) is used for monochrome display. The MTF of the monitor is applied on the image in intensity levels. For hardcopy display, the combination of film, printer, lightbox and viewing condition is modeled. The image is up-sampled and the DICOM-GSDF or a Kanamori Look-Up-Table is applied. An anisotropic model for the MTF of the printer is applied on the image in intensity levels. The density-dependent color (XYZ) of the hardcopy film is introduced by Look-Up-tables. Finally a Human Visual System Model is applied to the intensity images (XYZ in terms of cd/m2) in order to eliminate nonvisible differences. Comparison leads to visible differences, which are quantified by higher order image quality metrics. A specific image viewer is used for the visualization of the intensity image and the visual difference maps.

  17. Effect of dose reduction on image registration and image quality for cone-beam CT in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Loutfi-Krauss, B.; Koehn, J.; Bluemer, N.; Kara, E.; Scherf, C.; Roedel, C.; Ramm, U.; Licher, J. [Universitaetsklinikum Frankfurt, Klinik fuer Strahlentherapie und Onkologie, Frankfurt am Main (Germany); Freundl, K.; Koch, T. [Sozialstiftung Bamberg - MVZ am Bruderwald, Klinik und Praxis fuer Radioonkologie und Strahlentherapie, Bamberg (Germany)

    2014-09-20

    The additional radiation exposure applied to patients undergoing cone-beam computed tomography (CBCT) for image registration in radiation therapy is of great concern. Since a decrease in CBCT dose is linked to a degradation of image quality, the consequences of dose reduction on the registration process have to be investigated. This paper examines image quality and registration of low-contrast structures on an Elekta XVI for the two treatment areas prostate and chest while gradually decreasing the mAs per frame and the number of projections per CBCT to achieve dose reduction. Ideal results for image quality were obtained for 1.6 mAs/frame and 377 projections in prostate scans and 0.63 mAs/frame and 440 projections in chest images. Lower as well as higher total mAs lead to a decrease in image quality. In spite of poor image quality, registration can be successfully performed even for lowest possible settings. The results for registration allow an extensive dose reduction in both treatment areas. Very low mAs, however, do not qualify for clinical use because subjective judgment of the registration process is impossible. Compared to default presets the use of settings for acceptable image quality already permit a decrease in exposure of about 40 % (29.0 to 16.7 mGy) in prostate scans and 60 % (18.3 to 7.7 mGy) in chest scans. (orig.) [German] Die zusaetzliche Strahlenbelastung von Patienten bei der Lagerungskontrolle mit einer Kegelstrahl-Computertomographie (CBCT) in der Strahlentherapie ist nicht zu vernachlaessigen. Die Reduzierung der Dosis durch das CBCT ist mit einer Verschlechterung der Bildqualitaet verbunden. Aus diesem Grund ist die Untersuchung der Effekte einer Dosisreduktion von grosser Bedeutung. Diese Arbeit untersucht die Bildqualitaet und Bildregistrierung in Bereichen niedrigen Kontrasts mit einem Kegelstrahl CT der Firma Elekta. Betrachtet werden die Behandlungsregionen Prostata und Thorax. Die Dosisreduktion wird durch stufenweise Verringerung der

  18. Image quality vs. sensitivity: fundamental sensor system engineering

    Science.gov (United States)

    Schueler, Carl F.

    2008-08-01

    This paper focuses on the fundamental system engineering tradeoff driving almost all remote sensing design efforts, affecting complexity, cost, performance, schedule, and risk: image quality vs. sensitivity. This single trade encompasses every aspect of performance, including radiometric accuracy, dynamic range and precision, as well as spatial, spectral, and temporal coverage and resolution. This single trade also encompasses every aspect of design, including mass, dimensions, power, orbit selection, spacecraft interface, sensor and spacecraft functional trades, pointing or scanning architecture, sensor architecture (e.g., field-of-view, optical form, aperture, f/#, material properties), electronics, mechanical and thermal properties. The relationship between image quality and sensitivity is introduced based on the concepts of modulation transfer function (MTF) and signal-to-noise ratio (SNR) with examples to illustrate the balance to be achieved by the system architect to optimize cost, complexity, performance and risk relative to end-user requirements.

  19. Reproducibility of Mammography Units, Film Processing and Quality Imaging

    Science.gov (United States)

    Gaona, Enrique

    2003-09-01

    The purpose of this study was to carry out an exploratory survey of the problems of quality control in mammography and processors units as a diagnosis of the current situation of mammography facilities. Measurements of reproducibility, optical density, optical difference and gamma index are included. Breast cancer is the most frequently diagnosed cancer and is the second leading cause of cancer death among women in the Mexican Republic. Mammography is a radiographic examination specially designed for detecting breast pathology. We found that the problems of reproducibility of AEC are smaller than the problems of processors units because almost all processors fall outside of the acceptable variation limits and they can affect the mammography quality image and the dose to breast. Only four mammography units agree with the minimum score established by ACR and FDA for the phantom image.

  20. Enhanced imaging of DNA via active quality factor control

    Science.gov (United States)

    Humphris, A. D. L.; Round, A. N.; Miles, M. J.

    2001-10-01

    Adsorption processes at single molecule level are of fundamental importance for the understanding and development of biomaterials. Atomic force microscopy (AFM) has played a critical role in this field due to its high resolution and ability to image in a liquid environment. We present a method that improves the dynamic force sensitivity and the resolution of a conventional AFM. This is achieved via a positive feedback loop that enhances the effective quality factor of the cantilever in a liquid environment to values in excess of 300, compared to a nominal value of ˜1. This active quality factor enhancement has been used to image DNA and an increase in the height of the molecule observed.

  1. Influence of biological oxygen demand degradation patterns on water-quality modeling for rivers running through urban areas.

    Science.gov (United States)

    Fan, Chihhao; Wang, Wei-Shen

    2008-10-01

    Water-quality modeling has been used as a support tool for water-resources management. The Streeter-Phelps (SP) equation is one often-used algorithm in river water-quality simulation because of its simplicity and ease in use. To characterize the river dissolved oxygen (DO) sag profile, it only considers that the first-order biological oxygen demand (BOD) degradation and atmospheric reaeration are the sink and source in a river, respectively. In the river water-quality calculation, the assumption may not always provide satisfactory simulation due to an inappropriate description of BOD degradation. In the study, various patterns of BOD degradation were combined with the oxygen reaeration to simulate the DO sag profile in a river. Different BOD degradation patterns used include the first-order decay, mixed second-order decay, and oxygen-inhibition decay. The results shows that the oxygen-inhibition SP equation calculates higher BOD and DO concentration, while the mixed second SP equation calculates the least among the three tested models. In river-water calculation of Keelung River, the SP and oxygen-inhibition SP equations calculate similar BOD and DO concentrations, and the mixed second SP equation calculates the least BOD and DO concentration. The pollution loading of BOD and atmospheric reaeration constant are the two important factors that have significant impacts on aqueous DO concentration. In the field application, it is suggested that the mixed second SP equation be employed in water-quality simulation when the monitoring data exhibits a faster trend in BOD decay. The oxygen-inhibition SP equation may calculate the water quality more accurately when BOD decay is slower.

  2. Factors Affecting Image Quality in Near-field Ultra-wideband Radar Imaging for Biomedical Applications

    Science.gov (United States)

    Curtis, Charlotte

    Near-field ultra-wideband radar imaging has potential as a new breast imaging modality. While a number of reconstruction algorithms have been published with the goal of reducing undesired responses or clutter, an in-depth analysis of the dominant sources of clutter has not been conducted. In this thesis, time domain radar image reconstruction is demonstrated to be equivalent to frequency domain synthetic aperture radar. This reveals several assumptions inherent to the reconstruction algorithm related to radial spreading, point source antennas, and the independent summation of point scatterers. Each of these assumptions is examined in turn to determine which has the greatest impact on the resulting image quality and interpretation. In addition, issues related to heterogeneous and dispersive media are addressed. Variations in imaging parameters are tested by observing their influence on the system point spread function. Results are then confirmed by testing on simple and detailed simulation models, followed by data acquired from human volunteers. Recommended parameters are combined into a new imaging operator that is demonstrated to generate results comparable to a more accurate signal model, but with a 50 fold improvement in computational efficiency. Finally, the most significant factor affecting image quality is determined to be the estimate of tissue properties used to form the image.

  3. Soil quality degradation processes along a deforestation chronosequence in the Ziwuling Area, China

    Science.gov (United States)

    Accelerated erosion caused by deforestation and soil degradation has become the primary factor limiting sustainable utilization of soil resources on the Loess Plateau of Northwestern China. We studied the physical, chemical, and microbiological processes of soil degradation along a chronosequence o...

  4. Quality evaluation of edge detection in a road image sequences

    Directory of Open Access Journals (Sweden)

    Rodrigo B. de A. Gallis

    2004-12-01

    Full Text Available Terrestrial mobile mapping systems map interest features along roads such as poles, traffic signs, curb lines, garbage cans etc. The lab work, concerned to the object reconstruction, consists of transforming the video into still images on which homologous points and features of the road sequence are selected and measured. By means of photogrammetric intersection the object coordinates of these features and points are computed for 3D reconstruction. Using Canny algorithm for the automatic edge detection in a road image sequence the article initially focuses on the empiric determination of the required parameters (standard deviation s and high Ta and low Tb threshold. Then it presents the quality in terms of displacement of the automatically detected edges similar to those visually (manually selected straight features extracted by a human operator that takes them as correct, therefore, as reference for the automatic extraction comparison and the quality evaluation. The results of the tests are discussed and show that the quality of the automatic detection – measured by a quantity of rights and wrongs – vary accordingly to the empirically determined standard deviation and high and low thresholds and also to the image sequence environment (street or road.

  5. Image Quality Assessment for Performance Evaluation of Focus Measure Operators

    Directory of Open Access Journals (Sweden)

    Farida Memon

    2015-10-01

    Full Text Available This paper presents the performance evaluation of eight focus measure operators namely Image CURV (Curvature, GRAE (Gradient Energy, HISE (Histogram Entropy, LAPM (Modified Laplacian, LAPV (Variance of Laplacian, LAPD (Diagonal Laplacian, LAP3 (Laplacian in 3D Window and WAVS (Sum of Wavelet Coefficients. Statistical matrics such as MSE (Mean Squared Error, PNSR (Peak Signal to Noise Ratio, SC (Structural Content, NCC (Normalized Cross Correlation, MD (Maximum Difference and NAE (Normalized Absolute Error are used to evaluate stated focus measures in this research. . FR (Full Reference method of the image quality assessment is utilized in this paper. Results indicate that LAPD method is comparatively better than other seven focus operators at typical imaging conditions

  6. Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo sequence: improvement of the image quality of oxygen-enhanced MRI

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, Yoshiharu E-mail: yosirad@kobe-u.ac.jpyosirad@med.kobe-u.ac.jpyoshiharuohno@aol.com; Hatabu, Hiroto; Higashino, Takanori; Kawamitsu, Hideaki; Watanabe, Hirokazu; Takenaka, Daisuke; Cauteren, Marc van; Sugimura, Kazuro

    2004-11-01

    Purpose: The purpose of the study presented here was to determine the improvement in image quality of oxygen-enhanced magnetic resonance (MR) subtraction imaging obtained with a centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence compared with that obtained with a conventional sequentially reordered inversion recovery single-shot HASTE (s-IR-HASTE) sequence for pulmonary imaging. Materials and methods: Oxygen-enhanced MR imaging using a 1.5 T whole body scanner was performed on 12 healthy, non-smoking volunteers. Oxygen-enhanced MR images were obtained with the coronal two-dimensional (2D) c-IR-HASTE sequence and 2D s-IR-HASTE sequence combined with respiratory triggering. For a 256x256 matrix, 132 phase-encoding steps were acquired including four steps for phase correction. Inter-echo spacing for each sequence was 4.0 ms. The effective echo time (TE) for c-IR-HASTE was 4.0 ms, and 16 ms for s-IR-HASTE. The inversion time (TI) was 900 ms. To determine the improvement in oxygen-enhanced MR subtraction imaging by c-IR-HASTE, CNRs of subtraction image, overall image quality, and image degradation of the c-IR-HASTE and s-IR-HASTE techniques were statistically compared. Results: CNR, overall image quality, and image degradation of c-IR-HASTE images showed significant improvement compared to those s-IR-HASTE images (P<0.05). Conclusion: Centrically reordered inversion recovery half-Fourier single-shot turbo spin-echo (c-IR-HASTE) sequence enhanced the signal from the lung and improved the image quality of oxygen-enhanced MR subtraction imaging.

  7. NEW VISUAL PERCEPTUAL POOLING STRATEGY FOR IMAGE QUALITY ASSESSMENT

    Institute of Scientific and Technical Information of China (English)

    Zhou Wujie; Jiang Gangyi; Yu Mei

    2012-01-01

    Most of Image Quality Assessment (IQA) metrics consist of two processes.In the first process,quality map of image is measured locally.In the second process,the last quality score is converted from the quality map by using the pooling strategy.The first process had been made effective and significant progresses,while the second process was always done in simple ways.In the second process of the pooling strategy,the optimal perceptual pooling weights should be determined and computed according to Human Visual System (HVS).Thus,a reliable spatial pooling mathematical model based on HVS is an important issue worthy of study.In this paper,a new Visual Perceptual Pooling Strategy (VPPS) for IQA is presented based on contrast sensitivity and luminance sensitivity of HVS.Experimental results with the LIVE database show that the visual perceptual weights,obtained by the proposed pooling strategy,can effectively and significantly improve the performances of the IQA metrics with Mean Structural SIMilarity (MSSIM) or Phase Quantization Code (PQC).It is confirmed that the proposed VPPS demonstrates promising results for improving the performances of existing IQA metrics.

  8. SU-E-J-36: Comparison of CBCT Image Quality for Manufacturer Default Imaging Modes

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, G [University of Wisconsin, Madison, WI (United States)

    2015-06-15

    Purpose CBCT is being increasingly used in patient setup for radiotherapy. Often the manufacturer default scan modes are used for performing these CBCT scans with the assumption that they are the best options. To quantitatively assess the image quality of these scan modes, all of the scan modes were tested as well as options with the reconstruction algorithm. Methods A CatPhan 504 phantom was scanned on a TrueBeam Linear Accelerator using the manufacturer scan modes (FSRT Head, Head, Image Gently, Pelvis, Pelvis Obese, Spotlight, & Thorax). The Head mode scan was then reconstructed multiple times with all filter options (Smooth, Standard, Sharp, & Ultra Sharp) and all Ring Suppression options (Disabled, Weak, Medium, & Strong). An open source ImageJ tool was created for analyzing the CatPhan 504 images. Results The MTF curve was primarily dictated by the voxel size and the filter used in the reconstruction algorithm. The filters also impact the image noise. The CNR was worst for the Image Gently mode, followed by FSRT Head and Head. The sharper the filter, the worse the CNR. HU varied significantly between scan modes. Pelvis Obese had lower than expected HU values than most while the Image Gently mode had higher than expected HU values. If a therapist tried to use preset window and level settings, they would not show the desired tissue for some scan modes. Conclusion Knowing the image quality of the set scan modes, will enable users to better optimize their setup CBCT. Evaluation of the scan mode image quality could improve setup efficiency and lead to better treatment outcomes.

  9. SU-E-J-183: Quantifying the Image Quality and Dose Reduction of Respiratory Triggered 4D Cone-Beam Computed Tomography with Patient- Measured Breathing

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, B; OBrien, R; Kipritidis, J; Keall, P [The University of Sydney, Sydney, New South Wales (Australia)

    2014-06-01

    Purpose: Respiratory triggered four dimensional cone-beam computed tomography (RT 4D CBCT) is a novel technique that uses a patient's respiratory signal to drive the image acquisition with the goal of imaging dose reduction without degrading image quality. This work investigates image quality and dose using patient-measured respiratory signals for RT 4D CBCT simulations instead of synthetic sinusoidal signals used in previous work. Methods: Studies were performed that simulate a 4D CBCT image acquisition using both the novel RT 4D CBCT technique and a conventional 4D CBCT technique from a database of oversampled Rando phantom CBCT projections. A database containing 111 free breathing lung cancer patient respiratory signal files was used to create 111 RT 4D CBCT and 111 conventional 4D CBCT image datasets from realistic simulations of a 4D RT CBCT system. Each of these image datasets were compared to a ground truth dataset from which a root mean square error (RMSE) metric was calculated to quantify the degradation of image quality. The number of projections used in each simulation is counted and was assumed as a surrogate for imaging dose. Results: Based on 111 breathing traces, when comparing RT 4D CBCT with conventional 4D CBCT the average image quality was reduced by 7.6%. However, the average imaging dose reduction was 53% based on needing fewer projections (617 on average) than conventional 4D CBCT (1320 projections). Conclusion: The simulation studies using a wide range of patient breathing traces have demonstrated that the RT 4D CBCT method can potentially offer a substantial saving of imaging dose of 53% on average compared to conventional 4D CBCT in simulation studies with a minimal impact on image quality. A patent application (PCT/US2012/048693) has been filed which is related to this work.

  10. Image Quality of the Helioseismic and Magnetic Imager (HMI) Onboard the Solar Dynamics Observatory (SDO)

    Science.gov (United States)

    Wachter, R.; Schou, Jesper; Rabello-Soares, M. C.; Miles, J. W.; Duvall, T. L., Jr.; Bush, R. I.

    2011-01-01

    We describe the imaging quality of the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as measured during the ground calibration of the instrument. We describe the calibration techniques and report our results for the final configuration of HMI. We present the distortion, modulation transfer function, stray light,image shifts introduced by moving parts of the instrument, best focus, field curvature, and the relative alignment of the two cameras. We investigate the gain and linearity of the cameras, and present the measured flat field.

  11. Imaging quality evaluation method of pixel coupled electro-optical imaging system

    Science.gov (United States)

    He, Xu; Yuan, Li; Jin, Chunqi; Zhang, Xiaohui

    2017-09-01

    With advancements in high-resolution imaging optical fiber bundle fabrication technology, traditional photoelectric imaging system have become ;flexible; with greatly reduced volume and weight. However, traditional image quality evaluation models are limited by the coupling discrete sampling effect of fiber-optic image bundles and charge-coupled device (CCD) pixels. This limitation substantially complicates the design, optimization, assembly, and evaluation image quality of the coupled discrete sampling imaging system. Based on the transfer process of grayscale cosine distribution optical signal in the fiber-optic image bundle and CCD, a mathematical model of coupled modulation transfer function (coupled-MTF) is established. This model can be used as a basis for following studies on the convergence and periodically oscillating characteristics of the function. We also propose the concept of the average coupled-MTF, which is consistent with the definition of traditional MTF. Based on this concept, the relationships among core distance, core layer radius, and average coupled-MTF are investigated.

  12. Optimum image compression rate maintaining diagnostic image quality of digital intraoral radiographs

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ju Seop; Koh, Kwang Joon [Dept. of Oral and Maxillofacial Radiology and Institute of Oral Bio Science, School of Dentistry, Chonbuk National University, Chonju (Korea, Republic of)

    2000-12-15

    The aims of the present study are to determine the optimum compression rate in terms of file size reduction and diagnostic quality of the images after compression and evaluate the transmission speed of original or each compressed images. The material consisted of 24 extracted human premolars and molars. The occlusal surfaces and proximal surfaces of the teeth had a clinical disease spectrum that ranged from sound to varying degrees of fissure discoloration and cavitation. The images from Digora system were exported in TIFF and the images from conventional intraoral film were scanned and digitalized in TIFF by Nikon SF-200 scanner(Nikon, Japan). And six compression factors were chosen and applied on the basis of the results from a pilot study. The total number of images to be assessed were 336. Three radiologists assessed the occlusal and proximal surfaces of the teeth with 5-rank scale. Finally diagnosed as either sound or carious lesion by one expert oral pathologist. And sensitivity and specificity and kappa value for diagnostic agreement was calculated. Also the area (Az) values under the ROC curve were calculated and paired t-test and oneway ANOVA test was performed. Thereafter, transmission time of the image files of the each compression level were compared with that of the original image files. No significant difference was found between original and the corresponding images up to 7% (1:14) compression ratio for both the occlusal and proximal caries (p<0.05). JPEG3 (1:14) image files are transmitted fast more than 10 times, maintained diagnostic information in image, compared with original image files. 1:14 compressed image file may be used instead of the original image and reduce storage needs and transmission time.

  13. Determination of the Early Time of Death by Computerized Image Analysis of DNA Degradation: Which Is the Best Quantitative Indicator of DNA Degradation?

    Institute of Scientific and Technical Information of China (English)

    LIU Lijiang; SHU Xiji; REN Liang; ZHOU Hongyan; LI Yan; LIU Wei; ZHU Cheng; LIU Liang

    2007-01-01

    This study evaluated the correlation between DNA degradation of the splenic lymphocytes and the early time of death, examined the early time of death by computerized image analysis technique (CIAT) and identified the best parameter that quantitatively reflects the DNA degradation.The spleen tissues from 34 SD rats were collected, subjected to cell smearing every 2 h within the first 36 h after death, stained by Feulgen-Van's staining, three indices reflecting DNA content in splenic lymphocytes, including integral optical density (IOD), average optical density (AOD), average gray scale (AG) were measured by the image analysis. Our results showed that IOD and AOD decreased and AG increased over time within the first 36 h. A stepwise linear regression analysis showed that only AG was fitted. A correlation between the postmortem interval (PMI) and AG was identified and the corresponding regression equation was obtained. Our study suggests that CIAT is a useful and promising tool for the estimation of early PMI with good objectivity and reproducibility,and AG is a more effective and better quantitative indicator for the estimation of PMI within the first 36 h after death in rats.

  14. Routine tests for both planning and evaluating image quality in tele-echocardiography

    Directory of Open Access Journals (Sweden)

    Sandra Morelli

    2009-12-01

    Full Text Available Both in real-time and "store & forward" tele-echocardiography (T-E, a coding process has to be applied to the echocardiography videoclips in order to limit the bandwidth needed and adapt it to the bandwidths furnished by network providers. The compression process degrades the videoclips, affecting thus the quality of the videoclips and potentially compromising the diagnostic accuracy of the T-E. In this work the authors investigated on the use of automatic tools for the video quality assessment by means of objective methods with particular care to the role of the system administrator. As the use of tests on video quality assessment (based on subjective methods is hampered by the high number of needed resources (persons, laboratories and time. The use of valid objective methods is thus desirable. The study reviewed different tools with this specific aim. One of the more suitable tool was found to be represented by a software package designed by the Institute of Telecommunication Sciences and the National Telecommunication and Information Administration, the NTIA/ITS VQM tool. This tool gives back objective-quantitative data as outcomes, however embeds models emulating the subjective perception. This study reviewed and analyzed in depth the functionalities of the tool to improve the image quality in TE over the network. The tool was also found suitable for a more general process of T-E assessment, from a health technology assessment (HTA perspective.

  15. Analysis of filtering techniques and image quality in pixel duplicated images

    Science.gov (United States)

    Mehrubeoglu, Mehrube; McLauchlan, Lifford

    2009-08-01

    When images undergo filtering operations, valuable information can be lost besides the intended noise or frequencies due to averaging of neighboring pixels. When the image is enlarged by duplicating pixels, such filtering effects can be reduced and more information retained, which could be critical when analyzing image content automatically. Analysis of retinal images could reveal many diseases at early stage as long as minor changes that depart from a normal retinal scan can be identified and enhanced. In this paper, typical filtering techniques are applied to an early stage diabetic retinopathy image which has undergone digital pixel duplication. The same techniques are applied to the original images for comparison. The effects of filtering are then demonstrated for both pixel duplicated and original images to show the information retention capability of pixel duplication. Image quality is computed based on published metrics. Our analysis shows that pixel duplication is effective in retaining information on smoothing operations such as mean filtering in the spatial domain, as well as lowpass and highpass filtering in the frequency domain, based on the filter window size. Blocking effects due to image compression and pixel duplication become apparent in frequency analysis.

  16. MR imaging of the cervical spine: assessment of image quality with parallel imaging compared to non-accelerated MR measurements

    Energy Technology Data Exchange (ETDEWEB)

    Noebauer-Huhmann, I.M.; Imhof, Herwig [Medical University of Vienna, Department of Radiology, Vienna (Austria); Glaser, Christian; Dietrich, Olaf; Wallner, C.P.; Klinger, Wolfgang; Schoenberg, Stefan O. [Ludwig-Maximilians-University of Munich, Institute of Clinical Radiology, Munich (Germany)

    2007-05-15

    To compare the quality of cervical spine MR images obtained by parallel imaging [generalized autocalibrating partially parallel acquisition (GRAPPA)] with those of non-accelerated imaging, we conducted both phantom studies and examinations of ten volunteers at 1.5Tesla with a dedicated 12-element coil system and a head-spine-neck coil combination. Acquisitions included axial T2-weighted (T2w) images with both methods, and sagittal T2w and T1w images in vivo with the latter coil combination. Non-accelerated MRI with two averages and GRAPPA (acceleration factor 2) with two averages (GRAPPA/2AV, time reduction of approximately 50%) and four averages (GRAPPA/4AV) were compared. In the phantom, the signal-to-noise ratio of the GRAPPA/2AV was lower than that of the other two settings. In vivo, the image inhomogeneity (non-uniformity, NU) was significantly higher in T2w GRAPPA/2AV than in both other settings, and in T1w GRAPPA/2AV compared to GRAPPA/4AV. Subjectively, the delineation of anatomical structures was sufficient in all sequences. Only the spinal cord was considered to be better delineable on the non-accelerated T1w sequence compared to GRAPPA/2AV. In part, GRAPPA/4AV performed better than the other settings. The subjective image noise was lowest with GRAPPA/4AV. In cervical spine MRI, the examination time can be reduced by nearly 42% with GRAPPA, while preserving sufficient image quality. (orig.)

  17. Accelerated weathering-induced degradation of poly(lactic acid) fiber studied by near-infrared (NIR) hyperspectral imaging.

    Science.gov (United States)

    Shinzawa, Hideyuki; Nishida, Masakazu; Tanaka, Toshiyuki; Kanematsu, Wataru

    2012-04-01

    Hydrolysis degradation of a set of drawn poly(lactic acid) (PLA) fibers was induced by an accelerated weathering test, radiating ultraviolet (UV) light under a certain temperature and humidity. The fine features of the transient behavior of the PLA fibers were captured by near-infrared (NIR) hyperspectral imaging. The PLA fibers showed a gradual decrease in mechanical property (e.g., tensile strength), indicating hydrolysis degradation. Thus, the detailed analysis of the spectral variation, in turn, offers useful information on the molecular-level degradation behavior of the drawn PLA fibers. The variation of the spectral intensity as well as band position shift of the crystalline band of PLA was analyzed. The spectral intensity of the crystalline band of PLA showed gradual decrease, suggesting the decrease in molecular weight induced by the hydrolysis degradation. In addition, the crystalline band also exhibited a coinciding shift to the lower wavenumber direction with the weathering test, revealing cleavage-induced crystallization of the PLA samples. Consequently, the hydrolysis degradation induced by the weathering test substantially accelerates predominant degradation of the amorphous structure of the PLA and such variation of the molecular structure, in turn, brings less ductility to the PLA fiber.

  18. Poor quality of early evaluations of magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, L.S.; Chalmers, T.C.; McCally, M.; Berrier, J.; Sacks, H.S.

    1988-06-10

    To study the quality of early research on the clinical efficacy of diagnostic imaging with magnetic resonance, they assessed 54 evaluations published in the first four years after introduction of this modality using ten commonly accepted criteria of research methodology. The terms sensitivity, specificity, false-positive or false-negative, accuracy, and predictive values were used infrequently. 19% of the evaluations used three terms appropriately, 48% used one or two terms, and 33% used none. Data were presented appropriately for one or more of the five terms in 59% of evaluations. A gold standard comparison with the results of an independent procedure, such as surgical or autopsy findings, was presented in 22% of evaluations. Results of another imaging procedure were described in 63% of evaluations. Only one evaluation clearly described a prospective study design, although 11 evaluations apparently were planned in advance. Not one evaluation contained an appropriate statistical analysis of the distributions of quantitative readings, blinded image readers to diagnosis or other test results, measured observer error, or randomized the order of magnetic resonance imaging and other imaging procedures. The authors concludes that health care professionals paying for expensive innovative diagnostic technology should demand better research on diagnostic efficacy.

  19. The Limbic Degradation of Aging Brain: A Quantitative Analysis with Diffusion Tensor Imaging

    Directory of Open Access Journals (Sweden)

    Hediye Pınar Gunbey

    2014-01-01

    Full Text Available Introduction. The limbic system primarily responsible for our emotional life and memories is known to undergo degradation with aging and diffusion tensor imaging (DTI is capable of revealing the white matter integrity. The aim of this study is to investigate age-related changes of quantitative diffusivity parameters and fiber characteristics on limbic system in healthy volunteers. Methods. 31 healthy subjects aged 25–70 years were examined at 1,5 TMR. Quantitative fiber tracking was performed of fornix, cingulum, and the parahippocampal gyrus. The fractional anisotropy (FA and apparent diffusion coefficient (ADC measurements of bilateral hippocampus, amygdala, fornix, cingulum, and parahippocampal gyrus were obtained as related components. Results. The FA values of left hippocampus, bilateral parahippocampal gyrus, and fornix showed negative correlations with aging. The ADC values of right amygdala and left cingulum interestingly showed negative relation and the left hippocampus represented positive relation with age. The cingulum showed no correlation. The significant relative changes per decade of age were found in the cingulum and parahippocampal gyrus FA measurements. Conclusion. Our approach shows that aging affects hippocampus, parahippocampus, and fornix significantly but not cingulum. These findings reveal age-related changes of limbic system in normal population that may contribute to future DTI studies.

  20. Quality control of systems of portal imaging; Control de calidad de sistemas de imagen portal

    Energy Technology Data Exchange (ETDEWEB)

    Olasolo Alonso, J.; Martin Albina, M. L.; Otal Palacin, A.; Fuentemilla Urio, N.; Miquelez Alonso, S.; Pellejero Pellejero, S.; Maneru Camara, F.; Lozares Cordero, S.; Rubio Arroniz, A.

    2013-07-01

    The importance of accuracy and reproducibility of the positioning of the patient for the radiotherapy treatment, makes key the image quality of the image device portal used for the verification of such positioning. the objective of this work is the implementation of a procedure of quality control that easily and quickly verify the main parameters of image quality of the EPID. (Author)

  1. Using full-reference image quality metrics for automatic image sharpening

    Science.gov (United States)

    Krasula, Lukas; Fliegel, Karel; Le Callet, Patrick; Klíma, Miloš

    2014-05-01

    Image sharpening is a post-processing technique employed for the artificial enhancement of the perceived sharpness by shortening the transitions between luminance levels or increasing the contrast on the edges. The greatest challenge in this area is to determine the level of perceived sharpness which is optimal for human observers. This task is complex because the enhancement is gained only until the certain threshold. After reaching it, the quality of the resulting image drops due to the presence of annoying artifacts. Despite the effort dedicated to the automatic sharpness estimation, none of the existing metrics is designed for localization of this threshold. Nevertheless, it is a very important step towards the automatic image sharpening. In this work, possible usage of full-reference image quality metrics for finding the optimal amount of sharpening is proposed and investigated. The intentionally over-sharpened "anchor image" was included to the calculation as the "anti-reference" and the final metric score was computed from the differences between reference, processed, and anchor versions of the scene. Quality scores obtained from the subjective experiment were used to determine the optimal combination of partial metric values. Five popular fidelity metrics - SSIM, MS-SSIM, IW-SSIM, VIF, and FSIM - were tested. The performance of the proposed approach was then verified in the subjective experiment.

  2. Evaluation of dose reduction and image quality in CT colonography: Comparison of low-dose CT with iterative reconstruction and routine-dose CT with filtered back projection

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, Koichi [Kameda Medical Center, Department of Radiology, Kamogawa, Chiba (Japan); Jichi Medical University, Department of Radiology, Tochigi (Japan); National Cancer Center, Cancer Screening Technology Division, Research Center for Cancer Prevention and Screening, Tokyo (Japan); Fujiwara, Masanori; Mogi, Tomohiro; Iida, Nao [Kameda Medical Center Makuhari, Department of Radiology, Chiba (Japan); Kanazawa, Hidenori; Sugimoto, Hideharu [Jichi Medical University, Department of Radiology, Tochigi (Japan); Mitsushima, Toru [Kameda Medical Center Makuhari, Department of Gastroenterology, Chiba (Japan); Lefor, Alan T. [Jichi Medical University, Department of Surgery, Tochigi (Japan)

    2015-01-15

    To prospectively evaluate the radiation dose and image quality comparing low-dose CT colonography (CTC) reconstructed using different levels of iterative reconstruction techniques with routine-dose CTC reconstructed with filtered back projection. Following institutional ethics clearance and informed consent procedures, 210 patients underwent screening CTC using automatic tube current modulation for dual positions. Examinations were performed in the supine position with a routine-dose protocol and in the prone position, randomly applying four different low-dose protocols. Supine images were reconstructed with filtered back projection and prone images with iterative reconstruction. Two blinded observers assessed the image quality of endoluminal images. Image noise was quantitatively assessed by region-of-interest measurements. The mean effective dose in the supine series was 1.88 mSv using routine-dose CTC, compared to 0.92, 0.69, 0.57, and 0.46 mSv at four different low doses in the prone series (p < 0.01). Overall image quality and noise of low-dose CTC with iterative reconstruction were significantly improved compared to routine-dose CTC using filtered back projection. The lowest dose group had image quality comparable to routine-dose images. Low-dose CTC with iterative reconstruction reduces the radiation dose by 48.5 to 75.1 % without image quality degradation compared to routine-dose CTC with filtered back projection. (orig.)

  3. Oriented diffusion filtering for enhancing low-quality fingerprint images

    KAUST Repository

    Gottschlich, C.

    2012-01-01

    To enhance low-quality fingerprint images, we present a novel method that first estimates the local orientation of the fingerprint ridge and valley flow and next performs oriented diffusion filtering, followed by a locally adaptive contrast enhancement step. By applying the authors\\' new approach to low-quality images of the FVC2004 fingerprint databases, the authors are able to show its competitiveness with other state-of-the-art enhancement methods for fingerprints like curved Gabor filtering. A major advantage of oriented diffusion filtering over those is its computational efficiency. Combining oriented diffusion filtering with curved Gabor filters led to additional improvements and, to the best of the authors\\' knowledge, the lowest equal error rates achieved so far using MINDTCT and BOZORTH3 on the FVC2004 databases. The recognition performance and the computational efficiency of the method suggest to include oriented diffusion filtering as a standard image enhancement add-on module for real-time fingerprint recognition systems. In order to facilitate the reproduction of these results, an implementation of the oriented diffusion filtering for Matlab and GNU Octave is made available for download. © 2012 The Institution of Engineering and Technology.

  4. Systematic infrared image quality improvement using deep learning based techniques

    Science.gov (United States)

    Zhang, Huaizhong; Casaseca-de-la-Higuera, Pablo; Luo, Chunbo; Wang, Qi; Kitchin, Matthew; Parmley, Andrew; Monge-Alvarez, Jesus

    2016-10-01

    Infrared thermography (IRT, or thermal video) uses thermographic cameras to detect and record radiation in the longwavelength infrared range of the electromagnetic spectrum. It allows sensing environments beyond the visual perception limitations, and thus has been widely used in many civilian and military applications. Even though current thermal cameras are able to provide high resolution and bit-depth images, there are significant challenges to be addressed in specific applications such as poor contrast, low target signature resolution, etc. This paper addresses quality improvement in IRT images for object recognition. A systematic approach based on image bias correction and deep learning is proposed to increase target signature resolution and optimise the baseline quality of inputs for object recognition. Our main objective is to maximise the useful information on the object to be detected even when the number of pixels on target is adversely small. The experimental results show that our approach can significantly improve target resolution and thus helps making object recognition more efficient in automatic target detection/recognition systems (ATD/R).

  5. Quantitative phase imaging for cell culture quality control.

    Science.gov (United States)

    Kastl, Lena; Isbach, Michael; Dirksen, Dieter; Schnekenburger, Jürgen; Kemper, Björn

    2017-05-01

    The potential of quantitative phase imaging (QPI) with digital holographic microscopy (DHM) for quantification of cell culture quality was explored. Label-free QPI of detached single cells in suspension was performed by Michelson interferometer-based self-interference DHM. Two pancreatic tumor cell lines were chosen as cellular model and analyzed for refractive index, volume, and dry mass under varying culture conditions. Firstly, adequate cell numbers for reliable statistics were identified. Then, to characterize the performance and reproducibility of the method, we compared results from independently repeated measurements and quantified the cellular response to osmolality changes of the cell culture medium. Finally, it was demonstrated that the evaluation of QPI images allows the extraction of absolute cell parameters which are related to cell layer confluence states. In summary, the results show that QPI enables label-free imaging cytometry, which provides novel complementary integral biophysical data sets for sophisticated quantification of cell culture quality with minimized sample preparation. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

  6. A hyperspectral imaging prototype for online quality evaluation of pickling cucumbers

    Science.gov (United States)

    A hyperspectral imaging prototype was developed for online evaluation of external and internal quality of pickling cucumbers. The prototype had several new, unique features including simultaneous reflectance and transmittance imaging and inline, real time calibration of hyperspectral images of each ...

  7. Short communication: A printed image quality test phantom for mammography.

    Science.gov (United States)

    Kotre, C J; Porter, D J T

    2005-08-01

    This communication describes a novel design for a mammographic image quality test phantom, the final design of which was produced as a radiographer weekly quality assurance phantom for breast screening and symptomatic mammography. The phantom is based on low contrast test features which are built up by superimposing sheets of Mylar overhead projector transparency, on which the test features are printed using a standard LaserJet printer. The required radiation contrast at mammographic energies is produced by the approximately 50% by weight component of iron oxide (Fe(3)O(4)) present in the toner. An easily replicated design of mammographic image quality phantom based on LaserJet printed test features is described. Approximately 40 of these phantoms were constructed, and these have been used successfully for 5 years in both breast screening and symptomatic mammography. The phantom design offers a performance similar to much more expensive mammographic contrast-detail phantoms, but suffers from the disadvantage that high contrast resolution bar patterns cannot be produced using the standard printing process.

  8. Comparison of image quality in head CT studies with different dose-reduction strategies

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Nielsen, Rikke; Fink-Jensen, Vibeke

    -reduction maneuvers is reduction of image quality due to image noise or artifacts. The aim of our study was therefore to find the best diagnostic images with lowest possible dose. We present results of dose- and image quality optimizing strategies of brain CT examinations at our institution. We compare sequential...

  9. Image quality of a cone beam O-arm 3D imaging system

    Science.gov (United States)

    Zhang, Jie; Weir, Victor; Lin, Jingying; Hsiung, Hsiang; Ritenour, E. Russell

    2009-02-01

    The O-arm is a cone beam imaging system designed primarily to support orthopedic surgery and is also used for image-guided and vascular surgery. Using a gantry that can be opened or closed, the O-arm can function as a 2-dimensional (2D) fluoroscopy device or collect 3-dimensional (3D) volumetric imaging data like a CT system. Clinical applications of the O-arm in spine surgical procedures, assessment of pedicle screw position, and kyphoplasty procedures show that the O-arm 3D mode provides enhanced imaging information compared to radiographs or fluoroscopy alone. In this study, the image quality of an O-arm system was quantitatively evaluated. A 20 cm diameter CATPHAN 424 phantom was scanned using the pre-programmed head protocols: small/medium (120 kVp, 100 mAs), large (120 kVp, 128 mAs), and extra-large (120 kVp, 160 mAs) in 3D mode. High resolution reconstruction mode (512×512×0.83 mm) was used to reconstruct images for the analysis of low and high contrast resolution, and noise power spectrum. MTF was measured using the point spread function. The results show that the O-arm image is uniform but with a noise pattern which cannot be removed by simply increasing the mAs. The high contrast resolution of the O-arm system was approximately 9 lp/cm. The system has a 10% MTF at 0.45 mm. The low-contrast resolution cannot be decided due to the noise pattern. For surgery where locations of a structure are emphasized over a survey of all image details, the image quality of the O-arm is well accepted clinically.

  10. Assessment of image quality in x-ray radiography imaging using a small plasma focus device

    Science.gov (United States)

    Kanani, A.; Shirani, B.; Jabbari, I.; Mokhtari, J.

    2014-08-01

    This paper offers a comprehensive investigation of image quality parameters for a small plasma focus as a pulsed hard x-ray source for radiography applications. A set of images were captured from some metal objects and electronic circuits using a low energy plasma focus at different voltages of capacitor bank and different pressures of argon gas. The x-ray source focal spot of this device was obtained to be about 0.6 mm using the penumbra imaging method. The image quality was studied by several parameters such as image contrast, line spread function (LSF) and modulation transfer function (MTF). Results showed that the contrast changes by variations in gas pressure. The best contrast was obtained at a pressure of 0.5 mbar and 3.75 kJ stored energy. The results of x-ray dose from the device showed that about 0.6 mGy is sufficient to obtain acceptable images on the film. The measurements of LSF and MTF parameters were carried out by means of a thin stainless steel wire 0.8 mm in diameter and the cut-off frequency was obtained to be about 1.5 cycles/mm.

  11. Collimation and Image Quality of C-Arm Computed Tomography: Potential of Radiation Dose Reduction While Maintaining Equal Image Quality.

    Science.gov (United States)

    Werncke, Thomas; von Falck, Christian; Luepke, Matthias; Stamm, Georg; Wacker, Frank K; Meyer, Bernhard Christian

    2015-08-01

    The aim of this study was to assess the potential for radiation dose reduction in collimated C-arm computed tomography (CACT) while maintaining the image quality of the full field of view (FFOV) acquisition. A whole-body anthropomorphic phantom representing a 70-kg male was used in this study. The upper abdomen of the phantom was imaged using an angiographic system (Artis Zeego Q; Siemens Healthcare, Germany) with either the standard detector radiation dose level (RDL; D100, 360 nGy) or 14 experimental reduced RDLs ranging from 95% (D95, 342 nGy) to 30% D100 (D30, 108 nGy). Either the FFOV (craniocaudal coverage, 18 cm) or a collimated field of view (CFOV; craniocaudal coverage, 6 cm) was applied. The organ dose was measured using thermoluminescence detector dosimetry, and the mean effective dose was computed according to the recommendations by the International Commission on Radiological Protection Publication 103. To compare the CFOV and the FFOV data sets, image quality was assessed in terms of high- and low-contrast resolution by calculating the modulation transfer function using the wire method as well as the image noise, signal-to-noise ratio, and contrast-to-noise ratio using a low-contrast insert placed in the upper abdomen (Δ50 HU). Collimated imaging (CFOV) covering 33% of the FFOV led to an increase in the x-ray tube output of 152% for CFOV (D100; FFOV, 95.5 mGy; CFOV, 147.7 mGy) to maintain the detector dose. The mean effective dose of D100 was 6.0 mSv (male) and 6.2 mSv (female) for the FFOV and 3.7 mSv (male) and 4.1 mSv (female) for the CFOV. High-contrast resolution was comparable for all acquisition protocols (mean 10% modulation transfer function ± 95% confidence interval; FFOV, 8.8 ± 0.1 line pairs/cm; CFOV, 8.8 ± 0.1 line pairs/cm). Low-contrast resolution was superior for the CFOV compared with that for the FFOV for each RDL (D100; image noise: FFOV, 34 ± 2 HU; CFOV, 22 ± 1 HU; contrast-to-noise ratio: FFOV, 1.3 ± 0.2; CFOV, 1.8 ± 0

  12. A study on the influence of track discontinuities on the degradation of the geometric quality supported by GPR

    Science.gov (United States)

    Paixao, Andre; Fontul, Simona; Salcedas, Tânia; Marques, Margarida

    2017-04-01

    It is known that locations in the track denoting sudden structural changes induce dynamic amplifications in the train-track interaction, thus leading to higher impact loads from trains, which in turn promote a faster development of track defects and increase the degradation of components. Consequently, a reduction in the quality of service can be expected at such discontinuities in the track, inducing higher maintenance costs and decreasing the life-cycle of components. To finding actual evidences on how track discontinuities influence the degradation of the geometric quality, a 50-km long railway section is used as case study. The track geometry data obtained with a recording car is firstly characterized according to the European standard series EN 13848. Then, the results of successive surveys are analysed, making use of various tools such as the standard deviation with moving windows of different sizes and calculating degradation rates. The GPR data was also analysed at the locations corresponding to track discontinuities aiming at better identifying situations where sudden changes occur regarding either the structural characteristics or the track behaviour over the years. The results indicate that the geometric quality degrades faster at locations denoting discontinuities in the track, such as changes in track components, approaches to bridges, tunnels, etc. This behaviour suggests that these sites should be monitored more carefully in the scope of asset management activities in order to maximize the life-cycle of the track and its components. This work is a contribution to COST (European COoperation on Science and Technology) Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

  13. Visible and infrared spectroscopy to evaluate soil quality in degraded sites: an applicative study in southern Italy

    Science.gov (United States)

    Ancona, Valeria; Matarrese, Raffaella; Salvatori, Rosamaria; Salzano, Roberto; Regano, Simona; Calabrese, Angelantonio; Campanale, Claudia; Felice Uricchio, Vito

    2014-05-01

    Land degradation processes like organic matter impoverishment and contamination are growing increasingly all over the world due to a non-rational and often sustainable spread of human activities on the territory. Consequently the need to characterize and monitor degraded sites is becoming very important, with the aim to hinder such main threats, which could compromise drastically, soil quality. Visible and infrared spectroscopy is a well-known technique/tool to study soil properties. Vis-NIR spectral reflectance, in fact, can be used to characterize spatial and temporal variation in soil constituents (Brown et al., 2006; Viscarra Rossel et al., 2006), and potentially its surface structure (Chappell et al., 2006, 2007). It is a rapid, non-destructive, reproducible and cost-effective analytical method to analyse soil properties and therefore, it can be a useful method to study land degradation phenomena. In this work, we present the results of proximal sensing investigations of three degraded sites (one affected by organic and inorganic contamination and two affected by soil organic matter decline) situated southern Italy close to Taranto city (in Apulia Region). A portable spectroradiometer (ASD-FieldSpec) was used to measure the reflectance properties in the spectral range between 350-2500 nm of the soil, in the selected sites, before and after a recovery treatment by using compost (organic fertilizer). For each measurement point the soil was sampled in order to perform chemical analyses to evaluate soil quality status. Three in-situ campaigns have been carried out (September 2012, June 2013, and September 2013), collecting about 20 soil samples for each site and for each campaign. Chemical and spectral analyses have been focused on investigating soil organic carbon, carbonate content, texture and, in the case of polluted site, heavy metals and organic toxic compounds. Statistical analyses have been carried out to test a prediction model of different soil quality

  14. Relationship between image plates physical structure and quality of digital radiographic images in weld inspections

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Davi F.; Silva, Aline S.S.; Machado, Alessandra S.; Gomes, Celio S.; Nascimento, Joseilson; Lopes, Ricardo T., E-mail: davi@lin.ufrj.br.br, E-mail: aline@lin.ufrj.br, E-mail: celio@lin.ufrj.br, E-mail: alemachado@lin.ufrj.br, E-mail: joseilson@lin.ufrj.br, E-mail: ricardo@lin.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Instrumentacao Nuclear

    2015-07-01

    In the last decades a new type of detector which is based on photostimulable luminescence was developed. There are currently many kinds of image plates (IPs) available on the market, originating from different manufacturers. Each kind of plate distinguishes itself from the others by its peculiar physical structure and composition, two factors which have a direct influence upon the quality of the digital radiographic images obtained through them. For this study, several kinds of IPs were tested in order to determine in which way such influence takes place. For this purpose, each kind of IP has been characterized and correlated to its response in the final image. The aim of this work was to evaluate procedures for employing Computed Radiography (CR) to welding inspections in laboratory conditions using the Simple Wall Simple Image Technique (SWSI). Tests were performed in steel welded joins of thickness 5.33, 12.70 and 25.40 mm, using CR scanner and IPs available on the market. It was used an X-Ray equipment as radiation source. The image quality parameters Basic Spatial Resolution (BSR), Normalized Signal-to-Noise Ratio (SNR{sub N}), contrast and detectability were evaluated. In order to determine in which way the IPs' properties are correlated to its response in the final image, the thickness of the sensitive layer was determined and the grain size and the elemental composition of this layer were evaluated. Based on the results drawn from this study, it is possible to conclude that the physical characteristics of image plates are essential for determining the quality of the digital radiography images acquired with them. Regarding the chemical composition of the plates, it was possible to determine that, apart from the chemical elements that were expected to be found (Ba, I and Br), only two plates, with high resolution, do not have fluorine in their composition; the presence of Strontium was also detected in the chemical composition of the plates supplied by a

  15. Free-breathing motion-corrected late-gadolinium-enhancement imaging improves image quality in children

    Energy Technology Data Exchange (ETDEWEB)

    Olivieri, Laura; O' Brien, Kendall J. [Children' s National Health System, Division of Cardiology, Washington, DC (United States); National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD (United States); Cross, Russell [Children' s National Health System, Division of Cardiology, Washington, DC (United States); Xue, Hui; Kellman, Peter; Hansen, Michael S. [National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD (United States)

    2016-06-15

    The value of late-gadolinium-enhancement (LGE) imaging in the diagnosis and management of pediatric and congenital heart disease is clear; however current acquisition techniques are susceptible to error and artifacts when performed in children because of children's higher heart rates, higher prevalence of sinus arrhythmia, and inability to breath-hold. Commonly used techniques in pediatric LGE imaging include breath-held segmented FLASH (segFLASH) and steady-state free precession-based (segSSFP) imaging. More recently, single-shot SSFP techniques with respiratory motion-corrected averaging have emerged. This study tested and compared single-shot free-breathing LGE techniques with standard segmented breath-held techniques in children undergoing LGE imaging. Thirty-two consecutive children underwent clinically indicated late-enhancement imaging using intravenous gadobutrol 0.15 mmol/kg. Breath-held segSSFP, breath-held segFLASH, and free-breathing single-shot SSFP LGE sequences were performed in consecutive series in each child. Two blinded reviewers evaluated the quality of the images and rated them on a scale of 1-5 (1 = poor, 5 = superior) based on blood pool-myocardial definition, presence of cardiac motion, presence of respiratory motion artifacts, and image acquisition artifact. We used analysis of variance (ANOVA) to compare groups. Patients ranged in age from 9 months to 18 years, with a mean +/- standard deviation (SD) of 13.3 +/- 4.8 years. R-R interval at the time of acquisition ranged 366-1,265 milliseconds (ms) (47-164 beats per minute [bpm]), mean +/- SD of 843+/-231 ms (72+/-21 bpm). Mean +/- SD quality ratings for long-axis imaging for segFLASH, segSSFP and single-shot SSFP were 3.1+/-0.9, 3.4+/-0.9 and 4.0+/-0.9, respectively (P < 0.01 by ANOVA). Mean +/- SD quality ratings for short-axis imaging for segFLASH, segSSFP and single-shot SSFP were 3.4+/-1, 3.8+/-0.9 and 4.3+/-0.7, respectively (P < 0.01 by ANOVA). Single-shot late

  16. Determining quality and maturity of pomegranates using multispectral imaging

    Directory of Open Access Journals (Sweden)

    Rasool Khodabakhshian

    2017-10-01

    Full Text Available In this paper, we investigated the use of multispectral imaging technique to quantify pomegranate fruit quality. Three quality factors including total soluble solids (TSS, pH and firmness were studied at four different maturity stages of 88, 109, 124 and 143 days after full bloom (DAFB and were correlated with the spectral information extracted from images taken at four wavelength spectra. TSS, pH and firmness of the same samples were recorded using nondestructive methods and then modeled with their corresponding spectral data using partial least squire regression (PLSR. The correlation coefficient (r, RMSEC and RPD for the calibration models was found to be: r = 0.97, RMSEC = 0.21 °Brix and RPD = 6.7 °Brix for TSS; r = 0.93, RMSEC = 0.035 and RPD = 5.01 for pH; r = 0.95, RMSEC = 0.65 N and RPD = 5.65 N for firmness. Also these parameters for the validation models were as follows: r = 0.97, RMSEP = 0.22 °Brix and RPD = 5.77 °Brix for TSS; r = 0.94, RMSEP = 0.038 and RPD = 4.98 for pH; r = 0.94, RMSEP = 0.68 N and RPD = 5.33 N for firmness. The results demonstrated the capability of multispectral imaging and chemometrics as useful techniques to nondestructively monitoring pomegranate main quality attributes.

  17. Image quality in CT: From physical measurements to model observers.

    Science.gov (United States)

    Verdun, F R; Racine, D; Ott, J G; Tapiovaara, M J; Toroi, P; Bochud, F O; Veldkamp, W J H; Schegerer, A; Bouwman, R W; Giron, I Hernandez; Marshall, N W; Edyvean, S

    2015-12-01

    Evaluation of image quality (IQ) in Computed Tomography (CT) is important to ensure that diagnostic questions are correctly answered, whilst keeping radiation dose to the patient as low as is reasonably possible. The assessment of individual aspects of IQ is already a key component of routine quality control of medical x-ray devices. These values together with standard dose indicators can be used to give rise to 'figures of merit' (FOM) to characterise the dose efficiency of the CT scanners operating in certain modes. The demand for clinically relevant IQ characterisation has naturally increased with the development of CT technology (detectors efficiency, image reconstruction and processing), resulting in the adaptation and evolution of assessment methods. The purpose of this review is to present the spectrum of various methods that have been used to characterise image quality in CT: from objective measurements of physical parameters to clinically task-based approaches (i.e. model observer (MO) approach) including pure human observer approach. When combined together with a dose indicator, a generalised dose efficiency index can be explored in a framework of system and patient dose optimisation. We will focus on the IQ methodologies that are required for dealing with standard reconstruction, but also for iterative reconstruction algorithms. With this concept the previously used FOM will be presented with a proposal to update them in order to make them relevant and up to date with technological progress. The MO that objectively assesses IQ for clinically relevant tasks represents the most promising method in terms of radiologist sensitivity performance and therefore of most relevance in the clinical environment.

  18. Enhancing the quality metric of protein microarray image

    Institute of Scientific and Technical Information of China (English)

    王立强; 倪旭翔; 陆祖康; 郑旭峰; 李映笙

    2004-01-01

    The novel method of improving the quality metric of protein microarray image presented in this paper reduces impulse noise by using an adaptive median filter that employs the switching scheme based on local statistics characters; and achieves the impulse detection by using the difference between the standard deviation of the pixels within the filter window and the current pixel of concern. It also uses a top-hat filter to correct the background variation. In order to decrease time consumption, the top-hat filter core is cross structure. The experimental results showed that, for a protein microarray image contaminated by impulse noise and with slow background variation, the new method can significantly increase the signal-to-noise ratio, correct the trends in the background, and enhance the flatness of the background and the consistency of the signal intensity.

  19. Modelling the Cost and Quality of Preservation Imaging and Archiving

    DEFF Research Database (Denmark)

    Kejser, Ulla Bøgvad

    2009-01-01

    materials held by national cultural heritage institutions in Denmark, a study was undertaken to provide a generic cost model for digital preservation. The outcome of the study is an activity based cost model, which accounts for full economic costs. It is structured around the functional descriptions...... investigated and specifications based on best practice and testing established. Also, the image quality parameters, which influence the long term preservation costs, were identified. In addition, the suitability for preservation of different image file formats and compression algorithms was evaluated...... in the OAIS Reference Model. The cost model divides the OAIS functions in a hierarchy of cost critical activities and measurable components, which are implemented as formulas in a spreadsheet. So far the model has only been completed for activities relating to preservation planning and digital migrations...

  20. Crowdsourcing quality control for Dark Energy Survey images

    CERN Document Server

    Melchior, P; Drlica-Wagner, A; Rykoff, E S; Abbott, T M C; Abdalla, F B; Allam, S; Benoit-Levy, A; Brooks, D; Buckley-Geer, E; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; D'Andrea, C B; da Costa, L N; Desai, S; Doel, P; Evrard, A E; Finley, D A; Flaugher, B; Frieman, J; Gaztanaga, E; Gerdes, D W; Gruen, D; Gruendl, R A; Honscheid, K; James, D J; Jarvis, M; Kuehn, K; Li, T S; Maia, M A G; March, M; Marshall, J L; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Sanchez, E; Scarpine, V; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Suchyta, E; Swanson, M E C; Tarle, G; Vikram, V; Walker, A R; Wester, W; Zhang, Y

    2015-01-01

    We have developed a crowdsourcing web application for image quality control employed by the Dark Energy Survey. Dubbed the "DES exposure checker", it renders science-grade images directly to a web browser and allows users to mark problematic features from a set of predefined classes. Users can also generate custom labels and thus help identify previously unknown problem classes. User reports are fed back to hardware and software experts to help mitigate and eliminate recognized issues. We report on the implementation of the application and our experience with its over 100 users, the majority of which are professional or prospective astronomers but not data management experts. We discuss aspects of user training and engagement, and demonstrate how problem reports have been pivotal to rapidly correct artifacts which would likely have been too subtle or infrequent to be recognized otherwise. We conclude with a number of important lessons learned, suggest possible improvements, and recommend this collective explo...

  1. SPOT4 HRVIR first in-flight image quality results

    Science.gov (United States)

    Kubik, Philippe; Breton, Eric; Meygret, Aime; Cabrieres, Bernard; Hazane, Philippe; Leger, Dominique

    1998-12-01

    The SPOT4 remote sensing satellite was successfully launched at the end of March 1998. It was designed first of all to guarantee continuity of SPOT services beyond the year 2000 but also to improve the mission. Its two cameras are now called HRVIR since a short-wave infrared (SWIR) spectral band has been added. Like their predecessor HRV cameras, they provide 20-meter multispectral and 10-meter monospectral images with a 60 km swath for nadir viewing. SPOT4's first two months of life in orbit were dedicated to the evaluation of its image quality performances. During this period of time, the CNES team used specific target programming in order to compute image correction parameters and estimate the performance, at system level, of the image processing chain. After a description of SPOT4 system requirements and new features of the HRVIR cameras, this paper focuses on the performance deduced from in-flight measurements, methods used and their accuracy: MTF measurements, refocusing, absolute calibration, signal-to-noise Ratio, location, focal plane cartography, dynamic disturbances.

  2. Color management systems: methods and technologies for increased image quality

    Science.gov (United States)

    Caretti, Maria

    1997-02-01

    All the steps in the imaging chain -- from handling the originals in the prepress to outputting them on any device - - have to be well calibrated and adjusted to each other, in order to reproduce color images in a desktop environment as accurate as possible according to the original. Today most of the steps in the prepress production are digital and therefore it is realistic to believe that the color reproduction can be well controlled. This is true thanks to the last years development of fast, cost effective scanners, digital sources and digital proofing devices not the least. It is likely to believe that well defined tools and methods to control this imaging flow will lead to large cost and time savings as well as increased overall image quality. Until now, there has been a lack of good, reliable, easy-to- use systems (e.g. hardware, software, documentation, training and support) in an extent that has made them accessible to the large group of users of graphic arts production systems. This paper provides an overview of the existing solutions to manage colors in a digital pre-press environment. Their benefits and limitations are discussed as well as how they affect the production workflow and organization. The difference between a color controlled environment and one that is not is explained.

  3. Scale Control and Quality Management of Printed Image Parameters

    Science.gov (United States)

    Novoselskaya, O. A.; Kolesnikov, V. L.; Solov'eva, T. V.; Nagornova, I. V.; Babluyk, E. B.; Trapeznikova, O. V.

    2017-06-01

    The article provides a comparison of the main valuation techniques for a regulated parameter of printability of the offset paper by current standards GOST 24356 and ISO 3783: 2006. The results of development and implementation of a complex test scale for management and control the quality of printed production are represented. The estimation scale is introduced. It includes normalized parameters of print optical density, print uniformity, picking out speed, the value of dot gain, print contrast with the added criteria of minimizing microtexts, a paper slip, resolution threshold and effusing ability of paper surface. The results of analysis allow directionally form surface properties of the substrate to facilitate achieving the required quality of the printed image parameters, i. e. optical density of a print at a predetermined level not less than 1.3, the print uniformity with minimal deviation of dot gain about the order of 10 per cents.

  4. Color Image Quality Assessment Based on CIEDE2000

    Directory of Open Access Journals (Sweden)

    Yang Yang

    2012-01-01

    Full Text Available Combining the color difference formula of CIEDE2000 and the printing industry standard for visual verification, we present an objective color image quality assessment method correlated with subjective vision perception. An objective score conformed to subjective perception (OSCSP Q was proposed to directly reflect the subjective visual perception. In addition, we present a general method to calibrate correction factors of color difference formula under real experimental conditions. Our experiment results show that the present DE2000-based metric can be consistent with human visual system in general application environment.

  5. Nonlinear filtering for character recognition in low quality document images

    Science.gov (United States)

    Diaz-Escobar, Julia; Kober, Vitaly

    2014-09-01

    Optical character recognition in scanned printed documents is a well-studied task, where the captured conditions like sheet position, illumination, contrast and resolution are controlled. Nowadays, it is more practical to use mobile devices for document capture than a scanner. So as a consequence, the quality of document images is often poor owing to presence of geometric distortions, nonhomogeneous illumination, low resolution, etc. In this work we propose to use multiple adaptive nonlinear composite filters for detection and classification of characters. Computer simulation results obtained with the proposed system are presented and discussed.

  6. A biological quality index for volcanic Andisols and Aridisols (Canary Islands, Spain): variations related to the ecosystem degradation.

    Science.gov (United States)

    Armas, Cecilia María; Santana, Bayanor; Mora, Juan Luis; Notario, Jesús Santiago; Arbelo, Carmen Dolores; Rodríguez-Rodríguez, Antonio

    2007-05-25

    The aim of this work is to identify indicators of biological activity in soils from the Canary Islands, by studying the variation of selected biological parameters related to the processes of deforestation and accelerated soil degradation affecting the Canarian natural ecosystems. Ten plots with different degrees of maturity/degradation have been selected in three typical habitats in the Canary Islands: laurel forest, pine forest and xerophytic scrub with Andisols and Aridisols as the most common soils. The studied characteristics in each case include total organic carbon, field soil respiration, mineralized carbon after laboratory incubation, microbial biomass carbon, hot water-extractable carbon and carboxymethylcellulase, beta-d-glucosidase and dehydrogenase activities. A Biological Quality Index (BQI) has been designed on the basis of a regression model using these variables, assuming that the total soil organic carbon content is quite stable in nearly mature ecosystems. Total carbon in mature ecosystems has been related to significant biological variables (hot water-extractable carbon, soil respiration and carboxymethylcellulase, beta-d-glucosidase and dehydrogenase activities), accounting for nearly 100% of the total variance by a multiple regression analysis. The index has been calculated as the ratio of the value calculated from the regression model and the actual measured value. The obtained results show that soils in nearly mature ecosystems have BQI values close to unit, whereas those in degraded ecosystems range between 0.24 and 0.97, depending on the degradation degree.

  7. Image quality simulation and verification of x-ray volume imaging systems

    Science.gov (United States)

    Kroon, Han; Schoumans, Nicole; Snoeren, Ruud

    2006-03-01

    Nowadays, 2D X-ray systems are used more and more for 3-dimensional rotational X-ray imaging (3D-RX) or volume imaging, such as 3D rotational angiography. However, it is not evident that the application of settings for optimal 2D images also guarantee optimal conditions for 3D-RX reconstruction results. In particular the search for a good compromise between patient dose and IQ may lead to different results in case of 3D imaging. For this purpose we developed an additional 3D-RX module for our full-scale image quality & patient dose (IQ&PD) simulation model, with specific calculations of patient dose under rotational conditions, and contrast, sharpness and noise of 3D images. The complete X-ray system from X-ray tube up to and including the display device is modelled in separate blocks for each distinguishable component or process. The model acts as a tool for X-ray system design, image quality optimisation and patient dose reduction. The model supports the decomposition of system level requirements, and takes inherently care of the prerequisite mutual coherence between component requirements. The short calculation times enable comprehensive multi-parameter optimisation studies. The 3D-RX IQ&PD performance is validated by comparing calculation results with actual measurements performed on volume images acquired with a state-of-the-art 3D-RX system. The measurements include RXDI dose index, signal and contrast based on Hounsfield units (H and ΔH), modulation transfer function (MTF), noise variance (σ2) and contrast-to-noise ratio (CNR). Further we developed a new 3D contrast-delta (3D-CΔ) phantom with details of varying size and contrast medium material and concentration. Simulation and measurement results show a significant correlation.

  8. The Image Quality of a Digital Chest X-Ray Radiography System: Comparison of Quantitative Image Quality Analysis and Radiologists' Visual Scoring

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Ji Ho [Dept. of Radiology Oncology, Yongsan Hospital, Pusan National University College of Medicine, Yongsan (Korea, Republic of); Chung, Myung Jin [Dept. of Radiology, Samsung Medical Center, Seoul (Korea, Republic of); Park, Darl; Kim, Won Taek; Kim, Yong Ho; Ki, Yong Kan; Kim, DFong Hyun; Lee, Ju Hee; Kim, Dong Won [Dept. of Radiology Oncology, Yongsan Hospital, Pusan National University College of Medicine, Yongsan (Korea, Republic of); Jeon, Ho Sang [Reserach Institue for Convergence of Biomedical Science and Technology, Yongsan Hospital, Pusan National University College of Medicine, Yongsan (Korea, Republic of)

    2011-11-15

    To evaluate the performance of imaging devices, which should be periodically monitored to maintain high quality images to the radiologists. Additionally, this evaluation may prevent patients from radiation over-exposure. The most suitable engineering standard for imaging performance evaluation of digital X-ray thoracic images was determined. IEC 62220-1 standards were used to evaluate the performance of the images. In succession, the visibilities of overall image, pneumothorax, and humerus head in anthropomorphic thoracic phantom images were used to evaluate the image qualities by radiologists. The rank correlation coefficient (p) of visual scoring by radiologists with system spatial resolution is not meaningful (p-value, p = 0.295), but is significant with image noise (p-value, p -0.9267). Finally, the noise equivalent quanta (NEQ) presents a high rank correlation for visual scoring of radiologists (p-value, p = 0.9320). Image quality evaluation of radiologists were mainly affected by imaging noise. Hence, the engineered standard for evaluating image noise is the most important index to effectively monitor the performance of X-ray images. Additionally, the NEQ can be used to evaluate the performance of radiographic systems, because it theoretically corresponds to the synthetic image quality of systems.

  9. Assessing the effect of biodegradable and degradable plastics on the composting of green wastes and compost quality.

    Science.gov (United States)

    Unmar, G; Mohee, R

    2008-10-01

    An assessment of the effect of the composting potential of Mater-Bi biodegradable plastic with green wastes, noted by GBIO, and degradable plastic (PDQ-H additive) with green wastes, noted by GDEG, was carried out in a lagged two-compartment compost reactor. The composting time was determined until constant mass of the composting substrates was reached. The green wastes composting process was used as control (G). After one week of composting, the biodegradable plastics disappeared completely, while 2% of the original degradable plastic still remained after about 8 weeks of composting. A net reduction in volatile solids contents of 61.8%, 56.5% and 53.2% were obtained for G, GBIO and GDEG, respectively. Compost quality was assessed in terms of nitrogen, potassium and phosphorus contents, which were found to be highest for GBIO compost. From the phytotoxicity test, it has been observed that a diluted extract of GBIO compost has produced the longest length of radicle. From the respiration test, no significant difference in the amount of carbon dioxide released by the composting of GDEG and G was observed. This study showed that the quality of the compost is not affected by the presence of the biodegradable and degradable plastics in the raw materials.

  10. Quality Enhancement and Nerve Fibre Layer Artefacts Removal in Retina Fundus Images by Off Axis Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Giancardo, Luca [ORNL; Meriaudeau, Fabrice [ORNL; Karnowski, Thomas Paul [ORNL; Li, Yaquin [University of Tennessee, Knoxville (UTK); Tobin Jr, Kenneth William [ORNL; Chaum, Edward [University of Tennessee, Knoxville (UTK)

    2011-01-01

    Retinal fundus images acquired with non-mydriatic digital fundus cameras are a versatile tool for the diagnosis of various retinal diseases. Because of the ease of use of newer camera models and their relative low cost, these cameras are employed worldwide by retina specialists to diagnose diabetic retinopathy and other degenerative diseases. Even with relative ease of use, the images produced by these systems sometimes suffer from reflectance artefacts mainly due to the nerve fibre layer (NFL) or other camera lens related reflections. We propose a technique that employs multiple fundus images acquired from the same patient to obtain a single higher quality image without these reflectance artefacts. The removal of bright artefacts, and particularly of NFL reflectance, can have great benefits for the reduction of false positives in the detection of retinal lesions such as exudate, drusens and cotton wool spots by automatic systems or manual inspection. If enough redundant information is provided by the multiple images, this technique also compensates for a suboptimal illumination. The fundus images are acquired in straightforward but unorthodox manner, i.e. the stare point of the patient is changed between each shot but the camera is kept fixed. Between each shot, the apparent shape and position of all the retinal structures that do not exhibit isotropic reflectance (e.g. bright artefacts) change. This physical effect is exploited by our algorithm in order to extract the pixels belonging to the inner layers of the retina, hence obtaining a single artefacts-free image.

  11. An Automatic Image Processing Workflow for Daily Magnetic Resonance Imaging Quality Assurance.

    Science.gov (United States)

    Peltonen, Juha I; Mäkelä, Teemu; Sofiev, Alexey; Salli, Eero

    2017-04-01

    The performance of magnetic resonance imaging (MRI) equipment is typically monitored with a quality assurance (QA) program. The QA program includes various tests performed at regular intervals. Users may execute specific tests, e.g., daily, weekly, or monthly. The exact interval of these measurements varies according to the department policies, machine setup and usage, manufacturer's recommendations, and available resources. In our experience, a single image acquired before the first patient of the day offers a low effort and effective system check. When this daily QA check is repeated with identical imaging parameters and phantom setup, the data can be used to derive various time series of the scanner performance. However, daily QA with manual processing can quickly become laborious in a multi-scanner environment. Fully automated image analysis and results output can positively impact the QA process by decreasing reaction time, improving repeatability, and by offering novel performance evaluation methods. In this study, we have developed a daily MRI QA workflow that can measure multiple scanner performance parameters with minimal manual labor required. The daily QA system is built around a phantom image taken by the radiographers at the beginning of day. The image is acquired with a consistent phantom setup and standardized imaging parameters. Recorded parameters are processed into graphs available to everyone involved in the MRI QA process via a web-based interface. The presented automatic MRI QA system provides an efficient tool for following the short- and long-term stability of MRI scanners.

  12. Open source database of images DEIMOS: extension for large-scale subjective image quality assessment

    Science.gov (United States)

    Vítek, Stanislav

    2014-09-01

    DEIMOS (Database of Images: Open Source) is an open-source database of images and video sequences for testing, verification and comparison of various image and/or video processing techniques such as compression, reconstruction and enhancement. This paper deals with extension of the database allowing performing large-scale web-based subjective image quality assessment. Extension implements both administrative and client interface. The proposed system is aimed mainly at mobile communication devices, taking into account advantages of HTML5 technology; it means that participants don't need to install any application and assessment could be performed using web browser. The assessment campaign administrator can select images from the large database and then apply rules defined by various test procedure recommendations. The standard test procedures may be fully customized and saved as a template. Alternatively the administrator can define a custom test, using images from the pool and other components, such as evaluating forms and ongoing questionnaires. Image sequence is delivered to the online client, e.g. smartphone or tablet, as a fully automated assessment sequence or viewer can decide on timing of the assessment if required. Environmental data and viewing conditions (e.g. illumination, vibrations, GPS coordinates, etc.), may be collected and subsequently analyzed.

  13. Detection of Degradation Effects in Field-Aged c-Si Solar Cells through IR Thermography and Digital Image Processing

    Directory of Open Access Journals (Sweden)

    E. Kaplani

    2012-01-01

    Full Text Available Due to the vast expansion of photovoltaic (PV module production nowadays, a great interest is shown in factors affecting PV performance and efficiency under real conditions. Particular attention is being given to degradation effects of PV cells and modules, which during the last decade are seen to be responsible for significant power losses observed in PV systems. This paper presents and analyses degradation effects observed in severely EVA discoloured PV cells from field-aged modules operating already for 18–22 years. Temperature degradation effects are identified through IR thermography in bus bars, contact solder bonds, blisters, hot spots, and hot areas. I-V curve analysis results showed an agreement between the source of electrical performance degradation and the degradation effects in the defected cell identified by the IR thermography. Finally, an algorithm was developed to automatically detect EVA discoloration in PV cells through processing of the digital image alone in a way closely imitating human perception of color. This nondestructive and noncostly solution could be applied in the detection of EVA discoloration in existing PV installations and the automatic monitoring and remote inspection of PV systems.

  14. NUCLEOTIDE DEGRADATION PRODUCTS, TOTAL VOLATILE BASIC NITROGEN, SENSORY AND MICROBIOLOGICAL QUALITY OF NILE PERCH (LATES NILOTICUS FILLETS UNDER CHILLED STORAGE

    Directory of Open Access Journals (Sweden)

    Andrew Kiri Amegovu

    2012-10-01

    Full Text Available Degradation products of adenosine nucleotide and total volatile basic nitrogen (TVBN concentration provide means of ascertaining freshness of commercial fish products. A complementary sensory analysis has also been adopted by export markets for assessing the quality of fresh fish. Nucleotide breakdown products and TVBN was determined in fresh fillets from beach seined and gill netted Nile perch, a highly commercialized freshwater fish from Lake Victoria (Uganda, under chilled storage. Microbiological and sensory qualities were also evaluated. Total plate and Pseudomonas spp. counts positively correlated with TVBN. Basing on sensory, microbiological and biochemical attributes of the fillets, shelf-life of gill netted Nile perch was lower (13 days than that of the beach seined (17 days. Fillets of beach seined Nile perch have a better keeping quality than that of the gill netted.

  15. Cone beam computed tomography radiation dose and image quality assessments.

    Science.gov (United States)

    Lofthag-Hansen, Sara

    2010-01-01

    Diagnostic radiology has undergone profound changes in the last 30 years. New technologies are available to the dental field, cone beam computed tomography (CBCT) as one of the most important. CBCT is a catch-all term for a technology comprising a variety of machines differing in many respects: patient positioning, volume size (FOV), radiation quality, image capturing and reconstruction, image resolution and radiation dose. When new technology is introduced one must make sure that diagnostic accuracy is better or at least as good as the one it can be expected to replace. The CBCT brand tested was two versions of Accuitomo (Morita, Japan): 3D Accuitomo with an image intensifier as detector, FOV 3 cm x 4 cm and 3D Accuitomo FPD with a flat panel detector, FOVs 4 cm x 4 cm and 6 cm x 6 cm. The 3D Accuitomo was compared with intra-oral radiography for endodontic diagnosis in 35 patients with 46 teeth analyzed, of which 41 were endodontically treated. Three observers assessed the images by consensus. The result showed that CBCT imaging was superior with a higher number of teeth diagnosed with periapical lesions (42 vs 32 teeth). When evaluating 3D Accuitomo examinations in the posterior mandible in 30 patients, visibility of marginal bone crest and mandibular canal, important anatomic structures for implant planning, was high with good observer agreement among seven observers. Radiographic techniques have to be evaluated concerning radiation dose, which requires well-defined and easy-to-use methods. Two methods: CT dose index (CTDI), prevailing method for CT units, and dose-area product (DAP) were evaluated for calculating effective dose (E) for both units. An asymmetric dose distribution was revealed when a clinical situation was simulated. Hence, the CTDI method was not applicable for these units with small FOVs. Based on DAP values from 90 patient examinations effective dose was estimated for three diagnostic tasks: implant planning in posterior mandible and

  16. Comprehensive model for predicting perceptual image quality of smart mobile devices.

    Science.gov (United States)

    Gong, Rui; Xu, Haisong; Luo, M R; Li, Haifeng

    2015-01-01

    An image quality model for smart mobile devices was proposed based on visual assessments of several image quality attributes. A series of psychophysical experiments were carried out on two kinds of smart mobile devices, i.e., smart phones and tablet computers, in which naturalness, colorfulness, brightness, contrast, sharpness, clearness, and overall image quality were visually evaluated under three lighting environments via categorical judgment method for various application types of test images. On the basis of Pearson correlation coefficients and factor analysis, the overall image quality could first be predicted by its two constituent attributes with multiple linear regression functions for different types of images, respectively, and then the mathematical expressions were built to link the constituent image quality attributes with the physical parameters of smart mobile devices and image appearance factors. The procedure and algorithms were applicable to various smart mobile devices, different lighting conditions, and multiple types of images, and performance was verified by the visual data.

  17. Use of plan quality degradation to evaluate tradeoffs in delivery efficiency and clinical plan metrics arising from IMRT optimizer and sequencer compromises.

    Science.gov (United States)

    Wilkie, Joel R; Matuszak, Martha M; Feng, Mary; Moran, Jean M; Fraass, Benedick A

    2013-07-01

    Plan degradation resulting from compromises made to enhance delivery efficiency is an important consideration for intensity modulated radiation therapy (IMRT) treatment plans. IMRT optimization and/or multileaf collimator (MLC) sequencing schemes can be modified to generate more efficient treatment delivery, but the effect those modifications have on plan quality is often difficult to quantify. In this work, the authors present a method for quantitative assessment of overall plan quality degradation due to tradeoffs between delivery efficiency and treatment plan quality, illustrated using comparisons between plans developed allowing different numbers of intensity levels in IMRT optimization and/or MLC sequencing for static segmental MLC IMRT plans. A plan quality degradation method to evaluate delivery efficiency and plan quality tradeoffs was developed and used to assess planning for 14 prostate and 12 head and neck patients treated with static IMRT. Plan quality was evaluated using a physician's predetermined "quality degradation" factors for relevant clinical plan metrics associated with the plan optimization strategy. Delivery efficiency and plan quality were assessed for a range of optimization and sequencing limitations. The "optimal" (baseline) plan for each case was derived using a clinical cost function with an unlimited number of intensity levels. These plans were sequenced with a clinical MLC leaf sequencer which uses >100 segments, assuring delivered intensities to be within 1% of the optimized intensity pattern. Each patient's optimal plan was also sequenced limiting the number of intensity levels (20, 10, and 5), and then separately optimized with these same numbers of intensity levels. Delivery time was measured for all plans, and direct evaluation of the tradeoffs between delivery time and plan degradation was performed. When considering tradeoffs, the optimal number of intensity levels depends on the treatment site and on the stage in the process

  18. Aspects on Image Quality in Radiologic Evaluation of the Urinary Tract

    OpenAIRE

    2012-01-01

    The focus of this document is on image quality as one of the factors fundamental for the diagnostic process. With the rising number of procedures and the trend towards more complicated examinations, urinary tract investigations was chosen in this work as a good clinical model for evaluation of the factors influencing image quality and of the ways of evaluating image quality. In paper I, a method is described for optimisation during the introduction of a new imaging system, with a focus on the...

  19. [Effects of degraded sandy grassland afforestation on soil quality in semi-arid area of northern China].

    Science.gov (United States)

    Hu, Ya-lin; Zeng, De-hui; Fan, Zhi-ping; Ai, Gui-yan

    2007-11-01

    By the methods of field survey and incubation test, this paper studied the effects of degraded sandy grassland afforestation with Mongolian pine on the soil physical, chemical and biological properties in 0-10 cm layer on Keerqin sandy land. The results showed that after 32 years afforestation, soil organic C, total N and total P decreased by 21%, 42% and 45%, respectively. In May and November, soil NH4+ -N content was significantly higher under Mongolian pine plantation than under grassland (P = 0.001; P = 0.019), but in May, August and November, soil NO3- -N content was in adverse (P soil C mineralization rate was higher under Mongolian pine plantation than under grassland, but the difference in N mineralization rate was not significant (P > 0.05). In May and August, soil microbial biomass C under Mongolian pine plantation and grassland had little difference, but in November, it was significantly higher under Mongolian pine plantation than under grassland. Soil nutrients- and moisture contents were the important factors affecting soil microbial biomass C. Soil urease and invertase activities decreased but catalase activity increased under Mongolian pine plantation, compared with those under grassland. It was suggested that 32 years afforestation of degraded sandy grassland with Mongolian pine on Keerqin sandy land led to a definite degradation of soil quality. Owing to the changes of vegetation, the test indicators of soil quality had different seasonal dynamic characteristics under Mongolian pine plantation and grassland. As a means of degraded ecosystem restoration in semi-arid area of Northern China, afforestation had its definite limitations.

  20. Rumen degradability characteristics of normal maize stover and silage, and quality protein maize silage-based diets offered to cows.

    Science.gov (United States)

    Tamir, Berhan; Gebrehawariat, Ephrem; Tegegne, Azage; Kortu, Mohammed Y

    2012-10-01

    Rumen degradability characteristics of dry matter (DM), organic matter (OM) and crude protein (CP) of normal maize (NM) stover (T1)-, NM silage (T2)- and quality protein maize (QPM) silage (T3)-based diets were studied using three rumen-fistulated Boran × Friesian non-lactating cows (371 ± 32.00 kg) in 3 × 3 Latin Square Design. Cows were supplemented with a similar concentrate mix. In sacco degradability of DM and OM indicated that the (a) values of DM (128) and OM (114) for NM stover were lower (P silage (268 and 253) and for QPM silage (323 and 303), respectively. The (a) value for CP was lower (P silage (286) than for NM stover (404) and NM silage (326). The (b) values of DM in NM stover (597) and NM silage (535) were higher (P silage (499). The (b) value of CP in NM stover (372) was lower (P silage (655) and in QPM silage (608). Rate of degradation of OM in NM stover and NM silage, each with 0.03, was faster (P silage (0.02). Moreover, QPM silage had higher potentially degradable fraction for DM (821) (P silage was higher (P silage (170 mg/l). The average rumen pH (6.1) in cows fed QPM silage was lowest (P silage. The concentration of total volatile fatty acids (116 mmol/l) in the rumen of cows incubated with QPM silage was higher (P silage (110 mmol/l). It was concluded that QPM silage-based diet was superior in DM and OM degradability, and had higher ammonia and VFA concentration than NM stover-based diet. No differences have been observed in all parameters measured between QPM and NM silages.

  1. SOM quality and phosphorus fractionation to evaluate degradation organic matter: implications for the restoration of soils after fire

    Science.gov (United States)

    Merino, Agustin; Fonturbel, Maria T.; Omil, Beatriz; Chávez-Vergara, Bruno; Fernandez, Cristina; Garcia-Oliva, Felipe; Vega, Jose A.

    2016-04-01

    The design of emergency treatment for the rehabilitation of fire-affected soils requires a quick diagnosis to assess the degree of degradation. For its implication in the erosion and subsequent evolution, the quality of soil organic matter (OM) plays a particularly important role. This paper presents a methodology that combines the visual recognition of the severity of soil burning with the use of simple analytical techniques to assess the degree of degradation of OM. The content and quality of the OM was evaluated in litter and mineral soils using thermogravimetry-differential scanning calorimetry (DSC-TG) spectroscopy, and the results were contrasted with 13C CP-MAS NMR. The types of methodologies were texted to assess the thermal analysis: a) the direct calculation of the Q areas related to three degrees of thermal stabilities: Q1 (200-375 °C; labil OM); Q2 (375-475 °C, recalcitrant OM); and Q3 (475-550 °C). b) deconvolution of DSC curves and calculation of each peak was expressed as a fraction of the total DSC curve area. Additionally, a P fractionation was done following the Hedley sequential extraction method. The severity levels visually showed different degrees of SOM degradation. Although the fire caused important SOM losses in moderate severities, changes in the quality of OM only occurred at higher severities. Besides, the labile organic P fraction decreased and the occluded inorganic P fraction increased in the high severity soils. These changes affect the OM processes such as hydrophobicity and erosion largely responsible for soil degradation post-fire. The strong correlations between the thermal parameters and NMR regions and derived measurements such as hydrophobicity and aromaticity show the usefulness of this technique as rapid diagnosis to assess the soil degradation.The marked loss of polysaccharide and transition to highly thermic-resistant compounds, visible in deconvoluted thermograms, which would explain the changes in microbial activity

  2. Non-degradable contrast agent with selective phagocytosis for cellular and hepatic magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Fei-Yan [Nanchang University, College of Chemistry (China); Gu, Zhe-Jia [Nanchang University, Institute for Advanced Study (China); Zhao, Dawen [UT Southwestern Medical Center, Department of Radiology (United States); Tang, Qun, E-mail: tangqun@ncu.edu.cn [Nanchang University, Institute for Advanced Study (China)

    2015-09-15

    Degradation is the long-existing toxic issue of metal-containing inorganic medicine. In this paper, we fully investigated the degradation of dextran-coated KMnF{sub 3} nanocube in the in vitro and in vivo surroundings. Different from the general decomposing and ion releasing events, this special agent is resistant to acidic environment, as well as ion exchange. Non-degradability was proved by simulated and real cellular experiments. Moreover, it can be engulfed in the macrophage cells and kept stable in the lysosome. Due to its stability and highly selective phagocytosis, implanted liver cancer can be clearly visualized after administration.

  3. The application of the reduced order model Kalman filter to motion estimation of degraded image sequences. M.S. Thesis

    Science.gov (United States)

    Simpson, Elizabeth C.

    1989-01-01

    Motion estimation is a field of great interest because of its many applications in areas such as robotics and image coding. The optic flow method is one such scheme which, although fairly accurate, is prone to error in the presence of noise. This thesis describes the use of the reduced order model Kalman filter (ROMKF) in reducing errors in displacement estimation due to degradation of the sequence. The implementation of filtering and motion estimation algorithms on the SUN workstation is also discussed. Results from preliminary testing were used to determine the degrees of freedom available for the ROMKF in the SUN software. The tests indicated that increasing the state to the left leads to slight improvement over the minimum state case. Therefore, the software uses the minimum model, with the option of adding states to the left only. The ROMKF was then used in conjunction with a hierarchical pel recursive motion estimation algorithm. Applying the ROMKF to the degraded displacements themselves generally yielded slight improvements in cases with noise degradation and noise plus blur. Filtering the images of the degraded sequence prior to motion estimation was less effective in these cases. Both methods performed badly in the case of blur alone, resulting in increased displacement errors. This is thought to be due in part to filter artifacts. Some improvements were obtained by varying the filter parameters when filtering the displacements directly. This result suggests that further study in varying filter parameters may lead to better results. The results of this thesis indicate that the ROMKF can play a part in reducing motion estimation errors from degraded sequences. However, more work needs to be done before the use of the ROMKF can be a practical solution.

  4. SENTINEL-2 image quality and level 1 processing

    Science.gov (United States)

    Meygret, Aimé; Baillarin, Simon; Gascon, Ferran; Hillairet, Emmanuel; Dechoz, Cécile; Lacherade, Sophie; Martimort, Philippe; Spoto, François; Henry, Patrice; Duca, Riccardo

    2009-08-01

    In the framework of the Global Monitoring for Environment and Security (GMES) programme, the European Space Agency (ESA) in partnership with the European Commission (EC) is developing the SENTINEL-2 optical imaging mission devoted to the operational monitoring of land and coastal areas. The Sentinel-2 mission is based on a twin satellites configuration deployed in polar sun-synchronous orbit and is designed to offer a unique combination of systematic global coverage with a wide field of view (290km), a high revisit (5 days at equator with two satellites), a high spatial resolution (10m, 20m and 60 m) and multi-spectral imagery (13 bands in the visible and the short wave infrared spectrum). SENTINEL-2 will ensure data continuity of SPOT and LANDSAT multispectral sensors while accounting for future service evolution. This paper presents the main geometric and radiometric image quality requirements for the mission. The strong multi-spectral and multi-temporal registration requirements constrain the stability of the platform and the ground processing which will automatically refine the geometric physical model through correlation technics. The geolocation of the images will take benefits from a worldwide reference data set made of SENTINEL-2 data strips geolocated through a global space-triangulation. These processing are detailed through the description of the level 1C production which will provide users with ortho-images of Top of Atmosphere reflectances. The huge amount of data (1.4 Tbits per orbit) is also a challenge for the ground processing which will produce at level 1C all the acquired data. Finally we discuss the different geometric (line of sight, focal plane cartography, ...) and radiometric (relative and absolute camera sensitivity) in-flight calibration methods that will take advantage of the on-board sun diffuser and ground targets to answer the severe mission requirements.

  5. Use of plan quality degradation to evaluate tradeoffs in delivery efficiency and clinical plan metrics arising from IMRT optimizer and sequencer compromises

    Science.gov (United States)

    Wilkie, Joel R.; Matuszak, Martha M.; Feng, Mary; Moran, Jean M.; Fraass, Benedick A.

    2013-01-01

    Purpose: Plan degradation resulting from compromises made to enhance delivery efficiency is an important consideration for intensity modulated radiation therapy (IMRT) treatment plans. IMRT optimization and/or multileaf collimator (MLC) sequencing schemes can be modified to generate more efficient treatment delivery, but the effect those modifications have on plan quality is often difficult to quantify. In this work, the authors present a method for quantitative assessment of overall plan quality degradation due to tradeoffs between delivery efficiency and treatment plan quality, illustrated using comparisons between plans developed allowing different numbers of intensity levels in IMRT optimization and/or MLC sequencing for static segmental MLC IMRT plans. Methods: A plan quality degradation method to evaluate delivery efficiency and plan quality tradeoffs was developed and used to assess planning for 14 prostate and 12 head and neck patients treated with static IMRT. Plan quality was evaluated using a physician's predetermined “quality degradation” factors for relevant clinical plan metrics associated with the plan optimization strategy. Delivery efficiency and plan quality were assessed for a range of optimization and sequencing limitations. The “optimal” (baseline) plan for each case was derived using a clinical cost function with an unlimited number of intensity levels. These plans were sequenced with a clinical MLC leaf sequencer which uses >100 segments, assuring delivered intensities to be within 1% of the optimized intensity pattern. Each patient's optimal plan was also sequenced limiting the number of intensity levels (20, 10, and 5), and then separately optimized with these same numbers of intensity levels. Delivery time was measured for all plans, and direct evaluation of the tradeoffs between delivery time and plan degradation was performed. Results: When considering tradeoffs, the optimal number of intensity levels depends on the treatment

  6. Tin-filter enhanced dual-energy-CT: image quality and accuracy of CT numbers in virtual noncontrast imaging.

    Science.gov (United States)

    Kaufmann, Sascha; Sauter, Alexander; Spira, Daniel; Gatidis, Sergios; Ketelsen, Dominik; Heuschmid, Martin; Claussen, Claus D; Thomas, Christoph

    2013-05-01

    To measure and compare the objective image quality of true noncontrast (TNC) images with virtual noncontrast (VNC) images acquired by tin-filter-enhanced, dual-source, dual-energy computed tomography (DECT) of upper abdomen. Sixty-three patients received unenhanced abdominal CT and enhanced abdominal DECT (100/140 kV with tin filter) in portal-venous phase. VNC images were calculated from the DECT datasets using commercially available software. The mean attenuation of relevant tissues and image quality were compared between the TNC and VNC images. Image quality was rated objectively by measuring image noise and the sharpness of object edges using custom-designed software. Measurements were compared using Student two-tailed t-test. Correlation coefficients for tissue attenuation measurements between TNC and VNC were calculated and the relative deviations were illustrated using Bland-Altman plots. Mean attenuation differences between TNC and VNC (HUTNC - HUVNC) image sets were as follows: right liver lobe -4.94 Hounsfield units (HU), left liver lobe -3.29 HU, vena cava -2.19 HU, spleen -7.46 HU, pancreas 1.29 HU, fat -11.14 HU, aorta 1.29 HU, bone marrow 36.83 HU (all P Mean image noise was significantly higher in TNC images (P images (P = .19). The Hounsfield units in VNC images closely resemble TNC images in the majority of the organs of the upper abdomen (kidneys, liver, pancreas). In spleen and fat, Hounsfield numbers in VNC images are tend to be higher than in TNC images. VNC images show a low image noise and satisfactory edge sharpness. Other criteria of image quality and the depiction of certain lesions need to be evaluated additionally. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

  7. The Effect of Image Quality, Repeated Study, and Assessment Method on Anatomy Learning

    Science.gov (United States)

    Fenesi, Barbara; Mackinnon, Chelsea; Cheng, Lucia; Kim, Joseph A.; Wainman, Bruce C.

    2017-01-01

    The use of two-dimensional (2D) images is consistently used to prepare anatomy students for handling real specimen. This study examined whether the quality of 2D images is a critical component in anatomy learning. The visual clarity and consistency of 2D anatomical images was systematically manipulated to produce low-quality and high-quality…

  8. A Bayesian model for predicting face recognition performance using image quality

    NARCIS (Netherlands)

    Dutta, A.; Veldhuis, Raymond N.J.; Spreeuwers, Lieuwe Jan

    2014-01-01

    Quality of a pair of facial images is a strong indicator of the uncertainty in decision about identity based on that image pair. In this paper, we describe a Bayesian approach to model the relation between image quality (like pose, illumination, noise, sharpness, etc) and corresponding face

  9. Noise properties in breaking and loose contacts and their effect on quality degradation of digital signal

    Institute of Scientific and Technical Information of China (English)

    TAKAGI Tasuku

    2007-01-01

    Electric contact discharge is subject closely related to digital information transmission, and integrity of digital signals for realizing high reliablility transmission. This kind of problem is a part of EMC (electromagnetic compatibility). From such a viewpoint, contact noise problems will be mentioned which disturb and degrade digital signals. The induction noise and radiation noise from discharge, electrostatic discharge (ESD), and connector related fundamental subject will be mentioned.

  10. The image quality of ion computed tomography at clinical imaging dose levels

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, David C., E-mail: dch@oncology.au.dk [Department of Experimental Clinical Oncology, Aarhus University Hospital, 8000 Aarhus (Denmark); Bassler, Niels [Department of Physics and Astronomy, Aarhus University, 8000 Aarhus (Denmark); Sørensen, Thomas Sangild [Department of Computer Science, Aarhus University, 8000 Aarhus, Denmark and Department of Clinical Medicine, Aarhus University, 8000 Aarhus (Denmark); Seco, Joao [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School,Boston, Massachusetts 02114 (United States)

    2014-11-01

    Purpose: Accurately predicting the range of radiotherapy ions in vivo is important for the precise delivery of dose in particle therapy. Range uncertainty is currently the single largest contribution to the dose margins used in planning and leads to a higher dose to normal tissue. The use of ion CT has been proposed as a method to improve the range uncertainty and thereby reduce dose to normal tissue of the patient. A wide variety of ions have been proposed and studied for this purpose, but no studies evaluate the image quality obtained with different ions in a consistent manner. However, imaging doses ion CT is a concern which may limit the obtainable image quality. In addition, the imaging doses reported have not been directly comparable with x-ray CT doses due to the different biological impacts of ion radiation. The purpose of this work is to develop a robust methodology for comparing the image quality of ion CT with respect to particle therapy, taking into account different reconstruction methods and ion species. Methods: A comparison of different ions and energies was made. Ion CT projections were simulated for five different scenarios: Protons at 230 and 330 MeV, helium ions at 230 MeV/u, and carbon ions at 430 MeV/u. Maps of the water equivalent stopping power were reconstructed using a weighted least squares method. The dose was evaluated via a quality factor weighted CT dose index called the CT dose equivalent index (CTDEI). Spatial resolution was measured by the modulation transfer function. This was done by a noise-robust fit to the edge spread function. Second, the image quality as a function of the number of scanning angles was evaluated for protons at 230 MeV. In the resolution study, the CTDEI was fixed to 10 mSv, similar to a typical x-ray CT scan. Finally, scans at a range of CTDEI’s were done, to evaluate dose influence on reconstruction error. Results: All ions yielded accurate stopping power estimates, none of which were statistically

  11. Imaging wellbore cement degradation by carbon dioxide under geologic sequestration conditions using X-ray computed microtomography.

    Science.gov (United States)

    Jung, Hun Bok; Jansik, Danielle; Um, Wooyong

    2013-01-02

    X-ray microtomography (XMT), a nondestructive three-dimensional imaging technique, was applied to demonstrate its capability to visualize the mineralogical alteration and microstructure changes in hydrated Portland cement exposed to carbon dioxide under geologic sequestration conditions. Steel coupons and basalt fragments were added to the cement paste in order to simulate cement-steel and cement-rock interfaces. XMT image analysis showed the changes of material density and porosity in the degradation front (density: 1.98 g/cm(3), porosity: 40%) and the carbonated zone (density: 2.27 g/cm(3), porosity: 23%) after reaction with CO(2)-saturated water for 5 months compared to unaltered cement (density: 2.15 g/cm(3), porosity: 30%). Three-dimensional XMT imaging was capable of displaying spatially heterogeneous alteration in cement pores, calcium carbonate precipitation in cement cracks, and preferential cement alteration along the cement-steel and cement-rock interfaces. This result also indicates that the interface between cement and host rock or steel casing is likely more vulnerable to a CO(2) attack than the cement matrix in a wellbore environment. It is shown here that XMT imaging can potentially provide a new insight into the physical and chemical degradation of wellbore cement by CO(2) leakage.

  12. A Modified Soil Quality Index to Assess the Influence of Soil Degradation Processes on Desertification Risk: The Apulia Case

    Directory of Open Access Journals (Sweden)

    Valeria Ancona

    2010-10-01

    Full Text Available Apulia is one of the most prone Italian regions to soil alteration phenomena, due to geographical and climatic conditions and also to human activities’ impact. In this study, in order to investigate regional soil degradation processes, following the “European Directive for Soil Protection”, the ESA’s method has been adopted. It is based on the use of an indicator’s set to assess the desertification risk. This approach simplifies the diagnosis and monitoring of soil degradation processes, defining their status and trend. Special attention has been given to Soil Quality Index (SQI determined by six predisposing indicators (parent material, soil texture, rock fragment, soil depth, drainage and slope grade. The integration in the SQI calculation of two additional soil parameters (organic matter content and soil salinity has been considered particularly significant. In fact, through the evaluation of a so “modified SQI” and the Apulia land use too, it could be possible to assess the role of agriculture management on soil degradation processes, which predisposing regional area to desertification threat. Moreover this approach provides short, but accurate, information thanks to GIS integration, which defines phenomena in detail, offering helpful planning tools.

  13. Improving image quality in laboratory x-ray phase-contrast imaging

    Science.gov (United States)

    De Marco, F.; Marschner, M.; Birnbacher, L.; Viermetz, M.; Noël, P.; Herzen, J.; Pfeiffer, F.

    2017-03-01

    Grating-based X-ray phase-contrast (gbPC) is known to provide significant benefits for biomedical imaging. To investigate these benefits, a high-sensitivity gbPC micro-CT setup for small (≍ 5 cm) biological samples has been constructed. Unfortunately, high differential-phase sensitivity leads to an increased magnitude of data processing artifacts, limiting the quality of tomographic reconstructions. Most importantly, processing of phase-stepping data with incorrect stepping positions can introduce artifacts resembling Moiré fringes to the projections. Additionally, the focal spot size of the X-ray source limits resolution of tomograms. Here we present a set of algorithms to minimize artifacts, increase resolution and improve visual impression of projections and tomograms from the examined setup. We assessed two algorithms for artifact reduction: Firstly, a correction algorithm exploiting correlations of the artifacts and differential-phase data was developed and tested. Artifacts were reliably removed without compromising image data. Secondly, we implemented a new algorithm for flatfield selection, which was shown to exclude flat-fields with strong artifacts. Both procedures successfully improved image quality of projections and tomograms. Deconvolution of all projections of a CT scan can minimize blurring introduced by the finite size of the X-ray source focal spot. Application of the Richardson-Lucy deconvolution algorithm to gbPC-CT projections resulted in an improved resolution of phase-contrast tomograms. Additionally, we found that nearest-neighbor interpolation of projections can improve the visual impression of very small features in phase-contrast tomograms. In conclusion, we achieved an increase in image resolution and quality for the investigated setup, which may lead to an improved detection of very small sample features, thereby maximizing the setup's utility.

  14. Use of multi-temporal SPOT-5 satellite images for land degradation assessment in Cameron Highlands, Malaysia using Geospatial techniques

    Science.gov (United States)

    Nampak, Haleh; Pradhan, Biswajeet

    2016-07-01

    Soil erosion is the common land degradation problem worldwide because of its economic and environmental impacts. Therefore, land-use change detection has become one of the major concern to geomorphologists, environmentalists, and land use planners due to its impact on natural ecosystems. The objective of this paper is to evaluate the relationship between land use/cover changes and land degradation in the Cameron highlands (Malaysia) through multi-temporal remotely sensed satellite images and ancillary data. Land clearing in the study area has resulted increased soil erosion due to rainfall events. Also unsustainable development and agriculture, mismanagement and lacking policies contribute to increasing soil erosion rates. The LULC distribution of the study area was mapped for 2005, 2010, and 2015 through SPOT-5 satellite imagery data which were classified based on object-based classification. A soil erosion model was also used within a GIS in order to study the susceptibility of the areas affected by changes to overland flow and rain splash erosion. The model consists of four parameters, namely soil erodibility, slope, vegetation cover and overland flow. The results of this research will be used in the selection of the areas that require mitigation processes which will reduce their degrading potential. Key words: Land degradation, Geospatial, LULC change, Soil erosion modelling, Cameron highlands.

  15. Gelatin-based Hydrogel Degradation and Tissue Interaction in vivo: Insights from Multimodal Preclinical Imaging in Immunocompetent Nude Mice

    Science.gov (United States)

    Tondera, Christoph; Hauser, Sandra; Krüger-Genge, Anne; Jung, Friedrich; Neffe, Axel T.; Lendlein, Andreas; Klopfleisch, Robert; Steinbach, Jörg; Neuber, Christin; Pietzsch, Jens

    2016-01-01

    Hydrogels based on gelatin have evolved as promising multifunctional biomaterials. Gelatin is crosslinked with lysine diisocyanate ethyl ester (LDI) and the molar ratio of gelatin and LDI in the starting material mixture determines elastic properties of the resulting hydrogel. In order to investigate the clinical potential of these biopolymers, hydrogels with different ratios of gelatin and diisocyanate (3-fold (G10_LNCO3) and 8-fold (G10_LNCO8) molar excess of isocyanate groups) were subcutaneously implanted in mice (uni- or bilateral implantation). Degradation and biomaterial-tissue-interaction were investigated in vivo (MRI, optical imaging, PET) and ex vivo (autoradiography, histology, serum analysis). Multimodal imaging revealed that the number of covalent net points correlates well with degradation time, which allows for targeted modification of hydrogels based on properties of the tissue to be replaced. Importantly, the degradation time was also dependent on the number of implants per animal. Despite local mechanisms of tissue remodeling no adverse tissue responses could be observed neither locally nor systemically. Finally, this preclinical investigation in immunocompetent mice clearly demonstrated a complete restoration of the original healthy tissue. PMID:27698944

  16. Quantitative Image Quality Comparison of Reduced- and Standard-Dose Dual-Energy Multiphase Chest, Abdomen, and Pelvis CT.

    Science.gov (United States)

    Buty, Mario; Xu, Ziyue; Wu, Aaron; Gao, Mingchen; Nelson, Chelyse; Papadakis, Georgios Z; Teomete, Uygar; Celik, Haydar; Turkbey, Baris; Choyke, Peter; Mollura, Daniel J; Bagci, Ulas; Folio, Les R

    2017-06-01

    We present a new image quality assessment method for determining whether reducing radiation dose impairs the image quality of computed tomography (CT) in qualitative and quantitative clinical analyses tasks. In this Institutional Review Board-exempt study, we conducted a review of 50 patients (male, 22; female, 28) who underwent reduced-dose CT scanning on the first follow-up after standard-dose multiphase CT scanning. Scans were for surveillance of von Hippel-Lindau disease (N = 26) and renal cell carcinoma (N = 10). We investigated density, morphometric, and structural differences between scans both at tissue (fat, bone) and organ levels (liver, heart, spleen, lung). To quantify structural variations caused by image quality differences, we propose using the following metrics: dice similarity coefficient, structural similarity index, Hausdorff distance, gradient magnitude similarity deviation, and weighted spectral distance. Pearson correlation coefficient and Welch 2-sample t test were used for quantitative comparisons of organ morphometry and to compare density distribution of tissue, respectively. For qualitative evaluation, 2-sided Kendall Tau test was used to assess agreement among readers. Both qualitative and quantitative evaluations were designed to examine significance of image differences for clinical tasks. Qualitative judgment served as an overall assessment, whereas detailed quantifications on structural consistency, intensity homogeneity, and texture similarity revealed more accurate and global difference estimations. Qualitative and quantitative results indicated no significant image quality degradation. Our study concludes that low(er)-dose CT scans can be routinely used because of no significant loss in quantitative image information compared with standard-dose CT scans.

  17. Improving a DWT-based compression algorithm for high image-quality requirement of satellite images

    Science.gov (United States)

    Thiebaut, Carole; Latry, Christophe; Camarero, Roberto; Cazanave, Grégory

    2011-10-01

    Past and current optical Earth observation systems designed by CNES are using a fixed-rate data compression processing performed at a high-rate in a pushbroom mode (also called scan-based mode). This process generates fixed-length data to the mass memory and data downlink is performed at a fixed rate too. Because of on-board memory limitations and high data rate processing needs, the rate allocation procedure is performed over a small image area called a "segment". For both PLEIADES compression algorithm and CCSDS Image Data Compression recommendation, this rate allocation is realised by truncating to the desired rate a hierarchical bitstream of coded and quantized wavelet coefficients for each segment. Because the quantisation induced by truncation of the bit planes description is the same for the whole segment, some parts of the segment have a poor image quality. These artefacts generally occur in low energy areas within a segment of higher level of energy. In order to locally correct these areas, CNES has studied "exceptional processing" targeted for DWT-based compression algorithms. According to a criteria computed for each part of the segment (called block), the wavelet coefficients can be amplified before bit-plane encoding. As usual Region of Interest handling, these multiplied coefficients will be processed earlier by the encoder than in the nominal case (without exceptional processing). The image quality improvement brought by the exceptional processing has been confirmed by visual image analysis and fidelity criteria. The complexity of the proposed improvement for on-board application has also been analysed.

  18. Preprocessing and Quality Control Strategies for Illumina DASL Assay-Based Brain Gene Expression Studies with Semi-Degraded Samples.

    Science.gov (United States)

    Chow, Maggie L; Winn, Mary E; Li, Hai-Ri; April, Craig; Wynshaw-Boris, Anthony; Fan, Jian-Bing; Fu, Xiang-Dong; Courchesne, Eric; Schork, Nicholas J

    2012-01-01

    Available statistical preprocessing or quality control analysis tools for gene expression microarray datasets are known to greatly affect downstream data analysis, especially when degraded samples, unique tissue samples, or novel expression assays are used. It is therefore important to assess the validity and impact of the assumptions built in to preprocessing schemes for a dataset. We developed and assessed a data preprocessing strategy for use with the Illumina DASL-based gene expression assay with partially degraded postmortem prefrontal cortex samples. The samples were obtained from individuals with autism as part of an investigation of the pathogenic factors contributing to autism. Using statistical analysis methods and metrics such as those associated with multivariate distance matrix regression and mean inter-array correlation, we developed a DASL-based assay gene expression preprocessing pipeline to accommodate and detect problems with microarray-based gene expression values obtained with degraded brain samples. Key steps in the pipeline included outlier exclusion, data transformation and normalization, and batch effect and covariate corrections. Our goal was to produce a clean dataset for subsequent downstream differential expression analysis. We ultimately settled on available transformation and normalization algorithms in the R/Bioconductor package lumi based on an assessment of their use in various combinations. A log2-transformed, quantile-normalized, and batch and seizure-corrected procedure was likely the most appropriate for our data. We empirically tested different components of our proposed preprocessing strategy and believe that our results suggest that a preprocessing strategy that effectively identifies outliers, normalizes the data, and corrects for batch effects can be applied to all studies, even those pursued with degraded samples.

  19. Learning a channelized observer for image quality assessment.

    Science.gov (United States)

    Brankov, Jovan G; Yang, Yongyi; Wei, Liyang; El Naqa, Issam; Wernick, Miles N

    2009-07-01

    It is now widely accepted that image quality should be evaluated using task-based criteria, such as human-observer performance in a lesion-detection task. The channelized Hotelling observer (CHO) has been widely used as a surrogate for human observers in evaluating lesion detectability. In this paper, we propose that the problem of developing a numerical observer can be viewed as a system-identification or supervised-learning problem, in which the goal is to identify the unknown system of the human observer. Following this approach, we explore the possibility of replacing the Hotelling detector within the CHO with an algorithm that learns the relationship between measured channel features and human observer scores. Specifically, we develop a channelized support vector machine (CSVM) which we compare to the CHO in terms of its ability to predict human-observer performance. In the examples studied, we find that the CSVM is better able to generalize to unseen images than the CHO, and therefore may represent a useful improvement on the CHO methodology, while retaining its essential features.

  20. Crowdsourcing quality control for Dark Energy Survey images

    Science.gov (United States)

    Melchior, P.; Sheldon, E.; Drlica-Wagner, A.; Rykoff, E. S.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Brooks, D.; Buckley-Geer, E.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Crocce, M.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Doel, P.; Evrard, A. E.; Finley, D. A.; Flaugher, B.; Frieman, J.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D. J.; Jarvis, M.; Kuehn, K.; Li, T. S.; Maia, M. A. G.; March, M.; Marshall, J. L.; Nord, B.; Ogando, R.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Vikram, V.; Walker, A. R.; Wester, W.; Zhang, Y.

    2016-07-01

    We have developed a crowdsourcing web application for image quality control employed by the Dark Energy Survey. Dubbed the "DES exposure checker", it renders science-grade images directly to a web browser and allows users to mark problematic features from a set of predefined classes. Users can also generate custom labels and thus help identify previously unknown problem classes. User reports are fed back to hardware and software experts to help mitigate and eliminate recognized issues. We report on the implementation of the application and our experience with its over 100 users, the majority of which are professional or prospective astronomers but not data management experts. We discuss aspects of user training and engagement, and demonstrate how problem reports have been pivotal to rapidly correct artifacts which would likely have been too subtle or infrequent to be recognized otherwise. We conclude with a number of important lessons learned, suggest possible improvements, and recommend this collective exploratory approach for future astronomical surveys or other extensive data sets with a sufficiently large user base. We also release open-source code of the web application and host an online demo version at http://des-exp-checker.pmelchior.net.

  1. Spatial evaluation of the risk of groundwater quality degradation. A comparison between disjunctive kriging and geostatistical simulation.

    Science.gov (United States)

    Barca, E; Passarella, G

    2008-02-01

    In some previous papers a probabilistic methodology was introduced to estimate a spatial index of risk of groundwater quality degradation, defined as the conditional probability of exceeding assigned thresholds of concentration of a generic chemical sampled in the studied water system. A crucial stage of this methodology was the use of geostatistical techniques to provide an estimation of the above-mentioned probability in a number of selected points by crossing spatial and temporal information. In this work, spatial risk values were obtained using alternatively stochastic conditional simulation and disjunctive kriging. A comparison between the resulting two sets of spatial risks, based on global and local statistical tests, showed that they do not come from the same statistical population and, consequently, they cannot be viewed as equivalent in a statistical sense. At a first glance, geostatistical conditional simulation may appear to represent the spatial variability of the phenomenon more effectively, as the latter tends to be smoothed by DK. However, a close examination of real case study results suggests that disjunctive kriging is more effective than simulation in estimating the spatial risk of groundwater quality degradation. In the study case, the potentially 'harmful event' considered, threatening a natural 'vulnerable groundwater system,' is fertilizer and manure application.

  2. Digital radiography: optimization of image quality and dose using multi-frequency software

    Energy Technology Data Exchange (ETDEWEB)

    Precht, H. [University College Lillebelt, Conrad Research Center, Odense (Denmark); Gerke, O. [Odense University Hospital, Department of Nuclear Medicine, Odense (Denmark); University of Southern Denmark, Research Unit of Health Economics, Odense (Denmark); Rosendahl, K. [Haukeland University Hospital, Section of Pediatric Radiology, Bergen (Norway); University of Bergen, Institute of Surgical Sciences, Bergen (Norway); Tingberg, A. [Skaane University Hospital, Lund University (Sweden); Medical Radiation Physics, Department of Clinical Sciences, Malmoe (Sweden); Waaler, D. [Gjoevik University College, Gjoevik (Norway)

    2012-09-15

    New developments in processing of digital radiographs (DR), including multi-frequency processing (MFP), allow optimization of image quality and radiation dose. This is particularly promising in children as they are believed to be more sensitive to ionizing radiation than adults. To examine whether the use of MFP software reduces the radiation dose without compromising quality at DR of the femur in 5-year-old-equivalent anthropomorphic and technical phantoms. A total of 110 images of an anthropomorphic phantom were imaged on a DR system (Canon DR with CXDI-50 C detector and MLT[S] software) and analyzed by three pediatric radiologists using Visual Grading Analysis. In addition, 3,500 images taken of a technical contrast-detail phantom (CDRAD 2.0) provide an objective image-quality assessment. Optimal image-quality was maintained at a dose reduction of 61% with MLT(S) optimized images. Even for images of diagnostic quality, MLT(S) provided a dose reduction of 88% as compared to the reference image. Software impact on image quality was found significant for dose (mAs), dynamic range dark region and frequency band. By optimizing image processing parameters, a significant dose reduction is possible without significant loss of image quality. (orig.)

  3. Imaging-based logics for ornamental stone quality chart definition

    Science.gov (United States)

    Bonifazi, Giuseppe; Gargiulo, Aldo; Serranti, Silvia; Raspi, Costantino

    2007-02-01

    Ornamental stone products are commercially classified on the market according to several factors related both to intrinsic lythologic characteristics and to their visible pictorial attributes. Sometimes these latter aspects prevail in quality criteria definition and assessment. Pictorial attributes are in any case also influenced by the performed working actions and the utilized tools selected to realize the final stone manufactured product. Stone surface finishing is a critical task because it can contribute to enhance certain aesthetic features of the stone itself. The study was addressed to develop an innovative set of methodologies and techniques able to quantify the aesthetic quality level of stone products taking into account both the physical and the aesthetical characteristics of the stones. In particular, the degree of polishing of the stone surfaces and the presence of defects have been evaluated, applying digital image processing strategies. Morphological and color parameters have been extracted developing specific software architectures. Results showed as the proposed approaches allow to quantify the degree of polishing and to identify surface defects related to the intrinsic characteristics of the stone and/or the performed working actions.

  4. Improved structural similarity metric for the visible quality measurement of images

    Science.gov (United States)

    Lee, Daeho; Lim, Sungsoo

    2016-11-01

    The visible quality assessment of images is important to evaluate the performance of image processing methods such as image correction, compressing, and enhancement. The structural similarity is widely used to determine the visible quality; however, existing structural similarity metrics cannot correctly assess the perceived human visibility of images that have been slightly geometrically transformed or images that have undergone significant regional distortion. We propose an improved structural similarity metric that is more close to human visible evaluation. Compared with the existing metrics, the proposed method can more correctly evaluate the similarity between an original image and various distorted images.

  5. Relationships among muscle dysmorphia characteristics, body image quality of life, and coping in males.

    Science.gov (United States)

    Tod, D; Edwards, C

    2015-09-01

    The purpose of this study was to examine relationships among bodybuilding dependence, muscle satisfaction, body image-related quality of life and body image-related coping strategies, and test the hypothesis that muscle dysmorphia characteristics may predict quality of life via coping strategies. Participants (294 males, Mage=20.5 years, SD=3.1) participated in a cross-sectional survey. Participants completed questionnaires assessing muscle satisfaction, bodybuilding dependence, body image-related quality of life and body image-related coping. Quality of life was correlated positively with muscle satisfaction and bodybuilding dependence but negatively with body image coping (Plife both directly and indirectly via body image coping strategies (as evidenced by the bias corrected and accelerated bootstrapped confidence intervals). These results provide preliminary evidence regarding the ways that muscularity concerns might influence body image-related quality of life. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  6. Novel Card Games for Learning Radiographic Image Quality and Urologic Imaging in Veterinary Medicine.

    Science.gov (United States)

    Ober, Christopher P

    Second-year veterinary students are often challenged by concepts in veterinary radiology, including the fundamentals of image quality and generation of differential lists. Four card games were developed to provide veterinary students with a supplemental means of learning about radiographic image quality and differential diagnoses in urogenital imaging. Students played these games and completed assessments of their subject knowledge before and after playing. The hypothesis was that playing each game would improve students' understanding of the topic area. For each game, students who played the game performed better on the post-test than students who did not play that game (all pgames, students who played each respective game demonstrated significant improvement in scores between the pre-test and the post-test (pgames were both helpful and enjoyable. Educationally focused games can help students learn classroom and laboratory material. However, game design is important, as the game using the most passive learning process also demonstrated the weakest results. In addition, based on participants' comments, the games were very useful in improving student engagement in the learning process. Thus, use of games in the classroom and laboratory setting seems to benefit the learning process.

  7. Image quality in CT perfusion imaging of the brain. The role of iodine concentration

    Energy Technology Data Exchange (ETDEWEB)

    Koenig, Matthias; Bueltmann, Eva; Bode-Schnurbus, Lucas; Koenen, Dirk; Mielke, Eckhart; Heuser, Lothar [Knappschaftskrankenhaus Langendreer, Department of Diagnostic and Interventional Radiology and Nuclear Medicine, Ruhr-University Bochum, Bochum (Germany)

    2007-01-15

    The purpose of this study was to evaluate the impact of various iodine contrast concentrations on image quality in computed tomography (CT) perfusion studies. Twenty-one patients with suspicion of cerebral ischemia underwent perfusion CT using two different iodine contrast concentrations: 11 patients received iomeprol 300 (iodine concentration: 300 mg/ml) while ten received the same volume of iomeprol 400 (iodine concentration: 400 mg/ml). Scan parameters were kept constant for both groups. Maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and time to peak (TTP) were calculated from two adjacent slices. Quantitative comparisons were based on measurements of the maximum enhancement [Hounsfield units (HU)] and signal-to-noise index (SNI) on CBF, CBV, and TTP images. Determinations of grey-to-white-matter delineation for each iodine concentration were performed by two blinded readers. Only data from the non-ischemic hemispheres were considered. Both maximum enhancement and SNI values were higher after iomeprol 400, resulting in significantly better image quality in areas of low perfusion. No noteworthy differences were found for normal values of CBF, CBV, and TTP. Qualitative assessment of grey/white matter contrast on CBF and CBV maps revealed better performance for iomeprol 400. For brain perfusion studies, highly concentrated contrast media such as iomeprol 400 is superior to iomeprol 300. (orig.)

  8. Optical imaging beyond the diffraction limit by SNEM: Effects of AFM tip modifications with thiol monolayers on imaging quality

    NARCIS (Netherlands)

    Cumurcu, Aysegul; Diaz, J.; Lindsay, I.D.; Beer, de S.; Duvigneau, J.; Schön, P.M.; Vancso, G.J.

    2015-01-01

    Tip-enhanced nanoscale optical imaging techniques such as apertureless scanning near-field optical microscopy (a-SNOM) and scanning near-field ellipsometric microscopy (SNEM) applications can suffer from a steady degradation in performance due to adhesion of atmospheric contaminants to the metal coa

  9. Seasonal quality profile and production of foliage from trees grown on degraded cropland in arid Uzbekistan, Central Asia.

    Science.gov (United States)

    Lamers, J P A; Khamzina, A

    2010-10-01

    Feed shortages hamper livestock rearing and thus impede the development of rural livelihoods in Central Asia. The production and in vitro quality of foliage from Ulmus pumila, Elaeagnus angustifolia and Populus euphratica on degraded cropland were examined to determine the potential of these species to supplement diary cattle diets. Leaf dry matter (DM) production of the species, respectively, averaged 6, 8 and 17 t DM/ha, 4 years after planting. Over seasons and years, crude protein concentrations (g/kg DM) ranged within 151-257 for E. angustifolia, 70-241 for U. pumila and 92-187 for P. euphratica. The metabolizable energy concentrations (MJ/kg DM) were the highest in U. pumila and ranged within 9-10, followed by 7-10 of E. angustifolia and 7-9 of P. euphratica. The organic matter digestibility (%) ranged within 58-70, 54-66, and 51-66, respectively, for these species. These indicators combined denoted a medium-to-good feed quality of E. angustifolia and U. pumila leaves as a cheap protein supplement to roughages. The foliage of P. euphratica was the least suitable. The seasonal profile of in vitro indicators revealed the highest feed quality in spring but early fall seems most appropriate for forage collection given the peak leaf production and an adequate quality.

  10. Image quality and diagnostic performance of free-breathing diffusion-weighted imaging for hepatocellular carcinoma.

    Science.gov (United States)

    Takayama, Yukihisa; Nishie, Akihiro; Asayama, Yoshiki; Ishigami, Kousei; Kakihara, Daisuke; Ushijima, Yasuhiro; Fujita, Nobuhiro; Shirabe, Ken; Takemura, Atsushi; Honda, Hiroshi

    2017-05-18

    To retrospectively evaluate the diagnostic performance of free-breathing diffusion-weighted imaging (FB-DWI) with modified imaging parameter settings for detecting hepatocellular carcinomas (HCCs). Fifty-one patients at risk for HCC were scanned with both FB-DWI and respiratory-triggered DWI with the navigator echo respiratory-triggering technique (RT-DWI). Qualitatively, the sharpness of the liver contour, the image noise and the chemical shift artifacts on each DWI with b-values of 1000 s/mm(2) were independently evaluated by three radiologists using 4-point scoring. We compared the image quality scores of each observer between the two DWI methods, using the Wilcoxon signed-rank test. Quantitatively, we compared the signal-to-noise ratios (SNRs) of the liver parenchyma and lesion-to-nonlesion contrast-to-noise ratios (CNRs) after measuring the signal intensity on each DWI with a b-factor of 1000 s/mm(2). The average SNRs and CNRs between the two DWI methods were compared by the paired t-test. The detectability of HCC on each DWI was also analyzed by three radiologists. The detectability provided by the two DWI methods was compared using McNemar's test. For all observers, the averaged image quality scores of FB-DWI were: Sharpness of the liver contour [observer (Obs)-1, 3.08 ± 0.81; Obs-2, 2.98 ± 0.73; Obs-3, 3.54 ± 0.75], those of the distortion (Obs-1, 2.94 ± 0.50; Obs-2, 2.71 ± 0.70; Obs-3, 3.27 ± 0.53), and the chemical shift artifacts (Obs-1, 3.38 ± 0.60; Obs-2, 3.15 ± 1.07; Obs-3, 3.21 ± 0.85). The averaged image quality scores of RT-DWI were: Sharpness of the liver contour (Obs-1, 2.33 ± 0.65; Obs-2, 2.37 ± 0.74; Obs-3, 2.75 ± 0.81), distortion (Obs-1, 2.81 ± 0.56; Obs-2, 2.25 ± 0.74; Obs-3, 2.96 ± 0.71), and the chemical shift artifacts (Obs-1, 2.92 ± 0.59; Obs-2, 2.21 ± 0.85; Obs-3, 2.77 ± 1.08). All image quality scores of FB-DWI were significantly higher than those of RT-DWI (P quality and higher detectability of HCC compared to RT

  11. Factors affecting computed tomography image quality for assessment of mechanical aortic valves.

    Science.gov (United States)

    Suh, Young Joo; Kim, Young Jin; Hong, Yoo Jin; Lee, Hye-Jeong; Hur, Jin; Hong, Sae Rom; Im, Dong Jin; Kim, Yun Jung; Choi, Byoung Wook

    2016-06-01

    Evaluating mechanical valves with computed tomography (CT) can be problematic because artifacts from the metallic components of valves can hamper image quality. The purpose of this study was to determine factors affecting the image quality of cardiac CT to improve assessment of mechanical aortic valves. A total of 144 patients who underwent aortic valve replacement with mechanical valves (ten different types) and who underwent cardiac CT were included. Using a four-point grading system, the image quality of the CT scans was assessed for visibility of the valve leaflets and the subvalvular regions. Data regarding the type of mechanical valve, tube voltage, average heart rate (HR), and HR variability during CT scanning were compared between the non-diagnostic (overall image quality score ≤2) and diagnostic (overall image quality score >2) image quality groups. Logistic regression analyses were performed to identify predictors of non-diagnostic image quality. The percentage of valve types that incorporated a cobalt-chrome component (two types in total) and HR variability were significantly higher in the non-diagnostic image group than in the diagnostic group (P  0.05). Valve type was the only independent predictor of non-diagnostic quality. The CT image quality for patients with mechanical aortic valves differed significantly depending on the type of mechanical valve used and on the degree of HR variability.

  12. Image quality and cancer visibility of T2-weighted Magnetic Resonance Imaging of the prostate at 7 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Vos, E.K.; Lagemaat, M.W.; Barentsz, J.O.; Fuetterer, J.J.; Zamecnik, P.; Roozen, H.; Maas, M.C. [Radboud University Medical Centre, Department of Radiology, P.O. box 9101, Nijmegen (Netherlands); Orzada, S.; Bitz, A.K. [Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen (Germany); Scheenen, T.W.J. [Radboud University Medical Centre, Department of Radiology, P.O. box 9101, Nijmegen (Netherlands); Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen (Germany)

    2014-08-15

    To assess the image quality of T2-weighted (T2w) magnetic resonance imaging of the prostate and the visibility of prostate cancer at 7 Tesla (T). Seventeen prostate cancer patients underwent T2w imaging at 7T with only an external transmit/receive array coil. Three radiologists independently scored images for image quality, visibility of anatomical structures, and presence of artefacts. Krippendorff's alpha and weighted kappa statistics were used to assess inter-observer agreement. Visibility of prostate cancer lesions was assessed by directly linking the T2w images to the confirmed location of prostate cancer on histopathology. T2w imaging at 7T was achievable with 'satisfactory' (3/5) to 'good' (4/5) quality. Visibility of anatomical structures was predominantly scored as 'satisfactory' (3/5) and 'good' (4/5). If artefacts were present, they were mostly motion artefacts and, to a lesser extent, aliasing artefacts and noise. Krippendorff's analysis revealed an α = 0.44 between three readers for the overall image quality scores. Clinically significant cancer lesions in both peripheral zone and transition zone were visible at 7T. T2w imaging with satisfactory to good quality can be routinely acquired, and cancer lesions were visible in patients with prostate cancer at 7T using only an external transmit/receive body array coil. (orig.)

  13. Radiation dose optimization in pediatric temporal bone computed tomography: influence of tube tension on image contrast and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Nauer, Claude Bertrand [University Hospital Berne, Institute of Diagnostic and Interventional Neuroradiology, Berne (Switzerland); Zentrales Roentgeninstitut, Kantonsspital Graubuenden, Chur (Switzerland); Zubler, Christoph; Weisstanner, Christian [University Hospital Berne, Institute of Diagnostic and Interventional Neuroradiology, Berne (Switzerland); Stieger, Christof [University Berne, Group for Artificial Hearing Research, ARTORG Center, Berne (Switzerland); Senn, Pascal [University Hospital Berne, Department of ENT, Head and Neck Surgery, Berne (Switzerland); Arnold, Andreas [University Berne, Group for Artificial Hearing Research, ARTORG Center, Berne (Switzerland); University Hospital Berne, Department of ENT, Head and Neck Surgery, Berne (Switzerland)

    2012-03-15

    The purpose of this experimental study was to investigate the effect of tube tension reduction on image contrast and image quality in pediatric temporal bone computed tomography (CT). Seven lamb heads with infant-equivalent sizes were scanned repeatedly, using four tube tensions from 140 to 80 kV while the CT-Dose Index (CTDI) was held constant. Scanning was repeated with four CTDI values from 30 to 3 mGy. Image contrast was calculated for the middle ear as the Hounsfield unit (HU) difference between bone and air and for the inner ear as the HU difference between bone and fluid. The influence of tube tension on high-contrast detail delineation was evaluated using a phantom. The subjective image quality of eight middle and inner ear structures was assessed using a 4-point scale (scores 1-2 = insufficient; scores 3-4 = sufficient). Middle and inner ear contrast showed a near linear increase with tube tension reduction (r = -0.94/-0.88) and was highest at 80 kV. Tube tension had no influence on spatial resolution. Subjective image quality analysis showed significantly better scoring at lower tube tensions, with highest image quality at 80 kV. However, image quality improvement was most relevant for low-dose scans. Image contrast in the temporal bone is significantly higher at low tube tensions, leading to a better subjective image quality. Highest contrast and best quality were found at 80 kV. This image quality improvement might be utilized to further reduce the radiation dose in pediatric low-dose CT protocols. (orig.)

  14. Image Quality and Radiation Exposure in Coronary CT Angiography According to Tube Voltage and Body Mass Index

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yoon Kyung [Korea University Guro Hospital, Seoul (Korea, Republic of); Kim, Yoo Kyung [Ewha Womans University MokDong Hospital, Seoul (Korea, Republic of)

    2010-01-15

    and a low-dose CCTA with 100 kVp leads to a significant reduction in radiation exposure without degradation of image quality.

  15. Determination of Water Quality Degradation Due to Industrial and Household Wastewater in the Galing River in Kuantan, Malaysia Using Ion Chromatograph and Water Quality Data

    Directory of Open Access Journals (Sweden)

    Daisuke Kozaki

    2017-04-01

    Full Text Available Water quality of the Galing River in Kuantan, Malaysia was examined to understand the anthropogenic environmental load in each administrative section, using water quality monitoring data and land use pattern. The National Physical Plan 2005 identified Kuantan as one of the country’s future growth centers, which has resulted in rapid development and environmental degradation in the past decade. Multiple water quality indexes used by the Department of Environment, Malaysia and concentrations of several ionic species were examined to assess the river’s water quality. The following inferences were drawn in this study: (1 Cl− and Na+ concentrations indicated that the basin area near the eastern urbanized area was subject to lesser human influence and lower environmental burden; (2 the Western side of the Galing River was subject to higher anthropogenic influence and indicated lower class levels of ammoniacal nitrogen, chemical oxygen demand, and dissolved oxygen, compared to the eastern side; (3 Class V or near class V pH values were obtained upstream at the western side of the Galing River in the industrial area; (4 Two types of environmental burden were identified in the western side of the Galing River, namely, inflow of industrial wastewater upstream on the western side and the effect of household wastewater or untreated raw sewage wastewater.

  16. Land use and water quality degradation in the Peixe-Boi River watershed

    Directory of Open Access Journals (Sweden)

    Bruno Wendell de Freitas Pereira

    2016-04-01

    Full Text Available This study mapped the land use and land cover of the catchment area of the Peixe-Boi River watershed, in northeast Pará, in order to identify conflicts of land use in the permanent preservation areas, and to relate them to water quality. We used LISS-3 sensor imagery from the Resourcesat satellite with a spatial resolution of 23.5 m for supervised classification of land use and land cover based on 22 training samples. Water quality was determined based on 28 sampling points in drainage network. The relationship between human disturbance and water quality was analyzed based on observations of land use changes using satellite imagery and in situ collection of water samples. The results show that 46% of the permanent preservation areas have conflicted uses, especially with respect to urban squatters, exposed soil and, most notably, pasture, with over 84 % of the area in conflict. Critical levels of dissolved oxygen reaching 2.14 mg L-1 and pH of 5.12 were observed in some sampling points. These values are below the fresh water standards set by Resolution 357/05 of CONAMA. The poorest water quality may be related to irregular use and occupation of areas within the permanent preservation areas. There is therefore an urgent need to develop a plan for the sustainable use and occupation of catchment area land in the Peixe-Boi River watershed in order to restore the environment and improve water quality.

  17. The image simulation arithmetic of the degradating process of porous biologic ceramic in life-form

    Institute of Scientific and Technical Information of China (English)

    CHEN Zuo-bing; HUANG Jian-zhong; YAN Yu-hua; LI Shi-pu

    2001-01-01

    @@ It is a complex and difficult task to simulate the degradating process of porous biologic ceramic in life-form by computer. Because the evolvement of crystal' s structure deals with not only the mechanism of many factors, such as crystallography tropism, the reciprocity of wafer, interfacial movement, but also topology geometry mechanism of dimensional padding.

  18. Physics of Limiting Phenomena in Superconducting Microwave Resonators: Vortex Dissipation, Ultimate Quench and Quality Factor Degradation Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Checchin, Mattia [IIT, Chicago

    2016-01-01

    Superconducting niobium accelerating cavities are devices operating in radio-frequency and able to accelerate charged particles up to energy of tera-electron-volts. Such accelerating structures are though limited in terms of quality factor and accelerating gradient, that translates--in some cases--in higher capital costs of construction and operation of superconducting rf accelerators. Looking forward for a new generation of more affordable accelerators, the physical description of limiting mechanisms in superconducting microwave resonators is discussed. In particular, the physics behind the dissipation introduced by vortices in the superconductor, the ultimate quench limitations and the quality factor degradation mechanism after a quench are described in detail. One of the limiting factor of the quality factor is the dissipation introduced by trapped magnetic flux vortices. The radio-frequency complex response of trapped vortices in superconductors is derived by solving the motion equation for a magnetic flux line, assuming a bi-dimensional and mean free path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the bell-shaped trend as a function of the mean free path, in agreement with the experimental data observed. Such bell-shaped trend of the surface resistance is described in terms of the interplay of the two limiting regimes identified as pinning and flux flow regimes, for low and large mean free path values respectively. The model predicts that the dissipation regime--pinning- or flux-flow-dominated--can be tuned either by acting on the frequency or on the electron mean free path value. The effect of different configurations of pinning sites and strength on the vortex surface resistance are also discussed. Accelerating cavities are also limited by the quench of the superconductive state, which limits the maximum accelerating gradient achievable. The accelerating field limiting factor is usually associate d to the

  19. Physics of Limiting Phenomena in Superconducting Microwave Resonators: Vortex Dissipation, Ultimate Quench and Quality Factor Degradation Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Checchin, Mattia [Illinois Inst. of Technology, Chicago, IL (United States)

    2016-12-01

    Superconducting niobium accelerating cavities are devices operating in radio-frequency and able to accelerate charged particles up to energy of tera-electron-volts. Such accelerating structures are though limited in terms of quality factor and accelerating gradient, that translates--in some cases--in higher capital costs of construction and operation of superconducting rf accelerators. Looking forward for a new generation of more affordable accelerators, the physical description of limiting mechanisms in superconducting microwave resonators is discussed. In particular, the physics behind the dissipation introduced by vortices in the superconductor, the ultimate quench limitations and the quality factor degradation mechanism after a quench are described in detail. One of the limiting factor of the quality factor is the dissipation introduced by trapped magnetic flux vortices. The radio-frequency complex response of trapped vortices in superconductors is derived by solving the motion equation for a magnetic flux line, assuming a bi-dimensional and mean free path-dependent Lorentzian-shaped pinning potential. The resulting surface resistance shows the bell-shaped trend as a function of the mean free path, in agreement with the experimental data observed. Such bell-shaped trend of the surface resistance is described in terms of the interplay of the two limiting regimes identified as pinning and flux flow regimes, for low and large mean free path values respectively. The model predicts that the dissipation regime--pinning- or flux-flow-dominated--can be tuned either by acting on the frequency or on the electron mean free path value. The effect of different configurations of pinning sites and strength on the vortex surface resistance are also discussed. Accelerating cavities are also limited by the quench of the superconductive state, which limits the maximum accelerating gradient achievable. The accelerating field limiting factor is usually associate d to the

  20. Investigation of the Degradation Mechanisms of a Variety of Organic Photovoltaic Devices by Combination of Imaging Techniques - The ISOS-3 Inter-Laboratory Collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Rosch, R.; Tanenbaum, D. M.; Jrgensen, M.; Seeland, M.; Barenklau, M.; Hermenau, M.; Voroshazi, E.; Lloyd, M. T.; Galagan, Y.; Zimmermann, B.; Wurfel, U.; Hosel, M.; Dam, H. F.; Gevorgyan, S. A.; Kudret, S.; Maes, W.; Lutsen, L.; Vanderzande, D.; Andriessen, R.; Teran-Escobar, G.

    2012-04-01

    The investigation of degradation of seven distinct sets (with a number of individual cells of n {>=} 12) of state of the art organic photovoltaic devices prepared by leading research laboratories with a combination of imaging methods is reported. All devices have been shipped to and degraded at Riso DTU up to 1830 hours in accordance with established ISOS-3 protocols under defined illumination conditions. Imaging of device function at different stages of degradation was performed by laser-beam induced current (LBIC) scanning; luminescence imaging, specifically photoluminescence (PLI) and electroluminescence (ELI); as well as by lock-in thermography (LIT). Each of the imaging techniques exhibits its specific advantages with respect to sensing certain degradation features, which will be compared and discussed here in detail. As a consequence, a combination of several imaging techniques yields very conclusive information about the degradation processes controlling device function. The large variety of device architectures in turn enables valuable progress in the proper interpretation of imaging results -- hence revealing the benefits of this large scale cooperation in making a step forward in the understanding of organic solar cell aging and its interpretation by state-of-the-art imaging methods.

  1. Investigation of the Degradation Mechanisms of a Variety of Organic Photovoltaic Devices by Combination of Imaging Techniques—the ISOS-3Inter-laboratory Collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Germack D.; Rosch, R.; Tanenbaum, D.M.; Jorgensen, M.; Seeland, M.; Barenklau, M.; Hermenau, M.; Voroshazi, E.; Lloyd, M.T.; Galagan, Y.; Zimmermann, B.; Wurfel, U.; Hosel, M.; Dam, H.F.; Gevorgyan, S.A.; Kudret, S.; Maes, W.; Lutsen, L.; Vanderzande, D.; Andriessen, R.; Teran-Escobar, G.; Lira-Cantu, M.; Rivaton, A.; Uzunoglu, G.Y.; Andreasen, B.; Madsen, M.V.; Norrman, K.; Hoppe, H.; Krebs, F.C.

    2012-04-01

    The investigation of degradation of seven distinct sets (with a number of individual cells of n {ge} 12) of state of the art organic photovoltaic devices prepared by leading research laboratories with a combination of imaging methods is reported. All devices have been shipped to and degraded at Risoe DTU up to 1830 hours in accordance with established ISOS-3 protocols under defined illumination conditions. Imaging of device function at different stages of degradation was performed by laser-beam induced current (LBIC) scanning; luminescence imaging, specifically photoluminescence (PLI) and electroluminescence (ELI); as well as by lock-in thermography (LIT). Each of the imaging techniques exhibits its specific advantages with respect to sensing certain degradation features, which will be compared and discussed here in detail. As a consequence, a combination of several imaging techniques yields very conclusive information about the degradation processes controlling device function. The large variety of device architectures in turn enables valuable progress in the proper interpretation of imaging results - hence revealing the benefits of this large scale cooperation in making a step forward in the understanding of organic solar cell aging and its interpretation by state-of-the-art imaging methods.

  2. Super-resolution convolutional neural network for the improvement of the image quality of magnified images in chest radiographs

    Science.gov (United States)

    Umehara, Kensuke; Ota, Junko; Ishimaru, Naoki; Ohno, Shunsuke; Okamoto, Kentaro; Suzuki, Takanori; Shirai, Naoki; Ishida, Takayuki

    2017-02-01

    Single image super-resolution (SR) method can generate a high-resolution (HR) image from a low-resolution (LR) image by enhancing image resolution. In medical imaging, HR images are expected to have a potential to provide a more accurate diagnosis with the practical application of HR displays. In recent years, the super-resolution convolutional neural network (SRCNN), which is one of the state-of-the-art deep learning based SR methods, has proposed in computer vision. In this study, we applied and evaluated the SRCNN scheme to improve the image quality of magnified images in chest radiographs. For evaluation, a total of 247 chest X-rays were sampled from the JSRT database. The 247 chest X-rays were divided into 93 training cases with non-nodules and 152 test cases with lung nodules. The SRCNN was trained using the training dataset. With the trained SRCNN, the HR image was reconstructed from the LR one. We compared the image quality of the SRCNN and conventional image interpolation methods, nearest neighbor, bilinear and bicubic interpolations. For quantitative evaluation, we measured two image quality metrics, peak signal-to-noise ratio (PSNR) and structural similarity (SSIM). In the SRCNN scheme, PSNR and SSIM were significantly higher than those of three interpolation methods (pmethods without any obvious artifacts. These preliminary results indicate that the SRCNN scheme significantly outperforms conventional interpolation algorithms for enhancing image resolution and that the use of the SRCNN can yield substantial improvement of the image quality of magnified images in chest radiographs.

  3. Interactions between mRNA export commitment, 3'-end quality control, and nuclear degradation

    DEFF Research Database (Denmark)

    Libri, Domenico; Dower, Ken; Boulay, Jocelyne;

    2002-01-01

    elongation. Indeed, we find that a pool of heat shock HSP104 transcripts are 3'-end truncated in THO complex mutant as well as sub2 mutant backgrounds. Surprisingly, however, this defect can be suppressed by deletion of the 3'-5' exonuclease Rrp6p. This indicates that incomplete RNAs result from nuclear...... that the failure to retain and/or degrade defective mRNAs is deleterious. mRNAs produced in the 3'-end processing mutants rna14-3 and rna15-2, as well as an RNA harboring a 3' end generated by a self-cleaving hammerhead ribozyme, are also retained in Rrp6p-dependent transcription site foci. Taken together, our...

  4. Digital breast tomosynthesis: Dose and image quality assessment.

    Science.gov (United States)

    Maldera, A; De Marco, P; Colombo, P E; Origgi, D; Torresin, A

    2017-01-01

    The aim of this work was to evaluate how different acquisition geometries and reconstruction parameters affect the performance of four digital breast tomosynthesis (DBT) systems (Senographe Essential - GE, Mammomat Inspiration - Siemens, Selenia Dimensions - Hologic and Amulet Innovality - Fujifilm) on the basis of a physical characterization. Average Glandular Dose (AGD) and image quality parameters such as in-plane/in-depth resolution, signal difference to noise ratio (SDNR) and artefact spread function (ASF) were examined. Measured AGD values resulted below EUREF limits for 2D imaging. A large variability was recorded among the investigated systems: the mean dose ratio DBT/2D ranged between 1.1 and 1.9. In-plane resolution was in the range: 2.2mm(-1)-3.8mm(-1) in chest wall-nipple direction. A worse resolution was found for all devices in tube travel direction. In-depth resolution improved with increasing scan angle but was also affected by the choice of reconstruction and post-processing algorithms. The highest z-resolution was provided by Siemens (50°, FWHM=2.3mm) followed by GE (25°, FWHM=2.8mm), while the Fujifilm HR showed the lowest one, despite its wide scan angle (40°, FWHM=4.1mm). The ASF was dependent on scan angle: smaller range systems showed wider ASF curves; however a clear relationship was not found between scan angle and ASF, due to the different post processing and reconstruction algorithms. SDNR analysis, performed on Fujifilm system, demonstrated that pixel binning improves detectability for a fixed dose/projection. In conclusion, we provide a performance comparison among four DBT systems under a clinical acquisition mode. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  5. High-quality image magnification applying Gerchberg-Papoulis iterative algorithm with discrete cosine transform

    Science.gov (United States)

    Shinbori, Eiji; Takagi, Mikio

    1992-11-01

    A new image magnification method, called 'IM-GPDCT' (image magnification applying the Gerchberg-Papoulis (GP) iterative algorithm with discrete cosine transform (DCT)), is described and its performance evaluated. This method markedly improves image quality of a magnified image using a concept which restores the spatial high frequencies which are conventionally lost due to use of a low pass filter. These frequencies are restored using two known constraints applied during iterative DCT: (1) correct information in a passband is known and (2) the spatial extent of an image is finite. Simulation results show that the IM- GPDCT outperforms three conventional interpolation methods from both a restoration error and image quality standpoint.

  6. 3D imaging with an isocentric mobile C-arm. Comparison of image quality with spiral CT

    Energy Technology Data Exchange (ETDEWEB)

    Kotsianos, Dorothea; Wirth, Stefan; Fischer, Tanja; Euler, Ekkehard; Rock, Clemens; Linsenmaier, Ulrich; Pfeifer, Klaus Juergen; Reiser, Maximilian [Departments of Radiology and Surgery, Klinikum der Universitaet Muenchen, Innenstadt, Nussbaumstrasse 20, 80336, Munchen (Germany)

    2004-09-01

    The purpose of this study was to evaluate the image quality of the new 3D imaging system (ISO-C-3D) for osteosyntheses of tibial condylar fractures in comparison with spiral CT (CT). Sixteen human cadaveric knees were examined with a C-arm 3D imaging system and spiral computed tomography. Various screws and plates of steel and titanium were used for osteosynthesis in these specimens. Image quality and clinical value of multiplanar (MP) reformatting of both methods were analyzed. In addition, five patients with tibial condylar fractures were examined for diagnosis and intra-operative control. The image quality of the C-arm 3D imaging system in the cadaveric study was rated as significantly worse than that of spiral CT with and without prostheses. After implantation of prostheses an increased incidence of artifacts was observed, but the diagnostic accuracy was not affected. Titanium implants caused the smallest number of artifacts. The image quality of ISO-C is inferior to CT, and metal artifacts were more prominent, but the clinical value was equal. ISO-C-3D can be useful in planning operative reconstructions and can verify the reconstruction of articular surfaces and the position of implants with diagnostic image quality. (orig.)

  7. 3D imaging with an isocentric mobile C-arm comparison of image quality with spiral CT.

    Science.gov (United States)

    Kotsianos, Dorothea; Wirth, Stefan; Fischer, Tanja; Euler, Ekkehard; Rock, Clemens; Linsenmaier, Ulrich; Pfeifer, Klaus Jürgen; Reiser, Maximilian

    2004-09-01

    The purpose of this study was to evaluate the image quality of the new 3D imaging system (ISO-C-3D) for osteosyntheses of tibial condylar fractures in comparison with spiral CT (CT). Sixteen human cadaveric knees were examined with a C-arm 3D imaging system and spiral computed tomography. Various screws and plates of steel and titanium were used for osteosynthesis in these specimens. Image quality and clinical value of multiplanar (MP) reformatting of both methods were analyzed. In addition, five patients with tibial condylar fractures were examined for diagnosis and intra-operative control. The image quality of the C-arm 3D imaging system in the cadaveric study was rated as significantly worse than that of spiral CT with and without prostheses. After implantation of prostheses an increased incidence of artifacts was observed, but the diagnostic accuracy was not affected. Titanium implants caused the smallest number of artifacts. The image quality of ISO-C is inferior to CT, and metal artifacts were more prominent, but the clinical value was equal. ISO-C-3D can be useful in planning operative reconstructions and can verify the reconstruction of articular surfaces and the position of implants with diagnostic image quality.

  8. Control of Perceptual Image Quality Based on PID for Streaming Video

    Institute of Scientific and Technical Information of China (English)

    SONG Jian-xin

    2003-01-01

    Constant levels of perceptual quality of streaming video is what ideall users expect. In most cases, however, they receive time-varying levels of quality of video. In this paper, the author proposes a new control method of perceptual quality in variable bit rate video encoding for streaming video. The image quality calculation based on the perception of human visual systems is presented. Quantization properties of DCT coefficients are analyzed to control effectively. Quantization scale factors are ascertained based on the visual mask effect. A Proportional Integral Difference ( PID ) controller is used to control the image quality. Experimental results show that this method improves the perceptual quality uniformity of encoded video.

  9. The effect of image quality, repeated study, and assessment method on anatomy learning.

    Science.gov (United States)

    Fenesi, Barbara; Mackinnon, Chelsea; Cheng, Lucia; Kim, Joseph A; Wainman, Bruce C

    2017-06-01

    The use of two-dimensional (2D) images is consistently used to prepare anatomy students for handling real specimen. This study examined whether the quality of 2D images is a critical component in anatomy learning. The visual clarity and consistency of 2D anatomical images was systematically manipulated to produce low-quality and high-quality images of the human hand and human eye. On day 0, participants learned about each anatomical specimen from paper booklets using either low-quality or high-quality images, and then completed a comprehension test using either 2D images or three-dimensional (3D) cadaveric specimens. On day 1, participants relearned each booklet, and on day 2 participants completed a final comprehension test using either 2D images or 3D cadaveric specimens. The effect of image quality on learning varied according to anatomical content, with high-quality images having a greater effect on improving learning of hand anatomy than eye anatomy (high-quality vs. low-quality for hand anatomy P = 0.018; high-quality vs. low-quality for eye anatomy P = 0.247). Also, the benefit of high-quality images on hand anatomy learning was restricted to performance on short-answer (SA) questions immediately after learning (high-quality vs. low-quality on SA questions P = 0.018), but did not apply to performance on multiple-choice (MC) questions (high-quality vs. low-quality on MC questions P = 0.109) or after participants had an additional learning opportunity (24 hours later) with anatomy content (high vs. low on SA questions P = 0.643). This study underscores the limited impact of image quality on anatomy learning, and questions whether investment in enhancing image quality of learning aids significantly promotes knowledge development. Anat Sci Educ 10: 249-261. © 2016 American Association of Anatomists. © 2016 American Association of Anatomists.

  10. Oxidative Degradation of High Quality CVD Diamond%高质量CVD金刚石膜的氧化损伤

    Institute of Scientific and Technical Information of China (English)

    刘敬明; 唐伟忠; 吕反修

    2001-01-01

    Studies of the oxidative degradation of high quality diamond have been conducted to better define the limits of application at high temperature.The infrared(IR)and visible optical performance of polished chemical vapor deposition (CVD) diamond films were degraded seriously after heating at 780℃ for 15min,while heating at 780℃ for 3 min produced a little change .Microscopic etched features were revealed by scanning electron microscopy(SEM),atomic force microscopy (AFM),and Talystep surface profiles.Many of the etched features are concentrated at a variety of defects including grain boundaries,surface porosity etc. The results of heating are increasing the surface roughness of CVD diamond films and degradation of the infrared transmittance.%高质量CVD金刚石膜的高温损伤的研究是其高温应用的基础。抛光的金刚石膜经780℃保温3min后,红外透过和可见光的透过率开始下降;780℃保温15min后,其红外透过和可见光的透过率严重受损。扫描电镜、原子力学显微镜及台阶仪的结果表明:CVD金刚石膜氧化的开始阶段主要集中在晶界、表面孔洞等缺陷处,随后导致金刚石膜的晶面也开始刻蚀,表面粗糙度增大,最终使得金刚石膜丧失红外和可见光的透过。

  11. Threats of habitat and water-quality degradation to mussel diversity in the Meramec River Basin, Missouri, USA

    Science.gov (United States)

    Hinck, Jo Ellen; Ingersoll, Christopher G.; Wang, Ning; Augspurger, Tom; Barnhart, M. Christopher; McMurray, Stephen E.; Roberts, Andrew D.; Schrader, Lynn

    2011-01-01

    The Meramec River Basin in east-central Missouri is an important stronghold for native freshwater mussels (Order: Unionoida) in the United States. Whereas the basin supports more than 40 mussel species, previous studies indicate that the abundance and distribution of most species are declining. Therefore, resource managers have identified the need to prioritize threats to native mussel populations in the basin and to design a mussel monitoring program. The objective of this study was to identify threats of habitat and water-quality degradation to mussel diversity in the basin. Affected habitat parameters considered as the main threats to mussel conservation included excess sedimentation, altered stream geomorphology and flow, effects on riparian vegetation and condition, impoundments, and invasive non-native species. Evaluating water-quality parameters for conserving mussels was a main focus of this study. Mussel toxicity data for chemical contaminants were compared to national water quality criteria (NWQC) and Missouri water quality standards (MWQS). However, NWQC and MWQS have not been developed for many chemical contaminants and some MWQS may not be protective of native mussel populations. Toxicity data indicated that mussels are sensitive to ammonia, copper, temperature, certain pesticides, pharmaceuticals, and personal care products; these compounds were identified as the priority water-quality parameters for mussel conservation in the basin. Measures to conserve mussel diversity in the basin include expanding the species and life stages of mussels and the list of chemical contaminants that have been assessed, establishing a long term mussel monitoring program that measures physical and chemical parameters of high priority, conducting landscape scale modeling to predict mussel distributions, determining sublethal effects of primary contaminants of concern, deriving risk-based guidance values for mussel conservation, and assessing the effects of wastewater

  12. IR image quality assessment and real-time optimum seeking method based on dynamic visual characteristics

    Science.gov (United States)

    Li, Bin; Liu, Gang; Gao, Yongmin; Lei, Hao; Wu, Haiying; Wang, Yu; Rong, Xiaolong

    2016-10-01

    Image quality is an important factor that influences the dynamic target information perception; it is the key factor of real-time target state analysis and judgment. In order to solve the multi-observation station comparison and video optimum seeking problem in the process of target information perception and recognition, an image quality assessment method based on visual characteristics is proposed for infrared target tracking. First, it analyses the basic infrared target image characteristics and application requirements, analyses the status and problems of the multi station optimum seeking technology. According to the expected research results, the processing flow of image processing is established. Then, the image quality objective assessment index is established, which reflects the basic characteristics of the target image, and the assessment index is integrated into the normalized assessment function. According to the quality assessment function, the infrared image quality assessment based on infrared target recognition and image analysis processing is realized, which is mainly characterized by the region of interest and dynamic visual characteristics. And on the basis of this technology, the real-time optimum seeking of multi station infrared target tracking image is completed. In order to verify the effectiveness of the method and the practical application effect, it designs the quality assessment and comparison of different station infrared images. Example shows that the method proposed in this paper can realize multi-observation station infrared image assessment comparison, image quality sorting, the optimum seeking of the infrared image based on the quality assessment. The results accord with the characteristics of infrared target image and dynamic visual characteristics.

  13. Effect of ruminal vs postruminal administration of degradable protein on utilization of low-quality forage by beef steers.

    Science.gov (United States)

    Bandyk, C A; Cochran, R C; Wickersham, T A; Titgemeyer, E C; Farmer, C G; Higgins, J J

    2001-01-01

    An experiment was designed to determine the effects of ruminal and postruminal infusions of ruminally degradable protein (casein) on intake and digestion of low-quality hay by beef steers. Twelve ruminally fistulated Angus x Hereford steers (initial BW = 563 kg) were blocked by weight and assigned to one of three treatments: control (C; hay only) or hay plus ruminal (R) or postruminal (P) infusion of 400 g/d of sodium caseinate. The trial consisted of five periods: 1) 10-d adaptation to the hay diet; 2) 7-d measurement of hay intake (without infusions); 3) 10-d adaptation to protein infusion treatments (intake measurements continued); 4) 7-d measurement of hay intake and digestibility (infusions continued); and 5) 3-d ruminal sampling period (infusions continued). Steers were given ad libitum access to tallgrass-prairie hay (3.4% CP, 76.6% NDF) throughout the study. Casein was administered once daily before feeding, either directly into the rumen or via anchored infusion lines into the abomasum. Hay intake was increased by supplementation (P infusion elicited a greater (P = 0.04) increase in hay intake than postruminal infusion. Intake tended (P = 0.11) to be lower in period 4 than in period 2 for control steers but was greater in period 4 than in period 2 (P infusion of a degradable protein source improved forage utilization, although the response in forage OM intake and total digestible OM intake was greater for ruminal infusion than for postruminal infusion.

  14. Proteasomal degradation of preemptive quality control (pQC) substrates is mediated by an AIRAPL–p97 complex

    Science.gov (United States)

    Braunstein, Ilana; Zach, Lolita; Allan, Susanne; Kalies, Kai-Uwe; Stanhill, Ariel

    2015-01-01

    The initial folding of secreted proteins occurs in the ER lumen, which contains specific chaperones and where posttranslational modifications may occur. Therefore lack of translocation, regardless of entry route or protein identity, is a highly toxic event, as the newly synthesized polypeptide is misfolded and can promiscuously interact with cytosolic factors. Mislocalized proteins bearing a signal sequence that did not successfully translocate through the translocon complex are subjected to a preemptive quality control (pQC) pathway and are degraded by the ubiquitin-proteasome system (UPS). In contrast to UPS-mediated, ER-associated degradation, few components involved in pQC have been identified. Here we demonstrate that on specific translocation inhibition, a p97–AIRAPL complex directly binds and regulates the efficient processing of polyubiquitinated pQC substrates by the UPS. We also demonstrate p97’s role in pQC processing of preproinsulin in cases of naturally occurring mutations within the signal sequence of insulin. PMID:26337389

  15. Microbiological indicators for assessing ecosystem soil quality and changes in it at degraded sites treated with compost

    Science.gov (United States)

    Ancona, Valeria; Barra Caracciolo, Anna; Grenni, Paola; Di Lenola, Martina; Calabrese, Angelantonio; Campanale, Claudia; Felice Uricchio, Vito

    2014-05-01

    Soil quality is defined as the capacity of a soil to function as a vital system, within natural or managed ecosystem boundaries, sustain plant and animal health and productivity, maintain or enhance air and water environment quality and support human health and habitation. Soil organisms are extremely diverse and contribute to a wide range of ecosystem services that are essential to the sustainable functioning of natural and managed ecosystems. In particular, microbial communities provide several ecosystem services, which ensure soil quality and fertility. In fact, they adapt promptly to environmental changes by varying their activity and by increasing the reproduction of populations that have favourable skills. The structure (e.g. cell abundance) and functioning (e.g. viability and activity) of natural microbial communities and changes in them under different environmental conditions can be considered useful indicators of soil quality state. In this work we studied the quality state of three different soils, located in Taranto Province (Southern Italy), affected by land degradation processes, such as organic matter depletion, desertification and contamination (PCB and metals). Moreover, compost, produced from selected organic waste, was added to the soils studied in order to improve their quality state. Soil samples were collected before and after compost addition and both microbial and chemical analyses were performed in order to evaluate the soil quality state at each site at different times. For this purpose, the microbiological indicators evaluated were bacterial abundance (DAPI counts), cell viability (Live/Dead method), dehydrogenase activity (DHA) and soil respiration. At the same time, the main physico-chemical soil characteristics (organic carbon, available phosphorous, total nitrogen, carbonate and water content, texture and pH) were also measured. Moreover, in the contaminated soil samples PCB and inorganic (e.g. Pb, Se, Sn, Zn) contaminants were

  16. Near-Infrared Fluorescence Imaging for Noninvasive Trafficking of Scaffold Degradation

    OpenAIRE

    Soon Hee Kim; Jeong Heon Lee; Hoon Hyun; Yoshitomo Ashitate; GwangLi Park; Kyle Robichaud; Elaine Lunsford; Sang Jin Lee; Gilson Khang; Hak Soo Choi

    2013-01-01

    Biodegradable scaffolds could revolutionize tissue engineering and regenerative medicine; however, in vivo matrix degradation and tissue ingrowth processes are not fully understood. Currently a large number of samples and animals are required to track biodegradation of implanted scaffolds, and such nonconsecutive single-time-point information from various batches result in inaccurate conclusions. To overcome this limitation, we developed functional biodegradable scaffolds by employing invisib...

  17. Dynamic CT perfusion imaging of the myocardium: a technical note on improvement of image quality.

    Directory of Open Access Journals (Sweden)

    Daniela Muenzel

    Full Text Available OBJECTIVE: To improve image and diagnostic quality in dynamic CT myocardial perfusion imaging (MPI by using motion compensation and a spatio-temporal filter. METHODS: Dynamic CT MPI was performed using a 256-slice multidetector computed tomography scanner (MDCT. Data from two different patients-with and without myocardial perfusion defects-were evaluated to illustrate potential improvements for MPI (institutional review board approved. Three datasets for each patient were generated: (i original data (ii motion compensated data and (iii motion compensated data with spatio-temporal filtering performed. In addition to the visual assessment of the tomographic slices, noise and contrast-to-noise-ratio (CNR were measured for all data. Perfusion analysis was performed using time-density curves with regions-of-interest (ROI placed in normal and hypoperfused myocardium. Precision in definition of normal and hypoperfused areas was determined in corresponding coloured perfusion maps. RESULTS: The use of motion compensation followed by spatio-temporal filtering resulted in better alignment of the cardiac volumes over time leading to a more consistent perfusion quantification and improved detection of the extend of perfusion defects. Additionally image noise was reduced by 78.5%, with CNR improvements by a factor of 4.7. The average effective radiation dose estimate was 7.1±1.1 mSv. CONCLUSION: The use of motion compensation and spatio-temporal smoothing will result in improved quantification of dynamic CT MPI using a latest generation CT scanner.

  18. Investigation of the degradation mechanisms of a variety of organic photovoltaic devices by combination of imaging techniques—the ISOS-3 inter-laboratory collaboration

    DEFF Research Database (Denmark)

    Rösch, Roland; Tanenbaum, David; Jørgensen, Mikkel

    2012-01-01

    ) and electroluminescence (ELI); as well as by lock-in thermography (LIT). Each of the imaging techniques exhibits its specific advantages with respect to sensing certain degradation features, which will be compared and discussed here in detail. As a consequence, a combination of several imaging techniques yields very...

  19. Site quality assessment of degraded Quercus frainetto stands in central Greece

    Directory of Open Access Journals (Sweden)

    Kitikidou K

    2015-02-01

    Full Text Available The potential yield of a site is measured by site index, which is defined as the dominant height of a stand at a base age. A site index model for site quality assessment of Quercus frainetto (Hungarian oak stands in central Greece was developed using a base age of 50 years. Data were collected from 39 temporary sample plots of 10 x 10 m. Linear regression models widely used in site index studies were fitted to height-age data. The adjusted coefficient of determination (R2adj, root mean square error (RMSE, bias, coefficient of determination for the prediction (R2pr and residual plots were used for the choice of the best-fitting model. The best model was H = -0.231+0.251A-0.001A2, where H is the predicted height at age A. The guide curve method was adopted in constructing the sites curves, with the chosen model as the guide curve. Based on this curve, the study area was divided into three site quality classes (I to III, with class I representing the best and class III the poorest. Also, the presence of a Simpson’s paradox in these analyses is discussed. The results showed that a 50-year-old stand in the study area attained an average dominant height of about 11, 8 and 6 m on site quality classes I, II and III, respectively. The Hungarian oak stands of the present study can be considered very low productivity stands.

  20. IR-images of PV-modules with potential induced degradation (PID) correlated to monitored string power output

    Science.gov (United States)

    Buerhop, Claudia; Pickel, Tobias; Blumberg, Tiberius; Adams, Jens; Wrana, Simon; Dalsass, Manuel; Zetzmann, Cornelia; Camus, Christian; Hauch, Jens; Brabec, Christoph J.

    2016-09-01

    Many PV-plants suffer from potential induced degradation (PID) which causes severe power reduction of installed PVmodules. Fast and reliable methods to detect PID and evaluate the impact on the module performance are gaining importance. Drone-assisted IR-inspection is a suitable method. PID affected modules are detected by their characteristic IR-fingerprint, modules with differing number of slightly heated cells occur more frequently at the negative string end. These modules show a degraded IV-curve, lowered Voc and Isc, and electroluminescence (EL)-images with suspicious, dark cells. Also, the measured string power is reduced. For a first quantitative data evaluation the suspicious cell are counted in the IR-images and correlated with the module power. A linear decrease of the module power with increasing number of suspicious cells results. A correlation function for estimating the module power was deduced, which has a mean deviation of less than 7%. This correlation function allows an acceptable approximation of the string power.

  1. Statistical Quality Assessment of Pre-fried Carrots Using Multispectral Imaging

    DEFF Research Database (Denmark)

    Sharifzadeh, Sara; Clemmensen, Line Katrine Harder; Løje, Hanne

    2013-01-01

    Multispectral imaging is increasingly being used for quality assessment of food items due to its non-invasive benefits. In this paper, we investigate the use of multispectral images of pre-fried carrots, to detect changes over a period of 14 days. The idea is to distinguish changes in quality from...

  2. The impact of image quality on the performance of face recognition

    NARCIS (Netherlands)

    Dutta, Abhishek; Veldhuis, Raymond; Spreeuwers, Luuk

    2012-01-01

    The performance of a face recognition system depends on the quality of both test and reference images participating in the face comparison process. In a forensic evaluation case involving face recognition, we do not have any control over the quality of the trace (image captured by a CCTV at a crime

  3. A historical review of the methods of determination of soil properties for soil quality and land degradation assessment

    Science.gov (United States)

    Pulido, Manuel; Schnabel, Susanne; Francisco Lavado Contador, Joaquín; Gómez-Gutiérrez, Álvaro; Miralles, Isabel; Lozano-Parra, Javier; Antoneli, Valdemir; Brevik, Eric C.; Cerdà, Artemi

    2017-04-01

    Properly assessing soil quality and land degradation is one of the main concerns of soil scientists in recent decades. Nowadays there are several available assessment systems based mainly on indicators, i.e. on soil-related parameters, that allow one to determine the current state of natural soils at different scales. These systems vary depending on ecosystem type and soil function studied as well as the accuracy of the methods (techniques and tools) historically used in the determination of several soil parameters. In this study, we show a historical review of many methods of determining soil properties used regularly as soil quality and land degradation indicators. We have considered 5 worldwide historical periods: [1] The pioneers: before 1889, [2] USDA impulse: 1889 - 1945, [3] Productivity paradigm: 1946 - 1972, [4] Conservationist paradigm: 1973 - 2001, and [5] Current methodologies: 2002 - present. The limits of each period have been determined according to some key milestones, for humanity in general and soil science in particular, such as the creation of the United States Department of Agriculture (USDA) in 1889, the end of World War II in 1945 or the publication of relevant works such as The limits to growth in 1972. The development of the Soil Management Assessment Framework (SMAF) indexing tool by American soil scientists in 2001 marks a turning point from which new methodologies and paradigms began to be dominant among methods of determination. Finally, the methods historically used to determine more than 100 soil properties have been reviewed by consulting around 1,500 references published between 1305 and 2017. Approximately 10% of the references were key works to contextualize the first two historical periods, i.e. before 1945, and almost half of all references were published in the second half of the twentieth century (1946 - 2001). A logical tendency in gaining progressively accuracy in methods has been observed as well as a major boom in the

  4. Real-time imaging of HIF-1alpha stabilization and degradation.

    Directory of Open Access Journals (Sweden)

    Ekaterina Moroz

    Full Text Available HIF-1alpha is overexpressed in many human cancers compared to normal tissues due to the interaction of a multiplicity of factors and pathways that reflect specific genetic alterations and extracellular stimuli. We developed two HIF-1alpha chimeric reporter systems, HIF-1alpha/FLuc and HIF-1alpha(DeltaODDD/FLuc, to investigate the tightly controlled level of HIF-1alpha protein in normal (NIH3T3 and HEK293 and glioma (U87 cells. These reporter systems provided an opportunity to investigate the degradation of HIF-1alpha in different cell lines, both in culture and in xenografts. Using immunofluorescence microscopy, we observed different patterns of subcellular localization of HIF-1alpha/FLuc fusion protein between normal cells and cancer cells; similar differences were observed for HIF-1alpha in non-transduced, wild-type cells. A dynamic cytoplasmic-nuclear exchange of the fusion protein and HIF-1alpha was observed in NIH3T3 and HEK293 cells under different conditions (normoxia, CoCl2 treatment and hypoxia. In contrast, U87 cells showed a more persistent nuclear localization pattern that was less affected by different growing conditions. Employing a kinetic model for protein degradation, we were able to distinguish two components of HIF-1alpha/FLuc protein degradation and quantify the half-life of HIF-1alpha fusion proteins. The rapid clearance component (t(1/2 approximately 4-6 min was abolished by the hypoxia-mimetic CoCl2 MG132 treatment and deletion of ODD domain, and reflects the oxygen/VHL-dependent degradation pathway. The slow clearance component (t(1/2 approximately 200 min is consistent with other unidentified non-oxygen/VHL-dependent degradation pathways. Overall, the continuous bioluminescence readout of HIF-1alpha/FLuc stabilization in vitro and in vivo will facilitate the development and validation of therapeutics that affect the stability and accumulation of HIF-1alpha.

  5. Study of quality perception in medical images based on comparison of contrast enhancement techniques in mammographic images

    Science.gov (United States)

    Matheus, B.; Verçosa, L. B.; Barufaldi, B.; Schiabel, H.

    2014-03-01

    With the absolute prevalence of digital images in mammography several new tools became available for radiologist; such as CAD schemes, digital zoom and contrast alteration. This work focuses in contrast variation and how the radiologist reacts to these changes when asked to evaluated image quality. Three contrast enhancing techniques were used in this study: conventional equalization, CCB Correction [1] - a digitization correction - and value subtraction. A set of 100 images was used in tests from some available online mammographic databases. The tests consisted of the presentation of all four versions of an image (original plus the three contrast enhanced images) to the specialist, requested to rank each one from the best up to worst quality for diagnosis. Analysis of results has demonstrated that CCB Correction [1] produced better images in almost all cases. Equalization, which mathematically produces a better contrast, was considered the worst for mammography image quality enhancement in the majority of cases (69.7%). The value subtraction procedure produced images considered better than the original in 84% of cases. Tests indicate that, for the radiologist's perception, it seems more important to guaranty full visualization of nuances than a high contrast image. Another result observed is that the "ideal" scanner curve does not yield the best result for a mammographic image. The important contrast range is the middle of the histogram, where nodules and masses need to be seen and clearly distinguished.

  6. Cardiovascular CT angiography in neonates and children : Image quality and potential for radiation dose reduction with iterative image reconstruction techniques

    NARCIS (Netherlands)

    Tricarico, Francesco; Hlavacek, Anthony M.; Schoepf, U. Joseph; Ebersberger, Ullrich; Nance, John W.; Vliegenthart, Rozemarijn; Cho, Young Jun; Spears, J. Reid; Secchi, Francesco; Savino, Giancarlo; Marano, Riccardo; Schoenberg, Stefan O.; Bonomo, Lorenzo; Apfaltrer, Paul

    To evaluate image quality (IQ) of low-radiation-dose paediatric cardiovascular CT angiography (CTA), comparing iterative reconstruction in image space (IRIS) and sinogram-affirmed iterative reconstruction (SAFIRE) with filtered back-projection (FBP) and estimate the potential for further dose

  7. Cardiovascular CT angiography in neonates and children : Image quality and potential for radiation dose reduction with iterative image reconstruction techniques

    NARCIS (Netherlands)

    Tricarico, Francesco; Hlavacek, Anthony M.; Schoepf, U. Joseph; Ebersberger, Ullrich; Nance, John W.; Vliegenthart, Rozemarijn; Cho, Young Jun; Spears, J. Reid; Secchi, Francesco; Savino, Giancarlo; Marano, Riccardo; Schoenberg, Stefan O.; Bonomo, Lorenzo; Apfaltrer, Paul

    2013-01-01

    To evaluate image quality (IQ) of low-radiation-dose paediatric cardiovascular CT angiography (CTA), comparing iterative reconstruction in image space (IRIS) and sinogram-affirmed iterative reconstruction (SAFIRE) with filtered back-projection (FBP) and estimate the potential for further dose reduct

  8. Digital mammography--DQE versus optimized image quality in clinical environment: an on site study

    Science.gov (United States)

    Oberhofer, Nadia; Fracchetti, Alessandro; Springeth, Margareth; Moroder, Ehrenfried

    2010-04-01

    The intrinsic quality of the detection system of 7 different digital mammography units (5 direct radiography DR; 2 computed radiography CR), expressed by DQE, has been compared with their image quality/dose performances in clinical use. DQE measurements followed IEC 62220-1-2 using a tungsten test object for MTF determination. For image quality assessment two different methods have been applied: 1) measurement of contrast to noise ratio (CNR) according to the European guidelines and 2) contrast-detail (CD) evaluation. The latter was carried out with the phantom CDMAM ver. 3.4 and the commercial software CDMAM Analyser ver. 1.1 (both Artinis) for automated image analysis. The overall image quality index IQFinv proposed by the software has been validated. Correspondence between the two methods has been shown figuring out a linear correlation between CNR and IQFinv. All systems were optimized with respect to image quality and average glandular dose (AGD) within the constraints of automatic exposure control (AEC). For each equipment, a good image quality level was defined by means of CD analysis, and the corresponding CNR value considered as target value. The goal was to achieve for different PMMA-phantom thicknesses constant image quality, that means the CNR target value, at minimum dose. All DR systems exhibited higher DQE and significantly better image quality compared to CR systems. Generally switching, where available, to a target/filter combination with an x-ray spectrum of higher mean energy permitted dose savings at equal image quality. However, several systems did not allow to modify the AEC in order to apply optimal radiographic technique in clinical use. The best ratio image quality/dose was achieved by a unit with a-Se detector and W anode only recently available on the market.

  9. Enhancement of low quality reconstructed digital hologram images based on frequency extrapolation of large objects under the diffraction limit

    Science.gov (United States)

    Liu, Ning; Chen, Xiaohong; Yang, Chao

    2016-11-01

    During the reconstruction of a digital hologram, the reconstructed image is usually degraded by speckle noise, which makes it hard to observe the original object pattern. In this paper, a new reconstructed image enhancement method is proposed, which first reduces the speckle noise using an adaptive Gaussian filter, then calculates the high frequencies that belong to the object pattern based on a frequency extrapolation strategy. The proposed frequency extrapolation first calculates the frequency spectrum of the Fourier-filtered image, which is originally reconstructed from the +1 order of the hologram, and then gives the initial parameters for an iterative solution. The analytic iteration is implemented by continuous gradient threshold convergence to estimate the image level and vertical gradient information. The predicted spectrum is acquired through the analytical iteration of the original spectrum and gradient spectrum analysis. Finally, the reconstructed spectrum of the restoration image is acquired from the synthetic correction of the original spectrum using the predicted gradient spectrum. We conducted our experiment very close to the diffraction limit and used low quality equipment to prove the feasibility of our method. Detailed analysis and figure demonstrations are presented in the paper.

  10. Enhancement of low-quality reconstructed digital hologram images based on frequency extrapolation of large objects under the diffraction limit

    Science.gov (United States)

    Liu, Ning; Li, Weiliang; Zhao, Dongxue

    2016-06-01

    During the reconstruction of a digital hologram, the reconstructed image is usually degraded by speckle noise, which makes it hard to observe the original object pattern. In this paper, a new reconstructed image enhancement method is proposed, which first reduces the speckle noise using an adaptive Gaussian filter, then calculates the high frequencies that belong to the object pattern based on a frequency extrapolation strategy. The proposed frequency extrapolation first calculates the frequency spectrum of the Fourier-filtered image, which is originally reconstructed from the +1 order of the hologram, and then gives the initial parameters for an iterative solution. The analytic iteration is implemented by continuous gradient threshold convergence to estimate the image level and vertical gradient information. The predicted spectrum is acquired through the analytical iteration of the original spectrum and gradient spectrum analysis. Finally, the reconstructed spectrum of the restoration image is acquired from the synthetic correction of the original spectrum using the predicted gradient spectrum. We conducted our experiment very close to the diffraction limit and used low-quality equipment to prove the feasibility of our method. Detailed analysis and figure demonstrations are presented in the paper.

  11. Hierarchical Segmentation of Falsely Touching Characters from Camera Captured Degraded Document Images

    Directory of Open Access Journals (Sweden)

    Satadal Saha

    2011-07-01

    Full Text Available An innovative hierarchical image segmentation scheme is reported in this research communication. Unlike static/ spatially divided sub-images, the current innovation concentrates on object level hierarchy for segmentation of gray scale or color images into constituent component/ sub-parts. As for example, a gray scale document image may be segmented (binarized in case of two-level segmentation into connected foreground components (text/ graphics and background component by hierarchically applying a gray level threshold selection algorithm in the object-space. In any hierarchy, constituent objects are identified as connected foreground pixels, as classified by the gray scale threshold selection algorithm. To preserve the global information, thresholds for each object in any hierarchy are estimated as a weighted aggregate of the current and previous thresholds relevant to the object. The developed technique may be customized as a general purpose hierarchical information clustering algorithm in the domain of pattern analysis, data mining, bioinformatics etc.

  12. Towards Improving the NIST Fingerprint Image Quality (NFIQ) Algorithm (Extended Version)

    CERN Document Server

    Merkle, Johannes; Bausinger, Oliver; Breitenstein, Marco; Elwart, Kristina; Nuppeney, Markus

    2010-01-01

    The NIST Fingerprint Image Quality (NFIQ) algorithm has become a standard method to assess fingerprint image quality. However, in many applications a more accurate and reliable assessment is desirable. In this publication, we report on our efforts to optimize the NFIQ algorithm by a re-training of the underlying neural network based on a large fingerprint image database. Although we only achieved a marginal improvement, our work has revealed several areas for potential optimization.

  13. Comparison of radiographic image quality from four digitization devices as viewed on computer monitors

    OpenAIRE

    Davidson, HC; Johnston, DJ; Christian, ME; Harnsberger, HR

    2001-01-01

    The objective of this study was to compare the quality of radiographic images digitized from commercial-grade and consumer-grade digital cameras and scanners as viewed on computer monitor. Radiographic images were digitized from hardcopy film using a commercial-grade laser scanner, a consumer-grade desktop flatbed scanner, a commercial-grade digital camera, and a consumer-grade digital camera. The quality of images without and with grayscale histogram adjustment was evaluated subjectively by ...

  14. Improved quality of optical coherence tomography imaging of basal cell carcinomas using speckle reduction

    DEFF Research Database (Denmark)

    Mogensen, Mette; Jørgensen, Thomas Martini; Thrane, Lars

    2010-01-01

    BACKGROUND: Optical coherence tomography (OCT) is a possible imaging method for delineation of non-melanoma skin cancer. Speckle noise is the dominant noise contribution in OCT images; it limits the ability to identify cellular structures especially skin cancer. QUESTIONS ADDRESSED: This report...... suggests a method for improving OCT image quality for skin cancer imaging. EXPERIMENTAL DESIGN: OCT is an optical imaging method analogous to ultrasound. Two basal cell carcinomas (BCC) were imaged using an OCT speckle reduction technique (SR-OCT) based on repeated scanning by altering the distance between...... to a clinically relevant level when imaging BCC lesions....

  15. Quantitative measurement of holographic image quality using Adobe Photoshop

    Science.gov (United States)

    Wesly, E.

    2013-02-01

    Measurement of the characteristics of image holograms in regards to diffraction efficiency and signal to noise ratio are demonstrated, using readily available digital cameras and image editing software. Illustrations and case studies, using currently available holographic recording materials, are presented.

  16. How histological features of basal cell carcinomas influence image quality in optical coherence tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Nürnberg, Birgit M.; Thrane, Lars

    2011-01-01

    Optical coherence tomography (OCT) has the potential to diagnose and measure the depth of nonmelanoma skin cancer (NMSC) in skin, but some lesions appear blurred in OCT images. The aim of this study is to identify histological characteristics of basal cell carcinomas (BCC) that correlate with good...... quality OCT images of the same lesions. A total of 34 patients with BCC were OCT scanned. The influence of histology parameters (e.g. inflammation, sun damage of skin, carcinoma cell size) on OCT image quality was studied by comparing 15 BCC lesions easily identified compared to 19 BCC lesions...... that produced only blurred in OCT images. Inflammation was more pronounced in blurred OCT images, whereas solar elastosis dominated in easily identified lesions. Hyperkeratosis did not impair imaging significantly. OCT image quality of BCC may depend on specific histology parameters....

  17. Which histological characteristics of basal cell carcinomas influence the quality of optical coherence tomography imaging?

    DEFF Research Database (Denmark)

    Mogensen, M.; Thrane, Lars; Jørgensen, Thomas Martini;

    2009-01-01

    We explore how histopathology parameters influence OCT imaging of basal cell carcinomas (BCC) and address whether such parameters correlate with the quality of the recorded OCT images. Our results indicate that inflammation impairs OCT imaging and that sun-damaged skin can sometimes provide more...

  18. Quality assessment of stereoscopic 3D image compression by binocular integration behaviors.

    Science.gov (United States)

    Lin, Yu-Hsun; Wu, Ja-Ling

    2014-04-01

    The objective approaches of 3D image quality assessment play a key role for the development of compression standards and various 3D multimedia applications. The quality assessment of 3D images faces more new challenges, such as asymmetric stereo compression, depth perception, and virtual view synthesis, than its 2D counterparts. In addition, the widely used 2D image quality metrics (e.g., PSNR and SSIM) cannot be directly applied to deal with these newly introduced challenges. This statement can be verified by the low correlation between the computed objective measures and the subjectively measured mean opinion scores (MOSs), when 3D images are the tested targets. In order to meet these newly introduced challenges, in this paper, besides traditional 2D image metrics, the binocular integration behaviors-the binocular combination and the binocular frequency integration, are utilized as the bases for measuring the quality of stereoscopic 3D images. The effectiveness of the proposed metrics is verified by conducting subjective evaluations on publicly available stereoscopic image databases. Experimental results show that significant consistency could be reached between the measured MOS and the proposed metrics, in which the correlation coefficient between them can go up to 0.88. Furthermore, we found that the proposed metrics can also address the quality assessment of the synthesized color-plus-depth 3D images well. Therefore, it is our belief that the binocular integration behaviors are important factors in the development of objective quality assessment for 3D images.

  19. A fourier transform quality measure for iris images

    CSIR Research Space (South Africa)

    Makinana, S

    2014-08-01

    Full Text Available Iris recognition systems have attracted much attention for their uniqueness, stability and reliability. However, performance of this system depends on quality of acquired iris sample. This is because in order to obtain reliable features good quality...

  20. IMAGE COMPRESSION APPROACH FOR MEDICAL PROCESSING USING MODIFIED NEURO MODELING

    OpenAIRE

    S. ABDUL KHADER JILANI; Dr. S. ABDUL SATTAR

    2010-01-01

    Image compression is applied to many fields such as television broadcasting, remote sensing, image storage etc. Digitized images are compressed by a technique which exploits the redundancy of the images so that the number of bits required to represent the image can be reduced with acceptable degradation of the decoded image. The degradation of the image quality is limited wrt. the application used. There are various application where accuracy is of major concern. To achieve the objective of p...

  1. Atmospheric pollution: a case study of degrading urban air quality over Punjab, India.

    Science.gov (United States)

    Sehra, Parmjit Singh

    2007-01-01

    This paper presents the results of a case study of urban air quality over a densely populated city Ludhiana situated in Punjab, India, in the form of monthly and annual average concentrations of Suspended Particulate Matter (SPM), NO2 and SO2 for the periods 1988-1989, 1994-1999 and 2001-2005 which is generally found to be increasing with time and thus requires immediate corrective measures lest the situation becomes totally uncontrollable. The present situation is as bad as in other metropolitan Indian cities, although it seems to have somewhat improved as indicated by the latest 2001-2005 data in comparison with the past 1988-1989 and 1994-1999 data, but much more still needs to be done. In addition to the industrial and vehicular pollution, the agricultural pollution due to the burning of wheat and rice straws by the farmers should also be checked because it also creates tremendous pollution in the atmosphere.

  2. State of the art in quality assurance issues of structures with particular emphasis on strength degradation

    Directory of Open Access Journals (Sweden)

    Suchart Limkatanyu

    2006-11-01

    Full Text Available With the increase of the economic competition in the industrial world, much attention is being paid to the deterioration of the design structures before and after their first use. Even with the highest quality of materials and workmanship, the occurrence of some form of imperfections during manufacture is inevitable and there will be a typical distribution of imperfection sizes associated with a particular manufacturing process and quality. The origin of defects in a material can take place during manufacturing stage, or during assembly, installation, commissioning or during in service. The defects will be generated due to deterioration of the component/structure which, in turn, results in deterioration of mechanical properties, crack initiation and propagation, leaks in pressurized components and catastrophic failures. Hence, Non Destructive Inspection (NDI is required at regular intervals and the results can be used for maintenance to mitigate fatigue risk. However, no in-service inspection is perfect. NDI outputs normally depend on many uncertain factors such as the condition of the inspected structure and its service environment etc. In order to take into account those uncertainties, the probabilistic approach is capable of identifying variables affecting the design life of the components. It has also been proved that the probabilistic method can be extended to provide very useful information to help managers in making decisions regarding the operation and inspection time of the structures in order to maintain their reliability. In the present paper, a literature review of the current approaches and methodologies that has been utilized in the area of structural risk and reliability analysis for structures is presented. The parameters used to quantify the uncertainty and reliability of NDI technique is explored. Several probabilistic models regarding the updating flaw information and inspection schedule using different approaches are

  3. Spatial heterogeneity of water quality in a highly degraded tropical freshwater ecosystem.

    Science.gov (United States)

    Zambrano, Luis; Contreras, Victoria; Mazari-Hiriart, Marisa; Zarco-Arista, Alba E

    2009-02-01

    Awareness of environmental heterogeneity in ecosystems is critical for management and conservation. We used the Xochimilco freshwater system to describe the relationship between heterogeneity and human activities. This tropical aquatic ecosystem south of Mexico City is comprised of a network of interconnected canals and lakes that are influenced by agricultural and urban activities. Environmental heterogeneity was characterized by spatially extensive surveys within four regions of Xochimilco during rainy and dry seasons over 2 years. These surveys revealed a heterogeneous system that was shallow (1.1 m, SD=0.4 ), warm (17 degrees C, SD=2.9), well oxygenated (5.0 mg l(-1), SD=3), turbid (45.7 NTU SD = 26.96), and extremely nutrient-rich (NO(3)-N=15.9 mg l(-1), SD=13.7; NH(4)-N=2.88 mg l(-1), SD=4.24; and PO(4)-P=8.3 mg l(-1), SD=2.4). Most of the variables were not significantly different between years, but did differ between seasons, suggesting a dynamic system within a span of a year but with a high resilience over longer periods of time. Maps were produced using interpolations to describe distributions of all variables. There was no correlation between individual variables and land use. Consequently, we searched for relationships using all variables together by generating a combined water quality index. Significant differences in the index were apparent among the four regions. Index values also differed within individual region and individual water bodies (e.g., within canals), indicating that Xochimilco has high local heterogeneity. Using this index on a map helped to relate water quality to human activities and provides a simple and clear tool for managers and policymakers.

  4. Flood frequency matters: Why climate change degrades deep-water quality of peri-alpine lakes

    Science.gov (United States)

    Fink, Gabriel; Wessels, Martin; Wüest, Alfred

    2016-09-01

    Sediment-laden riverine floods transport large quantities of dissolved oxygen into the receiving deep layers of lakes. Hence, the water quality of deep lakes is strongly influenced by the frequency of riverine floods. Although flood frequency reflects climate conditions, the effects of climate variability on the water quality of deep lakes is largely unknown. We quantified the effects of climate variability on the potential shifts in the flood regime of the Alpine Rhine, the main catchment of Lake Constance, and determined the intrusion depths of riverine density-driven underflows and the subsequent effects on water exchange rates in the lake. A simplified hydrodynamic underflow model was developed and validated with observed river inflow and underflow events. The model was implemented to estimate underflow statistics for different river inflow scenarios. Using this approach, we integrated present and possible future flood frequencies to underflow occurrences and intrusion depths in Lake Constance. The results indicate that more floods will increase the number of underflows and the intensity of deep-water renewal - and consequently will cause higher deep-water dissolved oxygen concentrations. Vice versa, fewer floods weaken deep-water renewal and lead to lower deep-water dissolved oxygen concentrations. Meanwhile, a change from glacial nival regime (present) to a nival pluvial regime (future) is expected to decrease deep-water renewal. While flood frequencies are not expected to change noticeably for the next decades, it is most likely that increased winter discharge and decreased summer discharge will reduce the number of deep density-driven underflows by 10% and favour shallower riverine interflows in the upper hypolimnion. The renewal in the deepest layers is expected to be reduced by nearly 27%. This study underlines potential consequences of climate change on the occurrence of deep river underflows and water residence times in deep lakes.

  5. Application of Analytical Quality by Design concept for bilastine and its degradation impurities determination by hydrophilic interaction liquid chromatographic method.

    Science.gov (United States)

    Terzić, Jelena; Popović, Igor; Stajić, Ana; Tumpa, Anja; Jančić-Stojanović, Biljana

    2016-06-05

    This paper deals with the development of hydrophilic interaction liquid chromatographic (HILIC) method for the analysis of bilastine and its degradation impurities following Analytical Quality by Design approach. It is the first time that the method for bilastine and its impurities is proposed. The main objective was to identify the conditions where an adequate separation in minimal analysis duration could be achieved within a robust region. Critical process parameters which have the most influence on method performance were defined as acetonitrile content in the mobile phase, pH of the aqueous phase and ammonium acetate concentration in the aqueous phase. Box-Behnken design was applied for establishing a relationship between critical process parameters and critical quality attributes. The defined mathematical models and Monte Carlo simulations were used to identify the design space. Fractional factorial design was applied for experimental robustness testing and the method is validated to verify the adequacy of selected optimal conditions: the analytical column Luna(®) HILIC (100mm×4.6mm, 5μm particle size); mobile phase consisted of acetonitrile-aqueous phase (50mM ammonium acetate, pH adjusted to 5.3 with glacial acetic acid) (90.5:9.5, v/v); column temperature 30°C, mobile phase flow rate 1mLmin(-1), wavelength of detection 275nm.

  6. Quality evaluation of adaptive optical image based on DCT and Rényi entropy

    Science.gov (United States)

    Xu, Yuannan; Li, Junwei; Wang, Jing; Deng, Rong; Dong, Yanbing

    2015-04-01

    The adaptive optical telescopes play a more and more important role in the detection system on the ground, and the adaptive optical images are so many that we need find a suitable method of quality evaluation to choose good quality images automatically in order to save human power. It is well known that the adaptive optical images are no-reference images. In this paper, a new logarithmic evaluation method based on the use of the discrete cosine transform(DCT) and Rényi entropy for the adaptive optical images is proposed. Through the DCT using one or two dimension window, the statistical property of Rényi entropy for images is studied. The different directional Rényi entropy maps of an input image containing different information content are obtained. The mean values of different directional Rényi entropy maps are calculated. For image quality evaluation, the different directional Rényi entropy and its standard deviation corresponding to region of interest is selected as an indicator for the anisotropy of the images. The standard deviation of different directional Rényi entropy is obtained as the quality evaluation value for adaptive optical image. Experimental results show the proposed method that the sorting quality matches well with the visual inspection.

  7. Image quality improvement by the structured light illumination method in an optical readout cantilever array infrared imaging system.

    Science.gov (United States)

    Feng, Yun; Zhao, Yuejin; Liu, Ming; Dong, Liquan; Yu, Xiaomei; Kong, Lingqin; Ma, Wei; Liu, Xiaohua

    2015-04-01

    The structured light illumination method is applied in an optical readout uncooled infrared imaging system to improve the IR image quality. The unavoidable nonuniform distribution of the initial bending angles of the bimaterial cantilever pixels in the focal plane array (FPA) can be well compensated by this method. An ordinary projector is used to generate structured lights of different intensity distribution. The projected light is divided into patches of rectangular regions, and the brightness of each region can be set automatically according to the deflection angles of the FPA and the light intensity focused on the imaging plane. By this method, the FPA image on the CCD plane can be much more uniform and the image quality of the IR target improved significantly. A comparative experiment is designed to verify the effectiveness. The theoretical analysis and experimental results show that the proposed structured light illumination method outperforms the conventional one, especially when it is difficult to perfect the FPA fabrication.

  8. Identification, regression and validation of an image processing degradation model to assess the effects of aeromechanical turbulence due to installation aircraft

    Science.gov (United States)

    Miccoli, M.; Usai, A.; Tafuto, A.; Albertoni, A.; Togna, F.

    2016-10-01

    The propagation environment around airborne platforms may significantly degrade the performance of Electro-Optical (EO) self-protection systems installed onboard. To ensure the sufficient level of protection, it is necessary to understand that are the best sensors/effectors installation positions to guarantee that the aeromechanical turbulence, generated by the engine exhausts and the rotor downwash, does not interfere with the imaging systems normal operations. Since the radiation-propagation-in-turbulence is a hardly predictable process, it was proposed a high-level approach in which, instead of studying the medium under turbulence, the turbulence effects on the imaging systems processing are assessed by means of an equivalent statistical model representation, allowing a definition of a Turbulence index to classify different level of turbulence intensities. Hence, a general measurement methodology for the degradation of the imaging systems performance in turbulence conditions was developed. The analysis of the performance degradation started by evaluating the effects of turbulences with a given index on the image processing chain (i.e., thresholding, blob analysis). The processing in turbulence (PIT) index is then derived by combining the effects of the given turbulence on the different image processing primitive functions. By evaluating the corresponding PIT index for a sufficient number of testing directions, it is possible to map the performance degradation around the aircraft installation for a generic imaging system, and to identify the best installation position for sensors/effectors composing the EO self-protection suite.

  9. Extracting a Good Quality Frontal Face Image from a Low-Resolution Video Sequence

    DEFF Research Database (Denmark)

    Nasrollahi, Kamal; Moeslund, Thomas B.

    2011-01-01

    Feeding low-resolution and low-quality images, from inexpensive surveillance cameras, to systems like, e.g., face recognition, produces erroneous and unstable results. Therefore, there is a need for a mechanism to bridge the gap between on one hand low-resolution and low-quality images and on the......Feeding low-resolution and low-quality images, from inexpensive surveillance cameras, to systems like, e.g., face recognition, produces erroneous and unstable results. Therefore, there is a need for a mechanism to bridge the gap between on one hand low-resolution and low-quality images...... and on the other hand facial analysis systems. The proposed system in this paper deals with exactly this problem. Our approach is to apply a reconstruction-based super-resolution algorithm. Such an algorithm, however, has two main problems: first, it requires relatively similar images with not too much noise...

  10. Extracting a Good Quality Frontal Face Image from a Low-Resolution Video Sequence

    DEFF Research Database (Denmark)

    Nasrollahi, Kamal; Moeslund, Thomas B.

    2011-01-01

    Feeding low-resolution and low-quality images, from inexpensive surveillance cameras, to systems like, e.g., face recognition, produces erroneous and unstable results. Therefore, there is a need for a mechanism to bridge the gap between on one hand low-resolution and low-quality images and on the......Feeding low-resolution and low-quality images, from inexpensive surveillance cameras, to systems like, e.g., face recognition, produces erroneous and unstable results. Therefore, there is a need for a mechanism to bridge the gap between on one hand low-resolution and low-quality images...... and on the other hand facial analysis systems. The proposed system in this paper deals with exactly this problem. Our approach is to apply a reconstruction-based super-resolution algorithm. Such an algorithm, however, has two main problems: first, it requires relatively similar images with not too much noise...

  11. Simulating receptive fields of human visual cortex for 3D image quality prediction.

    Science.gov (United States)

    Shao, Feng; Chen, Wanting; Lin, Wenchong; Jiang, Qiuping; Jiang, Gangyi

    2016-07-20

    Quality assessment of 3D images presents many challenges when attempting to gain better understanding of the human visual system. In this paper, we propose a new 3D image quality prediction approach by simulating receptive fields (RFs) of human visual cortex. To be more specific, we extract the RFs from a complete visual pathway, and calculate their similarity indices between the reference and distorted 3D images. The final quality score is obtained by determining their connections via support vector regression. Experimental results on three 3D image quality assessment databases demonstrate that in comparison with the most relevant existing methods, the devised algorithm achieves high consistency alignment with subjective assessment, especially for asymmetrically distorted stereoscopic images.

  12. Image quality and radiopharmaceutical parameters of Indium-111 granulocytes in scintigraphy of inflammatory bowel disease

    Energy Technology Data Exchange (ETDEWEB)

    Arndt, J.W.; Blok, D.; Tjon, R.T.O.; Tham, A.; Pauwels, E.K.J.; Crama-Bohbouth, G.E.; Verspaget, H.W.; Pena, A.S.; Weterman, I.T.; Lamers, C.B.H.W.

    1989-04-01

    This study was undertaken to investigate the influence of various parameters of injected autologous /sup 111/In labelled granulocytes on scintigraphic image quality. Forty-two scintigrams of 37 patients with inflammatory bowel disease were evaluated. The images were divided into three groups according to quality: Good, intermediate and poor. The relationships between image quality and such radiopharmaceutical parameters as injected dose of /sup 111/In, number of injected cells and specific activity were investigated. It appeared that in order to obtain interpretable images, a specific activity of at least 85 kBq /sup 111/In/million cells was necessary. The activity of the injected dose must exceed 7 MBq if poor quality images and very long acquisition times are to be avoided.

  13. Local homogeneity combined with DCT statistics to blind noisy image quality assessment

    Science.gov (United States)

    Yang, Lingxian; Chen, Li; Chen, Heping

    2015-03-01

    In this paper a novel method for blind noisy image quality assessment is proposed. First, it is believed that human visual system (HVS) is more sensitive to the local smoothness area in a noise image, an adaptively local homogeneous block selection algorithm is proposed to construct a new homogeneous image named as homogeneity blocks (HB) based on computing each pixel characteristic. Second, applying the discrete cosine transform (DCT) for each HB and using high frequency component to evaluate image noise level. Finally, a modified peak signal to noise ratio (MPSNR) image quality assessment approach is proposed based on analysis DCT kurtosis distributions change and noise level above-mentioned. Simulations show that the quality scores that produced from the proposed algorithm are well correlated with the human perception of quality and also have a stability performance.

  14. Microstructural degradation of silicon electrodes during lithiation observed via operando X-ray tomographic imaging

    Science.gov (United States)

    Taiwo, Oluwadamilola O.; Paz-García, Juan M.; Hall, Stephen A.; Heenan, Thomas M. M.; Finegan, Donal P.; Mokso, Rajmund; Villanueva-Pérez, Pablo; Patera, Alessandra; Brett, Daniel J. L.; Shearing, Paul R.

    2017-02-01

    Due to their high theoretical capacity compared to that of state-of-the-art graphite-based electrodes, silicon electrodes have gained much research focus for use in the development of next generation lithium-ion batteries. However, a major drawback of silicon as an electrode material is that it suffers from particle fracturing due to huge volume expansion during electrochemical cycling, thus limiting commercialization of such electrodes. Understanding the role of material microstructure in electrode degradation will be instrumental in the design of stable silicon electrodes. Here, we demonstrate the application of synchrotron-based X-ray tomographic microscopy to capture and track microstructural evolution, phase transformation and fracturing within a silicon-based electrode during electrochemical lithiation.

  15. Despeckle filtering for ultrasound imaging and video, v.I algorithms and software

    CERN Document Server

    Loizou, Christos P

    2015-01-01

    It is well known that speckle is a multiplicative noise that degrades image and video quality and the visual expert's evaluation in ultrasound imaging and video. This necessitates the need for robust despeckling image and video techniques for both routine

  16. Determination of Rate of Degradation of Iron Plates Due To Rust Using Image Processing -A Review

    Directory of Open Access Journals (Sweden)

    Priyanka Choudhary

    2014-03-01

    Full Text Available Abstract: most of industries and bridges around us make use of iron for manufacturing their products. On the other hand corrosion is a natural process that deteriorates the integrity of iron surface. Therefore, rusting of iron takes place. To avoid unwanted accidents in industries and bridges, it is necessary to detect rusting in earlier stage, so that it can be prevented. Digital image processing for the detection of the rusting provides fast, accurate and objectives results. In this research paper, we have done a systematic review of algorithms that help us to detect the rust area from a metal (iron.it has been found that most of researches are bring their images, processing series in usage for this purpose due to its simplicity in implementing and due to fact the images help capturing the visual inspection process easily and due to the ground teeth. The image processing techniques explored by other peoples based on in-depth analysis, we have also proposed a novel technique to overcome the limitation.

  17. Determination of Rate of Degradation of Iron Plates due to Rust using Image Processing

    Directory of Open Access Journals (Sweden)

    Priyanka Choudhary

    2015-02-01

    Full Text Available Most of industries and bridges around us make use of iron for manufacturing their products. On the other hand corrosion is a natural process that deteriorates the integrity of iron surface. Therefore, rusting of iron takes place. To avoid unwanted accidents in industries and bridges, it is necessary to detect rusting in earlier stage, so that it can be prevented. Digital image processing for the detection of the rusting provides fast, accurate and objectives results. In this research paper, we have done a systematic review of algorithms that help us to detect the rust area from a metal (iron.it has been found that most of researches are bring their images, processing series in usage for this purpose due to its simplicity in implementing and due to fact the images help capturing the visual inspection process easily and due to the ground teeth. The image processing techniques explored by other peoples based on in-depth analysis, we have also proposed a novel technique to overcome the limitation.

  18. Ground water quality in environmentally degraded localities of Panipat city, India.

    Science.gov (United States)

    Bishnoi, Mukul; Malik, Ravinder

    2008-11-01

    Asystematic physico-chemical analysis of the groundwater at 41 different locations in Panipat city (Haryana), India has been taken up to evaluate its suitabilityfor domestic purposes. The data revealed considerable variations in the water samples with respect to chemical composition. For the analyzed water samples pH, EC, TDS, TA, TH, Na+, K+, Ca2+, HCO3-, Cl-, SO4(2-) and F(-) varied from 6.6-7.5, 0.09-3.28 mmhoS cm(-1), 700-2100 mg l(-1), 245-1054 mg l(-1) (as CaCO3), 153-520 mg l(-1) (as CaCO3), 57-560 mg l(-1), 5-22 mg l(-1), 36-95 mg l(-1), 298-1285 mg l(-1), 60-311 mgl(-1), 17-786 mg l(-1), 0.24-9.27 mg l(-1) respectively. All samples have high concentration of dissolved salts and all the samples were hard to very hard. Correlation coefficient "r" analysis has been worked out among different water quality parameters. The study shows a positive and significant, correlation of electrical conductivity with total dissolved salts (r = 0.979), total hardness (r = 0.507), sulphate (r = 0.453), total alkalinity (r = 0.725). Total hardness is positively and significantly correlated with magnesium (r = 0.833) and sulphate (r = 0.687). Where as total alkalinity was found to be positively and significantly correlated with bicarbonate (r = 0.992). Fluoride was higher than permissible limits in most of the samples.

  19. Imaging secondary metabolism of Streptomyces sp. Mg1 during cellular lysis and colony degradation of competing Bacillus subtilis.

    Science.gov (United States)

    Barger, Sarah R; Hoefler, B Chris; Cubillos-Ruiz, Andrés; Russell, William K; Russell, David H; Straight, Paul D

    2012-10-01

    Soil streptomycetes are saprotrophic bacteria that secrete numerous secondary metabolites and enzymes for extracellular functions. Many streptomycetes produce antibiotics thought to protect vegetative mycelia from competing organisms. Here we report that an organism isolated from soil, Streptomyces sp. Mg1, actively degrades colonies and causes cellular lysis of Bacillus subtilis when the organisms are cultured together. We predicted that the inhibition and degradation of B. subtilis colonies in this competition depends upon a combination of secreted factors, including small molecule metabolites and enzymes. To begin to unravel this complex competitive phenomenon, we use a MALDI imaging mass spectrometry strategy to map the positions of metabolites secreted by both organisms. In this report, we show that Streptomyces sp. Mg1 produces the macrolide antibiotic chalcomycin A, which contributes to inhibition of B. subtilis growth in combination with other, as yet unidentified factors. We suggest that efforts to understand competitive and cooperative interactions between bacterial species benefit from assays that pair living organisms and probe the complexity of metabolic exchanges between them.

  20. Optimization of image quality and dose for Varian aS500 electronic portal imaging devices (EPIDs).

    Science.gov (United States)

    McGarry, C K; Grattan, M W D; Cosgrove, V P

    2007-12-07

    This study was carried out to investigate whether the electronic portal imaging (EPI) acquisition process could be optimized, and as a result tolerance and action levels be set for the PIPSPro QC-3V phantom image quality assessment. The aim of the optimization process was to reduce the dose delivered to the patient while maintaining a clinically acceptable image quality. This is of interest when images are acquired in addition to the planned patient treatment, rather than images being acquired using the treatment field during a patient's treatment. A series of phantoms were used to assess image quality for different acquisition settings relative to the baseline values obtained following acceptance testing. Eight Varian aS500 EPID systems on four matched Varian 600C/D linacs and four matched Varian 2100C/D linacs were compared for consistency of performance and images were acquired at the four main orthogonal gantry angles. Images were acquired using a 6 MV beam operating at 100 MU min(-1) and the low-dose acquisition mode. Doses used in the comparison were measured using a Farmer ionization chamber placed at d(max) in solid water. The results demonstrated that the number of reset frames did not have any influence on the image contrast, but the number of frame averages did. The expected increase in noise with corresponding decrease in contrast was also observed when reducing the number of frame averages. The optimal settings for the low-dose acquisition mode with respect to image quality and dose were found to be one reset frame and three frame averages. All patients at the Northern Ireland Cancer Centre are now imaged using one reset frame and three frame averages in the 6 MV 100 MU min(-1) low-dose acquisition mode. Routine EPID QC contrast tolerance (+/-10) and action (+/-20) levels using the PIPSPro phantom based around expected values of 190 (Varian 600C/D) and 225 (Varian 2100C/D) have been introduced. The dose at dmax from electronic portal imaging has been

  1. High-quality digital imaging of art in Europe

    Science.gov (United States)

    Martinez, Kirk

    1996-02-01

    In the past decade various museums and galleries around Europe have been developing digital imaging as a tool for archiving and analysis. Accurate digital images can replace the conventional film archives which are not stable or accurate but are the standard record of art. The digital archives open up new research possibilities as well as become resources for CD- ROM production, damage analysis, research and publishing. In the VASARI project new scanners were devised to produce colorimetric images directly from paintings using multispectral (six band) imaging. These can produce images in CIE Lab format with resolutions over 10 k multiplied by 10 k and have been installed in London, England; Munich, Germany; and Florence, Italy. They are based around a large stepper-motor controlled scanner moving a high resolution CCD camera to obtain patches of 3 k multiplied by 2 k pels which are mosaiced together. The scanners can also be used for infra-red imaging with a different camera. The MARC project produced a portable scan-back, RGB camera capable of similar output and techniques for calibrated printing. The Narcisse project produced a fast high resolution scanner for X-radiographs and film and many projects have worked on networking the growing number of image databases. This paper presents a survey of some key European projects, particularly those funded by the European Union, involved in high resolution and colorimetric imaging of art. The design of the new scanners and examples of the applications of these images are presented.

  2. Quality Index for Stereoscopic Images by Separately Evaluating Adding and Subtracting.

    Directory of Open Access Journals (Sweden)

    Jiachen Yang

    Full Text Available The human visual system (HVS plays an important role in stereo image quality perception. Therefore, it has aroused many people's interest in how to take advantage of the knowledge of the visual perception in image quality assessment models. This paper proposes a full-reference metric for quality assessment of stereoscopic images based on the binocular difference channel and binocular summation channel. For a stereo pair, the binocular summation map and binocular difference map are computed first by adding and subtracting the left image and right image. Then the binocular summation is decoupled into two parts, namely additive impairments and detail losses. The quality of binocular summation is obtained as the adaptive combination of the quality of detail losses and additive impairments. The quality of binocular summation is computed by using the Contrast Sensitivity Function (CSF and weighted multi-scale (MS-SSIM. Finally, the quality of binocular summation and binocular difference is integrated into an overall quality index. The experimental results indicate that compared with existing metrics, the proposed metric is highly consistent with the subjective quality assessment and is a robust measure. The result have also indirectly proved hypothesis of the existence of binocular summation and binocular difference channels.

  3. Time-resolved photoluminescence spectroscopy and imaging: new approaches to the analysis of cultural heritage and its degradation.

    Science.gov (United States)

    Nevin, Austin; Cesaratto, Anna; Bellei, Sara; D'Andrea, Cosimo; Toniolo, Lucia; Valentini, Gianluca; Comelli, Daniela

    2014-04-02

    Applications of time-resolved photoluminescence spectroscopy (TRPL) and fluorescence lifetime imaging (FLIM) to the analysis of cultural heritage are presented. Examples range from historic wall paintings and stone sculptures to 20th century iconic design objects. A detailed description of the instrumentation developed and employed for analysis in the laboratory or in situ is given. Both instruments rely on a pulsed laser source coupled to a gated detection system, but differ in the type of information they provide. Applications of FLIM to the analysis of model samples and for the in-situ monitoring of works of art range from the analysis of organic materials and pigments in wall paintings, the detection of trace organic substances on stone sculptures, to the mapping of luminescence in late 19th century paintings. TRPL and FLIM are employed as sensors for the detection of the degradation of design objects made in plastic. Applications and avenues for future research are suggested.

  4. Time-Resolved Photoluminescence Spectroscopy and Imaging: New Approaches to the Analysis of Cultural Heritage and Its Degradation

    Directory of Open Access Journals (Sweden)

    Austin Nevin

    2014-04-01

    Full Text Available Applications of time-resolved photoluminescence spectroscopy (TRPL and fluorescence lifetime imaging (FLIM to the analysis of cultural heritage are presented. Examples range from historic wall paintings and stone sculptures to 20th century iconic design objects. A detailed description of the instrumentation developed and employed for analysis in the laboratory or in situ is given. Both instruments rely on a pulsed laser source coupled to a gated detection system, but differ in the type of information they provide. Applications of FLIM to the analysis of model samples and for the in-situ monitoring of works of art range from the analysis of organic materials and pigments in wall paintings, the detection of trace organic substances on stone sculptures, to the mapping of luminescence in late 19th century paintings. TRPL and FLIM are employed as sensors for the detection of the degradation of design objects made in plastic. Applications and avenues for future research are suggested.

  5. Effect of perceived Price, Brand Image, perceived Quality and Trust on Consumer’s buying Preferences

    Directory of Open Access Journals (Sweden)

    B. Afsar

    2014-06-01

    Full Text Available The study investigates the effect of factors such as perceived price, brand image, perceived quality and trust on consumers' evaluative judgments for beautification products. Results showed that brand image has positive and significant impact on consumer trust. Increase in perceived quality and trust depicted increase in a particular brand preference. Decrease in perceived price showed significant and positive impact on brand preference. This study measured the effect of brand image, price, quality and consumer trust information on how individuals subjectively evaluate a brand.

  6. EFFECT OF UN-DEGRADABLE PROTEIN SUPPLEMENTATION ON SEMEN QUALITY OF BUFFALO BULLS UNDER HEAT STRESS CONDITIONS

    Directory of Open Access Journals (Sweden)

    Shafqat Hussain, M.M. Siddiqui and G. Habib

    2002-04-01

    Full Text Available A study was conducted to investigate the effect of feeding un-degradable protein (UDP supplement on the semen quality of buffalo bulls during hot and humid part of summer season in Peshawar. Six Nili-Ravi buffalo bulls maintained at a semen production unit, Peshawar were randomly divided into two equal groups (control and treatment; Both groups were fed a basal diet of maize fodder ( 15 Kg/day/bull and wheat straw (6 Kg/day/bull. Bulls in the control group received 5 kg /day/head of a commercial concentrate while the treatment group was fed 3 Kg commercial concentrate and 1 Kg UDP supplement. Both supplements were iso-nitrogenous and provided 150g nitrogen /head/day. The diets were fed in a switch over design over two periods. Each period lasted for 32 days. One-week adaptation period was allowed at the start of each experimental period. In~sacco protein degradability at 12 hours incubation for commercial concentrate and UDP supplement was 72.87 and 43.46%, respectively. Mean ambient temperature, humidity and temperature-humidity-index were 32.01°C, 66.66% and 84.97, respectively: Semen volume of bulls in the control and treatment groups did not vary and averaged 6.87 ± 0.41 and 7.41 ± 0.56 mI/collection day with a mean sperm concentration of 1004.5 ± 69.06 and 969.14 ± 77.88 xI06/ml, respectively. Number, of defective sperms (head abl1ormalities, mid-piece defects, proximal droplet and tail defects in the control and treatment groups was not different. Feeding of UDP supplement did not influence the blood concentrations of calcium, phosphorus, urea al1d glucose. The absence of UDP effect on semen volume, and quality could be attributed to low thermal stress, feeding small quantity of UDP and less number of replicate bulls used in the present study.

  7. Testing the quality of images for permanent magnet desktop MRI systems using specially designed phantoms.

    Science.gov (United States)

    Qiu, Jianfeng; Wang, Guozhu; Min, Jiao; Wang, Xiaoyan; Wang, Pengcheng

    2013-12-21

    Our aim was to measure the performance of desktop magnetic resonance imaging (MRI) systems using specially designed phantoms, by testing imaging parameters and analysing the imaging quality. We designed multifunction phantoms with diameters of 18 and 60 mm for desktop MRI scanners in accordance with the American Association of Physicists in Medicine (AAPM) report no. 28. We scanned the phantoms with three permanent magnet 0.5 T desktop MRI systems, measured the MRI image parameters, and analysed imaging quality by comparing the data with the AAPM criteria and Chinese national standards. Image parameters included: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, signal-to-noise ratio (SNR), and image uniformity. The image parameters of three desktop MRI machines could be measured using our specially designed phantoms, and most parameters were in line with MRI quality control criterion, including: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, image uniformity and slice position accuracy. However, SNR was significantly lower than in some references. The imaging test and quality control are necessary for desktop MRI systems, and should be performed with the applicable phantom and corresponding standards.

  8. Investigation into image quality difference between total variation and nonlinear sparsifying transform based compressed sensing

    Science.gov (United States)

    Dong, Jian; Kudo, Hiroyuki

    2017-03-01

    Compressed sensing (CS) is attracting growing concerns in sparse-view computed tomography (CT) image reconstruction. The most standard approach of CS is total variation (TV) minimization. However, images reconstructed by TV usually suffer from distortions, especially in reconstruction of practical CT images, in forms of patchy artifacts, improper serrate edges and loss of image textures. Most existing CS approaches including TV achieve image quality improvement by applying linear transforms to object image, but linear transforms usually fail to take discontinuities into account, such as edges and image textures, which is considered to be the key reason for image distortions. Actually, discussions on nonlinear filter based image processing has a long history, leading us to clarify that the nonlinear filters yield better results compared to linear filters in image processing task such as denoising. Median root prior was first utilized by Alenius as nonlinear transform in CT image reconstruction, with significant gains obtained. Subsequently, Zhang developed the application of nonlocal means-based CS. A fact is gradually becoming clear that the nonlinear transform based CS has superiority in improving image quality compared with the linear transform based CS. However, it has not been clearly concluded in any previous paper within the scope of our knowledge. In this work, we investigated the image quality differences between the conventional TV minimization and nonlinear sparsifying transform based CS, as well as image quality differences among different nonlinear sparisying transform based CSs in sparse-view CT image reconstruction. Additionally, we accelerated the implementation of nonlinear sparsifying transform based CS algorithm.

  9. Image quality in the anteroposterior cervical spine radiograph: Comparison between moving, stationary and non-grid techniques in a lamb neck

    Energy Technology Data Exchange (ETDEWEB)

    Keating, Michelle [School of Health and Social Care, Faculty of Health and Life Sciences, University of the West of England, Stapleton, Bristol BS16 1DD (United Kingdom); Grange, Stuart, E-mail: Stuart2.Grange@uwe.ac.u [School of Health and Social Care, Faculty of Health and Life Sciences, University of the West of England, Stapleton, Bristol BS16 1DD (United Kingdom)

    2011-05-15

    Background: Cervical spine radiography is a commonly employed examination for degenerative disease and trauma in the cervical spine. Traditionally, the anteroposterior projection is undertaken with the use of an anti-scatter grid. Some practitioners appear to have rejected this practice in favour of a non-grid technique, possibly because of the dose saving it affords. It is necessary to determine if image quality in the cervical spine is significantly degraded and whether the omission of the grid is justified. Method: Using a slaughtered lamb neck as a model of the human neck triplicate radiographs were obtained using a non-grid, a stationary grid and a moving grid technique. Entrance surface dose and dose area product was measured for these techniques. Image quality in terms of contrast, sharpness and overall acceptability was evaluated by 9 independent and blinded observers. Results: A significant reduction in measured dose was observed when the non-grid technique was compared to stationary or moving grid techniques. A statistically significant reduction in image contrast, sharpness and acceptability was also seen in the non-grid compared to grid techniques. Conclusion: These results show evidence of significantly greater image quality in the presence of either a moving or stationary grid in the lamb model. As such they support the continued use of scatter rejection methods such as the anti-scatter grid in AP radiography of the human cervical spine, to optimise radiographic image quality in this critical structure.

  10. The Effect of Ethnocentrism and Image of Asian Industrialised Countries on Perceived Relative Quality

    Directory of Open Access Journals (Sweden)

    Sulhaini

    2014-12-01

    Full Text Available The study examined the effects of consumer ethnocentrism and country image on perceived relative quality. The respondents of the study were consumers at a shopping mall in Mataram, Indonesia. They compared the quality of televisions from three industrialised Asian countries, i.e. Japan, South Korea and China, to those from Indonesia. The result of the study was that image of those countries has a significant effect on perceived relative quality. Indonesian consumers perceived televisions from those countries to be more favourable in terms of quality compared to Indonesian televisions. Indonesian consumers have a similar perception on the quality of televisions made in those main Asian countries relative to those of Indonesia. The image of those countries is favourable leading to a better perception on quality of televisions made in the countries relative to domestically made. Domestic consumers view that those countries have better capabilities in producing higher quality televisions. However, consumer ethnocentrism do not lead them to negatively perceive the quality of imported televisions. Indeed, the image of those countries has a greater role in Indonesian consumers’ quality evaluation. The result calls for a substantial improvement in quality of domestically made televisions.

  11. Surface Investigation of Photo-Degraded Wood by Colour Monitoring, Infrared Spectroscopy, and Hyperspectral Imaging

    OpenAIRE

    Giorgia Agresti; Giuseppe Bonifazi; Luca Calienno; Giuseppe Capobianco; Angela Lo Monaco; Claudia Pelosi; Rodolfo Picchio; Silvia Serranti

    2013-01-01

    The aim of this investigation is to study the changes occurring on the surface of poplar wood exposed to artificial irradiation in a Solar Box. Colour changes were monitored with a reflectance spectrophotometer. Surface chemical modifications were evaluated by measuring the infrared spectra. Hyperspectral imaging was also applied to study the surface wood changes in the visible-near infrared and the short wave infrared wavelength ranges. The data obtained from the different techniques were co...

  12. Body image in adult women: Associations with health behaviors, quality of life, and functional impairment.

    Science.gov (United States)

    Becker, Carolyn B; Verzijl, Christina L; Kilpela, Lisa S; Wilfred, Salome A; Stewart, Tiffany

    2017-05-01

    This study examined body image in adult women along with probable correlates including health behaviors, negative affect, quality of life, and functional impairment. Adult women ( N = 738, age = 25-86 years) completed an online survey assessing these domains. Women across all ages reported similar body image concerns. Negative body image significantly correlated with poorer wellness behaviors, negative affect, quality of life, and functional impairment. The inverse held for positive body image. The majority of correlations remained even when controlling for negative affect. Further research is warranted to investigate nature of the correlational relationships identified in this study.

  13. From image quality to atmosphere experience: how evolutions in technology impact experience assessment

    Science.gov (United States)

    Heynderickx, Ingrid; de Ridder, Huib

    2013-03-01

    Image quality is a concept that for long very well served to optimize display performance and signal quality. New technological developments, however, forced the community to look into higher-level concepts to capture the full experience. Terms as naturalness and viewing experience were used to optimize the full experience of 3D-displays and Ambilight TV. These higher-level concepts capture differences in image quality and differences in perceived depth or perceived viewing field. With the introduction of solid-state lighting, further enhancing the multimedia experience, yet more advanced quality evaluation concepts to optimize the overall experience will be needed in the future.

  14. Quality assessment of images displayed on LCD screen with local backlight dimming

    DEFF Research Database (Denmark)

    Mantel, Claire; Burini, Nino; Korhonen, Jari

    2013-01-01

    This paper presents a subjective experiment collecting quality assessment of images displayed on a LCD with local backlight dimming using two methodologies: absolute category ratings and paired-comparison. Some well-known objective quality metrics are then applied to the stimuli and their respect......This paper presents a subjective experiment collecting quality assessment of images displayed on a LCD with local backlight dimming using two methodologies: absolute category ratings and paired-comparison. Some well-known objective quality metrics are then applied to the stimuli...

  15. Application of image quality metamerism to investigate gold color area in cultural property

    Science.gov (United States)

    Miyata, Kimiyoshi; Tsumura, Norimichi

    2013-01-01

    A concept of image quality metamerism as an expansion of conventional metamerism defined in color science is introduced, and it is applied to segment similar color areas in a cultural property. The image quality metamerism can unify different image quality attributes based on an index showing the degree of image quality metamerism proposed. As a basic research step, the index is consisted of color and texture information and examined to investigate a cultural property. The property investigated is a pair of folding screen paintings that depict the thriving city of Kyoto designated as a nationally important cultural property in Japan. Gold-colored areas painted by using high granularity colorants compared with other color areas are evaluated based on the image quality metamerism index locally, then the index is visualized as a map showing the possibility of the image quality metamer to the reference pixel set in the same image. This visualization means a segmentation of areas where color is similar but texture is different. The experimental result showed that the proposed method was effective to show areas of gold color areas in the property.

  16. Objectification of perceptual image quality for mobile video

    Science.gov (United States)

    Lee, Seon-Oh; Sim, Dong-Gyu

    2011-06-01

    This paper presents an objective video quality evaluation method for quantifying the subjective quality of digital mobile video. The proposed method aims to objectify the subjective quality by extracting edgeness and blockiness parameters. To evaluate the performance of the proposed algorithms, we carried out subjective video quality tests with the double-stimulus continuous quality scale method and obtained differential mean opinion score values for 120 mobile video clips. We then compared the performance of the proposed methods with that of existing methods in terms of the differential mean opinion score with 120 mobile video clips. Experimental results showed that the proposed methods were approximately 10% better than the edge peak signal-to-noise ratio of the J.247 method in terms of the Pearson correlation.

  17. DAF: differential ACE filtering image quality assessment by automatic color equalization

    Science.gov (United States)

    Ouni, S.; Chambah, M.; Saint-Jean, C.; Rizzi, A.

    2008-01-01

    Ideally, a quality assessment system would perceive and measure image or video impairments just like a human being. But in reality, objective quality metrics do not necessarily correlate well with perceived quality [1]. Plus, some measures assume that there exists a reference in the form of an "original" to compare to, which prevents their usage in digital restoration field, where often there is no reference to compare to. That is why subjective evaluation is the most used and most efficient approach up to now. But subjective assessment is expensive, time consuming and does not respond, hence, to the economic requirements [2,3]. Thus, reliable automatic methods for visual quality assessment are needed in the field of digital film restoration. The ACE method, for Automatic Color Equalization [4,6], is an algorithm for digital images unsupervised enhancement. It is based on a new computational approach that tries to model the perceptual response of our vision system merging the Gray World and White Patch equalization mechanisms in a global and local way. Like our vision system ACE is able to adapt to widely varying lighting conditions, and to extract visual information from the environment efficaciously. Moreover ACE can be run in an unsupervised manner. Hence it is very useful as a digital film restoration tool since no a priori information is available. In this paper we deepen the investigation of using the ACE algorithm as a basis for a reference free image quality evaluation. This new metric called DAF for Differential ACE Filtering [7] is an objective quality measure that can be used in several image restoration and image quality assessment systems. In this paper, we compare on different image databases, the results obtained with DAF and with some subjective image quality assessments (Mean Opinion Score MOS as measure of perceived image quality). We study also the correlation between objective measure and MOS. In our experiments, we have used for the first image

  18. Evaluation of image quality and factor for international telepathology through the Internet

    Science.gov (United States)

    Yagi, Yukako; Azumi, Norio; Elsayed, Alaa M.; Mun, Seong K.

    1997-05-01

    In the telepathology, rendering devices significantly influence the perceived image quality. If the resolution and color depth are reduced beyond a certain point, however, it is not possible to obtain images which can be used in telepathology even in an ideal situation. With this in mind, we evaluated image quality, compression, size and rates of data exchange with several histological cases on several kinds of systems for our International Consortium for Internet Telepathology (ICIT) project. The ICIT network uses widely available nonpropriety hardware and software with the Internet as a means of communication.In this study, we discuss the effective image acquisition methods for telepathology. To evaluate microscopic images, various resolution size were used. The images were also evaluated at different JPEG compression ratio, including zero compression, and different format. To evaluate an entire glass slide image, a scanner in transparency mode and an NTSC camera were used. Every case showed similar results. For he microscopic image, although the high resolution images, such as 2k X 1.5k or higher, contain more diagnostic information than lower resolution images; sufficient data was retained in the latter that it does not appear to negatively effect diagnosis. The circumstance and condition for image acquisition, such as specimen thickness or dast of glass slide, are most influenced on the highest image resolution. Usually, we use 5-10 images/case for a telepathology conference. To see all images of a case at a glance before detailed observation, or to switch to the other images immediately, a lower resolution,such as 1k X 0.7k is useful. For the entire glass slide, the reviewer could select the desired area by scanner; however, selecting it by the NTSC camera, was not easy to do. On the monitor, the scanned image has almost the same information as the microscopic image captured by the NTSC camera with 2x objective lens. To ge ta high enough quality image, the

  19. Image quality and dose optimisation for infant CT using a paediatric phantom

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, Jack W.; Phelps, Andrew S.; Courtier, Jesse L.; Gould, Robert G.; MacKenzie, John D. [University of California, San Francisco, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States)

    2016-05-15

    To optimise image quality and reduce radiation exposure for infant body CT imaging. An image quality CT phantom was created to model the infant body habitus. Image noise, spatial resolution, low contrast detectability and tube current modulation (TCM) were measured after adjusting CT protocol parameters. Reconstruction method (FBP, hybrid iterative and model-based iterative), image quality reference parameter, helical pitch and beam collimation were systematically investigated for their influence on image quality and radiation output. Both spatial and low contrast resolution were significantly improved with model-based iterative reconstruction (p < 0.05). A change in the helical pitch from 0.969 to 1.375 resulted in a 23 % reduction in total TCM, while a change in collimation from 20 to 40 mm resulted in a 46 % TCM reduction. Image noise and radiation output were both unaffected by changes in collimation, while an increase in pitch enabled a dose length product reduction of ∝6 % at equivalent noise. An optimised protocol with ∝30 % dose reduction was identified using model-based iterative reconstruction. CT technology continues to evolve and require protocol redesign. This work provides an example of how an infant-specific phantom is essential for leveraging this technology to maintain image quality while reducing radiation exposure. (orig.)

  20. Optimization of image quality in breast tomosynthesis using lumpectomy and mastectomy specimens

    Science.gov (United States)

    Timberg, Pontus; Ruschin, Mark; Båth, Magnus; Hemdal, Bengt; Andersson, Ingvar; Svahn, Tony; Mattsson, Sören; Tingberg, Anders

    2007-03-01

    The purpose of this study was to determine how image quality in breast tomosynthesis (BT) is affected when acquisition modes are varied, using human breast specimens containing malignant tumors and/or microcalcifications. Images of thirty-one breast lumpectomy and mastectomy specimens were acquired on a BT prototype based on a Mammomat Novation (Siemens) full-field digital mammography system. BT image acquisitions of the same specimens were performed varying the number of projections, angular range, and detector signal collection mode (binned and nonbinned in the scan direction). An enhanced filtered back projection reconstruction method was applied with constant settings of spectral and slice thickness filters. The quality of these images was evaluated via relative visual grading analysis (VGA) human observer performance experiments using image quality criteria. Results from the relative VGA study indicate that image quality increases with number of projections and angular range. A binned detector collecting mode results in less noise, but reduced resolution of structures. Human breast specimens seem to be suitable for comparing image sets in BT with image quality criteria.

  1. Developing an ANSI standard for image quality tools for the testing of active millimeter wave imaging systems

    Science.gov (United States)

    Barber, Jeffrey; Greca, Joseph; Yam, Kevin; Weatherall, James C.; Smith, Peter R.; Smith, Barry T.

    2017-05-01

    In 2016, the millimeter wave (MMW) imaging community initiated the formation of a standard for millimeter wave image quality metrics. This new standard, American National Standards Institute (ANSI) N42.59, will apply to active MMW systems for security screening of humans. The Electromagnetic Signatures of Explosives Laboratory at the Transportation Security Laboratory is supporting the ANSI standards process via the creation of initial prototypes for round-robin testing with MMW imaging system manufacturers and experts. Results obtained for these prototypes will be used to inform the community and lead to consensus objective standards amongst stakeholders. Images collected with laboratory systems are presented along with results of preliminary image analysis. Future directions for object design, data collection and image processing are discussed.

  2. Towards image quality assessment in mammography using model observers: detection of a calcification like object.

    Science.gov (United States)

    Bouwman, Ramona W; Mackenzie, Alistair; van Engen, Ruben E; M Broeders, Mireille J; Young, Kenneth C; Dance, David R; den Heeten, Gerard J; Veldkamp, Wouter J H

    2017-08-24

    Model observers (MOs) are of interest in the field of medical imaging to asses image quality. However, before procedures using MOs can be proposed in quality control guidelines for mammography systems, we need to know whether MOs are sensitive to changes in image quality and correlations in background structure. Therefore, as a proof of principle, in this study human and model observer (MO) performance are compared for the detection of calcification like objects using different background structures and image quality levels of unprocessed mammography images. Three different phantoms, homogeneous polymethyl methacrylate, BR3D slabs with swirled patterns (CIRS, Norfolk, USA) and a prototype anthropomorphic breast phantom (Institute of Medical Physics and Radiation Protection, Technische Hochschule Mittelhessen, Germany) were imaged on an Amulet Innovality (FujiFilm, Tokyo, Japan) mammographic X-ray unit. Because the complexities of the structures of these three phantoms were different and not optimized to match the characteristics of real mammographic images, image processing was not applied in this study. Additionally, real mammograms were acquired on the same system. Regions of interest (ROIs) were extracted from each image. In half of the ROIs a 0.25 mm diameter disk was inserted at four different contrast levels to represent a calcification-like object. Each ROI was then modified so four image qualities relevant for mammography were simulated. The signal-present and signal-absent ROIs were evaluated by a non-pre-whitening model observer with eye filter (NPWE) and a channelized Hotelling observer (CHO) using dense-difference of Gaussian channels. The ROIs were also evaluated by human observers in a 2 alternative forced choice experiment. Detectability results for the human and model observer experiments were correlated using a mixed effect regression model. Threshold disk contrasts for human and predicted human observer performance based on the NPWE MO and CHO

  3. Survey of mammography practice in Croatia: equipment performance, image quality and dose.

    Science.gov (United States)

    Faj, Dario; Posedel, Dario; Stimac, Damir; Ivezic, Zdravko; Kasabasic, Mladen; Ivkovic, Ana; Kubelka, Dragan; Ilakovac, Vesna; Brnic, Zoran; Bjelac, Olivera Ciraj

    2008-01-01

    A national audit of mammography equipment performance, image quality and dose has been conducted in Croatia. Film-processing parameters, optical density (OD), average glandular dose (AGD) to the standard breast, viewing conditions and image quality were examined using TOR(MAM) test object. Average film gradient ranged from 2.6 to 3.7, with a mean of 3.1. Tube voltage used for imaging of the standard 45 mm polymethylmethacrylate phantom ranged from 24 to 34 kV, and OD ranged from 0.75 to 1.94 with a mean of 1.26. AGD to the standard breast ranged from 0.4 to 2.3 mGy with a mean of 1.1 mGy. Besides clinical conditions, the authors have imaged the standard phantom in the referent conditions with 28 kV and OD as close as possible to 1.5. Then, AGD ranged from 0.5 to 2.6 mGy with a mean of 1.3 mGy. Image viewing conditions were generally unsatisfying with ambient light up to 500 lx and most of the viewing boxes with luminance between 1000 and 2000 cd per m(2). TOR(MAM) scoring of images taken in clinical and referent conditions was done by local radiologists in local image viewing conditions and by the referent radiologist in good image viewing conditions. Importance of OD and image viewing conditions for diagnostic information were analysed. The survey showed that the main problem in Croatia is the lack of written quality assurance/quality control (QA/QC) procedures. Consequently, equipment performance, image quality and dose are unstable and activities to improve image quality or to reduce the dose are not evidence-based. This survey also had an educational purpose, introducing in Croatia the QC based on European Commission Guidelines.

  4. A study on quality and availability of COCTS images of HY- 1 satellite by simulation

    Institute of Scientific and Technical Information of China (English)

    李淑菁; 毛天明; 潘德炉

    2002-01-01

    Hy-1 is a first China's ocean color satellite which will be launched as a piggyback satellite on FY- 1 satellite using Long March rocket. On the satellite there are two sensors: one is the China's ocean color and temperature scanner (COCTS), the other is CCD coastal zone imager (CZI).The COCTS is considered to be a main sensor to play a key role. In order to understand the characteristics of future ocean color images observed, a simulation and evaluation study on the quality and availability of the COCTS image has been done. First, the simulation models are introduced briefly, and typical simulated cases of radiance images at visible bands are introduced, in which the radiance distribution is based on geographic location, the satellite orbital parameters and sensor properties, the simulated method to evaluate the image quality and availability is developed by using the characteristics of image called the complex signal noise ratio ( CSNR ). Meanwhile, a series of the CSNR images are generated from the simulated radiance components for different cases, which can be used to evaluate the quality and availability of the COCTS images before the HY - 1 is placed in orbit. Finally, the quality and availability of the COCTS images are quantitatively analyzed with the simulated CSNR data. The results will be beneficial to all scientists who are in charge of the COCTS mission and to those who plan to use the data from the COCTS.

  5. Specific developed phantoms and software to assess radiological equipment image quality

    Energy Technology Data Exchange (ETDEWEB)

    Verdu, G., E-mail: gverdu@iqn.upv.es [Universidad Politecnica de Valencia (Spain). Dept. de Ingenieria Quimica y Nuclear; Mayo, P., E-mail: p.mayo@titaniast.com [TITANIA Servicios Teconologicos, Valencia (Spain); Rodenas, F., E-mail: frodenas@mat.upv.es [Universidad Politecnica de Valencia (Spain). Dept. de Matematica Aplicada; Campayo, J.M., E-mail: j.campayo@lainsa.com [Logistica y Acondicionamientos Industriales S.A.U (LAINSA), Valencia (Spain)

    2011-07-01

    The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be automatized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques, etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (mAs). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (author)

  6. Simulation and evaluation of the quality and availability of typical GLI ocean image

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    ADEOS-II satellite will be launched in the near future. It collocates many remote sensing instruments in the same platform. Among them, Global Image (GLI) is considered to be a main sensor which will play a key role. In order to understand the characteristics of future GLI ocean color images, a simulation and evaluation of the quality and availability of GLI typical ocean image has been done. In the paper, we first in