WorldWideScience

Sample records for adaptive speckle imaging

  1. Speckle imaging through turbulent atmosphere based on adaptable pupil segmentation.

    Science.gov (United States)

    Loktev, Mikhail; Soloviev, Oleg; Savenko, Svyatoslav; Vdovin, Gleb

    2011-07-15

    We report on the first results to our knowledge obtained with adaptable multiaperture imaging through turbulence on a horizontal atmospheric path. We show that the resolution can be improved by adaptively matching the size of the subaperture to the characteristic size of the turbulence. Further improvement is achieved by the deconvolution of a number of subimages registered simultaneously through multiple subapertures. Different implementations of multiaperture geometry, including pupil multiplication, pupil image sampling, and a plenoptic telescope, are considered. Resolution improvement has been demonstrated on a ∼550 m horizontal turbulent path, using a combination of aperture sampling, speckle image processing, and, optionally, frame selection.

  2. Adaptive speckle reduction of ultrasound images based on maximum likelihood estimation

    Institute of Scientific and Technical Information of China (English)

    Xu Liu(刘旭); Yongfeng Huang(黄永锋); Wende Shou(寿文德); Tao Ying(应涛)

    2004-01-01

    A method has been developed in this paper to gain effective speckle reduction in medical ultrasound images.To exploit full knowledge of the speckle distribution, here maximum likelihood was used to estimate speckle parameters corresponding to its statistical mode. Then the results were incorporated into the nonlinear anisotropic diffusion to achieve adaptive speckle reduction. Verified with simulated and ultrasound images,we show that this algorithm is capable of enhancing features of clinical interest and reduces speckle noise more efficiently than just applying classical filters. To avoid edge contribution, changes of contrast-to-noise ratio of different regions are also compared to investigate the performance of this approach.

  3. Speckle reduction in ultrasound medical images using adaptive filter based on second order statistics.

    Science.gov (United States)

    Thakur, A; Anand, R S

    2007-01-01

    This article discusses an adaptive filtering technique for reducing speckle using second order statistics of the speckle pattern in ultrasound medical images. Several region-based adaptive filter techniques have been developed for speckle noise suppression, but there are no specific criteria for selecting the region growing size in the post processing of the filter. The size appropriate for one local region may not be appropriate for other regions. Selection of the correct region size involves a trade-off between speckle reduction and edge preservation. Generally, a large region size is used to smooth speckle and a small size to preserve the edges into an image. In this paper, a smoothing procedure combines the first order statistics of speckle for the homogeneity test and second order statistics for selection of filters and desired region growth. Grey level co-occurrence matrix (GLCM) is calculated for every region during the region contraction and region growing for second order statistics. Further, these GLCM features determine the appropriate filter for the region smoothing. The performance of this approach is compared with the aggressive region-growing filter (ARGF) using edge preservation and speckle reduction tests. The processed image results show that the proposed method effectively reduces speckle noise and preserves edge details.

  4. Adaptive-neighborhood speckle removal in multitemporal synthetic aperture radar images.

    Science.gov (United States)

    Ciuc, M; Bolon, P; Trouve, E; Buzuloiu, V; Rudant, J P

    2001-11-10

    We present a new method for multitemporal synthetic aperture radar image filtering using three-dimensional (3D) adaptive neighborhoods. The method takes both spatial and temporal information into account to derive the speckle-free value of a pixel. For each pixel individually, a 3D adaptive neighborhood is determined that contains only pixels belonging to the same distribution as the current pixel. Then statistics computed inside the established neighborhood are used to derive the filter output. It is shown that the method provides good results by drastically reducing speckle over homogeneous areas while retaining edges and thin structures. The performances of the proposed method are compared in terms of subjective and objective measures with those given by several classical speckle-filtering methods.

  5. ICA Based Speckle Filtering for Target Extraction in SAR Images Using Adaptive Space Separation

    Institute of Scientific and Technical Information of China (English)

    LI Yu-tong; ZHOU Yue; YANG Lei

    2008-01-01

    A novel approach based on independent component analysis (ICA) for speckle filtering and target extraction of synthetic aperture radar (SAR) images is proposed using adaptive space separation with weighted information entropy (WIE) incorporated. First the basis and the independent components are respectively obtained by ICA technique, and WIE of the image is computed; then based on the threshold computed from function T-WIE (threshold versus weighted-information-entropy), independent components are adaptively separated and the bases are classified accordingly. Thus, the image space is separated into two subspaces: "clean" and "noise". Then, a proposed nonlinear operator ABO is applied on each component of the 'clean' subspace for further optimization. Finally, recovery image is obtained reconstructing this subspace and target is easily extracted with binarisation. Note that here T-WIE is an interpolated function based on several representative target SAR images using proposed space separation algorithm.

  6. Video surveillance with speckle imaging

    Science.gov (United States)

    Carrano, Carmen J.; Brase, James M.

    2007-07-17

    A surveillance system looks through the atmosphere along a horizontal or slant path. Turbulence along the path causes blurring. The blurring is corrected by speckle processing short exposure images recorded with a camera. The exposures are short enough to effectively freeze the atmospheric turbulence. Speckle processing is used to recover a better quality image of the scene.

  7. Speckle Decorrelation and Dynamic Range in Speckle Noise Limited Imaging

    CERN Document Server

    Sivaramakrishnan, A; Hodge, P E; MacIntosh, B A; Sivaramakrishnan, Anand; Lloyd, James P.; Hodge, Philip E.; Macintosh, Bruce A.

    2002-01-01

    The useful dynamic range of an image in the diffraction limited regime is usually limited by speckles caused by residual phase errors in the optical system forming the image. The technique of speckle decorrelation involves introducing many independent realizations of additional phase error into a wavefront during one speckle lifetime, changing the instantaneous speckle pattern. A commonly held assumption is that this results in the speckles being `moved around' at the rate at which the additional phase screens are applied. The intention of this exercise is to smooth the speckles out into a more uniform background distribution during their persistence time, thereby enabling companion detection around bright stars to be photon noise limited rather than speckle-limited. We demonstrate analytically why this does not occur, and confirm this result with numerical simulations. We show that the original speckles must persist, and that the technique of speckle decorrelation merely adds more noise to the original speck...

  8. AN ADAPTIVE SPECKLE SUPPRESSION AND EDGE ENHANCEMENT TECHNIQUE

    Institute of Scientific and Technical Information of China (English)

    Guo Shengwen; Luo Limin

    2003-01-01

    Speckle degrades severely the quality of medical B-scan ultrasonic images, especiallyit blurs edges and details of images. An adaptive speckle suppression and edge enhancementmethod based on Nakagami distribution is presented. The statistics of log-compressed echo im-ages is derived for Nakagami distribution. An adaptive filter based on local statistical propertyof speckle is designed. The stick technique that utilizes sticks with different sizes and variousorientations is applied to locally approximate certain linear features of image. The local regionis a stick instead of a usual window, the orientation of sticks is decided by hypothesis test op-timizing method and the length of sticks is obtained by region growing technique. Performanceof the new method has been tested on the phantom and ultrasound images of pig muscle andechocardiographic. The results show that the technique effectively reduces the speckle noise whilepreserving and enhancing the tissue edge and resolvable details.

  9. Speckle imaging algorithms for planetary imaging

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, E. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    I will discuss the speckle imaging algorithms used to process images of the impact sites of the collision of comet Shoemaker-Levy 9 with Jupiter. The algorithms use a phase retrieval process based on the average bispectrum of the speckle image data. High resolution images are produced by estimating the Fourier magnitude and Fourier phase of the image separately, then combining them and inverse transforming to achieve the final result. I will show raw speckle image data and high-resolution image reconstructions from our recent experiment at Lick Observatory.

  10. Speckle imaging from an array

    Science.gov (United States)

    Riker, Jim F.; Tyler, Glenn A.; Vaughn, Jeff L.

    2016-09-01

    In this paper, we present two analytic theories developed recently to predict the performance of an imaging system composed of a phased array illuminator and a set of receiver subapertures. The receiver need not coincide with the transmitter. The two theories have been documented separately (ref. 1, 2), and the reader can find more details there - the theories present the analytic phased array irradiance on target in the presence of piston errors, and the resulting speckle pattern-induced imaging noise. The principal results presented here are the Signal to Noise Ratios (SNR) for both the radiometric portion of the problem and the speckle imaging portion of the problem.

  11. Improvement of ultrasound speckle image velocimetry using image enhancement techniques.

    Science.gov (United States)

    Yeom, Eunseop; Nam, Kweon-Ho; Paeng, Dong-Guk; Lee, Sang Joon

    2014-01-01

    Ultrasound-based techniques have been developed and widely used in noninvasive measurement of blood velocity. Speckle image velocimetry (SIV), which applies a cross-correlation algorithm to consecutive B-mode images of blood flow has often been employed owing to its better spatial resolution compared with conventional Doppler-based measurement techniques. The SIV technique utilizes speckles backscattered from red blood cell (RBC) aggregates as flow tracers. Hence, the intensity and size of such speckles are highly dependent on hemodynamic conditions. The grayscale intensity of speckle images varies along the radial direction of blood vessels because of the shear rate dependence of RBC aggregation. This inhomogeneous distribution of echo speckles decreases the signal-to-noise ratio (SNR) of a cross-correlation analysis and produces spurious results. In the present study, image-enhancement techniques such as contrast-limited adaptive histogram equalization (CLAHE), min/max technique, and subtraction of background image (SB) method were applied to speckle images to achieve a more accurate SIV measurement. A mechanical sector ultrasound scanner was used to obtain ultrasound speckle images from rat blood under steady and pulsatile flows. The effects of the image-enhancement techniques on SIV analysis were evaluated by comparing image intensities, velocities, and cross-correlation maps. The velocity profiles and wall shear rate (WSR) obtained from RBC suspension images were compared with the analytical solution for validation. In addition, the image-enhancement techniques were applied to in vivo measurement of blood flow in human vein. The experimental results of both in vitro and in vivo SIV measurements show that the intensity gradient in heterogeneous speckles has substantial influence on the cross-correlation analysis. The image-enhancement techniques used in this study can minimize errors encountered in ultrasound SIV measurement in which RBCs are used as flow

  12. Speckle pattern processing by digital image correlation

    Directory of Open Access Journals (Sweden)

    Gubarev Fedor

    2016-01-01

    Full Text Available Testing the method of speckle pattern processing based on the digital image correlation is carried out in the current work. Three the most widely used formulas of the correlation coefficient are tested. To determine the accuracy of the speckle pattern processing, test speckle patterns with known displacement are used. The optimal size of a speckle pattern template used for determination of correlation and corresponding the speckle pattern displacement is also considered in the work.

  13. A new Speckle Imager and speckle observations at SHAO

    Science.gov (United States)

    Ding, Yuanyuan; Li, Kexin; Chen, Zhendong

    2015-08-01

    Speckle interferometry is achieved by the integration of a series of short-exposure images of the object. It has been the method of choice for high-resolution observations of binary stars. It has yielded thousands of excellent angular separations and position angles. This technique can easily be actualized because it doesn’t need exploration and revision system for wavefront. So it is widely used in observational astronomy, especially for observing binary stars. Recently, the research shows that it also can provide high-resolution satellite image.Speckle imaging of binary stars carried out by the research team of Shanghai Astronomical Observatory (SHAO) from 2006, and we have got some valuable results. With the increasing urbanization, the night sky background getting brighter at Sheshan area, the former speckle imager can't meet the needs of the observation experiment. In the years 2013-2014, a new speckle imager was developed at SHAO, we called it as NSIS. It is a speckle imaging system that use Ultra897 EMCCD as the image recording device. Short exposure images are recorded by this device at a 1.56-m telescope. Collimating lens and imaging lens are adopted for magnification, and the space between two lens can be changed which is set for the filter and Risley prisms or other future use. Construction of NSIS has been completed at SHAO, and more than twenty binary stars were observed in 2014. The results shows that the detection capability of the new imager is stronger than the original one. At present, the magnitude of the faintest star we observed is 7.67. In the future, we will observe more binary stars fainter than 8.In this paper, we will give the description of system design and the observations of binary stars. , The image reconstruction and initial results will be presented too.

  14. Speckle Suppression Method for SAR Image

    Directory of Open Access Journals (Sweden)

    Jiming Guo

    2013-04-01

    Full Text Available In this study, a new speckle reduction method was proposed in terms of by Bidimensional Empirical Mode Decomposition (BEMD. In this method, the SAR image containing speckle noise was decomposed into a number of elementary components by using BEMD and then the extremal points are done the boundary equivalent extension after screening and the residual continue to be done the boundary equivalent extension until screening is completed, finally, the image was reconstructed, which reduced the speckle noise. Experimental results show that this method has good effect on suppressing speckle noise, compared to the average filter, median filter and gaussian filter and has advantages of sufficiently retaining edge and detail information while suppressing speckle noise.

  15. Phase retrieval from speckle images.

    Science.gov (United States)

    Rondeau, Xavier; Thiébaut, Eric; Tallon, Michel; Foy, Renaud

    2007-10-01

    In ground-based astronomy, the inverse problem of phase retrieval from speckle images is a means to calibrate static aberrations for correction by active optics. It can also be used to sense turbulent wavefronts. However, the number of local minima drastically increases with the turbulence strength, mainly because of phase wrapping ambiguities. Multifocal phase diversity has been considered to overcome some ambiguities of the phase retrieval problem. We propose an effective algorithm for phase retrieval from a single focused image. Our algorithm makes use of a global optimization strategy and an automatically tuned smoothness prior to overcome local minima and phase degeneracies. We push the limit of D/r(0)=4 achieved by Irwan and Lane [J. Opt. Soc. Am. A.15, 2302 (1998)] up to D/r(0)=11, which is a major improvement owing to the drastic increase in the problem complexity. We estimate the performances of our approach from consistent simulations for different turbulence strengths and noise levels (down to 1500 photons per image). We also investigate the benefit of temporal correlation.

  16. Enhanced Video Surveillance (EVS) with speckle imaging

    Energy Technology Data Exchange (ETDEWEB)

    Carrano, C J

    2004-01-13

    Enhanced Video Surveillance (EVS) with Speckle Imaging is a high-resolution imaging system that substantially improves resolution and contrast in images acquired over long distances. This technology will increase image resolution up to an order of magnitude or greater for video surveillance systems. The system's hardware components are all commercially available and consist of a telescope or large-aperture lens assembly, a high-performance digital camera, and a personal computer. The system's software, developed at LLNL, extends standard speckle-image-processing methods (used in the astronomical community) to solve the atmospheric blurring problem associated with imaging over medium to long distances (hundreds of meters to tens of kilometers) through horizontal or slant-path turbulence. This novel imaging technology will not only enhance national security but also will benefit law enforcement, security contractors, and any private or public entity that uses video surveillance to protect their assets.

  17. High speed perfusion imaging based on laser speckle fluctuations

    NARCIS (Netherlands)

    Draijer, Matthijs Johannes

    2010-01-01

    Noninvasive methods to visualize blood flow in tissue are important in the clinical environment. Most methods use dynamic speckles to measure the level of perfusion. The most well-known techniques based on these speckle patterns are laser Doppler perfusion imaging (LDPI) and laser speckle contrast a

  18. Speckle temporal stability in XAO coronagraphic images II. Refine model for quasi-static speckle temporal evolution for VLT/SPHERE

    CERN Document Server

    Martinez, P; Costille, A; Sauvage, J F; Dohlen, K; Puget, P; Beuzit, J L

    2013-01-01

    Observing sequences have shown that the major noise source limitation in high-contrast imaging is due to the presence of quasi-static speckles. The timescale on which quasi-static speckles evolve, is determined by various factors, among others mechanical or thermal deformations. Understanding of these time-variable instrumental speckles, and especially their interaction with other aberrations, referred to as the pinning effect, is paramount for the search of faint stellar companions. The temporal evolution of quasi-static speckles is for instance required for a quantification of the gain expected when using angular differential imaging (ADI), and to determine the interval on which speckle nulling techniques must be carried out. Following an early analysis of a time series of adaptively corrected, coronagraphic images obtained in a laboratory condition with the High-Order Test bench (HOT) at ESO Headquarters, we confirm our results with new measurements carried out with the SPHERE instrument during its final t...

  19. A Novel Speckle Filter for SAR Images Based on Informationtheoretic Heterogeneity Measurements

    Institute of Scientific and Technical Information of China (English)

    Chen Jie; Zhu Jing; Li Chunsheng; Zhou Yinqing

    2009-01-01

    Most adaptive speckle filters are based on the local coefficient of variation, which serves to measure the heterogeneity of synthetic aperture radar (SAR) images. However, the sensitivity of the measurements to speckle and noise of SAR images would greatly deteriorate the speckle reduction. This article, based upon the information theory, presents a novel parameter for the heterogeneity measurement as a general index to quantitate the SAR image heterogeneity. Further, as a new speckle reduction algorithm based on the aforesaid quantitative heterogeneity measurements, it puts forward a heterogeneity-based speckle reduction filter (HBSRF), which uses the information-theoretic heterogeneity measurements as a criterion to classify the SAR images as belonging to homogeneous or heterogeneous regions. Then the finite iteration procedure and edge detection algorithms are adopted to strike the best balance between speckle reduction and edge preservation. The results from the computer simulation have demonstrated that the proposed effective method is superior to the conventional speckle filters based on the local coefficient of variation both in textural preservation and speckle reduction.

  20. Software phantom with realistic speckle modeling for validation of image analysis methods in echocardiography

    Science.gov (United States)

    Law, Yuen C.; Tenbrinck, Daniel; Jiang, Xiaoyi; Kuhlen, Torsten

    2014-03-01

    Computer-assisted processing and interpretation of medical ultrasound images is one of the most challenging tasks within image analysis. Physical phenomena in ultrasonographic images, e.g., the characteristic speckle noise and shadowing effects, make the majority of standard methods from image analysis non optimal. Furthermore, validation of adapted computer vision methods proves to be difficult due to missing ground truth information. There is no widely accepted software phantom in the community and existing software phantoms are not exible enough to support the use of specific speckle models for different tissue types, e.g., muscle and fat tissue. In this work we propose an anatomical software phantom with a realistic speckle pattern simulation to _ll this gap and provide a exible tool for validation purposes in medical ultrasound image analysis. We discuss the generation of speckle patterns and perform statistical analysis of the simulated textures to obtain quantitative measures of the realism and accuracy regarding the resulting textures.

  1. Speckle Scanning Based X-ray Imaging

    CERN Document Server

    Berujon, Sebastien

    2015-01-01

    The X-ray near field speckle scanning concept is an approach recently introduced to obtain absorption, phase and darkfield images of a sample. In this paper, we demonstrate ways of recovering from a sample its ultra-small angle X-ray scattering distribution using numerical deconvolution, and the 2D phase gradient signal from random step scans, the latter being used to elude the flat field correction error. Each feature is explained theoretically and demonstrated experimentally at a synchrotron X-ray facility.

  2. The Coherent Speckle Suppression Method in SAR image Based on Contourlet Domain Adaptive BivaShrink Model%基于Contourlet变换的自适应SAR图像相干斑噪声抑制算法

    Institute of Scientific and Technical Information of China (English)

    王文波; 张晓东; 费浦生; 羿旭明

    2009-01-01

    In order to preserve the textural feature affected by multiplicative speckle in high resolution synthetic aperture radar (SAR) images, a despeckling metod, based on contourlet domain adaptive BivaShrink denoising model, is proposed to suppress the speckle in SAR images. By calculating the variance homogeneous measurement and local energy ratio, the shape and size of variance estimating windows are determined adaptively, and then the variance of original images can be estimated optimally. Expriments show that the proposed algorithm performs better on not only speckle reduction but also preservation of structural detail information than wavelet BivaShrink algorithm and contourlet threshold algorithm. Visual effect and experimental numerical index both are improved apparently.%为了保持高岛分辨率合成孔径雷达(SAR)图像中的纹理结构,提出了一种基于BivaShrink模型的Contourlet 域SAR图像相干斑噪声抑制算法.联合当前层和父层的Contourlet系数,通过计算局部方差一致性范数和区域能量比,自适应地确定方差估计区域的形状和大小.从而对原始图像方差进行最优估计.实验结果表明,算法在噪声的去除和结构信息等细节的保持上均不同程度的优于小波BivaShrink去噪算法和Contourlet 阈值去噪算法,主观效果和数值指标都有较好改进.

  3. Stick Based Speckle Reduction for Real-Time Processing of OCT Images on an FPGA

    Directory of Open Access Journals (Sweden)

    H. Luecken

    2007-01-01

    Full Text Available This paper presents an FPGA based real-time implementation of an adaptive speckle reduction algorithm. Applied to the log-compressed image of a high-resolution optical coherence tomography (OCT system, all related signal processing steps from envelope detection to VGA video signal generation are executed on a single chip. Images from measured OCT data show that the chosen algorithm produces a smooth, detailed image with fewer image artifacts than comparable approaches. An estimation of the hardware effort, the possible throughput rate and the resulting image frame rate is given for different window sizes used here in speckle reduction. 

  4. Artificial incoherent speckles enable precision astrometry and photometry in high-contrast imaging

    CERN Document Server

    Jovanovic, Nemanja; Martinache, Frantz; Pathak, Prashant; Hagelberg, Janis; Kudo, Tomoyuki

    2015-01-01

    State-of-the-art coronagraphs employed on extreme adaptive optics enabled instruments, are constantly improving the contrast detection limit for companions at ever closer separations to the host star. In order to constrain their properties and ultimately compositions, it is important to precisely determine orbital parameters and contrasts with respect to the stars they orbit. This can be difficult in the post coronagraphic image plane, as by definition the central star has been occulted by the coronagraph. We demonstrate the flexibility of utilizing the deformable mirror in the adaptive optics system in SCExAO to generate a field of speckles for the purposes of calibration. Speckles can be placed up to $22.5~\\lambda/D$ from the star, with any position angle, brightness and abundance required. Most importantly, we show that a fast modulation of the added speckle phase, between $0$ and $\\pi$, during a long science integration renders these speckles effectively incoherent with the underlying halo. We quantitativ...

  5. Assessment of speckle-pattern quality in digital image correlation based on gray intensity and speckle morphology

    Science.gov (United States)

    Park, Jihyuk; Yoon, Sungsik; Kwon, Tae-Hyun; Park, Kyoungsoo

    2017-04-01

    In digital image correlation (DIC), speckle patterns are generated on the surface of a specimen to resolve uniqueness issues. Thus, speckle patterns significantly affect the accuracy of image correlation. To assess the quality of speckle patterns, the standard deviation of gray intensities within each speckle (SDGIS) is introduced as a new metric. On the basis of the cumulative distribution of SDGIS, speckle-pattern quality measurement (ρ) is proposed, which integrates the features of gray intensity and speckle morphology. Twelve speckle patterns are generated by changing the spraying time and nozzle sizes of an airbrush because these are associated with the speckle volume fraction and speckle size, respectively. In addition, three displacement fields are used to investigate the effects of speckle patterns on the accuracy of the DIC results. For the 12 speckle images associated with the three displacement fields, the correlation results demonstrate that the proposed speckle-pattern quality measurement is inversely proportional to the averaged error of the subset method. This is statistically confirmed by evaluating the correlation coefficient and p-value. Furthermore, the error of the subset method is more affected by speckle patterns than the subset size when the subset size is sufficiently large.

  6. FOCAL PLANE WAVEFRONT SENSING USING RESIDUAL ADAPTIVE OPTICS SPECKLES

    Energy Technology Data Exchange (ETDEWEB)

    Codona, Johanan L.; Kenworthy, Matthew, E-mail: jlcodona@gmail.com [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2013-04-20

    Optical imperfections, misalignments, aberrations, and even dust can significantly limit sensitivity in high-contrast imaging systems such as coronagraphs. An upstream deformable mirror (DM) in the pupil can be used to correct or compensate for these flaws, either to enhance the Strehl ratio or suppress the residual coronagraphic halo. Measurement of the phase and amplitude of the starlight halo at the science camera is essential for determining the DM shape that compensates for any non-common-path (NCP) wavefront errors. Using DM displacement ripples to create a series of probe and anti-halo speckles in the focal plane has been proposed for space-based coronagraphs and successfully demonstrated in the lab. We present the theory and first on-sky demonstration of a technique to measure the complex halo using the rapidly changing residual atmospheric speckles at the 6.5 m MMT telescope using the Clio mid-IR camera. The AO system's wavefront sensor measurements are used to estimate the residual wavefront, allowing us to approximately compute the rapidly evolving phase and amplitude of speckle halo. When combined with relatively short, synchronized science camera images, the complex speckle estimates can be used to interferometrically analyze the images, leading to an estimate of the static diffraction halo with NCP effects included. In an operational system, this information could be collected continuously and used to iteratively correct quasi-static NCP errors or suppress imperfect coronagraphic halos.

  7. Portable laser speckle perfusion imaging system based on digital signal processor.

    Science.gov (United States)

    Tang, Xuejun; Feng, Nengyun; Sun, Xiaoli; Li, Pengcheng; Luo, Qingming

    2010-12-01

    The ability to monitor blood flow in vivo is of major importance in clinical diagnosis and in basic researches of life science. As a noninvasive full-field technique without the need of scanning, laser speckle contrast imaging (LSCI) is widely used to study blood flow with high spatial and temporal resolution. Current LSCI systems are based on personal computers for image processing with large size, which potentially limit the widespread clinical utility. The need for portable laser speckle contrast imaging system that does not compromise processing efficiency is crucial in clinical diagnosis. However, the processing of laser speckle contrast images is time-consuming due to the heavy calculation for enormous high-resolution image data. To address this problem, a portable laser speckle perfusion imaging system based on digital signal processor (DSP) and the algorithm which is suitable for DSP is described. With highly integrated DSP and the algorithm, we have markedly reduced the size and weight of the system as well as its energy consumption while preserving the high processing speed. In vivo experiments demonstrate that our portable laser speckle perfusion imaging system can obtain blood flow images at 25 frames per second with the resolution of 640 × 480 pixels. The portable and lightweight features make it capable of being adapted to a wide variety of application areas such as research laboratory, operating room, ambulance, and even disaster site.

  8. Temporal ghost imaging with pseudo-thermal speckle light

    Science.gov (United States)

    Devaux, Fabrice; Phan Huy, Kien; Denis, Séverine; Lantz, Eric; Moreau, Paul-Antoine

    2017-02-01

    We report ghost imaging of a single non-reproducible temporal signal with kHz resolution by using pseudo-thermal speckle light patterns and a single detector array with a million of pixels working without any temporal resolution. A set of speckle patterns is generated deterministically at a sampling rate of tens kHz, multiplied by the temporal signal and time integrated in a single shot by the camera. The temporal information is retrieved by computing the spatial intensity correlations between this time integrated image and each speckle pattern of the set.

  9. Temporal ghost imaging with pseudo-thermal speckle light

    CERN Document Server

    Devaux, Fabrice; Moreau, Paul-Antoine; Denis, Severine; Lantz, Eric

    2016-01-01

    We report ghost imaging of a single non-reproducible temporal signal in the range of tens kHz by using pseudo-thermal speckle light patterns and a single detector array with a million of pixels working without any temporal resolution. A set of speckle patterns is generated deterministically at radio-frequency rate, multiplied by the temporal signal and time integrated in a single shot by the camera. The temporal information is retrieved by computing the spatial intensity correlations between this time integrated image and each speckle pattern of the set.

  10. Phase-processing as a tool for speckle reduction in pulse-echo images

    DEFF Research Database (Denmark)

    Healey, AJ; Leeman, S; Forsberg, F

    1991-01-01

    . Traditional speckle reduction procedures regard speckle correction as a stochastic process and trade image smoothing (resolution loss) for speckle reduction. Recently, a new phase acknowledging technique has been proposed that is unique in its ability to correct for speckle interference with no image......Due to the coherent nature of conventional ultrasound medical imaging systems interference artefacts occur in pulse echo images. These artefacts are generically termed 'speckle'. The phenomenon may severely limit low contrast resolution with clinically relevant information being obscured...

  11. A Level Set Filter for Speckle Reduction in SAR Images

    OpenAIRE

    Huang Bo; Li Hongga; Huang Xiaoxia

    2010-01-01

    Despite much effort and significant progress in recent years, speckle removal for Synthetic Aperture Radar (SAR) image still is a challenging problem in image processing. Unlike the traditional noise filters, which are mainly based on local neighborhood statistical average or frequencies transform, in this paper, we propose a speckle reduction method based on the theory of level set, one form of curvature flow propagation. Firstly, based on partial differential equation, the Lee filter can b...

  12. A Level Set Filter for Speckle Reduction in SAR Images

    Directory of Open Access Journals (Sweden)

    Xiaoxia Huang

    2010-01-01

    Full Text Available Despite much effort and significant progress in recent years, speckle removal for Synthetic Aperture Radar (SAR image still is a challenging problem in image processing. Unlike the traditional noise filters, which are mainly based on local neighborhood statistical average or frequencies transform, in this paper, we propose a speckle reduction method based on the theory of level set, one form of curvature flow propagation. Firstly, based on partial differential equation, the Lee filter can be cast as a formulation of anisotropic diffusion function; furthermore, we continued to deduce it into a level set formulation. Level set flow into the method allows the front interface to propagate naturally with topological changes, where the speed is proportional to the curvature of the intensity contours in an image. Hence, small speckle will disappear quickly, while large scale interfaces will be slow to evolve. Secondly, for preserving finer detailed structures in images when smoothing the speckle, the evolution is switched between minimum or maximum curvature speed depending on the scale of speckle. The proposed method has been illustrated by experiments on simulation image and ERS-2 SAR images under different circumstances. Its advantages over the traditional speckle reduction filter approaches have also been demonstrated.

  13. A Level Set Filter for Speckle Reduction in SAR Images

    Science.gov (United States)

    Li, Hongga; Huang, Bo; Huang, Xiaoxia

    2010-12-01

    Despite much effort and significant progress in recent years, speckle removal for Synthetic Aperture Radar (SAR) image still is a challenging problem in image processing. Unlike the traditional noise filters, which are mainly based on local neighborhood statistical average or frequencies transform, in this paper, we propose a speckle reduction method based on the theory of level set, one form of curvature flow propagation. Firstly, based on partial differential equation, the Lee filter can be cast as a formulation of anisotropic diffusion function; furthermore, we continued to deduce it into a level set formulation. Level set flow into the method allows the front interface to propagate naturally with topological changes, where the speed is proportional to the curvature of the intensity contours in an image. Hence, small speckle will disappear quickly, while large scale interfaces will be slow to evolve. Secondly, for preserving finer detailed structures in images when smoothing the speckle, the evolution is switched between minimum or maximum curvature speed depending on the scale of speckle. The proposed method has been illustrated by experiments on simulation image and ERS-2 SAR images under different circumstances. Its advantages over the traditional speckle reduction filter approaches have also been demonstrated.

  14. Laser speckle-imaging of blood microcirculation in the brain cortex of laboratory rats in stress

    Energy Technology Data Exchange (ETDEWEB)

    Vilensky, M A; Semyachkina-Glushkovskaya, Oxana V; Timoshina, P A; Kuznetsova, Jana V; Semyachkin-Glushkovskii, I A; Agafonov, Dmitry N; Tuchin, Valerii V

    2012-06-30

    The results of experimental approbation of the method of laser full-field speckle-imaging for monitoring the changes in blood microcirculation state of the brain cortex of laboratory rats under the conditions of developing stroke and administration of vasodilating and vasoconstrictive agents are presented. The studies aimed at the choice of the optimal conditions of speckle-image formation and recording were performed and the software implementing an adaptive algorithm for processing the data of measurements was created. The transfer of laser radiation to the probed region of the biotissue was implemented by means of a silica-polymer optical fibre. The problems and prospects of speckle-imaging of cerebral microcirculation of blood in laboratory and clinical conditions are discussed.

  15. Speckle Image Enhancement Using Recorded Shack-Hartmann Wavefront Sensor Data

    Science.gov (United States)

    Lobb, Janos

    Even today, when many large telescopes have high performance Adaptive Optics systems, speckle imaging is as important as ever to get useful high-spatial-resolution information about important astronomical objects, particularly in the detection of stellar companions of exoplanet host stars. Any methods that can extend the reach of speckle imaging to objects that are fainter or farther away would be welcome additions to the range of techniques for high-resolution imaging. In the first part of the thesis I describe a method to do a selection of frames of an image stack from an astronomical observation done by speckle imaging, using specific Renyi entropy as a classification, that is, a decision-making tool. With this automatic selection process the signal-to-noise ratio can be improved between 15-20% in some cases, although no method could consistently provide improvement in all cases. Another implication of the study is that, by using entropy as a criterion, a sub-stack of 10 to 40% of the "best" frames in a speckle stack can often demonstrate a signal-to-noise ratio comparable to a full stack, which could minimize computation time of the reconstructed image, making it feasible to compute at the telescope. In the second part of the thesis I describe how the data from a Shack-Hartmann sensor, as an a priori information source, can be used to create a better instantaneous Point-Spread-Function (PSF) that can be used to preprocess speckle data, leading to a scientific image with higher S/N and better detection limits for faint companions. This is of some importance in certain science applications of speckle imaging observations, such as the accurate measurement of the radii of exoplanets.

  16. BL_Wiener Denoising Method for Removal of Speckle Noise in Ultrasound Image

    Directory of Open Access Journals (Sweden)

    Suhaila Sari

    2015-02-01

    Full Text Available Medical imaging techniques are extremely important tools in medical diagnosis. One of these important imaging techniques is ultrasound imaging. However, during ultrasound image acquisition process, the quality of image can be degraded due to corruption by speckle noise. The enhancement of ultrasound images quality from the 2D ultrasound imaging machines is expected to provide medical practitioners more reliable medical images in their patients’ diagnosis. However, developing a denoising technique which could remove noise effectively without eliminating the image’s edges and details is still an ongoing issue. The objective of this paper is to develop a new method that is capable to remove speckle noise from the ultrasound image effectively. Therefore, in this paper we proposed the utilization of Bilateral Filter and Adaptive Wiener Filter (BL_Wiener denoising method for images corrupted by speckle noise. Bilateral Filter is a non-linear filter effective in removing noise, while Adaptive Wiener Filter balances the tradeoff between inverse filtering and noise smoothing by removing additive noise while inverting blurring. From our simulation results, it is found that the BL_Wiener method has improved between 0.89 [dB] to 3.35 [dB] in terms of PSNR for test images in different noise levels in comparison to conventional methods.

  17. Three Dimensional Imaging with Multiple Wavelength Speckle Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Bernacki, Bruce E.; Cannon, Bret D.; Schiffern, John T.; Mendoza, Albert

    2014-05-28

    We present the design, modeling, construction, and results of a three-dimensional imager based upon multiple-wavelength speckle interferometry. A surface under test is illuminated with tunable laser light in a Michelson interferometer configuration while a speckled image is acquired at each laser frequency step. The resulting hypercube is Fourier transformed in the frequency dimension and the beat frequencies that result map the relative offsets of surface features. Synthetic wavelengths resulting from the laser tuning can probe features ranging from 18 microns to hundreds of millimeters. Three dimensional images will be presented along with modeling results.

  18. Improving visibility in photoacoustic imaging using dynamic speckle illumination

    CERN Document Server

    Gateau, Jérôme; Katz, Ori; Gigan, Sylvain; Bossy, Emmanuel

    2013-01-01

    In high-frequency photoacoustic imaging with uniform illumination, homogenous photo-absorbing structures may be invisible because of their large size or limited-view issues. Here we show that it is possible to reveal features, which are normally invisible with a photoacoustic system comprised of a 20MHz linear ultrasound array, by exploiting dynamic speckle illumination. We demonstrate imaging of a \\emptyset 5mm absorbing cylinder and a 30 \\mu m black thread arranged in a complex shape. The hidden structures are directly retrieved from photoacoustic images recorded for different random speckle illuminations of the phantoms by assessing the variation in the value of each pixel over the illumination patterns.

  19. THE FAST FIXED-POINT ALGORITHM FOR SPECKLE REDUCTION OF POLARIMETRIC SAR IMAGE

    Institute of Scientific and Technical Information of China (English)

    Fu Yusheng; Chen Xiaoning; Pi Yiming; Hou Yinming

    2005-01-01

    In this letter, a simple and efficient method of image speckle reduction for polarimetric SAR is put forward. It is based on the fast fixed-point ICA (Independent Component Analysis) algorithm of orthogonal and symmetric matrix. Simulation experiment is carried out to separate speckle noise from the polarimetric SAR images, and it indicates that this algorithm has high convergency speed and stability, the image speckle noise is reduced effectively and the speckle index is low, and the image quality is improved obviously.

  20. Accelerated speckle imaging with the ATST visible broadband imager

    Science.gov (United States)

    Wöger, Friedrich; Ferayorni, Andrew

    2012-09-01

    The Advanced Technology Solar Telescope (ATST), a 4 meter class telescope for observations of the solar atmosphere currently in construction phase, will generate data at rates of the order of 10 TB/day with its state of the art instrumentation. The high-priority ATST Visible Broadband Imager (VBI) instrument alone will create two data streams with a bandwidth of 960 MB/s each. Because of the related data handling issues, these data will be post-processed with speckle interferometry algorithms in near-real time at the telescope using the cost-effective Graphics Processing Unit (GPU) technology that is supported by the ATST Data Handling System. In this contribution, we lay out the VBI-specific approach to its image processing pipeline, put this into the context of the underlying ATST Data Handling System infrastructure, and finally describe the details of how the algorithms were redesigned to exploit data parallelism in the speckle image reconstruction algorithms. An algorithm re-design is often required to efficiently speed up an application using GPU technology; we have chosen NVIDIA's CUDA language as basis for our implementation. We present our preliminary results of the algorithm performance using our test facilities, and base a conservative estimate on the requirements of a full system that could achieve near real-time performance at ATST on these results.

  1. Speckle suppression and companion detection using coherent differential imaging

    CERN Document Server

    Bottom, Michael; Bartos, Randall D; Shelton, J Chris; Serabyn, Eugene

    2016-01-01

    Residual speckles due to aberrations arising from optical errors after the split between the wavefront sensor and the science camera path are the most significant barriers to imaging extrasolar planets. While speckles can be suppressed using the science camera in conjunction with the deformable mirror, this requires knowledge of the phase of the electric field in the focal plane. We describe a method which combines a coronagraph with a simple phase-shifting interferometer to measure and correct speckles in the full focal plane. We demonstrate its initial use on the Stellar Double Coronagraph at the Palomar Observatory. We also describe how the same hardware can be used to distinguish speckles from true companions by measuring the coherence of the optical field in the focal plane. We present results observing the brown dwarf HD 49197b with this technique, demonstrating the ability to detect the presence of a companion even when it is buried in the speckle noise, without the use of any standard "calibration" te...

  2. Noise in laser speckle correlation and imaging techniques

    CERN Document Server

    Skipetrov, Sergey E; Cerbino, Roberto; Zakharov, Pavel; Weber, Bruno; Scheffold, Frank

    2010-01-01

    We study the noise of the intensity variance and of the intensity correlation and structure functions measured in light scattering from a random medium in the case when these quantities are obtained by averaging over a finite number N of pixels of a digital camera. We show that the noise scales as 1/N in all cases and that it is sensitive to correlations of signals corresponding to adjacent pixels as well as to the effective time averaging (due to the finite sampling time) and spatial averaging (due to the finite pixel size). Our results provide a guide to estimation of noise level in such applications as the multi-speckle dynamic light scattering, time-resolved correlation spectroscopy, speckle visibility spectroscopy, laser speckle imaging etc.

  3. Focal Plane Wavefront Sensing using Residual Adaptive Optics Speckles

    CERN Document Server

    Codona, Johanan L

    2013-01-01

    Optical imperfections, misalignments, aberrations, and even dust can significantly limit sensitivity in high-contrast imaging systems such as coronagraphs. An upstream deformable mirror (DM) in the pupil can be used to correct or compensate for these flaws, either to enhance Strehl ratio or suppress residual coronagraphic halo. Measurement of the phase and amplitude of the starlight halo at the science camera is essential for determining the DM shape that compensates for any non-common-path (NCP) wavefront errors. Using DM displacement ripples to create a series of probe and anti-halo speckles in the focal plane has been proposed for space-based coronagraphs and successfully demonstrated in the lab. We present the theory and first on-sky demonstration of a technique to measure the complex halo using the rapidly-changing residual atmospheric speckles at the 6.5m MMT telescope using the Clio mid-IR camera. The AO system's wavefront sensor (WFS) measurements are used to estimate the residual wavefront, allowing ...

  4. Strain Mapping in Metals Using Ultrasonic Array Speckle Images

    Science.gov (United States)

    Bowler, A. I.; Drinkwater, B. W.; Wilcox, P. D.

    2009-03-01

    The full-field non-destructive measurement of internal displacement and strain fields is of interest in many engineering applications. This paper describes an approach to measuring internal displacements and strains in metals which uses the correlation of ultrasonic speckle images of the internal structure of the material. This has the key advantage over optical surface displacement and strain measurement techniques in that internal information can be obtained. Experiments are described which use a 1-D ultrasonic array to map 2-D displacement fields for uniform translation and uniaxial tension of a metallic bar. The full matrix of transmit-receive signals from the array was post-processed to generate speckle images using a Fourier-domain imaging algorithm. Block-search cross-correlation was used to find the displacements of small sub-images corresponding to regions within the bar. Potential applications include characterising crack networks and creep damage detection.

  5. Super-resolution photoacoustic fluctuation imaging with multiple speckle illumination

    CERN Document Server

    Chaigne, Thomas; Allain, Marc; Katz, Ori; Gigan, Sylvain; Sentenac, Anne; Bossy, Emmanuel

    2015-01-01

    In deep tissue photoacoustic imaging, the spatial resolution is inherently limited by acoustic diffraction. Moreover, as the ultrasound attenuation increases with frequency, resolution is often traded-off for penetration depth. Here we report on super-resolution photoacoustic imaging by use of multiple speckle illumination. Specifically, we show that the analysis of second-order fluctuations of the photoacoustic images combined with image deconvolution enables resolving optically absorbing structures beyond the acoustic diffraction limit. A resolution increase of almost a factor 2 is demonstrated experimentally. Our method introduces a new framework that could potentially lead to deep tissue photoacoustic imaging with sub-acoustic resolution.

  6. Quantitative blood flow velocity imaging using laser speckle flowmetry

    Science.gov (United States)

    Nadort, Annemarie; Kalkman, Koen; van Leeuwen, Ton G.; Faber, Dirk J.

    2016-04-01

    Laser speckle flowmetry suffers from a debated quantification of the inverse relation between decorrelation time (τc) and blood flow velocity (V), i.e. 1/τc = αV. Using a modified microcirculation imager (integrated sidestream dark field - laser speckle contrast imaging [SDF-LSCI]), we experimentally investigate on the influence of the optical properties of scatterers on α in vitro and in vivo. We found a good agreement to theoretical predictions within certain limits for scatterer size and multiple scattering. We present a practical model-based scaling factor to correct for multiple scattering in microcirculatory vessels. Our results show that SDF-LSCI offers a quantitative measure of flow velocity in addition to vessel morphology, enabling the quantification of the clinically relevant blood flow, velocity and tissue perfusion.

  7. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images.

    Science.gov (United States)

    Zhang, Xuming; Li, Liu; Zhu, Fei; Hou, Wenguang; Chen, Xinjian

    2014-06-01

    Optical coherence tomography (OCT) images are usually degraded by significant speckle noise, which will strongly hamper their quantitative analysis. However, speckle noise reduction in OCT images is particularly challenging because of the difficulty in differentiating between noise and the information components of the speckle pattern. To address this problem, the spiking cortical model (SCM)-based nonlocal means method is presented. The proposed method explores self-similarities of OCT images based on rotation-invariant features of image patches extracted by SCM and then restores the speckled images by averaging the similar patches. This method can provide sufficient speckle reduction while preserving image details very well due to its effectiveness in finding reliable similar patches under high speckle noise contamination. When applied to the retinal OCT image, this method provides signal-to-noise ratio improvements of >16  dB with a small 5.4% loss of similarity.

  8. Spiking cortical model-based nonlocal means method for speckle reduction in optical coherence tomography images

    Science.gov (United States)

    Zhang, Xuming; Li, Liu; Zhu, Fei; Hou, Wenguang; Chen, Xinjian

    2014-06-01

    Optical coherence tomography (OCT) images are usually degraded by significant speckle noise, which will strongly hamper their quantitative analysis. However, speckle noise reduction in OCT images is particularly challenging because of the difficulty in differentiating between noise and the information components of the speckle pattern. To address this problem, the spiking cortical model (SCM)-based nonlocal means method is presented. The proposed method explores self-similarities of OCT images based on rotation-invariant features of image patches extracted by SCM and then restores the speckled images by averaging the similar patches. This method can provide sufficient speckle reduction while preserving image details very well due to its effectiveness in finding reliable similar patches under high speckle noise contamination. When applied to the retinal OCT image, this method provides signal-to-noise ratio improvements of >16 dB with a small 5.4% loss of similarity.

  9. Twinkle Twinkle Little Star - Speckle Imaging for Exoplanet Characterization

    Science.gov (United States)

    Howell, Steve B.; Scott, Nic; Horch, Elliott

    2016-06-01

    The NASA K2 mission is finding many high-value exoplanets and world-wide follow-up is ensuing. The NASA TESS mission will soon be launched, requiring additional ground-based observations as well. As a part of the NASA-NSFNN-EXPLORE program to enable exoplanet research, our group is building two new speckle interferometry cameras for the Kitt Peak WIYN 3.5-m telescope and the Gemini-N 8-m telescope. Modeled after the successful DSSI visitor instrument that has been used at these telescopes for many years, speckle observations provide the highest resolution images available today from any ground- or space-based single telescope. They are the premier method through which small, rocky exoplanets can be validated. Available for public use in early 2017, WIYNSPKL and GEMSPKL will obtain simultaneous images in two filters with fast EMCCD readout, "speckle" and “wide-field” imaging modes, and user support for proposal writing, observing, and data reduction. We describe the new cameras, their design, and their benefits for exoplanet follow-up, characterization, and validation. Funding for this project comes from the NASA Exoplanet Exploration Program and NASA HQ.

  10. Speckle lifetime in XAO coronagraphic images: temporal evolution of SPHERE coronagraphic images

    CERN Document Server

    Milli, J; Mouill, D; Mawet, D; Girard, J G; Vigan, A; Boccaletti, A; Kasper, M; Wahhaj, Z; Lagrange, A -M; Beuzit, J -L; Fusco, T; Sauvage, J -F; Galicher, R

    2016-01-01

    The major source of noise in high-contrast imaging is the presence of slowly evolving speckles that do not average with time. The temporal stability of the point-spread-function (PSF) is therefore critical to reach a high contrast with extreme adaptive optics (xAO) instruments. Understanding on which timescales the PSF evolves and what are the critical parameters driving the speckle variability allow to design an optimal observing strategy and data reduction technique to calibrate instrumental aberrations and reveal faint astrophysical sources. We have obtained a series of 52 min, AO-corrected, coronagraphically occulted, high-cadence (1.6Hz), H-band images of the star HR 3484 with the SPHERE (Spectro-Polarimeter High-contrast Exoplanet REsearch instrument on the VLT. This is a unique data set from an xAO instrument to study its stability on timescales as short as one second and as long as several tens of minutes. We find different temporal regimes of decorrelation. We show that residuals from the atmospheric...

  11. Handheld, point-of-care laser speckle imaging

    Science.gov (United States)

    Farraro, Ryan; Fathi, Omid; Choi, Bernard

    2016-09-01

    Laser speckle imaging (LSI) enables measurement of relative changes in blood flow in biological tissues. We postulate that a point-of-care form factor will lower barriers to routine clinical use of LSI. Here, we describe a first-generation handheld LSI device based on a tablet computer. The coefficient of variation of speckle contrast was 0.05) between the measured speckle contrast values using either a handheld or mounted configuration. In vivo data collected during occlusion experiments demonstrate that a handheld LSI is capable of both quantitative and qualitative assessment of changes in blood flow. Finally, as a practical application of handheld LSI, we collected data from a 53-day-old neonate with confirmed compromised blood flow in the hand. We readily identified with LSI a region of diminished blood flow in the thumb of the affected hand. Our data collectively suggest that handheld LSI is a promising technique to enable clinicians to obtain point-of-care measurements of blood flow.

  12. Effects of photon noise on speckle image reconstruction with the Knox-Thompson algorithm. [in astronomy

    Science.gov (United States)

    Nisenson, P.; Papaliolios, C.

    1983-01-01

    An analysis of the effects of photon noise on astronomical speckle image reconstruction using the Knox-Thompson algorithm is presented. It is shown that the quantities resulting from the speckle average arre biased, but that the biases are easily estimated and compensated. Calculations are also made of the convergence rate for the speckle average as a function of the source brightness. An illustration of the effects of photon noise on the image recovery process is included.

  13. A PDE based Method for Speckle Reduction of Log-compressed Ultrasound Image

    Directory of Open Access Journals (Sweden)

    Jie Huang

    2011-04-01

    Full Text Available Speckle noise is widely existence in coherent imaging systems, such as synthetic aperture radar, sonar, ultrasound and laser imaging, and is commonly described as signal correlated. In this paper, we focus on speckle reduction problem in real ultrasound image. Unlike traditional anisotropic diffusion methods usually taking image gradient as a diffusion index, in this paper, we present a new texture based anisotropic diffusion method for speckle reduction in real ultrasound image. The results comparing our new method with other well known methods on both synthetic images and real ultrasound images are reported to show the superiority of our method in keeping important features of real ultrasound images.

  14. A laser speckle imaging technique for measuring tissue perfusion.

    Science.gov (United States)

    Forrester, Kevin R; Tulip, J; Leonard, C; Stewart, C; Bray, Robert C

    2004-11-01

    Laser Doppler imaging (LDI) has become a standard method for optical measurement of tissue perfusion, but is limited by low resolution and long measurement times. We have developed an analysis technique based on a laser speckle imaging method that generates rapid, high-resolution perfusion images. We have called it laser speckle perfusion imaging (LSPI). This paper investigates LSPI output and compares it to LDI using blood flow models designed to simulate human skin at various levels of pigmentation. Results show that LSPI parameters can be chosen such that the instrumentation exhibits a similar response to changes in red blood cell concentration (0.1%-5%, 200 microL/min) and velocity (0-800 microL/min, 1% concentration) and, given its higher resolution and quicker response time, could provide a significant advantage over LDI for some applications. Differences were observed in the LDI and LSPI response to tissue optical properties. LDI perfusion values increased with increasing tissue absorption, while LSPI perfusion values showed a slight decrease. This dependence is predictable, owing to the perfusion algorithms specific to each instrument, and, if properly compensated for, should not influence each instrument's ability to measure relative changes in tissue perfusion.

  15. Speckle reduction algorithm for laser underwater image based on curvelet transform

    Institute of Scientific and Technical Information of China (English)

    Wei Ni; Baolong Guo; Liu Yang; Peiyan Fei

    2006-01-01

    @@ Based on the analysis on the statistical model of speckle noise in laser underwater image, a novel speckle reduction algorithm using curvelet transform is proposed. Logarithmic transform is performed to transform the original multiplicative speckle noise into additive noise. An improved hard thresholding algorithm is applied in curvelet transform domain. The classical Monte-Carlo method is adopted to estimate the statistics of contourlet coefficients for speckle noise, thus determining the optimal threshold set. To further improve the visual quality of despeckling laser image, the cycle spinning technique is also utilized. Experimental results show that the proposed algorithm can achieve better performance than classical wavelet method and maintain more detail information.

  16. Constructive role of sensors nonlinearities in the acquisition of partially polarized speckle images

    Energy Technology Data Exchange (ETDEWEB)

    Delahaies, Agnes; Rousseau, David; Chapeau-Blondeau, Francois [Laboratoire d' Ingenierie des Systemes Automatises (LISA), Universite d' Angers, 62 avenue Notre Dame du Lac, 49000 Angers (France); Gindre, Denis, E-mail: david.rousseau@univ-angers.f [Laboratoire des Proprietes Optiques des Materiaux et Applications (POMA), Universite d' Angers, 2 boulevard Lavoisier, 49000 Angers (France)

    2010-02-01

    We study the impact of the level of the speckle noise on data acquisition in a partially polarized coherent imaging system with the presence of a nonlinearity in the imaging sensor characteristic. In perfectly linear acquisition conditions, due to the essentially multiplicative action of the speckle, the image contrast is unchanged as the speckle noise level increases, and so it has no impact on the quality of the acquired images. On the contrary, in nonlinear conditions the acquisition is affected by the speckle noise level. However, this effect of the speckle is not always detrimental. We show that, in definite nonlinear conditions, there is usually an optimal level of the speckle noise that leads to a maximum quality of the acquired images. We theoretically analyze such nonlinear regimes with partially polarized speckled images. We specifically exhibit the existence of an optimal speckle noise level in the interesting case of images realized only by a depolarization contrast. Illustrations are given with a simple 1-bit hard limiter and binary images. Then, we propose and discuss as perspectives an experimental optical setup to confront theory and experiment.

  17. Intraoperative multi-exposure speckle imaging of cerebral blood flow.

    Science.gov (United States)

    Richards, Lisa M; Kazmi, Sm Shams; Olin, Katherine E; Waldron, James S; Fox, Douglas J; Dunn, Andrew K

    2017-01-01

    Multiple studies have demonstrated that laser speckle contrast imaging (LSCI) has high potential to be a valuable cerebral blood flow monitoring technique during neurosurgery. However, the quantitative accuracy and sensitivity of LSCI is limited, and highly dependent on the exposure time. An extension to LSCI called multi-exposure speckle imaging (MESI) overcomes these limitations, and was evaluated intraoperatively in patients undergoing brain tumor resection. This clinical study ( n = 8) recorded multiple exposure times from the same cortical tissue area spanning 0.5-20 ms, and evaluated images individually as single-exposure LSCI and jointly using the MESI model. This study demonstrated that the MESI estimates provided the broadest flow sensitivity for sampling the flow magnitude in the human brain, closely followed by the shorter exposure times. Conservation of flow analysis on vascular bifurcations was used to validate physiological accuracy, with highly conserved flow estimates (blood flow changes after tissue cautery. Results from this study demonstrate that intraoperative MESI can be performed with high quantitative accuracy and sensitivity for cerebral blood flow monitoring.

  18. Predicting Paroxysmal Atrial Fibrillation in Cerebrovascular Ischemia Using Tissue Doppler Imaging and Speckle Tracking Echocardiography

    DEFF Research Database (Denmark)

    Olsen, Flemming Javier; Jørgensen, Peter Godsk; Møgelvang, Rasmus

    2016-01-01

    , tissue Doppler imaging (TDI), and speckle tracking. TDI was performed to acquire myocardial peak velocities during systole/ventricular contraction (global s'), early diastole/ventricular filling (global e'), and late diastole/atrial contraction (global a'). Speckle tracking was performed for myocardial...

  19. Integration of image exposure time into a modified laser speckle imaging method

    Energy Technology Data Exchange (ETDEWEB)

    RamIrez-San-Juan, J C; Salazar-Hermenegildo, N; Ramos-Garcia, R; Munoz-Lopez, J [Optics Department, INAOE, Puebla (Mexico); Huang, Y C [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA (United States); Choi, B, E-mail: jcram@inaoep.m [Beckman Laser Institute and Medical Clinic, University of California, Irvine, CA (United States)

    2010-11-21

    Speckle-based methods have been developed to characterize tissue blood flow and perfusion. One such method, called modified laser speckle imaging (mLSI), enables computation of blood flow maps with relatively high spatial resolution. Although it is known that the sensitivity and noise in LSI measurements depend on image exposure time, a fundamental disadvantage of mLSI is that it does not take into account this parameter. In this work, we integrate the exposure time into the mLSI method and provide experimental support of our approach with measurements from an in vitro flow phantom.

  20. Fast multiscale directional filter bank-based speckle mitigation in gallstone ultrasound images.

    Science.gov (United States)

    Leavline, Epiphany Jebamalar; Sutha, Shunmugam; Singh, Danasingh Asir Antony Gnana

    2014-02-01

    Speckle noise is a multiplicative type of noise commonly seen in medical and remote sensing images. It gives a granular appearance that degrades the quality of the recorded images. These speckle noise components need to be mitigated before the image is used for further processing and analysis. This paper presents a novel approach for removing granular speckle noise in gray scale images. We used an efficient multiscale image representation scheme named fast multiscale directional filter bank (FMDFB) along with simple threshold methods such as Vishushrink for image processing. It is a perfect reconstruction framework that can be used for a wide range of image processing applications because of its directionality and reduced computational complexity. The FMDFB-based speckle mitigation is appealing over other traditional multiscale approaches such as wavelets and Contourlets. Our experimental results show that the despeckling performance of the proposed method outperforms the wavelet and Contourlet-based despeckling methods.

  1. Speckle Filtering in PolSAR Images by Enhanced Wavelet Thresholding

    Science.gov (United States)

    Boutarfa, Souhila; Bouchemakh, Lynda; Smara, Youcef

    2016-08-01

    The PolSAR images are affected by a noise called speckle, which deteriorates image quality and complicates image interpretation. The polarimetric filtering is a necessary treatment prior to analysis that allows to reduce speckle and to obtain an improved image quality.In this paper, we present a polarimetric speckle filtering method based on enhancement of wavelet thresholding, hard and soft thresholding using directional coefficients improvement to reduce speckle without destroying the information. This algorithm is based on the classification of significant coefficients and applying the thresholding to obtain a better image quality.The methods are applied to the three polarimetric E-SAR images acquired on Oberpfaffenhofen area located in Munich, Germany, in P-band and the fully polarimetric RADARSAT-2 images acquired on Algiers, Algeria, in C-band.To evaluate the performance of each filter, we based it on the following criteria: smoothing homogeneous areas, preserving structural characteristics of objects and maintaining the information.

  2. Nakagami-based total variation method for speckle reduction in thyroid ultrasound images.

    Science.gov (United States)

    Koundal, Deepika; Gupta, Savita; Singh, Sukhwinder

    2016-02-01

    A good statistical model is necessary for the reduction in speckle noise. The Nakagami model is more general than the Rayleigh distribution for statistical modeling of speckle in ultrasound images. In this article, the Nakagami-based noise removal method is presented to enhance thyroid ultrasound images and to improve clinical diagnosis. The statistics of log-compressed image are derived from the Nakagami distribution following a maximum a posteriori estimation framework. The minimization problem is solved by optimizing an augmented Lagrange and Chambolle's projection method. The proposed method is evaluated on both artificial speckle-simulated and real ultrasound images. The experimental findings reveal the superiority of the proposed method both quantitatively and qualitatively in comparison with other speckle reduction methods reported in the literature. The proposed method yields an average signal-to-noise ratio gain of more than 2.16 dB over the non-convex regularizer-based speckle noise removal method, 3.83 dB over the Aubert-Aujol model, 1.71 dB over the Shi-Osher model and 3.21 dB over the Rudin-Lions-Osher model on speckle-simulated synthetic images. Furthermore, visual evaluation of the despeckled images shows that the proposed method suppresses speckle noise well while preserving the textures and fine details.

  3. Early diagnosis of teeth erosion using polarized laser speckle imaging

    Science.gov (United States)

    Nader, Christelle Abou; Pellen, Fabrice; Loutfi, Hadi; Mansour, Rassoul; Jeune, Bernard Le; Brun, Guy Le; Abboud, Marie

    2016-07-01

    Dental erosion starts with a chemical attack on dental tissue causing tooth demineralization, altering the tooth structure and making it more sensitive to mechanical erosion. Medical diagnosis of dental erosion is commonly achieved through a visual inspection by the dentist during dental checkups and is therefore highly dependent on the operator's experience. The detection of this disease at preliminary stages is important since, once the damage is done, cares become more complicated. We investigate the difference in light-scattering properties between healthy and eroded teeth. A change in light-scattering properties is observed and a transition from volume to surface backscattering is detected by means of polarized laser speckle imaging as teeth undergo acid etching, suggesting an increase in enamel surface roughness.

  4. Speckle-metric-optimization-based adaptive optics for laser beam projection and coherent beam combining.

    Science.gov (United States)

    Vorontsov, Mikhail; Weyrauch, Thomas; Lachinova, Svetlana; Gatz, Micah; Carhart, Gary

    2012-07-15

    Maximization of a projected laser beam's power density at a remotely located extended object (speckle target) can be achieved by using an adaptive optics (AO) technique based on sensing and optimization of the target-return speckle field's statistical characteristics, referred to here as speckle metrics (SM). SM AO was demonstrated in a target-in-the-loop coherent beam combining experiment using a bistatic laser beam projection system composed of a coherent fiber-array transmitter and a power-in-the-bucket receiver. SM sensing utilized a 50 MHz rate dithering of the projected beam that provided a stair-mode approximation of the outgoing combined beam's wavefront tip and tilt with subaperture piston phases. Fiber-integrated phase shifters were used for both the dithering and SM optimization with stochastic parallel gradient descent control.

  5. Simulations of multi-contrast x-ray imaging using near-field speckles

    Energy Technology Data Exchange (ETDEWEB)

    Zdora, Marie-Christine [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom and Department of Physics & Astronomy, University College London, London, WC1E 6BT (United Kingdom); Thibault, Pierre [Department of Physics & Astronomy, University College London, London, WC1E 6BT (United Kingdom); Herzen, Julia; Pfeiffer, Franz [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Zanette, Irene [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom); Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany)

    2016-01-28

    X-ray dark-field and phase-contrast imaging using near-field speckles is a novel technique that overcomes limitations inherent in conventional absorption x-ray imaging, i.e. poor contrast for features with similar density. Speckle-based imaging yields a wealth of information with a simple setup tolerant to polychromatic and divergent beams, and simple data acquisition and analysis procedures. Here, we present a simulation software used to model the image formation with the speckle-based technique, and we compare simulated results on a phantom sample with experimental synchrotron data. Thorough simulation of a speckle-based imaging experiment will help for better understanding and optimising the technique itself.

  6. Momentum transfer Monte Carlo model for the simulation of laser speckle contrast imaging (Conference Presentation)

    Science.gov (United States)

    Regan, Caitlin; Hayakawa, Carole K.; Choi, Bernard

    2016-03-01

    Laser speckle imaging (LSI) enables measurement of relative blood flow in microvasculature and perfusion in tissues. To determine the impact of tissue optical properties and perfusion dynamics on speckle contrast, we developed a computational simulation of laser speckle contrast imaging. We used a discrete absorption-weighted Monte Carlo simulation to model the transport of light in tissue. We simulated optical excitation of a uniform flat light source and tracked the momentum transfer of photons as they propagated through a simulated tissue geometry. With knowledge of the probability distribution of momentum transfer occurring in various layers of the tissue, we calculated the expected laser speckle contrast arising with coherent excitation using both reflectance and transmission geometries. We simulated light transport in a single homogeneous tissue while independently varying either absorption (.001-100mm^-1), reduced scattering (.1-10mm^-1), or anisotropy (0.05-0.99) over a range of values relevant to blood and commonly imaged tissues. We observed that contrast decreased by 49% with an increase in optical scattering, and observed a 130% increase with absorption (exposure time = 1ms). We also explored how speckle contrast was affected by the depth (0-1mm) and flow speed (0-10mm/s) of a dynamic vascular inclusion. This model of speckle contrast is important to increase our understanding of how parameters such as perfusion dynamics, vessel depth, and tissue optical properties affect laser speckle imaging.

  7. Motion-contrast laser speckle imaging of microcirculation within tissue beds in vivo

    Science.gov (United States)

    Liu, Rong; Qin, Jia; Wang, Ruikang K.

    2013-06-01

    Laser speckle imaging is widely used to monitor functional blood perfusion within tissue beds in vivo but traditionally has difficulty visualizing small blood vessels even when the exposure time of the detector is long. We report a simple method that uses the motion contrast of dynamic speckle patterns to noninvasively visualize the distribution of blood flow within tissue beds in vivo. We experimentally demonstrate that the motion contrast can significantly suppress the effect of static scattering, leading to enhanced visibility of the functional blood vessels, including capillaries when compared to the traditional laser speckle contrast imaging.

  8. Speckle-reducing scale-invariant feature transform match for synthetic aperture radar image registration

    Science.gov (United States)

    Wang, Xianmin; Li, Bo; Xu, Qizhi

    2016-07-01

    The anisotropic scale space (ASS) is often used to enhance the performance of a scale-invariant feature transform (SIFT) algorithm in the registration of synthetic aperture radar (SAR) images. The existing ASS-based methods usually suffer from unstable keypoints and false matches, since the anisotropic diffusion filtering has limitations in reducing the speckle noise from SAR images while building the ASS image representation. We proposed a speckle reducing SIFT match method to obtain stable keypoints and acquire precise matches for the SAR image registration. First, the keypoints are detected in a speckle reducing anisotropic scale space constructed by the speckle reducing anisotropic diffusion, so that speckle noise is greatly reduced and prominent structures of the images are preserved, consequently the stable keypoints can be derived. Next, the probabilistic relaxation labeling approach is employed to establish the matches of the keypoints then the correct match rate of the keypoints is significantly increased. Experiments conducted on simulated speckled images and real SAR images demonstrate the effectiveness of the proposed method.

  9. Spatial sub-Rayleigh imaging analysis via speckle laser illumination

    CERN Document Server

    Wang, Yunlong; Liu, Ruifeng; Chen, Dongxu; Gao, Hong; Zhang, Pei; Li, Fuli

    2016-01-01

    It is commonly accepted that optical sub-Rayleigh imaging has potential application in many fields. In this Letter, by confining the divergence of the optical field, as well as the size of the illumination source, we show that the first-order averaged intensity measurement via speckle laser illumina- tion can make an actual breakthrough on the Rayleigh limit. For a high-order algorithm, it has been reported that the autocorrelation function can be utilized to achieve the sub-Rayleigh feature. However, we find that this sub- Rayleigh feature for the high-order algorithm is limited only to binary objects, and the image will be distorted when a gray object is placed. This property encourages us to find the physics behind the high-order correlation imaging algo- rithm. We address these explanations in this Letter and find that for different types of high-order algorithm, there is always a seat in the right place from the cross-correlation function.

  10. Dynamic Approaches for Facial Recognition Using Digital Image Speckle Correlation

    Science.gov (United States)

    Rafailovich-Sokolov, Sara; Guan, E.; Afriat, Isablle; Rafailovich, Miriam; Sokolov, Jonathan; Clark, Richard

    2004-03-01

    Digital image analysis techniques have been extensively used in facial recognition. To date, most static facial characterization techniques, which are usually based on Fourier transform techniques, are sensitive to lighting, shadows, or modification of appearance by makeup, natural aging or surgery. In this study we have demonstrated that it is possible to uniquely identify faces by analyzing the natural motion of facial features with Digital Image Speckle Correlation (DISC). Human skin has a natural pattern produced by the texture of the skin pores, which is easily visible with conventional digital cameras of resolution greater than 4 mega pixels. Hence the application of the DISC method to the analysis of facial motion appears to be very straightforward. Here we demonstrate that the vector diagrams produced by this method for facial images are directly correlated to the underlying muscle structure which is unique for an individual and is not affected by lighting or make-up. Furthermore, we will show that this method can also be used for medical diagnosis in early detection of facial paralysis and other forms of skin disorders.

  11. Estimation of vessel diameter and blood flow dynamics from laser speckle images

    DEFF Research Database (Denmark)

    Postnov, Dmitry D.; Tuchin, Valery V.; Sosnovtseva, Olga

    2016-01-01

    Laser speckle imaging is a rapidly developing method to study changes of blood velocity in the vascular networks. However, to assess blood flow and vascular responses it is crucial to measure vessel diameter in addition to blood velocity dynamics. We suggest an algorithm that allows for dynamical...... masking of a vessel position and measurements of it's diameter from laser speckle images. This approach demonstrates high reliability and stability....

  12. Speckle noise reduction in ultrasound images using a discrete wavelet transform-based image fusion technique.

    Science.gov (United States)

    Choi, Hyun Ho; Lee, Ju Hwan; Kim, Sung Min; Park, Sung Yun

    2015-01-01

    Here, the speckle noise in ultrasonic images is removed using an image fusion-based denoising method. To optimize the denoising performance, each discrete wavelet transform (DWT) and filtering technique was analyzed and compared. In addition, the performances were compared in order to derive the optimal input conditions. To evaluate the speckle noise removal performance, an image fusion algorithm was applied to the ultrasound images, and comparatively analyzed with the original image without the algorithm. As a result, applying DWT and filtering techniques caused information loss and noise characteristics, and did not represent the most significant noise reduction performance. Conversely, an image fusion method applying SRAD-original conditions preserved the key information in the original image, and the speckle noise was removed. Based on such characteristics, the input conditions of SRAD-original had the best denoising performance with the ultrasound images. From this study, the best denoising technique proposed based on the results was confirmed to have a high potential for clinical application.

  13. Fast blood flow visualization of high-resolution laser speckle imaging data using graphics processing unit.

    Science.gov (United States)

    Liu, Shusen; Li, Pengcheng; Luo, Qingming

    2008-09-15

    Laser speckle contrast analysis (LASCA) is a non-invasive, full-field optical technique that produces two-dimensional map of blood flow in biological tissue by analyzing speckle images captured by CCD camera. Due to the heavy computation required for speckle contrast analysis, video frame rate visualization of blood flow which is essentially important for medical usage is hardly achieved for the high-resolution image data by using the CPU (Central Processing Unit) of an ordinary PC (Personal Computer). In this paper, we introduced GPU (Graphics Processing Unit) into our data processing framework of laser speckle contrast imaging to achieve fast and high-resolution blood flow visualization on PCs by exploiting the high floating-point processing power of commodity graphics hardware. By using GPU, a 12-60 fold performance enhancement is obtained in comparison to the optimized CPU implementations.

  14. Adaptive red-black window algorithm for SAR image speckle reduction%抑制SAR图像相干斑的自适应红黑窗滤波算法

    Institute of Scientific and Technical Information of China (English)

    张毅; 张强; 王宇; 欧阳志新

    2012-01-01

    When using the classical spatial filtering algorithm to process synthetic aperture radar (SAR) images, the identical sliding window is assumed to have homogeneous characteristics, which results in losing of image detail information. To solve the problem described above, a new sliding window structure is presented. The improved algorithm selects pixels that have similar statistical characteristics to the central pixel for structure modeling. Meanwhile, a special detecting and processing strategy is designed to tackle strong scattering points. The airborne SAR image is processed to verify the effectiveness of the method. While maintaining the comparative ability in reducing speckle as the classical algorithm, the proposed algorithm achieves more edge and detail information as well as better image visual effects.%针对经典空域滤波算法处理SAR图像时,在同一滑动窗内完全按同质区域性质处理数据而导致图像细节信息损失的情况,提出一种新的滑动窗结构的算法.该算法选取与窗口中心像素统计特性相近的像素进行滤波处理,解决了经典空域滤波算法存在窗口内数据不满足滤波模型对同质区域要求的缺陷.同时,针对强散射点的特殊性,设计了相应的检测及处理方法.实验结果表明,该算法在获得与经典算法相当的相干斑抑制的同时,较经典算法具有更强的边缘和细节保持能力,同时获得更好的图像视觉效果.

  15. Modeling laser speckle imaging of perfusion in the skin (Conference Presentation)

    Science.gov (United States)

    Regan, Caitlin; Hayakawa, Carole K.; Choi, Bernard

    2016-02-01

    Laser speckle imaging (LSI) enables visualization of relative blood flow and perfusion in the skin. It is frequently applied to monitor treatment of vascular malformations such as port wine stain birthmarks, and measure changes in perfusion due to peripheral vascular disease. We developed a computational Monte Carlo simulation of laser speckle contrast imaging to quantify how tissue optical properties, blood vessel depths and speeds, and tissue perfusion affect speckle contrast values originating from coherent excitation. The simulated tissue geometry consisted of multiple layers to simulate the skin, or incorporated an inclusion such as a vessel or tumor at different depths. Our simulation used a 30x30mm uniform flat light source to optically excite the region of interest in our sample to better mimic wide-field imaging. We used our model to simulate how dynamically scattered photons from a buried blood vessel affect speckle contrast at different lateral distances (0-1mm) away from the vessel, and how these speckle contrast changes vary with depth (0-1mm) and flow speed (0-10mm/s). We applied the model to simulate perfusion in the skin, and observed how different optical properties, such as epidermal melanin concentration (1%-50%) affected speckle contrast. We simulated perfusion during a systolic forearm occlusion and found that contrast decreased by 35% (exposure time = 10ms). Monte Carlo simulations of laser speckle contrast give us a tool to quantify what regions of the skin are probed with laser speckle imaging, and measure how the tissue optical properties and blood flow affect the resulting images.

  16. Retooling Laser Speckle Contrast Analysis Algorithm to Enhance Non-Invasive High Resolution Laser Speckle Functional Imaging of Cutaneous Microcirculation

    Science.gov (United States)

    Gnyawali, Surya C.; Blum, Kevin; Pal, Durba; Ghatak, Subhadip; Khanna, Savita; Roy, Sashwati; Sen, Chandan K.

    2017-01-01

    Cutaneous microvasculopathy complicates wound healing. Functional assessment of gated individual dermal microvessels is therefore of outstanding interest. Functional performance of laser speckle contrast imaging (LSCI) systems is compromised by motion artefacts. To address such weakness, post-processing of stacked images is reported. We report the first post-processing of binary raw data from a high-resolution LSCI camera. Sharp images of low-flowing microvessels were enabled by introducing inverse variance in conjunction with speckle contrast in Matlab-based program code. Extended moving window averaging enhanced signal-to-noise ratio. Functional quantitative study of blood flow kinetics was performed on single gated microvessels using a free hand tool. Based on detection of flow in low-flow microvessels, a new sharp contrast image was derived. Thus, this work presents the first distinct image with quantitative microperfusion data from gated human foot microvasculature. This versatile platform is applicable to study a wide range of tissue systems including fine vascular network in murine brain without craniotomy as well as that in the murine dorsal skin. Importantly, the algorithm reported herein is hardware agnostic and is capable of post-processing binary raw data from any camera source to improve the sensitivity of functional flow data above and beyond standard limits of the optical system. PMID:28106129

  17. 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

    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...... the probe and the surface of the skin. RESULTS: SR-OCT resulted in improved visualisation and more accurate thickness measurements in BCC lesions. CONCLUSION: This OCT speckle reduction method led to improved visualisation and better defined delineations in two BCC lesions. Thus, OCT was improved...... to a clinically relevant level when imaging BCC lesions....

  18. A theoretical analysis of the super-resolution capacity of imagers using speckle illuminations

    CERN Document Server

    Idier, Jérôme; Liu, Penghuan; Allain, Marc; Bourguignon, Sébastien; Sentenac, Anne

    2015-01-01

    Speckle based imaging consists in forming a super-resolved reconstruction of an unknown object from low-resolution images obtained under random inhomogeneous illuminations (speckles). However, the origin of this super-resolution is unclear. In this work, we demonstrate that, under physically realistic conditions, the correlation of the data have a super-resolution power corresponding to the squaring of the imager point spread function. This theoretical result is important for many practical imaging systems such as acoustic and electromagnetic tomographies, fluorescence and photoacoustic microscopies or synthetic aperture radar imaging.

  19. Laser speckle imaging of blood flow in microcirculation

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Haiying; Luo Qingming; Liu Qian; Lu Qiang; Gong Hui; Zeng Shaoqun [Key Laboratory of Biomedical Photonics of Ministry of Education of China, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2004-04-07

    Monitoring the spatio-temporal characteristics of microcirculation is crucial for studying the functional activities of biotissue and the mechanism of disease. However, conventional methods used to measure blood flow suffer from limited spatial resolution or the injection of exogenous substances or the need of scanning to obtain the dynamic of regional blood flow. Laser speckle imaging (LSI) technique makes up these disadvantages by obtaining the regional blood flow distribution with high spatio-temporal resolution without the need to scan. In this paper, LSI was introduced to investigate the dynamic responses of the rat mesenteric microcirculation to an incremental dose of phentolamine. The results showed that when the dose of phentolamine was less than 4 {mu}g ml{sup -1}, local application of phentolamine on the mesentery would increase the blood perfusion as the concentration increased. When the dose increased further, the improvement decreased. At a dose of 200 {mu}g ml{sup -1}, a microcirculation impediment was caused. At the same time, different responses between veinules and arterioles were manifested. These suggested that LSI is promising to be a useful contribution to drug development and testing.

  20. Assessment of Left Ventricular Radial Deformation by Speckle Tracking Imaging

    Institute of Scientific and Technical Information of China (English)

    Min PAN; Hao LUO; Ashraf Muhammad; Schultheis Judy; Xiaokui LI; David J. Sahn

    2009-01-01

    The left ventricular radial strain in the inner and outer layers was evaluated by using two-dimensional speckle tracking imaging (2DS). Twenty-five piglets were studied. The short axis views were acquired. Peak systolic radial strain was measured from 6 circumferential points related to 6 standard segments in the inner and outer layers respectively using 2DS methods. The peak positive first derivative (dp/dt) of left ventricular pressure was compared to the radial strain from 2DS. The inner band showed higher peak radial strain values as compared to the outer band at all of the segments (P<0.0001), but the differences had significance just in anteroseptal, posterior, inferior and septal seg-ments (P<0.05). Good correlation could be found between radial strain of inner and outer layers and peak dp/dt (P<0.001). These preliminary results showed that the degree of local deformation or wall thickening of the ventricular wall in its inner layer was more obvious than its outer layer. It is suggested that the 2DS technique is useful and sensitive for better understanding the regional and global myocar-dial motion and its relationship to the complex architecture of myocardium.

  1. Monitoring free tissue transfer using laser speckle imaging

    Science.gov (United States)

    Winchester, Leonard W.; Chou, Nee-Yin

    2006-02-01

    Blood velocity information can be extracted by analyzing, either temporally or spatially, laser speckle (LS) patterns generated when a laser source illuminates the tissue. While a temporal analysis, such as that used for laser Doppler velocimetry (LDV), provides high spatial resolution, the time required to obtain flow data in vivo on large areas of tissue limits its utility. The LS imaging (LSI) technique combines the nonscanning, full-field, LS method and the modified multiple scattering algorithms developed for LDV analysis to retrieve blood velocity parameters. It provides a noninvasive means for realtime, quantitative measurements of subtle changes in the tissue vasculature. This paper describes the use of the LSI technique on free flap measurements of a swine model and compares the results with those obtained using an LDV probe. Both the LSI and the LDV measurements showed similar results - blood velocity and flow decreased about 10%-33% from the tip to the caudal base of the flap, respectively. The difference between the tip and the caudal base is a measure of flap ischemia. However, tissue pigmentation affects the blood flow parameters retrieved from the LDV measurements, it does not affect the blood velocity parameters retrieved from the LSI measurements. Both techniques were also used during free tissue transfer procedures in patients to demonstrate the utility of the LSI for monitoring the status of the graft.

  2. Three Dimensional Speckle Imaging Employing a Frequency-Locked Tunable Diode Laser

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, Bret D.; Bernacki, Bruce E.; Schiffern, John T.; Mendoza, Albert

    2015-09-01

    We describe a high accuracy frequency stepping method for a tunable diode laser to improve a three dimensional (3D) imaging approach based upon interferometric speckle imaging. The approach, modeled after Takeda, exploits tuning an illumination laser in frequency as speckle interferograms of the object (specklegrams) are acquired at each frequency in a Michelson interferometer. The resulting 3D hypercube of specklegrams encode spatial information in the x-y plane of each image with laser tuning arrayed along its z-axis. We present laboratory data of before and after results showing enhanced 3D imaging resulting from precise laser frequency control.

  3. Laser speckle contrast imaging to measure changes in cerebral blood flow.

    Science.gov (United States)

    Winship, Ian R

    2014-01-01

    Laser speckle contrast imaging (LSCI) is a powerful tool capable of acquiring detailed maps of blood flow in arteries and veins on the cortical surface. Based on the blurring of laser speckle patterns by the motion of blood cells, LSCI can be combined with a variety of optical imaging preparations to acquire high-spatiotemporal resolution images of blood flow, and track changes in blood flow over time, using relatively simple instrumentation. Here, we describe methods for LSCI of cerebral blood flow via a thin skull imaging preparation in mice or rats. This preparation allows precise semiquantitative mapping of changes in blood flow over time using straightforward surgical protocols and equipment.

  4. Design and simulation of GRIN objective lenses for an imaging fiber based speckle metrology system

    Science.gov (United States)

    Prabhathan, P.; Guru Prasad, A. S.; Haridas, Aswin; Chan, Kelvin H. K.; Murukeshan, V. M.

    2016-11-01

    Gradient-Index (GRIN) lenses are characterized by its small diameter and length, enabling them to be an effective lens for an integrated probe based imaging system. For a speckle-based surface metrology system, the imaging lens plays an important role in deciding the statistical dimensions of the speckles. In such cases, the design and simulation of the lens system would be a key process to better the performance of the lensed imaging fiber probe. In this context, this paper focuses on the design of lensed fiber probes for a speckle-based surface metrological imaging system that can find intra cavity interrogation applications. Different optical properties of GRIN lenses and imaging fibers are considered while designing the final probe distal end to meet the targeted specifications. Singlet GRIN lens configuration is analyzed for a front view configuration and a parameter optimization has been carried out to obtain the specifications including the field-of-view, resolution, working distance and magnification.

  5. Comparison of PDE based and other techniques for speckle reduction from digitally reconstructed holographic images

    Science.gov (United States)

    Srivastava, Rajeev; Gupta, JRP; Parthasarthy, Harish

    2010-05-01

    In this paper, the partial differential equation (PDE) based homomorphic filtering technique is proposed for speckle reduction from digitally reconstructed holographic images based on the concepts of complex diffusion processes. For digital implementations, the proposed scheme was discretized using finite differences scheme. Further, the performance of the proposed PDE-based technique is compared with other speckle reduction techniques such as homomorphic anisotropic diffusion filter based on extended concept of Perona and Malik (1990) [2], homomorphic Weiner filter, Lee filter, Frost filter, Kuan filter, speckle reducing anisotropic diffusion (SRAD) filter and hybrid filter in the context of digital holography. For the comparison of various speckle reduction techniques, the performance is evaluated quantitatively in terms of all possible parameters that justify the applicability of a scheme for a specific application. The chosen parameters are mean-square-error (MSE), normalized mean-square-error (NMSE), peak signal-to-noise ratio (PSNR), speckle index, average signal-to-noise ratio (SNR), effective number of looks (ENL), correlation parameter (CP), mean structure similarity index map (MSSIM) and execution time in seconds. For experimentation and computer simulation MATLAB 7.0 has been used and the performance is evaluated and tested for various sample holographic images for varying amount of speckle variance. The results obtained justify the applicability of proposed schemes.

  6. Laser speckle contrast imaging with extended depth of field for in-vivo tissue imaging.

    Science.gov (United States)

    Sigal, Iliya; Gad, Raanan; Caravaca-Aguirre, Antonio M; Atchia, Yaaseen; Conkey, Donald B; Piestun, Rafael; Levi, Ofer

    2013-12-06

    This work presents, to our knowledge, the first demonstration of the Laser Speckle Contrast Imaging (LSCI) technique with extended depth of field (DOF). We employ wavefront coding on the detected beam to gain quantitative information on flow speeds through a DOF extended two-fold compared to the traditional system. We characterize the system in-vitro using controlled microfluidic experiments, and apply it in-vivo to imaging the somatosensory cortex of a rat, showing improved ability to image flow in a larger number of vessels simultaneously.

  7. Information compression and speckle reduction for multifrequency polarimetric SAR images based on kernel PCA

    Institute of Scientific and Technical Information of China (English)

    Li Ying; Lei Xiaogang; Bai Bendu; Zhang Yanning

    2008-01-01

    Multifrequency polarimetric SAR imagery provides a very convenient approach for signal processing and acquisition of radar image. However, the amount of information is scattered in several images, and redundancies exist between different bands and polarizations. Similar to signal-polarimetric SAR image, multifrequency polarimetric SAR image is corrupted with speckle noise at the same time. A method of information compression and speckle reduction for multifrequency polarimetric SAR imagery is presented based on kernel principal component analysis (KPCA). KPCA is a nonlinear generalization of the linear principal component analysis using the kernel trick. The NASA/JPL polarimetric SAR imagery of P, L, and C bands quadpolarizations is used for illustration. The experimental results show that KPCA has better capability in information compression and speckle reduction as compared with linear PCA.

  8. Multiresolution edge detection using enhanced fuzzy c-means clustering for ultrasound image speckle reduction

    Energy Technology Data Exchange (ETDEWEB)

    Tsantis, Stavros [Department of Medical Physics, School of Medicine, University of Patras, Rion, GR 26504 (Greece); Spiliopoulos, Stavros; Karnabatidis, Dimitrios [Department of Radiology, School of Medicine, University of Patras, Rion, GR 26504 (Greece); Skouroliakou, Aikaterini [Department of Energy Technology Engineering, Technological Education Institute of Athens, Athens 12210 (Greece); Hazle, John D. [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Kagadis, George C., E-mail: gkagad@gmail.com, E-mail: George.Kagadis@med.upatras.gr, E-mail: GKagadis@mdanderson.org [Department of Medical Physics, School of Medicine, University of Patras, Rion, GR 26504, Greece and Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

    2014-07-15

    Purpose: Speckle suppression in ultrasound (US) images of various anatomic structures via a novel speckle noise reduction algorithm. Methods: The proposed algorithm employs an enhanced fuzzy c-means (EFCM) clustering and multiresolution wavelet analysis to distinguish edges from speckle noise in US images. The edge detection procedure involves a coarse-to-fine strategy with spatial and interscale constraints so as to classify wavelet local maxima distribution at different frequency bands. As an outcome, an edge map across scales is derived whereas the wavelet coefficients that correspond to speckle are suppressed in the inverse wavelet transform acquiring the denoised US image. Results: A total of 34 thyroid, liver, and breast US examinations were performed on a Logiq 9 US system. Each of these images was subjected to the proposed EFCM algorithm and, for comparison, to commercial speckle reduction imaging (SRI) software and another well-known denoising approach, Pizurica's method. The quantification of the speckle suppression performance in the selected set of US images was carried out via Speckle Suppression Index (SSI) with results of 0.61, 0.71, and 0.73 for EFCM, SRI, and Pizurica's methods, respectively. Peak signal-to-noise ratios of 35.12, 33.95, and 29.78 and edge preservation indices of 0.94, 0.93, and 0.86 were found for the EFCM, SIR, and Pizurica's method, respectively, demonstrating that the proposed method achieves superior speckle reduction performance and edge preservation properties. Based on two independent radiologists’ qualitative evaluation the proposed method significantly improved image characteristics over standard baseline B mode images, and those processed with the Pizurica's method. Furthermore, it yielded results similar to those for SRI for breast and thyroid images significantly better results than SRI for liver imaging, thus improving diagnostic accuracy in both superficial and in-depth structures. Conclusions: A

  9. Reaching the Diffraction Limit - Differential Speckle and Wide-Field Imaging for the WIYN Telescope

    Science.gov (United States)

    Scott, Nic J.; Howell, Steve; Horch, Elliott

    2016-01-01

    Speckle imaging allows telescopes to achieve diffraction limited imaging performance. The technique requires cameras capable of reading out frames at a very fast rate, effectively 'freezing out' atmospheric seeing. The resulting speckles can be correlated and images reconstructed that are at the diffraction limit of the telescope. These new instruments are based on the successful performance and design of the Differential Speckle Survey Instrument (DSSI).The instruments are being built for the Gemini-N and WIYN telescopes and will be made available to the community via the peer review proposal process. We envision their primary use to be validation and characterization of exoplanet targets from the NASA, K2 and TESS missions and RV discovered exoplanets. Such targets will provide excellent follow-up candidates for both the WIYN and Gemini telescopes. We expect similar data quality in speckle imaging mode with the new instruments. Additionally, both cameras will have a wide-field mode and standard SDSS filters. They will be highly versatile instruments and it is that likely many other science programs will request time on the cameras. The limiting magnitude for speckle observations will remain around 13-14th at WIYN and 16-17th at Gemini, while wide-field, normal CCD imaging operation should be able to go to much fainter, providing usual CCD imaging and photometric capabilities. The instruments will also have high utility as scoring cameras for telescope engineering purposes, or other applications where high time resolution is needed. Instrument support will be provided, including a software pipeline that takes raw speckle data to fully reconstructed images.

  10. Validation of near-infrared laser speckle imaging for assessing microvascular (re)perfusion

    NARCIS (Netherlands)

    R. Bezemer; E. Klijn; M. Khalilzada; A. Lima; M. Heger; J. van Bommel; C. Ince

    2010-01-01

    The present study was conducted to compare laser speckle imaging (LSI) with sidestream dark field (SDF) imaging (i.e. capillary microscopy) so as to validate the use of LSI for assessing microvascular (re)perfusion. For this purpose, LSI and SDF measurements were performed on the human nail fold dur

  11. Differential speckle and wide-field imaging for the Gemini-North and WIYN telescopes

    Science.gov (United States)

    Scott, Nicholas J.; Howell, Steve B.; Horch, Elliott P.

    2016-07-01

    Two new instruments are currently being built for the Gemini-North and WIYN telescopes. They are based on the existing DSSI (Differential Speckle Survey Instrument), but the new dual-channel instruments will have both speckle and "wide-field" imaging capabilities. Nearly identical copies of the instrument will be installed as a public access permanent loan at the Gemini-N and WIYN telescopes. Many exoplanet targets will come from the NASA K2 and TESS missions. The faint limiting magnitude, for speckle observations, will remain around 16 to 17th magnitude depending on observing conditions, while wide-field, high speed imaging should be able to go to 21+. For Gemini, the instrument will be remotely operable from either the mid-level facility at Hale Pohaku or the remote operations base in Hilo.

  12. Singularities in Speckled Speckle

    CERN Document Server

    Freund, Isaac

    2007-01-01

    Speckle patterns produced by random optical fields with two (or more) widely different correlation lengths exhibit speckle spots that are themselves highly speckled. Using computer simulations and analytic theory we present results for the point singularities of speckled speckle fields: optical vortices in scalar (one polarization component) fields; C points in vector (two polarization component) fields. In single correlation length fields both types of singularities tend to be more{}-or{}-less uniformly distributed. In contrast, the singularity structure of speckled speckle is anomalous: for some sets of source parameters vortices and C points tend to form widely separated giant clusters, for other parameter sets these singularities tend to form chains that surround large empty regions. The critical point statistics of speckled speckle is also anomalous. In scalar (vector) single correlation length fields phase (azimuthal) extrema are always outnumbered by vortices (C points). In contrast, in speckled speckl...

  13. The influence of hologram aperture on speckle noise in the reconstructed image of digital holography and its reduction

    Science.gov (United States)

    Cai, Xiao-ou; Wang, Hui

    2008-01-01

    Based on the whole process of the recording and reconstruction of digital holography, we study the formation cause of speckle noise in its reconstructed image and acquire the conclusion that the small size of hologram aperture diffraction aggravates the speckle noise of reconstructed image and the speckle noise has been one of primary noise sources in the reconstruction process. In order to reduce the speckle noise resulting from little hologram aperture diffraction, we set an appropriate aperture function matching the recording parameter and aperture size of hologram and deconvolve the reconstructed image with it. The validity has been proved in theory and experiment. Therefore, it offers a brand-new thought and practical way to reduce the speckle noise in the reconstructed image of digital holography.

  14. Impact of velocity distribution assumption on simplified laser speckle imaging equation

    Science.gov (United States)

    Ramirez-San-Juan, Julio C; Ramos-Garcia, Ruben; Guizar-Iturbide, Ileana; Martinez-Niconoff, Gabriel; Choi, Bernard

    2012-01-01

    Since blood flow is tightly coupled to the health status of biological tissue, several instruments have been developed to monitor blood flow and perfusion dynamics. One such instrument is laser speckle imaging. The goal of this study was to evaluate the use of two velocity distribution assumptions (Lorentzian- and Gaussian-based) to calculate speckle flow index (SFI) values. When the normalized autocorrelation function for the Lorentzian and Gaussian velocity distributions satisfy the same definition of correlation time, then the same velocity range is predicted for low speckle contrast (0 < C < 0.6) and predict different flow velocity range for high contrast. Our derived equations form the basis for simplified calculations of SFI values. PMID:18542407

  15. Myocardial Strain and Strain Rate Imaging: Comparison between Doppler Derived Strain Imaging and Speckle Tracking Echocardiography

    Directory of Open Access Journals (Sweden)

    Anita Sadeghpour

    2013-05-01

    Full Text Available Regional myocardial function has been traditionally assessed by visual estimation (1. Echocardiographic strain imaging which is known as deformation imaging, has been emerged as a quantitative technique to accurately estimate regional myocardial function and contractility. Currently, strain imaging has been regarded as a research tool in the most echocardiography laboratories. However, in recent years, strain imaging has gain momentum in daily clinical practice (2. The following two techniques have dominated the research arena of echocardiography: (1 Doppler based tissue velocity measurements, frequently referred to tissue Doppler or myocardial Doppler, and (2 speckle tracking on the basis of displacement measurements (3. Over the past two decades, Tissue Doppler Imaging (TDI and Doppler –derived strain (S and strain rate (SR imaging were introduced to quantify regional myocardial function. However, Doppler–derived strain variables faced criticisms, with regard to the angle dependency, noise interference, and substantial intraobserver and interobserver variability. The angle dependency is the major weakness of Doppler based methodology; however, it has the advantage of online measurements of velocities and time intervals with excellent temporal resolution, which is essential for the assessment of ischemia (4. Speckle-tracking echocardiography (STE or Non Doppler 2D strain echocardiography is a relatively new, largely angle-independent technique that analyzes motion by tracking natural acoustic reflections and interference patterns within an ultrasonic window. The image-processing algorithm tracks elements with approximately 20 to 40 pixels containing stable patterns and are described as ‘‘speckles’’ or ‘‘fingerprints’’. The speckles seen in grayscale B-mode (2D images are tracked consecutively frame to frame (5, 6. Assessment of 2D strain by STE is a semiautomatic method that requires definition of the myocardium

  16. Comparison of laser Doppler and laser speckle contrast imaging using a concurrent processing system

    Science.gov (United States)

    Sun, Shen; Hayes-Gill, Barrie R.; He, Diwei; Zhu, Yiqun; Huynh, Nam T.; Morgan, Stephen P.

    2016-08-01

    Full field laser Doppler imaging (LDI) and single exposure laser speckle contrast imaging (LSCI) are directly compared using a novel instrument which can concurrently image blood flow using both LDI and LSCI signal processing. Incorporating a commercial CMOS camera chip and a field programmable gate array (FPGA) the flow images of LDI and the contrast maps of LSCI are simultaneously processed by utilizing the same detected optical signals. The comparison was carried out by imaging a rotating diffuser. LDI has a linear response to the velocity. In contrast, LSCI is exposure time dependent and does not provide a linear response in the presence of static speckle. It is also demonstrated that the relationship between LDI and LSCI can be related through a power law which depends on the exposure time of LSCI.

  17. Modelling laser speckle photographs of decayed teeth by applying a digital image information technique

    Science.gov (United States)

    Ansari, M. Z.; da Silva, L. C.; da Silva, J. V. P.; Deana, A. M.

    2016-09-01

    We report on the application of a digital image model to assess early carious lesions on teeth. When decay is in its early stages, the lesions were illuminated with a laser and the laser speckle images were obtained. Due to the differences in the optical properties between healthy and carious tissue, both regions produced different scatter patterns. The digital image information technique allowed us to produce colour-coded 3D surface plots of the intensity information in the speckle images, where the height (on the z-axis) and the colour in the rendering correlate with the intensity of a pixel in the image. The quantitative changes in colour component density enhance the contrast between the decayed and sound tissue, and visualization of the carious lesions become significantly evident. Therefore, the proposed technique may be adopted in the early diagnosis of carious lesions.

  18. A testing method for the machine details state by means of the speckle image parameters analysis

    Science.gov (United States)

    Malov, A. N.; Pavlov, P. V.; Neupokoeva, A. V.

    2016-08-01

    Non destructive testing method, allowing to define a residual resource of power details of mechanical engineering designs under the analysis of registered speckle-image parameters, it is discussed. The "chessboard" algorithm based on calculation of correlation between the given speckle-image and the a chessboard image is considered. Experimental research results of an offered non destructive testing method are presented. It is established, that to increase in quantity of a power detail tests cycles there is an increase in roughness parameters that conducts to reduction of correlation factor between reference and to resultants the image at the given stage of test. Knowing of correlation factor change dynamics, it is possible to define a residual resource of power details while in exploitation.

  19. Speckle reduction for medical ultrasound images with an expectation-maximization framework

    Institute of Scientific and Technical Information of China (English)

    HOU Tao; WANG Yuanyuan; GUO Yi

    2011-01-01

    In view of inherent speckle noise in medical images, a speckle reduction method was proposed based on an expectation-maximization (EM) framework. First, the real component of the in-phase/quadrature (I/Q) ultrasound image is extracted. Then, it is used to blindly estimate the point spread function (PSF) of the imaging system. Finally, based on the EM framework, an iterative algorithm alternating between the Wiener Filter and the anisotropic diffusion (AD) is exploited to produce despeckled images. The comparison experiment is carried out on both simulated and in vivo ultrasound images. It is shown that, with respect to the I/Q image, the proposed method averagely improves the speckle-signal-to-noise ratio (S-SNR) and the edge preservation index (β) of images by the factor of 1.94 and 7.52. Meanwhile, it averagely reduces the normalized mean-squared error (NMSE) by the factor of 3.95. The simulation and in vivo results indicates that the proposed method has a better overall performance than exited ones.

  20. Reconstruction of static line images with reduced speckle using interlaced holograms for holographic laser cutting

    Science.gov (United States)

    Lee, Hwihyeong; Park, Sangwoo; Jeon, Byoung Goo; Kong, Hong Jin

    2016-07-01

    A hologram can be used for high-power laser processing applications such as cutting, drilling, patterning, or welding. However, not much progress has been made in cutting application compared to the others, because it requires optical reconstruction of static and uniform line images using holograms which have a high damage threshold. These static and uniform line images are difficult to be reconstructed with a single hologram, since they usually suffer from speckle between neighboring spots. We propose a method to reconstruct reduced-speckle static line images using two interlaced holograms which reconstruct odd and even pixel line images, corresponding to two orthogonal polarizations. Then, the two orthogonally polarized line images are superposed for interlacing in the image plane. The proposed method was studied by numerical simulations and demonstrated experimentally. The experimental results show that speckle contrast decreased by about one-third, compared to that of a non-interlaced hologram. This method can be applied also for complex-shaped images which include curved lines as well as straight lines, and we have a plan for laser cutting with this method in the near future.

  1. Non-iterative phase hologram computation for low speckle holographic image projection

    OpenAIRE

    Ürey, Hakan; Ulusoy, Erdem; Mengü, Deniz

    2016-01-01

    Phase-only spatial light modulators (SLMs) are widely used in holographic display applications, including holographic image projection (HIP). Most phase computer generated hologram (CGH) calculation algorithms have an iterative structure with a high computational load, and also are prone to speckle noise, as a result of the random phase terms applied on the desired images to mitigate the encoding noise. In this paper, we present a non-iterative algorithm, where simple Discrete Fourier Transfo...

  2. Integration of speckle de-noising and image segmentation using Synthetic Aperture Radar image for flood extent extraction

    Indian Academy of Sciences (India)

    J Senthilnath; H Vikram Shenoy; Ritwik Rajendra; S N Omkar; V Mani; P G Diwakar

    2013-06-01

    Flood is one of the detrimental hydro-meteorological threats to mankind. This compels very efficient flood assessment models. In this paper, we propose remote sensing based flood assessment using Synthetic Aperture Radar (SAR) image because of its imperviousness to unfavourable weather conditions. However, they suffer from the speckle noise. Hence, the processing of SAR image is applied in two stages: speckle removal filters and image segmentation methods for flood mapping. The speckle noise has been reduced with the help of Lee, Frost and Gamma MAP filters. A performance comparison of these speckle removal filters is presented. From the results obtained, we deduce that the Gamma MAP is reliable. The selected Gamma MAP filtered image is segmented using Gray Level Co-occurrence Matrix (GLCM) and Mean Shift Segmentation (MSS). The GLCM is a texture analysis method that separates the image pixels into water and non-water groups based on their spectral feature whereas MSS is a gradient ascent method, here segmentation is carried out using spectral and spatial information. As test case, Kosi river flood is considered in our study. From the segmentation result of both these methods are comprehensively analysed and concluded that the MSS is efficient for flood mapping.

  3. Thermo-mechanical toner transfer for high-quality digital image correlation speckle patterns

    Science.gov (United States)

    Mazzoleni, Paolo; Zappa, Emanuele; Matta, Fabio; Sutton, Michael A.

    2015-12-01

    The accuracy and spatial resolution of full-field deformation measurements performed through digital image correlation are greatly affected by the frequency content of the speckle pattern, which can be effectively controlled using particles with well-defined and consistent shape, size and spacing. This paper introduces a novel toner-transfer technique to impress a well-defined and repeatable speckle pattern on plane and curved surfaces of metallic and cement composite specimens. The speckle pattern is numerically designed, printed on paper using a standard laser printer, and transferred onto the measurement surface via a thermo-mechanical process. The tuning procedure to compensate for the difference between designed and toner-transferred actual speckle size is presented. Based on this evidence, the applicability of the technique is discussed with respect to surface material, dimensions and geometry. Proof of concept of the proposed toner-transfer technique is then demonstrated for the case of a quenched and partitioned welded steel plate subjected to uniaxial tensile loading, and for an aluminum plate exposed to temperatures up to 70% of the melting point of aluminum and past the melting point of typical printer toner powder.

  4. Low-spatial-coherence broadband fiber source for speckle free imaging

    CERN Document Server

    Redding, Brandon; Mokan, Vadim; Seifert, Martin; Choma, Michael A; Cao, Hui

    2015-01-01

    We designed and demonstrate a fiber-based amplified spontaneous emission (ASE) source with low spatial coherence, low temporal coherence, and high power per mode. ASE is produced by optically pumping a large gain core multimode fiber while minimizing optical feedback to avoid lasing. The fiber ASE source provides 270 mW of continuous wave emission, centered at {\\lambda}=1055 nm with a full-width half-maximum bandwidth of 74 nm. The emission is distributed among as many as ~70 spatial modes, enabling efficient speckle suppression when combined with spectral compounding. Finally, we demonstrate speckle-free full field imaging using the fiber ASE source. The fiber ASE source provides a unique combination of high power per mode with both low spatial and low temporal coherence, making it an ideal source for full-field imaging and ranging applications.

  5. Low-spatial-coherence high-radiance broadband fiber source for speckle free imaging.

    Science.gov (United States)

    Redding, Brandon; Ahmadi, Peyman; Mokan, Vadim; Seifert, Martin; Choma, Michael A; Cao, Hui

    2015-10-15

    We design and demonstrate a fiber-based amplified spontaneous emission (ASE) source with low spatial coherence, low temporal coherence, and high power per mode. ASE is produced by optically pumping a large gain core multimode fiber while minimizing optical feedback to avoid lasing. The fiber ASE source provides 270 mW of continuous wave emission, centered at λ=1055  nm, with a full width at half-maximum bandwidth of 74 nm. The emission is distributed among as many as ∼70 spatial modes, enabling efficient speckle suppression when combined with spectral compounding. Finally, we demonstrate speckle-free full-field imaging using the fiber ASE source. The fiber ASE source provides a unique combination of high power per mode with both low spatial and low temporal coherence, making it an ideal source for full-field imaging and ranging applications.

  6. Static laser speckle contrast analysis for noninvasive burn diagnosis using a camera-phone imager.

    Science.gov (United States)

    Ragol, Sigal; Remer, Itay; Shoham, Yaron; Hazan, Sivan; Willenz, Udi; Sinelnikov, Igor; Dronov, Vladimir; Rosenberg, Lior; Bilenca, Alberto

    2015-08-01

    Laser speckle contrast analysis (LASCA) is an established optical technique for accurate widefield visualization of relative blood perfusion when no or minimal scattering from static tissue elements is present, as demonstrated, for example, in LASCA imaging of the exposed cortex. However, when LASCA is applied to diagnosis of burn wounds, light is backscattered from both moving blood and static burn scatterers, and thus the spatial speckle contrast includes both perfusion and nonperfusion components and cannot be straightforwardly associated to blood flow. We extract from speckle contrast images of burn wounds the nonperfusion (static) component and discover that it conveys useful information on the ratio of static-to-dynamic scattering composition of the wound, enabling identification of burns of different depth in a porcine model in vivo within the first 48 h postburn. Our findings suggest that relative changes in the static-to-dynamic scattering composition of burns can dominate relative changes in blood flow for burns of different severity. Unlike conventional LASCA systems that employ scientific or industrial-grade cameras, our LASCA system is realized here using a camera phone, showing the potential to enable LASCA-based burn diagnosis with a simple imager.

  7. Speckle Imaging Excludes Low-mass Companions Orbiting the Exoplanet Host Star TRAPPIST-1

    Science.gov (United States)

    Howell, Steve B.; Everett, Mark E.; Horch, Elliott P.; Winters, Jennifer G.; Hirsch, Lea; Nusdeo, Dan; Scott, Nicholas J.

    2016-09-01

    We have obtained the highest-resolution images available of TRAPPIST-1 using the Gemini-South telescope and our speckle imaging camera. Observing at 692 and 883 nm, we reached the diffraction limit of the telescope providing a best resolution of 27 mas or, at the distance of TRAPPIST-1, a spatial resolution of 0.32 au. Our imaging of the star extends from 0.32 to 14.5 au. We show that to a high confidence level, we can exclude all possible stellar and brown dwarf companions, indicating that TRAPPIST-1 is a single star.

  8. Speckle Imaging Excludes Low-Mass Companions Orbiting the Exoplanet Host Star TRAPPIST-1

    OpenAIRE

    Howell, Steve B.; Everett, Mark E.; Elliott P. Horch; Winters, Jennifer G.; Hirsch, Lea; Nusdeo, Dan; Scott, Nicholas J.

    2016-01-01

    We have obtained the highest resolution images available of TRAPPIST-1 using the Gemini-South telescope and our speckle imaging camera. Observing at 692 and 883 nm, we reached the diffraction limit of the telescope providing a best resolution of 27 mas or, at the distance of TRAPPIST-1, a spatial resolution of 0.32 AU. Our imaging of the star extends from 0.32 to 14.5 AU. We show that to a high confidence level, we can exclude all possible stellar and brown dwarf companions, indicating that T...

  9. Speckle Imaging Excludes Low-Mass Companions Orbiting the Exoplanet Host Star TRAPPIST-1

    CERN Document Server

    Howell, Steve B; Horch, Elliott P; Winters, Jennifer G; Hirsch, Lea; Nusdeo, Dan; Scott, Nicholas J

    2016-01-01

    We have obtained the highest resolution images available of TRAPPIST-1 using the Gemini-South telescope and our speckle imaging camera. Observing at 692 and 883 nm, we reached the diffraction limit of the telescope providing a best resolution of 27 mas or, at the distance of TRAPPIST-1, a spatial resolution of 0.32 AU. Our imaging of the star extends from 0.32 to 14.5 AU. We show that to a high confidence level, we can exclude all possible stellar and brown dwarf companions, indicating that TRAPPIST-1 is a single star.

  10. Simulations of x-ray speckle-based dark-field and phase-contrast imaging with a polychromatic beam

    Energy Technology Data Exchange (ETDEWEB)

    Zdora, Marie-Christine, E-mail: marie-christine.zdora@diamond.ac.uk [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Department of Physics & Astronomy, University College London, London WC1E 6BT (United Kingdom); Thibault, Pierre [Department of Physics & Astronomy, University College London, London WC1E 6BT (United Kingdom); Pfeiffer, Franz [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Zanette, Irene [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2015-09-21

    Following the first experimental demonstration of x-ray speckle-based multimodal imaging using a polychromatic beam [I. Zanette et al., Phys. Rev. Lett. 112(25), 253903 (2014)], we present a simulation study on the effects of a polychromatic x-ray spectrum on the performance of this technique. We observe that the contrast of the near-field speckles is only mildly influenced by the bandwidth of the energy spectrum. Moreover, using a homogeneous object with simple geometry, we characterize the beam hardening artifacts in the reconstructed transmission and refraction angle images, and we describe how the beam hardening also affects the dark-field signal provided by speckle tracking. This study is particularly important for further implementations and developments of coherent speckle-based techniques at laboratory x-ray sources.

  11. Application of speckle and (multi-object) multi-frame blind deconvolution techniques on imaging and imaging spectropolarimetric data

    CERN Document Server

    Puschmann, K G

    2011-01-01

    We test the effects of reconstruction techniques on 2D data to determine the best approach. We obtained a time-series of spectropolarimetric data in the Fe I line at 630.25 nm with the Goettingen Fabry-Perot Interferometer (FPI) that are accompanied by imaging data at 431.3 nm and Ca II H. We apply both speckle and (MO)MFBD techniques. We compare the spatial resolution and investigate the impact of the reconstruction on spectral characteristics. The speckle reconstruction and MFBD perform similar for our imaging data with nearly identical intensity contrasts. MFBD provides a better and more homogeneous resolution at the shortest wavelength. The MOMFBD and speckle deconvolution of the intensity spectra lead to similar results, but our choice of settings for the MOMFBD yields an intensity contrast smaller by about 2% at a comparable spatial resolution. None of the reconstruction techniques introduces artifacts in the intensity spectra. The speckle deconvolution (MOMFBD) has a rms noise in V/I of 0.32% (0.20%). ...

  12. Speckle reduction of SAR images using ICA basis enhancement and separation

    Institute of Scientific and Technical Information of China (English)

    Yutong Li; Yue zhou

    2007-01-01

    @@ An approach for synthetic aperture radax (SAR) image de-noising based on independent component analysis (ICA) basis images is proposed. Firstly, the basis images and the code matrix of the original image are obtained using ICA algorithm. Then, pointwise H(o)lder exponent of each basis is computed as a cost criterion for basis enhancement, and then the enhanced basis images are classified into two sets according to a separation rule which separates the clean basis from the original basis. After these key procedures for speckle reduction, the clean image is finally obtained by reconstruction on the clean basis and original code matrix. The reconstructed image shows better visual perception and image quality compared with those obtained by other traditional techniques.

  13. The use of Speckle Reduction Imaging (SRI) Ultrasound in the characterization of carotid artery plaques

    Energy Technology Data Exchange (ETDEWEB)

    Liasis, Nikolaos [1st Department of Surgery, Vascular Division, ' LAIKON' Hospital, Athens University Medical School (Greece)], E-mail: nliasis@forthnet.gr; Klonaris, Chris [1st Department of Surgery, Vascular Division, ' LAIKON' Hospital, Athens University Medical School (Greece)], E-mail: chris_klonaris@yahoo.com; Katsargyris, Athanasios [1st Department of Surgery, Vascular Division, ' LAIKON' Hospital, Athens University Medical School (Greece)], E-mail: kthanassos@yahoo.com; Georgopoulos, Sotirios [1st Department of Surgery, Vascular Division, ' LAIKON' Hospital, Athens University Medical School (Greece)], E-mail: sgeorg@med.uoa.gr; Labropoulos, Nicos [Division of Vascular Surgery, University of Medicine and Dentistry of New Jersey, Newark (United States)], E-mail: nlabrop@yahoo.com; Tsigris, Chris [1st Department of Surgery, Vascular Division, ' LAIKON' Hospital, Athens University Medical School (Greece)], E-mail: ctsigris@yahoo.com; Giannopoulos, Athanasios [1st Department of Surgery, Vascular Division, ' LAIKON' Hospital, Athens University Medical School (Greece)], E-mail: dimitrak@mohaw.gr; Bastounis, Elias [1st Department of Surgery, Vascular Division, ' LAIKON' Hospital, Athens University Medical School (Greece)], E-mail: ebastoun@med.uoa.gr

    2008-03-15

    Background and purpose: Speckle Reduction Imaging is a new algorithm that improves the image quality of B-mode scanning by reducing the reverberation artifacts. In the present study the value of this method for the characterization of atherosclerotic plaques in the internal carotid artery was investigated. Methods: Two hundred and twenty two patients (161 men, 61 women; mean age 73 years) referred for carotid ultrasound evaluation were included in the study. Patients with plaques of the internal carotid artery as identified by conventional B-mode scanning were investigated also with the addition of Speckle Reduction Imaging (SRI) with the use of a 4-11-MHz wide band linear transducer. Plaque morphology was rated according to a standardized protocol by two independent observers. Results: For the determination of plaque echogenicity, the reproducibility of SRI ({kappa} = 0.83) was higher than that of conventional B-mode ultrasound ({kappa} = 0.68). The interobserver agreement for plaque surface characterization was also higher for SRI ({kappa} = 0.8) than for conventional B-mode ({kappa} = 0.61). At the evaluation of the image quality through a semiquantitative analysis, SRI was rated superior in the plaque texture resolution, plaque borders determination, vessel wall demarcation and fibrous cap depiction. In addition, the level of 'speckle' was reduced with the use of SRI. Conclusions: SRI is a technique that shows good general agreement with high-resolution B-mode and can be used for the characterization of atherosclerotic plaques in the carotid artery. Furthermore, because this advanced technique allows reduction of ultrasound artifacts, it improves the image quality allowing more precise visualization of plaque morphological details.

  14. Digital Image Correlation accuracy: influence of kind of speckle and recording setup

    Directory of Open Access Journals (Sweden)

    Germaneau A.

    2010-06-01

    Full Text Available Digital Image Correlation (DIC is a popular optical technique which allows the measurement of displacement and strain fields on an object surface showing a random speckle pattern. To use its extension to 3D cases (called Digital Volume Correlation, DVC, it is often necessary to include particles in the material in order to have a sufficient contrast. However, as these particles are more rigid than the material, it is not sure that the correlation technique is able to follow exactly strains on the speckle pattern made of powder. As the digital recording process by CCD camera and correlation algorithms are the same between 2D and 3D cases, this study is then conducted in 2D cases in order to show the influence of the powder in the speckle pattern on the evaluation of displacement by DIC linked to the choice of the type of interpolation, of CCD cameras and lighting. In displacement tests, only the recording setup seems to have a strong influence on the accuracy of measurements. For strain experiments, powder has an effect on strain measurements over 10%.

  15. Left Ventricular Longitudinal Function Assessed by Speckle Tracking Ultrasound from a Single Apical Imaging Plane

    Directory of Open Access Journals (Sweden)

    Thomas Bagger

    2012-01-01

    Full Text Available Background. Transthoracic ultrasonography of the heart is valuable in monitoring and treatment of critically ill patients. Speckle tracking ultrasound (STU has proven valid in estimating left ventricular systolic deformation. The aims of the study were to compare conventional and automated STU and to determine whether left ventricular systolic deformation could be estimated from one single imaging plane. Methods. 2D-echocardiography cine-loops were obtained from 20 patients for off-line speckle tracking analysis, consisting of manually tracing of the endocardial border (conventional method or automatically drawn boundaries (automated method. Results. We found a bias of 0,6 (95% CI −2.2−3.3 for global peak systolic strain comparing the automated and the conventional method. Comparing global peak systolic strain of apical 4-chamber cine-loops with averaged Global Peak Strain obtained from apical 4, 2 and long axis cine-loops, showed a bias of 0.1 (95% CI −3.9−4.0. The agreement between subcostal 4-chamber and apical 4-chamber global peak systolic strain was 4.4 (95% CI −3.7−12.5. Conclusion. We found good agreement between the conventional and the automated method. STU applied to single apical 4-chamber cine-loops is in excellent agreement with overall averaged global peak systolic strain, while subcostal 4-chamber cine-loops proved less compliant with speckle tracking ultrasound.

  16. Non-invasive real-time imaging through scattering layers and around corners via speckle correlations

    CERN Document Server

    Katz, Ori; Fink, Mathias; Gigan, Sylvain

    2014-01-01

    Imaging with optical resolution through and inside complex samples is a difficult challenge with important applications in many fields. The fundamental problem is that inhomogeneous samples, such as biological tissues, randomly scatter and diffuse light, impeding conventional image formation. Despite many advancements, no current method enables to noninvasively image in real-time using diffused light. Here, we show that owing to the memory-effect for speckle correlations, a single image of the scattered light, captured with a standard high-resolution camera, encodes all the information that is required to image through the medium or around a corner. We experimentally demonstrate single-shot imaging through scattering media and around corners using incoherent light and various samples, from white paint to dynamic biological samples. Our lensless technique is simple, does not require laser sources, wavefront-shaping, nor time-gated detection, and is realized here using a camera-phone. It has the potential to en...

  17. Laser speckle contrast imaging of skin blood perfusion responses induced by laser coagulation

    Energy Technology Data Exchange (ETDEWEB)

    Ogami, M; Kulkarni, R; Wang, H; Reif, R; Wang, R K [University of Washington, Department of Bioengineering, Seattle, Washington 98195 (United States)

    2014-08-31

    We report application of laser speckle contrast imaging (LSCI), i.e., a fast imaging technique utilising backscattered light to distinguish such moving objects as red blood cells from such stationary objects as surrounding tissue, to localise skin injury. This imaging technique provides detailed information about the acute perfusion response after a blood vessel is occluded. In this study, a mouse ear model is used and pulsed laser coagulation serves as the method of occlusion. We have found that the downstream blood vessels lacked blood flow due to occlusion at the target site immediately after injury. Relative flow changes in nearby collaterals and anastomotic vessels have been approximated based on differences in intensity in the nearby collaterals and anastomoses. We have also estimated the density of the affected downstream vessels. Laser speckle contrast imaging is shown to be used for highresolution and fast-speed imaging for the skin microvasculature. It also allows direct visualisation of the blood perfusion response to injury, which may provide novel insights to the field of cutaneous wound healing. (laser biophotonics)

  18. Laser speckle contrast imaging of skin blood perfusion responses induced by laser coagulation

    Science.gov (United States)

    Ogami, M.; Kulkarni, R.; Wang, H.; Reif, R.; Wang, R. K.

    2014-08-01

    We report application of laser speckle contrast imaging (LSCI), i.e., a fast imaging technique utilising backscattered light to distinguish such moving objects as red blood cells from such stationary objects as surrounding tissue, to localise skin injury. This imaging technique provides detailed information about the acute perfusion response after a blood vessel is occluded. In this study, a mouse ear model is used and pulsed laser coagulation serves as the method of occlusion. We have found that the downstream blood vessels lacked blood flow due to occlusion at the target site immediately after injury. Relative flow changes in nearby collaterals and anastomotic vessels have been approximated based on differences in intensity in the nearby collaterals and anastomoses. We have also estimated the density of the affected downstream vessels. Laser speckle contrast imaging is shown to be used for highresolution and fast-speed imaging for the skin microvasculature. It also allows direct visualisation of the blood perfusion response to injury, which may provide novel insights to the field of cutaneous wound healing.

  19. Intensify Denoisy Image Using Adaptive Multiscale Product Thresholding

    Directory of Open Access Journals (Sweden)

    Mr. Anup T. Gadre,

    2015-06-01

    Full Text Available This Paper presents a wavelet-based multiscale products thresholding scheme for noise suppression of magnetic resonance images. This paper proposed a method based on image de-noising and edge enhancement of noisy multidimensional imaging data sets. Medical images are generally suffered from signal dependent noises i.e. speckle noise and broken edges. Most of the noises signals appear from machine and environment generally not contribute to the tissue differentiation. But, the noise generated due to above mentioned reason causes a grainy appearance on the image, hence image enhancement is required. For the intent of image denoising, Adaptive Multiscale Product Thresholding based on 2-D wavelet transform is used. In this method, contiguous wavelet sub bands are multiplied to improve edge structure while reducing noise. In multiscale products, boundaries can be successfully distinguished from noise. Adaptive threshold is designed and forced on multiscale products as an alternative of wavelet coefficients or recognize important features. For the edge enhancement. Canny Edge Detection Algorithm is used with scale multiplication technique. Simulation results shows that the planned technique better suppress the Poisson noise among several noises i.e. salt & pepper, speckle noise and random noise. The Performance of Image Intesification can be estimate by means of PSNR, MSE.

  20. Detecting physiological systems with laser speckle perfusion imaging of the renal cortex.

    Science.gov (United States)

    Scully, Christopher G; Mitrou, Nicholas; Braam, Branko; Cupples, William A; Chon, Ki H

    2013-06-01

    Laser speckle perfusion imaging (LSPI) has become an increasingly popular technique for monitoring vascular perfusion over a tissue surface. However, few studies have utilized the full range of spatial and temporal information generated by LSPI to monitor spatial properties of physiologically relevant dynamics. In this study, we extend the use of LSPI to analyze renal perfusion dynamics over a spatial surface of ~5 × 7 mm of renal cortex. We identify frequencies related to five physiological systems that induce temporal changes in renal vascular perfusion (cardiac flow pulse, respiratory-induced oscillations, baroreflex components, the myogenic response, and tubuloglomerular feedback) across the imaged surface and compare the results with those obtained from renal blood flow measurements. We find that dynamics supplied from global sources (cardiac, respiration, and baroreflex) present with the same frequency at all locations across the imaged surface, but the local renal autoregulation dynamics can be heterogeneous in their distribution across the surface. Moreover, transfer function analysis with forced blood pressure as the input yields the same information with laser speckle imaging or renal blood flow as the output during control, intrarenal infusion of N(ω)-nitro-L-arginine methyl ester to enhance renal autoregulation, and intrarenal infusion of the rho-kinase inhibitor Y-27632 to inhibit vasomotion. We conclude that LSPI measurements can be used to analyze local as well as global renal perfusion dynamics and to study the properties of physiological systems across the renal cortex.

  1. Reaching the Diffraction Limit - Differential Speckle and Wide-Field Imaging for the Gemini-N Telescope

    Science.gov (United States)

    Scott, Nic J.; Howell, Steve; Horch, Elliott

    2016-01-01

    Speckle imaging allows telescopes to achieve di raction limited imaging performance. The technique requires cameras capable of reading out frames at a very fast rate, e ectively `freezing out' atmospheric seeing. The resulting speckles can be correlated and images reconstructed that are at the di raction limit of the telescope. These new instruments are based on the successful performance and design of the Di erential Speckle Survey Instrument (DSSI) [2, 1]. The instruments are being built for the Gemini-N and WIYN telescopes and will be made available to the community via the peer review proposal process. We envision their primary use to be validation and characterization of exoplanet targets from the NASA K2 and TESS missions and RV discovered exoplanets. Such targets will provide excellent follow-up candidates for both the WIYN and Gemini telescopes [3]. Examples of DSSI data are shown in the gures below. We expect similar data quality in speckle imaging mode with the new instruments. Additionally, both cameras will have a wide- eld mode and standard SDSS lters. They will be highly versatile instruments and it is that likely many other science programs will request time on the cameras. The limiting magnitude for speckle observations, will remain around 13-14th at WIYN and 16-17th at Gemini, while wide- eld, normal CCD imaging operation should be able to go to much fainter, providing usual CCD imaging and photometric capabilities. The instruments will also have high utility as scoring cameras for telescope engineering purposes, or other applications where high time resolution is needed. Instrument support will be provided, including a software pipeline that takes raw speckle data to fully reconstructed images.

  2. Optical diagnostics of vascular reactions triggered by weak allergens using laser speckle-contrast imaging technique

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, Yu L; Kalchenko, V V [Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, 76100 (Israel); Astaf' eva, N G [V.I.Razumovsky Saratov State Medical University, Saratov (Russian Federation); Meglinski, I V [N.G. Chernyshevsky Saratov State University, Saratov (Russian Federation)

    2014-08-31

    The capability of using the laser speckle contrast imaging technique with a long exposure time for visualisation of primary acute skin vascular reactions caused by a topical application of a weak contact allergen is considered. The method is shown to provide efficient and accurate detection of irritant-induced primary acute vascular reactions of skin. The presented technique possesses a high potential in everyday diagnostic practice, preclinical studies, as well as in the prognosis of skin reactions to the interaction with potentially allergenic materials. (laser biophotonics)

  3. Optical diagnostics of vascular reactions triggered by weak allergens using laser speckle-contrast imaging technique

    Science.gov (United States)

    Kuznetsov, Yu L.; Kalchenko, V. V.; Astaf'eva, N. G.; Meglinski, I. V.

    2014-08-01

    The capability of using the laser speckle contrast imaging technique with a long exposure time for visualisation of primary acute skin vascular reactions caused by a topical application of a weak contact allergen is considered. The method is shown to provide efficient and accurate detection of irritant-induced primary acute vascular reactions of skin. The presented technique possesses a high potential in everyday diagnostic practice, preclinical studies, as well as in the prognosis of skin reactions to the interaction with potentially allergenic materials.

  4. Near-field speckle-scanning-based x-ray imaging

    OpenAIRE

    Berujon, Sebastien; Ziegler, Eric

    2015-01-01

    The x-ray near-field speckle-scanning concept is an approach recently introduced to obtain absorption, phase, and dark-field images of a sample. In this paper, we present ways of recovering from a sample its ultrasmall-angle x-ray scattering distribution using numerical deconvolution. We also show how to access the 2D phase gradient signal from random step scans, the latter having the potential to elude the flat-field correction error. Each feature is explained theoretically and demonstrated ...

  5. Singularities in Speckled Speckle: Screening

    CERN Document Server

    Kessler, David A

    2008-01-01

    We study screening of optical singularities in random optical fields with two widely different length scales. We call the speckle patterns generated by such fields speckled speckle, because the major speckle spots in the pattern are themselves highly speckled. We study combinations of fields whose components exhibit short- and long-range correlations, and find unusual forms of screening.

  6. Imaging Aortic Regurgitation: The Incremental Benefit of Speckle Tracking Echocardiography

    Science.gov (United States)

    Garg, Pankaj; Yassin, Firas; Leischik, Roman

    2015-01-01

    Aortic regurgitation (AR) affects global left ventricular mechanics. However, limited literature is available on how it may affect regional longitudinal strain. We present a case where severe AR jet is thrashing the anterior-septal wall and reducing its overall longitudinal performance most likely secondary to increased wall shear stress in diastole. This new insight into patho-physiological process using deformation study may have supplementary impact in decision making for surgical intervention. Transthoracic echocardiography is the primary imaging modality for the assessment of AR as it offers evaluation of severity of AR, aetiology of AR, left ventricular (LV) dilatation, LV systolic function, left ventricular mass, diastolic function and global strain. This case highlights the regional disturbances in longitudinal strain in eccentric AR. PMID:27006711

  7. Mobile phone based laser speckle contrast imager for assessment of skin blood flow

    Science.gov (United States)

    Jakovels, Dainis; Saknite, Inga; Krievina, Gita; Zaharans, Janis; Spigulis, Janis

    2014-10-01

    Assessment of skin blood flow is of interest for evaluation of skin viability as well as for reflection of the overall condition of the circulatory system. Laser Doppler perfusion imaging (LDPI) and laser speckle contrast imaging (LASCI) are optical techniques used for assessment of skin perfusion. However, these systems are still too expensive and bulky to be widely available. Implementation of such techniques as connection kits for mobile phones have a potential for primary diagnostics. In this work we demonstrate simple and low cost LASCI connection kit for mobile phone and its comparison to laser Doppler perfusion imager. Post-occlusive hyperemia and local thermal hyperemia tests are used to compare both techniques and to demonstrate the potential of LASCI device.

  8. Exploiting the speckle-correlation scattering matrix for a compact reference-free holographic image sensor

    Science.gov (United States)

    Lee, Kyeoreh; Park, Yongkeun

    2016-10-01

    The word `holography' means a drawing that contains all of the information for light--both amplitude and wavefront. However, because of the insufficient bandwidth of current electronics, the direct measurement of the wavefront of light has not yet been achieved. Though reference-field-assisted interferometric methods have been utilized in numerous applications, introducing a reference field raises several fundamental and practical issues. Here we demonstrate a reference-free holographic image sensor. To achieve this, we propose a speckle-correlation scattering matrix approach; light-field information passing through a thin disordered layer is recorded and retrieved from a single-shot recording of speckle intensity patterns. Self-interference via diffusive scattering enables access to impinging light-field information, when light transport in the diffusive layer is precisely calibrated. As a proof-of-concept, we demonstrate direct holographic measurements of three-dimensional optical fields using a compact device consisting of a regular image sensor and a diffusor.

  9. An experimental model for minimizing errors in laser speckle contrast imaging for microcirculation analysis

    Science.gov (United States)

    Sujatha, N.; Banerjee, Arnab

    2015-03-01

    Understanding the changes in microcirculatory flow and its measurements are very important for assessing the progress of various vascular malfunctions and their subsequent treatment effectiveness. Laser Speckle Contrast Imaging (LSCI) has been evolved as a whole-field, non-invasive and non-contact technique which has inherent advantages for microcirculation assessment in an in vivo environment compared to its noninvasive counterparts such as laser Doppler technique and video capillaroscopy. However, representation of flow velocity values in absolute units is still challenging and yet to be completely explored. In this paper, we propose an experimental model for estimating the flow velocity based for optimum camera exposure time. The LSCI experiments were conducted on a custom made phantom flow channel with induced flow in the microcirculation range using a syringe pump. The speckle image contrast was estimated temporally and is used to calculate velocity values. The relative error in the flow values is estimated to be a function of the calculated contrast. The estimated error has been incorporated as a correction factor in the obtained velocity term using LSCI and final velocity estimation was found to be within an acceptable error range independent of the flow velocity and scatterer concentration of the sample for optimum camera exposure duration.

  10. Imaging through diffusive layers using speckle pattern fractal analysis and application to embedded object detection in tissues

    Science.gov (United States)

    Tremberger, George, Jr.; Flamholz, A.; Cheung, E.; Sullivan, R.; Subramaniam, R.; Schneider, P.; Brathwaite, G.; Boteju, J.; Marchese, P.; Lieberman, D.; Cheung, T.; Holden, Todd

    2007-09-01

    The absorption effect of the back surface boundary of a diffuse layer was studied via laser generated reflection speckle pattern. The spatial speckle intensity provided by a laser beam was measured. The speckle data were analyzed in terms of fractal dimension (computed by NIH ImageJ software via the box counting fractal method) and weak localization theory based on Mie scattering. Bar code imaging was modeled as binary absorption contrast and scanning resolution in millimeter range was achieved for diffusive layers up to thirty transport mean free path thick. Samples included alumina, porous glass and chicken tissue. Computer simulation was used to study the effect of speckle spatial distribution and observed fractal dimension differences were ascribed to variance controlled speckle sizes. Fractal dimension suppressions were observed in samples that had thickness dimensions around ten transport mean free path. Computer simulation suggested a maximum fractal dimension of about 2 and that subtracting information could lower fractal dimension. The fractal dimension was shown to be sensitive to sample thickness up to about fifteen transport mean free paths, and embedded objects which modified 20% or more of the effective thickness was shown to be detectable. The box counting fractal method was supplemented with the Higuchi data series fractal method and application to architectural distortion mammograms was demonstrated. The use of fractals in diffusive analysis would provide a simple language for a dialog between optics experts and mammography radiologists, facilitating the applications of laser diagnostics in tissues.

  11. Adaptive wiener image restoration kernel

    Science.gov (United States)

    Yuan, Ding

    2007-06-05

    A method and device for restoration of electro-optical image data using an adaptive Wiener filter begins with constructing imaging system Optical Transfer Function, and the Fourier Transformations of the noise and the image. A spatial representation of the imaged object is restored by spatial convolution of the image using a Wiener restoration kernel.

  12. Blood flow activation in rat somatosensory cortex under sciatic nerve stimulation revealed by laser speckle imaging

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In many functional neuroimaging research the change of local cerebral blood flow (CBF) induced by sensory stimulation is regarded as an indicator of the change in cortical neuronal activity although a precise and full spatio-temporal description of local CBF response coupled to neural activity has still not been laid out. Using the laser speckle imaging technique a relatively large exposed area in somatosensory cortex of rat was imaged for the observation of the variations of CBF during sciatic nerve stimulation. The results showed that cerebral blood flow activation was spatially localized and discretely distributed in the targeted microvasculature. Individual arteries, veins and capillaries in different diameters were activated with the time going. The response pattern of CBF related to the function of brain activity and energy metabolism is delineated exactly.

  13. Trans-illuminated laser speckle imaging of collateral artery blood flow in ischemic mouse hindlimb.

    Science.gov (United States)

    Meisner, Joshua K; Niu, Jacqueline; Sumer, Suna; Price, Richard J

    2013-09-01

    The mouse ischemic hindlimb model is used widely for studying collateral artery growth (i.e., arteriogenesis) in response to increased shear stress. Nonetheless, precise measurements of regional shear stress changes along individual collateral arteries are lacking. Our goal is to develop and verify trans-illumination laser speckle flowmetry (LSF) for this purpose. Studies of defibrinated bovine blood flow through tubes embedded in tissue-mimicking phantoms indicate that trans-illumination LSF better maintains sensitivity with an increasing tissue depth when compared to epi-illumination, with an ∼50% reduction in the exponential decay of the speckle velocity signal. Applying trans-illuminated LSF to the gracilis muscle collateral artery network in vivo yields both improved sensitivity and reduced noise when compared to epi-illumination. Trans-illuminated LSF images reveal regional differences in collateral artery blood velocity after femoral artery ligation and are used to measure an ∼2-fold increase in the shear stress at the entrance regions to the muscle. We believe these represent the first direct measurements of regional shear stress changes in individual mouse collateral arteries. The ability to capture deeper vascular signals using a trans-illumination configuration for LSF may expand the current applications for LSF, which could have bearing on determining how shear stress magnitude and direction regulate arteriogenesis.

  14. Laser speckle imaging identification of increases in cortical microcirculatory blood flow induced by motor activity during awake craniotomy ; Clinical article

    NARCIS (Netherlands)

    E. Klijn (Elko); M.E.J.L. Hulscher (Marlies); R.K. Balvers (Rutger); W.P.J. Holland (Wim); J. Bakker (Jan); A.J.P.E. Vincent (Arnoud); C.M.F. Dirven (Clemens); C. Ince (Can)

    2013-01-01

    textabstractObject. The goal of awake neurosurgery is to maximize resection of brain lesions with minimal injury to functional brain areas. Laser speckle imaging (LSI) is a noninvasive macroscopic technique with high spatial and temporal resolution used to monitor changes in capillary perfusion. In

  15. On-sky speckle nulling demonstration at small angular separation with SCExAO

    CERN Document Server

    Martinache, Frantz; Jovanovic, Nemanja; Clergeon, Christophe; Singh, Garima; Kudo, Tomoyuki; Currie, Thayne; Thalmann, Christian; McElwain, Michael; Tamura, Motohide

    2014-01-01

    This paper presents the first on-sky demonstration of speckle nulling, which was achieved at the Subaru Telescope in the context of the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) Project. Despite the absence of a high-order high-bandwidth closed-loop AO system, observations conducted with SCExAO show that even in poor-to-moderate observing conditions, speckle nulling can be used to suppress static and slow speckles even in the presence of a brighter dynamic speckle halo, suggesting that more advanced high-contrast imaging algorithms developed in the laboratory can be applied to ground-based systems.

  16. Experimental comparison between speckle and grating-based imaging technique using synchrotron radiation X-rays.

    Science.gov (United States)

    Kashyap, Yogesh; Wang, Hongchang; Sawhney, Kawal

    2016-08-08

    X-ray phase contrast and dark-field imaging techniques provide important and complementary information that is inaccessible to the conventional absorption contrast imaging. Both grating-based imaging (GBI) and speckle-based imaging (SBI) are able to retrieve multi-modal images using synchrotron as well as lab-based sources. However, no systematic comparison has been made between the two techniques so far. We present an experimental comparison between GBI and SBI techniques with synchrotron radiation X-ray source. Apart from the simple experimental setup, we find SBI does not suffer from the issue of phase unwrapping, which can often be problematic for GBI. In addition, SBI is also superior to GBI since two orthogonal differential phase gradients can be simultaneously extracted by one dimensional scan. The GBI has less stringent requirements for detector pixel size and transverse coherence length when a second or third grating can be used. This study provides the reference for choosing the most suitable technique for diverse imaging applications at synchrotron facility.

  17. Laser speckle contrast imaging for monitoring changes in microvascular blood flow

    DEFF Research Database (Denmark)

    Ambrus, Rikard; Strandby, Rune B.; Svendsen, Lars Bo;

    2016-01-01

    BACKGROUND/AIMS: Microvascular blood flow is essential for healing and predicts surgical outcome. The aim of the current study was to investigate the relation between fluxes measured with the laser speckle contrast imaging (LSCI) technique and changes in absolute blood flow. In addition, we studied...... the reproducibility of the LSCI technique when assessing the intra-abdominal microcirculation of the pig. METHODS: During trial 1, a fish gill arch was mechanically perfused with heparinized fish blood under controlled stepwise-altered flow rates alongside mechanically induced movement artefacts. The microcirculation...... = 6.0, 3.2, and 6.4%, respectively). CONCLUSION: Due to the non-contact and real-time assessment over large areas, LSCI is a promising technique for the intraoperative assessment of intra-abdominal microcirculation. A linear correlation between flux and volumetric flow was found, in accordance...

  18. Detection of early carious lesions using contrast enhancement with coherent light scattering (speckle imaging)

    Science.gov (United States)

    Deana, A. M.; Jesus, S. H. C.; Koshoji, N. H.; Bussadori, S. K.; Oliveira, M. T.

    2013-07-01

    Currently, dental caries still represent one of the chronic diseases with the highest prevalence and present in most countries. The interaction between light and teeth (absorption, scattering and fluorescence) is intrinsically connected to the constitution of the dental tissue. Decay induced mineral loss introduces a shift in the optical properties of the affected tissue; therefore, study of these properties may produce novel techniques aimed at the early diagnosis of carious lesions. Based on the optical properties of the enamel, we demonstrate the application of first-order spatial statistics in laser speckle imaging, allowing the detection of carious lesions in their early stages. A highlight of this noninvasive, non-destructive, real time and cost effective approach is that it allows a dentist to detect a lesion even in the absence of biofilm or moisture.

  19. InnoPOL: an EMCCD imaging polarimeter and 85-element curvature AO system on the 3.6-m AEOS telescope for cost effective polarimetric speckle suppression

    CERN Document Server

    Harrington, David; Chun, Mark; Ftaclas, Christ; Gisler, Daniel; Kuhn, Jeff

    2016-01-01

    The Hokupa'a-85 curvature adaptive optics system components have been adapted to create a new AO-corrected coud\\'{e} instrument at the 3.67m Advanced Electro-Optical System (AEOS) telescope. This new AO-corrected optical path is designed to deliver an f/40 diffraction-limited focus at wavelengths longer than 800nm. A new EMCCD-based dual-beam imaging polarimeter called InnoPOL has been designed and is presently being installed behind this corrected f/40 beam. The InnoPOL system is a flexible platform for optimizing polarimetric performance using commercial solutions and for testing modulation strategies. The system is designed as a technology test and demonstration platform as the coud\\'{e} path is built using off-the-shelf components wherever possible. Models of the polarimetric performance after AO correction show that polarization modulation at rates as slow as 200Hz can cause speckle correlations in brightness and focal plane location sufficient enough to change the speckle suppression behavior of the mod...

  20. High spatial resolution and high contrast optical speckle imaging with FASTCAM at the ORM

    CERN Document Server

    Labadie, L; Femenia, B; Villo, Isidro; Diaz-Sanchez, A; Oscoz, A; Lopez, R; Perez-Prieto, J; Perez-Garrido, A; Hildebrandt, S R; Bejar-Sanchez, V; Piqueras, J; Rodriguez, L F; 10.1117/12.857998

    2010-01-01

    In this paper, we present an original observational approach, which combines, for the first time, traditional speckle imaging with image post-processing to obtain in the optical domain diffraction-limited images with high contrast (1e-5) within 0.5 to 2 arcseconds around a bright star. The post-processing step is based on wavelet filtering an has analogy with edge enhancement and high-pass filtering. Our I-band on-sky results with the 2.5-m Nordic Telescope (NOT) and the lucky imaging instrument FASTCAM show that we are able to detect L-type brown dwarf companions around a solar-type star with a contrast DI~12 at 2" and with no use of any coronographic capability, which greatly simplifies the instrumental and hardware approach. This object has been detected from the ground in J and H bands so far only with AO-assisted 8-10 m class telescopes (Gemini, Keck), although more recently detected with small-class telescopes in the K band. Discussing the advantage and disadvantage of the optical regime for the detecti...

  1. Nanoparticles speckled by ready-to-conjugate lanthanide complexes for multimodal imaging

    Science.gov (United States)

    Biju, Vasudevanpillai; Hamada, Morihiko; Ono, Kenji; Sugino, Sakiko; Ohnishi, Takashi; Shibu, Edakkattuparambil Sidharth; Yamamura, Shohei; Sawada, Makoto; Nakanishi, Shunsuke; Shigeri, Yasushi; Wakida, Shin-Ichi

    2015-09-01

    Multimodal and multifunctional contrast agents receive enormous attention in the biomedical imaging field. Such contrast agents are routinely prepared by the incorporation of organic molecules and inorganic nanoparticles (NPs) into host materials such as gold NPs, silica NPs, polymer NPs, and liposomes. Despite their non-cytotoxic nature, the large size of these NPs limits the in vivo distribution and clearance and inflames complex pharmacokinetics, which hinder the regulatory approval for clinical applications. Herein, we report a unique method that combines magnetic resonance imaging (MRI) and fluorescence imaging modalities together in nanoscale entities by the simple, direct and stable conjugation of novel biotinylated coordination complexes of gadolinium(iii) to CdSe/ZnS quantum dots (QD) and terbium(iii) to super paramagnetic iron oxide NPs (SPION) but without any host material. Subsequently, we evaluate the potentials of such lanthanide-speckled fluorescent-magnetic NPs for bioimaging at single-molecule, cell and in vivo levels. The simple preparation and small size make such fluorescent-magnetic NPs promising contrast agents for biomedical imaging.

  2. Dedicated hardware processor and corresponding system-on-chip design for real-time laser speckle imaging.

    Science.gov (United States)

    Jiang, Chao; Zhang, Hongyan; Wang, Jia; Wang, Yaru; He, Heng; Liu, Rui; Zhou, Fangyuan; Deng, Jialiang; Li, Pengcheng; Luo, Qingming

    2011-11-01

    Laser speckle imaging (LSI) is a noninvasive and full-field optical imaging technique which produces two-dimensional blood flow maps of tissues from the raw laser speckle images captured by a CCD camera without scanning. We present a hardware-friendly algorithm for the real-time processing of laser speckle imaging. The algorithm is developed and optimized specifically for LSI processing in the field programmable gate array (FPGA). Based on this algorithm, we designed a dedicated hardware processor for real-time LSI in FPGA. The pipeline processing scheme and parallel computing architecture are introduced into the design of this LSI hardware processor. When the LSI hardware processor is implemented in the FPGA running at the maximum frequency of 130 MHz, up to 85 raw images with the resolution of 640×480 pixels can be processed per second. Meanwhile, we also present a system on chip (SOC) solution for LSI processing by integrating the CCD controller, memory controller, LSI hardware processor, and LCD display controller into a single FPGA chip. This SOC solution also can be used to produce an application specific integrated circuit for LSI processing.

  3. Comet Shoemaker-Levy 9/Jupiter collision observed with a high resolution speckle imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Gravel, D. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    During the week of July 16, 1994, comet Shoemaker-Levy 9, broken into 20 plus pieces by tidal forces on its last orbit, smashed into the planet Jupiter, releasing the explosive energy of 500 thousand megatons. A team of observers from LLNL used the LLNL Speckle Imaging Camera mounted on the University of California`s Lick Observatory 3 Meter Telescope to capture continuous sequences of planet images during the comet encounter. Post processing with the bispectral phase reconstruction algorithm improves the resolution by removing much of the blurring due to atmospheric turbulence. High resolution images of the planet surface showing the aftermath of the impact are probably the best that were obtained from any ground-based telescope. We have been looking at the regions of the fragment impacts to try to discern any dynamic behavior of the spots left on Jupiter`s cloud tops. Such information can lead to conclusions about the nature of the comet and of Jupiter`s atmosphere. So far, the Hubble Space Telescope has observed expanding waves from the G impact whose mechanism is enigmatic since they appear to be too slow to be sound waves and too fast to be gravity waves, given the present knowledge of Jupiter`s atmosphere. Some of our data on the G and L impact region complements the Hubble observations but, so far, is inconclusive about spot dynamics.

  4. Monitoring microcirculation changes in port wine stains during vascular targeted photodynamic therapy by laser speckle imaging.

    Science.gov (United States)

    Qiu, Haixia; Zhou, Yang; Gu, Ying; Ang, Qing; Zhao, ShiYong; Wang, Ying; Zeng, Jing; Huang, Naiyan

    2012-01-01

    This study was conducted to test laser speckle perfusion imaging (LSPI) for imaging microcirculation and monitoring microcirculatory changes of port wine stains (PWS) during vascular targeted photodynamic therapy (V-PDT). Before and 5 min after V-PDT, PWS lesions and the corresponding contralateral healthy skins of 24 PWS patients were scanned, whereas seven PWS patients were scanned throughout V-PDT. V-PDT was conducted immediately after intravenous injection of photocarcinorin (4-5 mg kg(-1)). A 532 nm laser was used for irradiation (power density: 80-100 mW cm(-2), exposure time: 20-50 min). Before V-PDT, all 24 PWS patients demonstrated a significant difference in perfusion between the PWS lesion and the contralateral healthy control skin (1132 ± 724 and 619 ± 478 PU, respectively, P 0.05). During V-PDT, the perfusion of seven PWS patients increased rapidly after initiation of V-PDT, reached a maximum within 10 min, lasted for several minutes, and slowly returned to a relatively lower level at the end of V-PDT. On the basis of these results, LSPI is capable of imaging PWS microvasculature and monitoring microvascular reactivity to V-PDT.

  5. Singularities in Speckled Speckle: Statistics

    CERN Document Server

    Freund, Isaac

    2008-01-01

    Random optical fields with two widely different correlation lengths generate far field speckle spots that are themselves highly speckled. We call such patterns speckled speckle, and study their critical points (singularities and stationary points) using analytical theory and computer simulations. We find anomalous spatial arrangements of the critical points and orders of magnitude anomalies in their relative number densities, and in the densities of the associated zero crossings.

  6. Widefield lensless endoscopy via speckle-correlations

    CERN Document Server

    Porat, Amir; Rigneault, Hervé; Oron, Dan; Gigan, Sylvain; Katz, Ori

    2016-01-01

    Flexible fiber-optic endoscopes provide a minimally-invasive solution for imaging at depths beyond the reach of conventional microscopes. Current endoscopes require focusing and/or scanning mechanisms at the distal end, which limit miniaturization and frame-rate, and induce aberrations. Alternative lensless solutions are based on adaptive wavefront-correction, but are extremely sensitive to fiber bending. Here, we demonstrate a novel endoscopic approach, which enables single-shot imaging at a variable working distance through a conventional fiber bundle, without the use of any distal optics. Our approach computationally retrieves the object image from a single speckle pattern transmitted through the bundle, exploiting phase information preserved through inherent angular speckle correlations. Unlike conventional fiber-bundle endoscopes, the resulting image is unpixelated, the resolution is diffraction-limited, objects can be imaged at variable working distance, and the technique is completely insensitive to fi...

  7. Role of speckle tracking imaging in the assessment of myocardial regional ventricular function in experimental blunt cardiac injury

    Institute of Scientific and Technical Information of China (English)

    Wen-Hua Du; Xiang Wang; Xiu-Qin Xiong; Tao Li; Hua-Ping Liang

    2015-01-01

    Purpose:To evaluate the usefulness and information collecting ability of speckle tracking imaging techniques in the assessment of myocardial regional ventricular contractility in a rabbit model with blunt cardiac injury.Methods:Fifteen healthy New Zealand rabbits weighing (2.70 ± 0.28) kg were anesthetized (3% pentobarbital sodium/i.v) and impacted using the BIM-Ⅱ biological impact machine to induce myocardial contusion (MC).Hemodynamic parameters,such as heart rate,systolic pressure,mean arterial pressure,diastolic pressure and central venous pressure,were determined before and after MC.Further,parameters reflecting left ventricular functions,such as left ventricular end systolic pressure,left ventricular end diastolic pressure,isovolumic pressure (IP) and the maximal increasing/decreasing rate of left intraventricular pressure (±dp/dtmax),were also determined before and after MC.Left ventricular functions were determined either by two dimensional transthoracic echocardiography or by speckle tracking imaging for segmental abnormal ventricular wall motions.Results:Heart rate,systolic pressure,diastolic pressure and mean arterial pressure decreased significantly but transiently,while central venous pressure markedly increased after MC.In contrast to significant changes in diastolic functions,there was no significant change in cardiac systolic functions after MC.The speckle tracking imaging demonstrated that strain values of different myocardial segment significantly decreased post impact,and that of the ventricular segment decreased from segment to segment.Conclusion:Speckle tracking imaging is useful and informative to assess myocardial regional dysfunctions post MC.

  8. A reduced gastric corpus microvascular blood flow during Ivor-Lewis esophagectomy detected by laser speckle contrast imaging technique

    DEFF Research Database (Denmark)

    Ambrus, Rikard; Svendsen, Lars B; Secher, Niels H;

    2017-01-01

    BACKGROUND: Reduced microvascular blood flow is related to anastomotic insufficiency following esophagectomy, emphasizing a need for intraoperative monitoring of the microcirculation. This study evaluated if laser speckle contrast imaging (LSCI) was able to detect intraoperative changes in gastric......). The decrease in corpus microcirculation took place unrelated to central cardiovascular variables. CONCLUSION: Using LSCI technique, we identified a reduced microcirculation at the corpus area during open Ivor-Lewis esophagectomy. LSCI provides an option for real-time assessment of gastric microcirculation...

  9. Combined effects of scattering and absorption on laser speckle contrast imaging

    Science.gov (United States)

    Khaksari, Kosar; Kirkpatrick, Sean J.

    2016-07-01

    Several variables may affect the local contrast values in laser speckle contrast imaging (LSCI), irrespective of relative motion. It has been suggested that the optical properties of the moving fluid and surrounding tissues can affect LSCI values. However, a detailed study of this has yet to be presented. In this work, we examined the combined effects of the reduced scattering and absorption coefficients on LSCI. This study employs fluid phantoms with different optical properties that were developed to mimic whole blood with varying hematocrit levels. These flow phantoms were imaged with an LSCI system developed for this study. The only variable parameter was the optical properties of the flowing fluid. A negative linear relationship was seen between the changes in contrast and changes in reduced scattering coefficient, absorption coefficient, and total attenuation coefficient. The change in contrast observed due to an increase in the scattering coefficient was greater than what was observed with an increase in the absorption coefficient. The results indicate that optical properties affect contrast values and that they should be considered in the interpretation of LSCI data.

  10. Quantitative Assessment of Graded Burn Wounds in a Porcine Model using Spatial Frequency Domain Imaging (SFDI) and Laser Speckle Imaging (LSI)

    Science.gov (United States)

    2014-09-08

    custom LabVIEW (Version 8.0, National Instruments, Austin, TX) software, integrating CUDA GPU code to carry out real-time LSI imaging and processing...was equipped with a GTX650 Graphics Processing Unit ( GPU ) (NVIDIA, Santa Clara, CA). A laser speckle pattern was generated by the 633nm laser source

  11. Gabor-based anisotropic diffusion for speckle noise reduction in medical ultrasonography.

    Science.gov (United States)

    Zhang, Qi; Han, Hong; Ji, Chunhong; Yu, Jinhua; Wang, Yuanyuan; Wang, Wenping

    2014-06-01

    In ultrasound (US), optical coherence tomography, synthetic aperture radar, and other coherent imaging systems, images are corrupted by multiplicative speckle noise that obscures image interpretation. An anisotropic diffusion (AD) method based on the Gabor transform, named Gabor-based anisotropic diffusion (GAD), is presented to suppress speckle in medical ultrasonography. First, an edge detector using the Gabor transform is proposed to capture directionality of tissue edges and discriminate edges from noise. Then the edge detector is embedded into the partial differential equation of AD to guide the diffusion process and iteratively denoise images. To enhance GAD's adaptability, parameters controlling diffusion are determined from a fully formed speckle region that is automatically detected. We evaluate the GAD on synthetic US images simulated with three models and clinical images acquired in vivo. Compared with seven existing speckle reduction methods, the GAD is superior to other methods in terms of noise reduction and detail preservation.

  12. Enlarging the linear response range of velocity with optimum imaging parameters and modified data processing in laser speckle imaging

    Science.gov (United States)

    Qiu, Jianjun; Li, Pengcheng; Ul'yanov, Sergey S.; Zeng, Shaoqun; Luo, Qingming

    2008-02-01

    Laser speckle imaging (LSI) technique is considered as a promising method of accessing cerebral blood flow (CBF) of animals for its high spatiotemporal resolution and simplicity. It is important in LSI that optimum imaging parameters and limited noises should be confirmed to promote the imaging precision. We investigated in this paper different factors which may affect the imaging results with a moving white plate model, and then proposed a method of enlarging the linear response range of velocity. Through experiment, we proposed in our LSI system the optimum imaging parameters, including the numerical aperture and magnification of microscopy, the integration time, the gain mode of CCD camera. The average intensity was found optimum at about 800 counts out of 4096 grey level, which permits the highest contrast in our experiment. To eliminate the influence of uneven illumination, a direct current weight of 27 counts was subtracted during data processing. The result indicated that the relationship between measured velocity and the real one remained linear with R2 equaling to 0.99 throughout the scale of 80 mm/s.

  13. Laser speckle contrast imaging identifies ischemic areas on gastric tube reconstructions following esophagectomy.

    Science.gov (United States)

    Milstein, Dan M J; Ince, Can; Gisbertz, Suzanne S; Boateng, Kofi B; Geerts, Bart F; Hollmann, Markus W; van Berge Henegouwen, Mark I; Veelo, Denise P

    2016-06-01

    Gastric tube reconstruction (GTR) is a high-risk surgical procedure with substantial perioperative morbidity. Compromised arterial blood supply and venous congestion are believed to be the main etiologic factors associated with early and late anastomotic complications. Identifying low blood perfusion areas may provide information on the risks of future anastomotic leakage and could be essential for improving surgical techniques. The aim of this study was to generate a method for gastric microvascular perfusion analysis using laser speckle contrast imaging (LSCI) and to test the hypothesis that LSCI is able to identify ischemic regions on GTRs.Patients requiring elective laparoscopy-assisted GTR participated in this single-center observational investigation. A method for intraoperative evaluation of blood perfusion and postoperative analysis was generated and validated for reproducibility. Laser speckle measurements were performed at 3 different time pointes, baseline (devascularized) stomach (T0), after GTR (T1), and GTR at 20° reverse Trendelenburg (T2).Blood perfusion analysis inter-rater reliability was high, with intraclass correlation coefficients for each time point approximating 1 (P < 0.0001). Baseline (T0) and GTR (T1) mean blood perfusion profiles were highest at the base of the stomach and then progressively declined towards significant ischemia at the most cranial point or anastomotic tip (P < 0.01). After GTR, a statistically significant improvement in mean blood perfusion was observed in the cranial gastric regions of interest (P < 0.05). A generalized significant decrease in mean blood perfusion was observed across all GTR regions of interest during 20° reverse Trendelenburg (P < 0.05).It was feasible to implement LSCI intraoperatively to produce blood perfusion assessments on intact and reconstructed whole stomachs. The analytical design presented in this study resulted in good reproducibility of gastric perfusion measurements

  14. Assessment of Right Ventricular Free Wall Longitudinal Myocardial Deformation Using Speckle Tracking Imaging in Normal Subjects

    Institute of Scientific and Technical Information of China (English)

    Chun TONG; Chunlei LI; Jialin SONG; Hongyun LIU; Youbin DENG

    2008-01-01

    To assess right ventricular free wall longitudinal myocardium deformation and examine the changes with normal age by speckle tracking imaging (STI), myocardial systolic peak strain (ε), systolic peak strain rate (SRs), early diastolic peak strain rate (Sre), late diastolic peak strain rate (Sra), the ratio of Sre/Sra were measured in the basal, middle and apical segments of right ventricular free wall in 75 healthy volunteers (age range: 21-71 y) by STI from the apical 4-chamber view. RV longitudinal strain and strain rate were highest in the basal segment of the free wall. Older subjects had lower early diastolic strain rate (Sre) than younger subjects, but they had higher late diastolic strain rate (Sra). A negative correlation between age and the ratio of Sre/Sra was found in all RV free wall segments (r=-0.466 - -0.614, P<0.01). It is concluded that RV diastolic strain rate changes with age and STI can be used for the study of RV myocardial deformation.

  15. Assessment of Left Ventricular Global Twist in Essential Hypertensive Heart by Speckle Tracking Imaging

    Institute of Scientific and Technical Information of China (English)

    Wei HAN; Mingxing XIE; Xinfang WANG; Qing LU

    2008-01-01

    The left ventdcular twist was evaluated by 2-dimensional ultrasound speckle-tracking imaging (STI) in 50 patients with hypertension with normal geometric left ventricle (LV) and 45 normal subjects as control group. The mean value of LV rotation was obtained at each plane using STI. LV twist and twist velocity were defined as apical rotation/rotation rate relative to the base re- spectively. To adjust the intersubject differences in heart rates, the time sequence were normalized. The results showed that peak twist developed near the end of systole. Peak LV twist was significantly higher in patients with hypertension than normal controls (P<0.001). The diastolic untwisting mainly occurred in early diastole (≈38%). Compared with normal controls, untwisting rate (Untw R) in pa- tients with hypertension was significantly reduced (P<0.001), and untwisting half-time (UHT) was significantly delayed (P<0.05). This study demonstrated that STI has a potential ability to evaluate the early change of heart function in patients with hypertension by measuring the twist of LV.

  16. Design and evaluation of a miniature laser speckle imaging device to assess gingival health

    Science.gov (United States)

    Regan, Caitlin; White, Sean M.; Yang, Bruce Y.; Takesh, Thair; Ho, Jessica; Wink, Cherie; Wilder-Smith, Petra; Choi, Bernard

    2016-10-01

    Current methods used to assess gingivitis are qualitative and subjective. We hypothesized that gingival perfusion measurements could provide a quantitative metric of disease severity. We constructed a compact laser speckle imaging (LSI) system that could be mounted in custom-made oral molds. Rigid fixation of the LSI system in the oral cavity enabled measurement of blood flow in the gingiva. In vitro validation performed in controlled flow phantoms demonstrated that the compact LSI system had comparable accuracy and linearity compared to a conventional bench-top LSI setup. In vivo validation demonstrated that the compact LSI system was capable of measuring expected blood flow dynamics during a standard postocclusive reactive hyperemia and that the compact LSI system could be used to measure gingival blood flow repeatedly without significant variation in measured blood flow values (pgingival bleeding on probing. A statistically significant correlation (ρ=0.53 pgingival perfusion measurements performed using our system may aid in the diagnosis and prognosis of periodontal disease.

  17. Non invasive blood flow assessment in diabetic foot ulcer using laser speckle contrast imaging technique

    Science.gov (United States)

    Jayanthy, A. K.; Sujatha, N.; Reddy, M. Ramasubba; Narayanamoorthy, V. B.

    2014-03-01

    Measuring microcirculatory tissue blood perfusion is of interest for both clinicians and researchers in a wide range of applications and can provide essential information of the progress of treatment of certain diseases which causes either an increased or decreased blood flow. Diabetic ulcer associated with alterations in tissue blood flow is the most common cause of non-traumatic lower extremity amputations. A technique which can detect the onset of ulcer and provide essential information on the progress of the treatment of ulcer would be of great help to the clinicians. A noninvasive, noncontact and whole field laser speckle contrast imaging (LSCI) technique has been described in this paper which is used to assess the changes in blood flow in diabetic ulcer affected areas of the foot. The blood flow assessment at the wound site can provide critical information on the efficiency and progress of the treatment given to the diabetic ulcer subjects. The technique may also potentially fulfill a significant need in diabetic foot ulcer screening and management.

  18. 利用小波变换抑制星载SAR图象的斑点噪声%Speckle Restraint of Satellite SAR Image Using Wavelet Transform

    Institute of Scientific and Technical Information of China (English)

    胡召玲; 郭达志; 盛业华

    2001-01-01

    A speckle restraint algorithm was described for satellite SAR image using wavelet transform. The SAR image was decomposed using appropriate wavelet bases, and the contribution of speckle to wavelet coefficients was analyzed. Based on the multiplicative relation between speckle and gray and the correlation of speckle, a suitable threshold was selected. The SAR image after speckle restraining was reconstructed using wavelet reconstruction technique. The experiment shows that speckle can be effectively restrained using this algorithm.%利用小波变换技术对星载合成孔径雷达(SAR)图象斑点噪声进行抑制与滤除.选择合适的小波基对SAR图象进行小波分解,分析噪声对小波系数的贡献;针对噪声与图象灰度之间的乘性关系和SAR图象斑点噪声在空间上相关的特点设置适当的阈值,在小波域内滤波;通过小波重构技术获得滤波后的SAR图象.实验证明,该方法能有效地抑制SAR图象中的斑点噪声.

  19. Characterization of SEM speckle pattern marking and imaging distortion by Digital Image Correlation

    OpenAIRE

    Guery, Adrien; Latourte, Felix; Hild, François; Roux, Stéphane

    2014-01-01

    International audience; Surface patterning by e-beam lithography and SEM imaging distortions are studied via digital image correlation. The global distortions from the reference pattern, which has been numerically generated, are first quantified from a digital image correlation procedure between the (virtual) reference pattern and the actual SEM image both in secondary and backscattered electron imaging modes. These distortions result from both patterning and imaging techniques. These two con...

  20. Two-dimentional speckle tracking strain imaging in the assessment of myocardial diastolic function in patients with stable angina pectoris

    Directory of Open Access Journals (Sweden)

    Somaye Farokhnejad

    2015-06-01

    Full Text Available Introduction: Ischemic heart disease is caused mainly by obstruction of coronary arteries. The ischemic assessment through echocardiography is dependent on wall motion abnormality detection during systole. In patients with ischemic heart disease the diastolic function is impaired before systolic function and measurement of regional diastolic dysfunction if possible will be most sensitive for assessment of obstructed coronary artery region. This study was designed to determine whether regional left ventricular delayed relaxation diagnosis could be detected with strain imaging derived from two-dimensional speckle-tracking echocardiography in patients with coronary artery disease.Methods: All the articles reviewed were obtained using MEDLINE & ScienceDirect (up to October 2014. All data extracted by speckle tracking echocardiography. The index which is used is strain imaging diastolic index which is calculated as: (A-B A×100  . A is the amount of strain at the time Aortic value closure and B is the amount of strain in first one-third point of diastolic duration.Result: Four articles were reviewed. Three articles assessed patients with echocardiography at rest and one with stress echocardiography. All articles showed the coronary artery tracking with significant stenosis is possible by regional deformation analysis through two-dimensional strain.Discussion: The usage of strain images obtained through two-dimensional speckle tracking has been validated for the quantitation assessment of regional dysfunction in ischemic heart disease. Regional LV delayed relaxation diagnosis with strain imaging is a reliable method after treadmill stress test.Conclusion:  Strain imaging is reasonable for evaluation of ischemia as a low cost noninvasive test with high accuracy.

  1. Early detection of cardiac dysfunction in the type 1 diabetic heart using speckle-tracking based strain imaging.

    Science.gov (United States)

    Shepherd, Danielle L; Nichols, Cody E; Croston, Tara L; McLaughlin, Sarah L; Petrone, Ashley B; Lewis, Sara E; Thapa, Dharendra; Long, Dustin M; Dick, Gregory M; Hollander, John M

    2016-01-01

    Enhanced sensitivity in echocardiographic analyses may allow for early detection of changes in cardiac function beyond the detection limits of conventional echocardiographic analyses, particularly in a small animal model. The goal of this study was to compare conventional echocardiographic measurements and speckle-tracking based strain imaging analyses in a small animal model of type 1 diabetes mellitus. Conventional analyses revealed differences in ejection fraction, fractional shortening, cardiac output, and stroke volume in diabetic animals relative to controls at 6-weeks post-diabetic onset. In contrast, when assessing short- and long-axis speckle-tracking based strain analyses, diabetic mice showed changes in average systolic radial strain, radial strain rate, radial displacement, and radial velocity, as well as decreased circumferential and longitudinal strain rate, as early as 1-week post-diabetic onset and persisting throughout the diabetic study. Further, we performed regional analyses for the LV and found that the free wall region was affected in both the short- and long-axis when assessing radial dimension parameters. These changes began 1-week post-diabetic onset and remained throughout the progression of the disease. These findings demonstrate the use of speckle-tracking based strain as an approach to elucidate cardiac dysfunction from a global perspective, identifying left ventricular cardiac regions affected during the progression of type 1 diabetes mellitus earlier than contractile changes detected by conventional echocardiographic measurements.

  2. Query Adaptive Image Retrieval System

    Directory of Open Access Journals (Sweden)

    Amruta Dubewar

    2014-03-01

    Full Text Available Images play a crucial role in various fields such as art gallery, medical, journalism and entertainment. Increasing use of image acquisition and data storage technologies have enabled the creation of large database. So, it is necessary to develop appropriate information management system to efficiently manage these collections and needed a system to retrieve required images from these collections. This paper proposed query adaptive image retrieval system (QAIRS to retrieve images similar to the query image specified by user from database. The goal of this system is to support image retrieval based on content properties such as colour and texture, usually encoded into feature vectors. In this system, colour feature extracted by various techniques such as colour moment, colour histogram and autocorrelogram and texture feature extracted by using gabor wavelet. Hashing technique is used to embed high dimensional image features into hamming space, where search can be performed by hamming distance of compact hash codes. Depending upon minimum hamming distance it returns the similar image to query image.

  3. Velocity field measurements of valvular blood flow in a human superficial vein using high-frequency ultrasound speckle image velocimetry.

    Science.gov (United States)

    Nam, Kweon-Ho; Yeom, Eunseop; Ha, Hojin; Lee, Sang-Joon

    2012-01-01

    This study aims to investigate the blood flow around the perivalvular area in a human superficial vein using high-frequency ultrasound (HFUS) speckle image velocimetry. HFUS B-mode images were captured from the superficial veins of human lower extremity with a 35-MHz transducer. To measure the instantaneous velocity fields of blood flow, a cross-correlation particle image velocimetry (PIV) algorithm was applied to two B-mode images that were captured consecutively. The echo speckles of red blood cells (RBCs) were used as flow tracers. In the vicinity of the venous valve, the opening and closing motions of valve cusps were simultaneously visualized with the phasic variation of velocity fields. Large-scale vortices were observed behind the sinus pockets while the main bloodstream was directed proximally. This measurement technique combining PIV algorithm and HFUS B-mode imaging was found to be unique and useful for investigating the hemodynamic characteristics of blood flow in the perivalvular area and for diagnosing venous insufficiency and valve abnormality in superficial blood vessels.

  4. Polarization speckle imaging as a potential technique for in vivo skin cancer detection

    Science.gov (United States)

    Tchvialeva, Lioudmila; Dhadwal, Gurbir; Lui, Harvey; Kalia, Sunil; Zeng, Haishan; McLean, David I.; Lee, Tim K.

    2013-06-01

    Skin cancer is the most common cancer in the Western world. In order to accurately detect the disease, especially malignant melanoma-the most fatal form of skin cancer-at an early stage when the prognosis is excellent, there is an urgent need to develop noninvasive early detection methods. We believe that polarization speckle patterns, defined as a spatial distribution of depolarization ratio of traditional speckle patterns, can be an important tool for skin cancer detection. To demonstrate our technique, we conduct a large in vivo clinical study of 214 skin lesions, and show that statistical moments of the polarization speckle pattern could differentiate different types of skin lesions, including three common types of skin cancers, malignant melanoma, squamous cell carcinoma, basal cell carcinoma, and two benign lesions, melanocytic nevus and seborrheic keratoses. In particular, the fourth order moment achieves better or similar sensitivity and specificity than many well-known and accepted optical techniques used to differentiate melanoma and seborrheic keratosis.

  5. Polarization speckle imaging as a potential technique for in vivo skin cancer detection.

    Science.gov (United States)

    Tchvialeva, Lioudmila; Dhadwal, Gurbir; Lui, Harvey; Kalia, Sunil; Zeng, Haishan; McLean, David I; Lee, Tim K

    2013-06-01

    Skin cancer is the most common cancer in the Western world. In order to accurately detect the disease, especially malignant melanoma-the most fatal form of skin cancer-at an early stage when the prognosis is excellent, there is an urgent need to develop noninvasive early detection methods. We believe that polarization speckle patterns, defined as a spatial distribution of depolarization ratio of traditional speckle patterns, can be an important tool for skin cancer detection. To demonstrate our technique, we conduct a large in vivo clinical study of 214 skin lesions, and show that statistical moments of the polarization speckle pattern could differentiate different types of skin lesions, including three common types of skin cancers, malignant melanoma, squamous cell carcinoma, basal cell carcinoma, and two benign lesions, melanocytic nevus and seborrheic keratoses. In particular, the fourth order moment achieves better or similar sensitivity and specificity than many well-known and accepted optical techniques used to differentiate melanoma and seborrheic keratosis.

  6. Speckle Imaging and Spectroscopy of Kepler Exo-planet Transit Candidate Stars

    Science.gov (United States)

    Howell, Steve B.; Sherry, William; Horch, Elliott; Doyle, Laurance

    2010-02-01

    The NASA Kepler mission was successfully launched on 6 March 2009 and has begun science operations. Commissioning tests done early on in the mission have shown that for the bright sources, 10-15 ppm relative photometry can be achieved. This level assures we will detect Earth- like transits if they are present. ``Hot Jupiter" and similar large planet candidates have already been discovered and will be discussed at the Jan. AAS meeting as well as in a special issue of Science magazine to appear near years end. The plethora of variability observed is astounding and includes a number of eclipsing binaries which appear to have Jupiter and smaller size objects as an orbiting their body. Our proposal consists of three highly related objectives: 1) To continue our highly successful speckle imaging program which is a major component of defense to weed out false positive candidate transiting planets found by Kepler and move the rest to probable or certain exo-planet detections; 2) To obtain low resolution ``discovery" type spectra for planet candidate stars in order to provide spectral type and luminosity class indicators as well as a first look triage to eliminate binaries and rapid rotators; and 3) to obtain ~1Aresolution time ordered spectra of eclipsing binaries that are exo-planet candidates in order to obtain the velocity solution for the binary star, allowing its signal to be modeled and removed from the Keck or HET exo-planet velocity search. As of this writing, Kepler has produced a list of 227 exo-planet candidates which require false positive decision tree observations. Our proposed effort performs much of the first line of defense for the mission.

  7. Speckle Reduction for Ultrasonic Imaging Using Frequency Compounding and Despeckling Filters along with Coded Excitation and Pulse Compression

    Directory of Open Access Journals (Sweden)

    Joshua S. Ullom

    2012-01-01

    Full Text Available A method for improving the contrast-to-noise ratio (CNR while maintaining the −6 dB axial resolution of ultrasonic B-mode images is proposed. The technique proposed is known as eREC-FC, which enhances a recently developed REC-FC technique. REC-FC is a combination of the coded excitation technique known as resolution enhancement compression (REC and the speckle-reduction technique frequency compounding (FC. In REC-FC, image CNR is improved but at the expense of a reduction in axial resolution. However, by compounding various REC-FC images made from various subband widths, the tradeoff between axial resolution and CNR enhancement can be extended. Further improvements in CNR can be obtained by applying postprocessing despeckling filters to the eREC-FC B-mode images. The despeckling filters evaluated were the following: median, Lee, homogeneous mask area, geometric, and speckle-reducing anisotropic diffusion (SRAD. Simulations and experimental measurements were conducted with a single-element transducer (f/2.66 having a center frequency of 2.25 MHz and a −3 dB bandwidth of 50%. In simulations and experiments, the eREC-FC technique resulted in the same axial resolution that would be typically observed with conventional excitation with a pulse. Moreover, increases in CNR of 348% were obtained in experiments when comparing eREC-FC with a Lee filter to conventional pulsing methods.

  8. Feasibility of endoscopic laser speckle imaging modality in the evaluation of auditory disorder: study in bone-tissue phantom

    Science.gov (United States)

    Yu, Sungkon; Jang, Seulki; Lee, Sangyeob; Park, Jihoon; Ha, Myungjin; Radfar, Edalat; Jung, Byungjo

    2016-03-01

    This study investigates the feasibility of an endoscopic laser speckle imaging modality (ELSIM) in the measurement of perfusion of flowing fluid in optical bone tissue phantom(OBTP). Many studies suggested that the change of cochlear blood flow was correlated with auditory disorder. Cochlear microcirculation occurs under the 200μm thickness bone which is the part of the internal structure of the temporal bone. Concern has been raised regarding of getting correct optical signal from hard tissue. In order to determine the possibility of the measurement of cochlear blood flow under bone tissue using the ELSIM, optical tissue phantom (OTP) mimicking optical properties of temporal bone was applied.

  9. Objective speckle velocimetry for autonomous vehicle odometry.

    Science.gov (United States)

    Francis, D; Charrett, T O H; Waugh, L; Tatam, R P

    2012-06-01

    Speckle velocimetry is investigated as a means of determining odometry data with potential for application on autonomous robotic vehicles. The technique described here relies on the integration of translation measurements made by normalized cross-correlation of speckle patterns to determine the change in position over time. The use of objective (non-imaged) speckle offers a number of advantages over subjective (imaged) speckle, such as a reduction in the number of optical components, reduced modulation of speckles at the edges of the image, and improved light efficiency. The influence of the source/detector configuration on the speckle translation to vehicle translation scaling factor for objective speckle is investigated using a computer model and verified experimentally. Experimental measurements are presented at velocities up to 80  mm s(-1) which show accuracy better than 0.4%.

  10. Speckle Reduction for Ultrasound Image Using Edge Directions in DTCWT Domain%基于DTCWT方向信息的超声图像斑点噪声消除

    Institute of Scientific and Technical Information of China (English)

    许慰玲; 沈民奋; 杨金耀

    2011-01-01

    针对一般的小波去噪方法在去除超声图像斑点噪声时不能有效保持图像边缘信息的问题,本文提出基于双树复小波变换(Dual tree complex wavelet transform,DTCWT)方向信息的超声图像斑点噪声消除算法.利用双树复小波变换6个方向复小波系数的相对方差来确定该点是否位于边缘或纹理上,对低于门限的像素高频复系数置零以实现超声图像DTCWT域的自适应滤波.实验结果表明,与Lee,Frost,Kuan滤波方法相比,本文算法具有明显的优势;在图像平滑效果接近的情况下,本文算法边缘保持度略优于Yu提出的各向异性斑点噪声抑制(Speckle reducing anisotropic diffusion,SRAD)方法.%In general, the edge information of an image can not be effectively preserved when traditional wavelet de-noising methods are adopted to reduce the speckle in ultrasound images. In view of this problem, a novel speckle reducing algorithm for ultrasound images is proposed based on the dual tree complex wavelet transform (DD-DTCWT) direction information. The relative variance of the six directional complex detail coefficients about DTCWT is used to determine whether points are located at the edges or in the textures. Specifically, speckle is reduced by resetting complex detail coefficients to zero for the pixels beyond the threshold. Through such a way the adaptive filter in DTCWT domain is realized. Experimental results show that the proposed method significantly outperforms the state-of-the-art competitors including Lee, Frost and Kuan filtering methods. Also, the degree of edge maintaining of the method is better than the speckle reducing anisotropic diffusion (SRAD) method proposed by Yu for images with similar smoothing effects.

  11. Trans-illuminated laser speckle imaging of collateral artery blood flow in ischemic mouse hindlimb

    OpenAIRE

    Meisner, Joshua K.; Niu, Jacqueline; Sumer, Suna; Price, Richard J.

    2013-01-01

    Abstract. The mouse ischemic hindlimb model is used widely for studying collateral artery growth (i.e., arteriogenesis) in response to increased shear stress. Nonetheless, precise measurements of regional shear stress changes along individual collateral arteries are lacking. Our goal is to develop and verify trans-illumination laser speckle flowmetry (LSF) for this purpose. Studies of defibrinated bovine blood flow through tubes embedded in tissue-mimicking phantoms indicate that trans-illumi...

  12. Feasibility and reference values of left atrial longitudinal strain imaging by two-dimensional speckle tracking

    Directory of Open Access Journals (Sweden)

    Lisi Matteo

    2009-02-01

    Full Text Available Abstract Background The role of speckle tracking in the assessment of left atrial (LA deformation dynamics is not established. We sought to determine the feasibility and reference ranges of LA longitudinal strain indices measured by speckle tracking in a population of normal subjects. Methods In 60 healthy individuals, peak atrial longitudinal strain (PALS and time to peak longitudinal strain (TPLS were measured using a 12-segment model for the left atrium. Values were obtained by averaging all segments (global PALS and TPLS and by separately averaging segments measured in the two apical views (4- and 2-chamber average PALS and TPLS. Results Adequate tracking quality was achieved in 97% of segments analyzed. Inter and intra-observer variability coefficients of measurements ranged between 2.9% and 5.4%. Global PALS was 42.2 ± 6.1% (5–95° percentile range 32.2–53.2%, and global TPLS was 368 ± 30 ms (5–95° percentile range 323–430 ms. The 2-chamber average PALS was slightly higher than the 4-chamber average PALS (44.3 ± 6.0% vs 40.1 ± 7.9%, p Conclusion Speckle tracking is a feasible technique for the assessment of longitudinal myocardial LA deformation. Reference ranges of strain indices were reported.

  13. Three-dimensional shear wave imaging based on full-field laser speckle contrast imaging with one-dimensional mechanical scanning.

    Science.gov (United States)

    Chao, Pei-Yu; Li, Pai-Chi

    2016-08-22

    The high imaging resolution and motion sensitivity of optical-based shear wave detection has made it an attractive technique in biomechanics studies with potential for improving the capabilities of shear wave elasticity imaging. In this study we implemented laser speckle contrast imaging for two-dimensional (X-Z) tracking of transient shear wave propagation in agarose phantoms. The mechanical disturbances induced by the propagation of the shear wave caused temporal and spatial fluctuations in the local speckle pattern, which manifested as local blurring. By mechanically moving the sample in the third dimension (Y), and performing two-dimensional shear wave imaging at every scan position, the three-dimensional shear wave velocity distribution of the phantom could be reconstructed. Based on comparisons with the reference shear wave velocity measurements obtained using a commercial ultrasound shear wave imaging system, the developed system can estimate the shear wave velocity with an error of less than 6% for homogeneous phantoms with shear moduli ranging from 1.52 kPa to 7.99 kPa. The imaging sensitivity of our system makes it capable of measuring small variations in shear modulus; the estimated standard deviation of the shear modulus was found to be less than 0.07 kPa. A submillimeter spatial resolution for three-dimensional shear wave imaging has been achieved, as demonstrated by the ability to detect a 1-mm-thick stiff plate embedded inside heterogeneous agarose phantoms.

  14. The development of laser speckle or particle image displacement velocimetry. Part 1: The role of photographic parameters

    Science.gov (United States)

    Lourenco, L. M. M.; Krothapalli, A.

    1987-01-01

    One of the difficult problems in experimental fluid dynamics remains the determination of the vorticity field in fluid flows. Recently, a novel velocity measurement technique, commonly known as Laser Speckle or Particle Image Displacement Velocimetry became available. This technique permits the simultaneous visualization of the 2 dimensional streamline pattern in unsteady flows and the quantification of the velocity field. The main advantage of this new technique is that the whole 2 dimensional velocity field can be recorded with great accuracy and spatial resolution, from which the instantaneous vorticity field can be easily obtained. A apparatus used for taking particle displacement images is described. Local coherent illumination by the probe laser beam yielded Young's fringes of good quality at almost every location of the flow field. These fringes were analyzed and the velocity and vorticity fields were derived. Several conclusions drawn are discussed.

  15. Laser speckle evaluation methods based on power spectrum of images%基于图像功率谱的激光散斑评价方法

    Institute of Scientific and Technical Information of China (English)

    曹金凤; 贺锋涛

    2015-01-01

    Laser speckle has important applications in many areas , such as optical coherence tomography , holography , multimode optical fiber communication and metrology .In order to evaluate the laser speckle , the power spectrum width of speckle image in frequency domain was proposed as the evaluation method of laser speckle .The experiment device of power spectrum speckle evaluation was designed based on optical fiber vibration .A 0.5W, 532nm laser was used as light source and a voltage-driven voice coil motor was used to vibrate the fiber and control laser speckle . A CCD image acquisition card was used to collect images .Speckle contrast method and power spectrum method were respectively used to evaluate the speckle images under different driving voltages .The results show that the method of power spectrum has higher sensitivity and wider range of evaluation .%激光散斑在相干光成像、全息术、多模光纤通信、计量等领域具有重要的应用。为了对激光散斑进行评价,提出一种在频域采用散斑图像功率谱谱宽作为激光散斑评价的方法,设计了一种基于光纤振动的功率谱散斑评价实验装置。采用0.5W,532nm激光作为光源,通过电压驱动音圈电机振动光纤对激光散斑进行控制,利用CCD图像采集卡采集图像后,分别采用散斑图像的对比度方法和功率谱方法对不同驱动电压下的散斑图像进行了分析评价。结果表明,功率谱方法具有较高的灵敏度及较宽的评价范围。

  16. A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging

    Energy Technology Data Exchange (ETDEWEB)

    Borges, J.P. [Laboratório de Atividade Física e Promoção è Saúde, Departamento de Desporto Coletivo, Instituto de Educação Física e Desportos, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ (Brazil); Lopes, G.O. [Laboratório de Atividade Física e Promoção è Saúde, Departamento de Desporto Coletivo, Instituto de Educação Física e Desportos, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ (Brazil); Instituto Nacional de Cardiologia, Rio de Janeiro, RJ (Brazil); Verri, V.; Coelho, M.P.; Nascimento, P.M.C.; Kopiler, D.A. [Instituto Nacional de Cardiologia, Rio de Janeiro, RJ (Brazil); Tibirica, E. [Instituto Nacional de Cardiologia, Rio de Janeiro, RJ (Brazil); Laboratório de Investigação Cardiovascular, Departamento Osório de Almeida, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, RJ (Brazil)

    2016-09-01

    Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61) and healthy age-matched subjects (n=24). Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; P<0.01). With regard to post-occlusive reactive hyperemia-induced vasodilation, the patients also presented reduced responses compared to the controls (0.42±0.15 vs 0.50±0.13 APU/mmHg; P=0.04). In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men.

  17. A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging

    Directory of Open Access Journals (Sweden)

    J.P. Borges

    2016-01-01

    Full Text Available Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61 and healthy age-matched subjects (n=24. Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; P<0.01. With regard to post-occlusive reactive hyperemia-induced vasodilation, the patients also presented reduced responses compared to the controls (0.42±0.15 vs 0.50±0.13 APU/mmHg; P=0.04. In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men.

  18. A novel effective method for the assessment of microvascular function in male patients with coronary artery disease: a pilot study using laser speckle contrast imaging.

    Science.gov (United States)

    Borges, J P; Lopes, G O; Verri, V; Coelho, M P; Nascimento, P M C; Kopiler, D A; Tibirica, E

    2016-09-01

    Evaluation of microvascular endothelial function is essential for investigating the pathophysiology and treatment of cardiovascular and metabolic diseases. Although laser speckle contrast imaging technology is well accepted as a noninvasive methodology for assessing microvascular endothelial function, it has never been used to compare male patients with coronary artery disease with male age-matched healthy controls. Thus, the aim of this study was to determine whether laser speckle contrast imaging could be used to detect differences in the systemic microvascular functions of patients with established cardiovascular disease (n=61) and healthy age-matched subjects (n=24). Cutaneous blood flow was assessed in the skin of the forearm using laser speckle contrast imaging coupled with the transdermal iontophoretic delivery of acetylcholine and post-occlusive reactive hyperemia. The maximum increase in skin blood flow induced by acetylcholine was significantly reduced in the cardiovascular disease patients compared with the control subjects (74 vs 116%; PAPU/mmHg; P=0.04). In conclusion, laser speckle contrast imaging can identify endothelial and microvascular dysfunctions in male individuals with cardiovascular disease. Thus, this technology appears to be an efficient non-invasive technique for evaluating systemic microvascular and endothelial functions, which could be valuable as a peripheral marker of atherothrombotic diseases in men.

  19. Adaptive Computed Tomography Imaging Spectrometer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The present proposal describes the development of an adaptive Computed Tomography Imaging Spectrometer (CTIS), or "Snapshot" spectrometer which can "instantaneously"...

  20. Blood perfusion values of laser speckle contrast imaging and laser Doppler flowmetry: is a direct comparison possible?

    Science.gov (United States)

    Binzoni, Tiziano; Humeau-Heurtier, Anne; Abraham, Pierre; Mahe, Guillaume

    2013-05-01

    Laser Doppler flowmetry (LDF) and laser speckle contrast imaging (LSCI) allow the monitoring of microvascular blood perfusion. The relationship between the measurements obtained by these two techniques remains unclear. In the present contribution, we demonstrate, experimentally and theoretically, that skin blood flow measurements obtained by LDF and LSCI techniques cannot be compared directly even after "classical" normalization procedure. This technical problem is generated by the nonlinear relationship existing between LDF and LSCI flow data. The experiments have been performed on five healthy voluntary subjects (forearm) by using repeated ischemia/reperfusion cycles to induce the necessary skin blood flow changes. LDF and LSCI data were simultaneously acquired on the same region of interest. Considering the importance of this problem from the clinical point of view, it is concluded that the definition of new corrected algorithms for LSCI is probably a mandatory step that must be taken into account if LDF and LSCI blood flow have to be compared.

  1. Image analysis of speckle patterns as a probe of melting transitions in laser-heated diamond anvil cell experiments.

    Science.gov (United States)

    Salem, Ran; Matityahu, Shlomi; Melchior, Aviva; Nikolaevsky, Mark; Noked, Ori; Sterer, Eran

    2015-09-01

    The precision of melting curve measurements using laser-heated diamond anvil cell (LHDAC) is largely limited by the correct and reliable determination of the onset of melting. We present a novel image analysis of speckle interference patterns in the LHDAC as a way to define quantitative measures which enable an objective determination of the melting transition. Combined with our low-temperature customized IR pyrometer, designed for measurements down to 500 K, our setup allows studying the melting curve of materials with low melting temperatures, with relatively high precision. As an application, the melting curve of Te was measured up to 35 GPa. The results are found to be in good agreement with previous data obtained at pressures up to 10 GPa.

  2. Evaluation of left ventricular mechanical dyssynchrony in chronic heart failure patients by two-dimensional speckle tracking imaging.

    Science.gov (United States)

    Jiang, Feng-Xia; Guo, Rui-Qiang; Chen, Jin-Ling

    2013-07-01

    The purpose of this study was to evaluate left ventricular mechanical dyssynchrony (LVMD) in chronic heart failure (CHF) patients using two-dimensional speckle tracking imaging (2D-STI), and also to compare the usefulness of three patterns of myocardial deformation in mechanical dyssynchrony assessment. Furthermore, the relationships between left ventricular ejection fraction (LVEF), QRS duration (QRSd), and LVMD were explored. In total, 78 patients and 60 healthy individuals (group 3) were enrolled. The patients were classified into two subgroups: LVEF≤35% (group 1), 35%0.05). CHF patients have different extents of LVMD. Longitudinal deformation shows the best detectability of dyssynchrony motion. Left ventricular systolic function was closely related to mechanical dyssynchrony, whereas QRSd showed no significant correlation.

  3. An in vivo analysis of facial muscle change treated with botulinum toxin type A using digital image speckle correlation

    Science.gov (United States)

    Xu, Yan; Palmaccio, Samantha Palmaccio; Bui, Duc; Dagum, Alexander; Rafailovich, Miriam

    Been famous for clinical use from early 1980s, the neuromuscular blocking agent Botulinum toxin type A (BTX-A), has been used to reduce wrinkles for a long time. Only little research has been done to quantify the change of muscle contraction before and after injection and most research paper depend on subjective evaluation from both patients and surgeons. In our research, Digital Image Speckle Correlation (DISC) was employed to study the mechanical properties of skin, contraction mode of muscles (injected) and reaction of neighbor muscle group (un-injected).At the same time, displacement patterns (vector maps)generated by DISC can predict injection locus for surgeons who normally handle it depending only on visual observation.

  4. Image Compression using Space Adaptive Lifting Scheme

    Directory of Open Access Journals (Sweden)

    Ramu Satyabama

    2011-01-01

    Full Text Available Problem statement: Digital images play an important role both in daily life applications as well as in areas of research and technology. Due to the increasing traffic caused by multimedia information and digitized form of representation of images; image compression has become a necessity. Approach: Wavelet transform has demonstrated excellent image compression performance. New algorithms based on Lifting style implementation of wavelet transforms have been presented in this study. Adaptively is introduced in lifting by choosing the prediction operator based on the local properties of the image. The prediction filters are chosen based on the edge detection and the relative local variance. In regions where the image is locally smooth, we use higher order predictors and near edges we reduce the order and thus the length of the predictor. Results: We have applied the adaptive prediction algorithms to test images. The original image is transformed using adaptive lifting based wavelet transform and it is compressed using Set Partitioning In Hierarchical Tree algorithm (SPIHT and the performance is compared with the popular 9/7 wavelet transform. The performance metric Peak Signal to Noise Ratio (PSNR for the reconstructed image is computed. Conclusion: The proposed adaptive algorithms give better performance than 9/7 wavelet, the most popular wavelet transforms. Lifting allows us to incorporate adaptivity and nonlinear operators into the transform. The proposed methods efficiently represent the edges and appear promising for image compression. The proposed adaptive methods reduce edge artifacts and ringing and give improved PSNR for edge dominated images.

  5. The role of photographic parameters in laser speckle or particle image displacement velocimetry

    Science.gov (United States)

    Lourenco, L.; Krothapalli, A.

    1987-01-01

    The parameters involved in obtaining the multiple exposure photographs in the laser speckle velocimetry method (to record the light scattering by the seeding particles) were optimized. The effects of the type, concentration, and dimensions of the tracer, the exposure conditions (time between exposures, exposure time, and number of exposures), and the sensitivity and resolution of the film on the quality of the final results were investigated, photographing an experimental flow behind an impulsively started circular cylinder. The velocity data were acquired by digital processing of Young's fringes, produced by point-by-point scanning of a photographic negative. Using the optimal photographing conditions, the errors involved in the estimation of the fringe angle and spacing were of the order of 1 percent for the spacing and +/1 deg for the fringe orientation. The resulting accuracy in the velocity was of the order of 2-3 percent of the maximum velocity in the field.

  6. Color speckle in laser displays

    Science.gov (United States)

    Kuroda, Kazuo

    2015-07-01

    At the beginning of this century, lighting technology has been shifted from discharge lamps, fluorescent lamps and electric bulbs to solid-state lighting. Current solid-state lighting is based on the light emitting diodes (LED) technology, but the laser lighting technology is developing rapidly, such as, laser cinema projectors, laser TVs, laser head-up displays, laser head mounted displays, and laser headlamps for motor vehicles. One of the main issues of laser displays is the reduction of speckle noise1). For the monochromatic laser light, speckle is random interference pattern on the image plane (retina for human observer). For laser displays, RGB (red-green-blue) lasers form speckle patterns independently, which results in random distribution of chromaticity, called color speckle2).

  7. EVALUATION OF FILTERS FOR ENVISAT ASAR SPECKLE SUPPRESSION IN PASTURE AREA

    Directory of Open Access Journals (Sweden)

    X. Wang

    2012-07-01

    Full Text Available In order to quantify real time pasture biomass from SAR image, regression model between ground measurements of biomass and ENVISAT ASAR backscattering coefficient should be built up. An important prerequisite of valid and accurate regression model is accurate grass backscattering coefficient which, however, cannot be obtained when there is speckle. Speckle noise is the best known problem of SAR images because of the coherent nature of radar illumination imaging system. This study aims to choose better adaptive filter from NEST software to reduce speckle noise in homogeneous pasture area, with little regard to linear feature (e.g. edge between pasture and forest or point feature (e.g. pond, tree preservation. This paper presents the speckle suppression result of ENVISAT ASAR VV/VH images in pasture of Western Australia (WA using four built-in adaptive filters of the NEST software: Frost, Gamma Map, Lee, and Refined Lee filter. Two indices are usually used for evaluation of speckle suppression ability: ENL (Equivalent Number of Looks and SSI (Speckle Suppression Index. These two, however, are not reliable because sometimes they overestimate mean value. Therefore, apart from ENL and SSI, the authors also used a new index SMPI (Speckle Suppression and Mean Preservation Index. It was found that, Lee filter with window size 7×7 and Frost filter (damping factor = 2 with window size 5×5 gave the best performance for VV and VH polarization, respectively. The filtering, together with radiometric calibration and terrain correction, paves the way to extraction of accurate backscattering coefficient of grass in homogeneous pasture area in WA.

  8. Digital Image Speckle Correlation for the Quantification of the Cosmetic Treatment with Botulinum Toxin Type A (BTX-A)

    Science.gov (United States)

    Bhatnagar, Divya; Conkling, Nicole; Rafailovich, Miriam; Dagum, Alexander

    2012-02-01

    The skin on the face is directly attached to the underlying muscles. Here, we successfully introduce a non-invasive, non-contact technique, Digital Image Speckle Correlation (DISC), to measure the precise magnitude and duration of facial muscle paralysis inflicted by BTX-A. Subjective evaluation by clinicians and patients fail to objectively quantify the direct effect and duration of BTX-A on the facial musculature. By using DISC, we can (a) Directly measure deformation field of the facial skin and determine the locus of facial muscular tension(b)Quantify and monitor muscular paralysis and subsequent re-innervation following injection; (c) Continuously correlate the appearance of wrinkles and muscular tension. Two sequential photographs of slight facial motion (frowning, raising eyebrows) are taken. DISC processes the images to produce a vector map of muscular displacement from which spatially resolved information is obtained regarding facial tension. DISC can track the ability of different muscle groups to contract and can be used to predict the site of injection, quantify muscle paralysis and the rate of recovery following BOTOX injection.

  9. SU-D-210-05: The Accuracy of Raw and B-Mode Image Data for Ultrasound Speckle Tracking in Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    O’Shea, T; Bamber, J; Harris, E [The Institute of Cancer Research & Royal Marsden, Sutton and London (United Kingdom)

    2015-06-15

    Purpose: For ultrasound speckle tracking there is some evidence that the envelope-detected signal (the main step in B-mode image formation) may be more accurate than raw ultrasound data for tracking larger inter-frame tissue motion. This study investigates the accuracy of raw radio-frequency (RF) versus non-logarithmic compressed envelope-detected (B-mode) data for ultrasound speckle tracking in the context of image-guided radiation therapy. Methods: Transperineal ultrasound RF data was acquired (with a 7.5 MHz linear transducer operating at a 12 Hz frame rate) from a speckle phantom moving with realistic intra-fraction prostate motion derived from a commercial tracking system. A normalised cross-correlation template matching algorithm was used to track speckle motion at the focus using (i) the RF signal and (ii) the B-mode signal. A range of imaging rates (0.5 to 12 Hz) were simulated by decimating the imaging sequences, therefore simulating larger to smaller inter-frame displacements. Motion estimation accuracy was quantified by comparison with known phantom motion. Results: The differences between RF and B-mode motion estimation accuracy (2D mean and 95% errors relative to ground truth displacements) were less than 0.01 mm for stable and persistent motion types and 0.2 mm for transient motion for imaging rates of 0.5 to 12 Hz. The mean correlation for all motion types and imaging rates was 0.851 and 0.845 for RF and B-mode data, respectively. Data type is expected to have most impact on axial (Superior-Inferior) motion estimation. Axial differences were <0.004 mm for stable and persistent motion and <0.3 mm for transient motion (axial mean errors were lowest for B-mode in all cases). Conclusions: Using the RF or B-mode signal for speckle motion estimation is comparable for translational prostate motion. B-mode image formation may involve other signal-processing steps which also influence motion estimation accuracy. A similar study for respiratory-induced motion

  10. Speckle perception and disturbance limit in laser based projectors

    Science.gov (United States)

    Verschaffelt, Guy; Roelandt, Stijn; Meuret, Youri; Van den Broeck, Wendy; Kilpi, Katriina; Lievens, Bram; Jacobs, An; Janssens, Peter; Thienpont, Hugo

    2016-04-01

    We investigate the level of speckle that can be tolerated in a laser cinema projector. For this purpose, we equipped a movie theatre room with a prototype laser projector. A group of 186 participants was gathered to evaluate the speckle perception of several, short movie trailers in a subjective `Quality of Experience' experiment. This study is important as the introduction of lasers in projection systems has been hampered by the presence of speckle in projected images. We identify a speckle disturbance threshold by statistically analyzing the observers' responses for different values of the amount of speckle, which was monitored using a well-defined speckle measurement method. The analysis shows that the speckle perception of a human observer is not only dependent on the objectively measured amount of speckle, but it is also strongly influenced by the image content. As is also discussed in [Verschaffelt et al., Scientific Reports 5, art. nr. 14105, 2015] we find that, for moving images, the speckle becomes disturbing if the speckle contrast becomes larger than 6.9% for the red, 6.0% for the green, and 4.8% for the blue primary colors of the projector, whereas for still images the speckle detection threshold is about 3%. As we could not independently tune the speckle contrast of each of the primary colors, this speckle disturbance limit seems to be determined by the 6.9% speckle contrast of the red color as this primary color contains the largest amount of speckle. The speckle disturbance limit for movies thus turns out to be substantially larger than that for still images, and hence is easier to attain.

  11. Adaptive Beamforming for Medical Ultrasound Imaging

    DEFF Research Database (Denmark)

    Holfort, Iben Kraglund

    This dissertation investigates the application of adaptive beamforming for medical ultrasound imaging. The investigations have been concentrated primarily on the Minimum Variance (MV) beamformer. A broadband implementation of theMV beamformer is described, and simulated data have been used...... to demonstrate the performance. The MV beamformer has been applied to different sets of ultrasound imaging sequences; synthetic aperture ultrasound imaging and plane wave ultrasound imaging. And an approach for applying MV optimized apodization weights on both the transmitting and the receiving apertures...

  12. Arterial elasticity imaging: comparison of finite-element analysis models with high-resolution ultrasound speckle tracking

    Directory of Open Access Journals (Sweden)

    Park Dae

    2010-06-01

    Full Text Available Abstract Background The nonlinear mechanical properties of internal organs and tissues may be measured with unparalleled precision using ultrasound imaging with phase-sensitive speckle tracking. The many potential applications of this important noninvasive diagnostic approach include measurement of arterial stiffness, which is associated with numerous major disease processes. The accuracy of previous ultrasound measurements of arterial stiffness and vascular elasticity has been limited by the relatively low strain of nonlinear structures under normal physiologic pressure and the measurement assumption that the effect of the surrounding tissue modulus might be ignored in both physiologic and pressure equalized conditions. Methods This study performed high-resolution ultrasound imaging of the brachial artery in a healthy adult subject under normal physiologic pressure and the use of external pressure (pressure equalization to increase strain. These ultrasound results were compared to measurements of arterial strain as determined by finite-element analysis models with and without a surrounding tissue, which was represented by homogenous material with fixed elastic modulus. Results Use of the pressure equalization technique during imaging resulted in average strain values of 26% and 18% at the top and sides, respectively, compared to 5% and 2%, at the top and sides, respectively, under physiologic pressure. In the artery model that included surrounding tissue, strain was 19% and 16% under pressure equalization versus 9% and 13% at the top and sides, respectively, under physiologic pressure. The model without surrounding tissue had slightly higher levels of strain under physiologic pressure compared to the other model, but the resulting strain values under pressure equalization were > 60% and did not correspond to experimental values. Conclusions Since pressure equalization may increase the dynamic range of strain imaging, the effect of the

  13. Non-invasive single-shot 3D imaging through a scattering layer using speckle interferometry

    CERN Document Server

    Somkuwar, Atul S; R., Vinu; Park, Yongkeun; Singh, Rakesh Kumar

    2015-01-01

    Optical imaging through complex scattering media is one of the major technical challenges with important applications in many research fields, ranging from biomedical imaging, astronomical telescopy, and spatially multiplex optical communications. Although various approaches for imaging though turbid layer have been recently proposed, they had been limited to two-dimensional imaging. Here we propose and experimentally demonstrate an approach for three-dimensional single-shot imaging of objects hidden behind an opaque scattering layer. We demonstrate that under suitable conditions, it is possible to perform the 3D imaging to reconstruct the complex amplitude of objects situated at different depths.

  14. Investigation of Hepatic Blood Perfusion by Laser Speckle Imaging and Changes of Hepatic Vasoactive Substances in Mice after Electroacupuncture

    Directory of Open Access Journals (Sweden)

    Xiao-jing Song

    2014-01-01

    Full Text Available The study was conducted to observe the effect of electroacupuncture (EA on hepatic blood perfusion (HBP and vascular regulation. We investigated 60 male anesthetized mice under the following 3 conditions: without EA stimulation (control group; EA stimulation at Zusanli (ST36 group; EA stimulation at nonacupoint (NA group during 30 min. The HBP was measured using the laser speckle perfusion imaging (LSPI. The level of nitric oxide (NO, endothelin-1 (ET-1, and noradrenaline (NE in liver tissue was detected by biochemical methods. Results were as follows. At each time point, HBP increase in ST36 group was higher than that in the NA group in anesthetized mice. HBP gradually decreased during 30 min in control group. The level of NO in ST36 group was higher than that in NA group. The level of both ET-1 and NE was the highest in control group, followed by NA group and ST36 group. It is concluded that EA at ST36 could increase HBP possibly by increasing the blood flow velocity (BFV, changing vascular activity, increasing the level of NO, and inhibiting the level of ET-1 in liver tissue.

  15. Investigation of hepatic blood perfusion by laser speckle imaging and changes of hepatic vasoactive substances in mice after electroacupuncture.

    Science.gov (United States)

    Song, Xiao-Jing; Zhang, Dong; Wang, Shu-You; Li, Shun-Yue

    2014-01-01

    The study was conducted to observe the effect of electroacupuncture (EA) on hepatic blood perfusion (HBP) and vascular regulation. We investigated 60 male anesthetized mice under the following 3 conditions: without EA stimulation (control group); EA stimulation at Zusanli (ST36 group); EA stimulation at nonacupoint (NA group) during 30 min. The HBP was measured using the laser speckle perfusion imaging (LSPI). The level of nitric oxide (NO), endothelin-1 (ET-1), and noradrenaline (NE) in liver tissue was detected by biochemical methods. Results were as follows. At each time point, HBP increase in ST36 group was higher than that in the NA group in anesthetized mice. HBP gradually decreased during 30 min in control group. The level of NO in ST36 group was higher than that in NA group. The level of both ET-1 and NE was the highest in control group, followed by NA group and ST36 group. It is concluded that EA at ST36 could increase HBP possibly by increasing the blood flow velocity (BFV), changing vascular activity, increasing the level of NO, and inhibiting the level of ET-1 in liver tissue.

  16. Assessment of Age-related Changes in Left Ventricular Twist by Two-dimensional Ultrasound Speckle Tracking Imaging

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; XIANG Feixiang; XIE Mingxing; FU Manli; WANG Xinfang; L(U) Qing; HAN Wei; ZHANG Jing; LIU Yingying; WANG Jing

    2007-01-01

    To assess the normal value of left ventricular twist (LVtw) and examine the changeswith normal aging by 2-dimensional ultrasound speckle-tracking imaging (STI), 121 healthy volunteers were divided into three age groups: a youth group (19-45 y old), a middle-age group (46-64 y old ) and an old-age group (≥65 y old). Basal and apical short-axis images of left ventricular were ac- quired to analyse LV rotation (LVrot) and LVrot velocity. LVtw and LVtw velocity was defined as apical LVrot and LVrot velocity relative to the base. Peak twist (Ptw), twist at aortic valve closure (AVCtw), twist at mitral valve opening (MVOtw), untwisting rate (UntwR), half time of untwisting (HTU), peak twist velocity (PTV), time to peak twist velocity (TPTV), peak untwisting velocity (PUV), time to peak untwisting velocity (TPUV) were separately measured. The results showed that the normal LV performs a wringing motion with a clockwise rotation at the base and a counterclock- wise rotation at the apex (as seen from the apex). The LVtw velocity showed a systolic counterclock- wise twist followed by a diastolic clockwise twist. Peak twist develops near the end of systole (96%±4.2% of systole). With aging, Ptw, AVCtw, MVOtw, HTU and PUV increased significantly (P<0.05) and UntwR decreased significantly (P<0.05). However, no significant differences in TPUV, PTV and TPTV were noted among the 3 groups (P0.05). It is concluded that LV twist can be meas- ured non-invasively by 2-dimensional ultrasound STI imaging. The age-related changes of LVtw should be fully taken into consideration in the assessment of LV function.

  17. CS Radar Imaging via Adaptive CAMP

    NARCIS (Netherlands)

    Anitori, L.; Otten, M.P.G.; Hoogeboom, P.

    2012-01-01

    In this paper we present results on application of Compressive Sensing (CS) to high resolution radar imaging and pro- pose the adaptive Complex Approximate Message Passing (CAMP) algorithm for image reconstruction. CS provides a theoretical framework that guarantees, under certain assumptions, recon

  18. Analysis of laser speckle contrast images variability using a novel empirical mode decomposition: comparison of results with laser Doppler flowmetry signals variability.

    Science.gov (United States)

    Humeau-Heurtier, Anne; Abraham, Pierre; Mahe, Guillaume

    2015-02-01

    Laser Doppler flowmetry (LDF) and laser speckle contrast imaging (LSCI) have emerged as noninvasive optical modalities to monitor microvascular blood flow. Many studies proposed to extract physiological information from LDF by analyzing signals variability. By opposition, such analyses for LSCI data have not been conducted yet. We propose to analyze LSCI variability using a novel data-driven method: the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN). CEEMDAN is suitable for nonlinear and nonstationary data and leads to intrinsic mode functions (IMFs). It is based on the ensemble empirical mode decomposition (EEMD) which relies on empirical mode decomposition (EMD). In our work the average frequencies of LSCI IMFs given by CEEMDAN are compared with the ones given by EMD and EEMD. Moreover, LDF signals acquired simultaneously to LSCI data are also processed with CEEMDAN, EMD and EEMD. We show that the average frequencies of IMFs given by CEEMDAN depend on the signal-to-noise ratio (SNR) used in the computation but, for a given SNR, the average frequencies found for LSCI are close to the ones obtained for LDF. By opposition, EEMD leads to IMFs with frequencies that do not vary much when the SNR level is higher than a threshold. The new CEEMDAN algorithm has the advantage of achieving a complete decomposition with no error in the reconstruction but our study suggests that further work is needed to gain knowledge in the adjustment of the added noise level. CEEMDAN, EMD and EEMD are data-driven methods that can provide a better knowledge of LSCI.

  19. Functional assessment of hand vasculature using infrared and laser speckle imaging

    Science.gov (United States)

    Gorbach, A. M.; Wang, H.; Wiedenbeck, B.; Liu, W.; Smith, P. D.; Elster, E.

    2009-02-01

    To assess vascular responses of the human hand to inspiratory gasps and hand cooling, two imaging "remote sensing" instruments were utilized: 1) a high-resolution infrared (IR) imaging camera and 2) a full-field laser perfusion imager (FLPI). Data analysis was performed on the data sets collected simultaneously from both instruments. A non-localized drop of both FLPI and IR signals was observed at ~0.5-2.0 min after gasp onset. Spontaneous oscillations, much below the human cardiac and respiratory frequencies, were observed with both imagers. The dominant oscillations for both imaging modalities centered around 0.01Hz. Spectral frequencies, their power, and the duration of temperature oscillations (bursts) for different hand areas changed in time and were spatially heterogeneous. The highest spatial correlation between the two data sets was found between the mean IR derivative image and the mean original FLPI image for the baseline conditions. Heterogeneous images of the human hand were consistently detected non-invasively by both instruments. After cooling, a temperature elevation of ~0.5ºC was seen as a spotted pattern mainly in the thenar and hypothenar areas. A generalized increase in perfusion over the same areas was observed in FLPI images. Both IR and FLPI imagers sensitively identify vasoconstrictor responses induced by inspiratory gasp and hand cooling maneuvers. The specificity to physiological changes and high imaging rate for both instruments, coupled with the current ease of use of optical cameras in clinical settings, make the described combination of two instruments an ideal imaging approach to studying the dynamics of thermal and perfusion heterogeneity in human skin.

  20. High-frame-rate deformation imaging in two dimensions using continuous speckle-feature tracking

    DEFF Research Database (Denmark)

    Andersen, Martin Vandborg; Moore, Cooper; Arges, Kristine;

    2016-01-01

    The study describes a novel algorithm for deriving myocardial strain from an entire cardiac cycle using high-frame-rate ultrasound images. Validation of the tracking algorithm was conducted in vitro prior to the application to patient images. High-frame-rate ultrasound images were acquired in vivo...... from 10 patients, and strain curves were derived in six myocardial regions around the left ventricle from the apical four-chamber view. Strain curves derived from high-frame-rate images had a higher frequency content than those derived using conventional methods, reflecting improved temporal sampling....

  1. ACL deficiency impairs the vasoconstrictive efficacy of neuropeptide Y and phenylephrine in articular tissues: a laser speckle perfusion imaging study.

    Science.gov (United States)

    Miller, Daniel; Forrester, Kevin; Leonard, Catherine; Salo, Paul; Bray, Robert C

    2005-01-01

    Sympathetic-derived neuropeptide Y (NPY) helps regulate inflammatory responses in injury and disease, is a vasoconstrictor, and stimulates angiogenesis. Rupture of the anterior cruciate ligament (ACL) is a common clinical presentation that results in tissue inflammation, hyperemia, and angiogenesis in the intact medial collateral ligament (MCL). This study is the first to examine the vasoregulatory role of NPY in ACL-deficient knee joints by using the newly developed technique of laser speckle perfusion imaging (LSPI). MCL blood flow was measured in two groups of adult rabbits: unoperated control (n = 6), and 6-wk ACL transected (n = 5). Under anesthesia, the MCL was surgically exposed and tissue blood flow was imaged at high resolution using LSPI. NPY was applied to the MCL vasculature in topical boluses of 100 mul (dose range 10(-14) to 10(-9) mol), and the alpha-adrenoceptor agonist phenylephrine was applied in doses of 10(-14), 10(-10), and 10(-7) mol. In control rabbits, topical administration of NPY or phenylephrine produced dose-dependent vasopressor responses (maximal effect at 10(-9) mol NPY and 10(-7) mol phenylephrine). In ACL-transected knees, there was little or no vasoconstrictive response to NPY at any dose. The response to phenylephrine was significantly reduced compared with control ligaments. Possible causes of the reduced vasoconstrictive response to NPY in the MCL after 6 wk of ACL deficiency include development of tolerance to the peptide due to a prolonged increase in sympathetic nerve activity or change in the distribution or functionality of the NPY Y(1) receptors. Chronic ACL deficiency leads to profound and protracted hyperemia in associated articular tissues. Abrogation of a vasoconstrictor response to both NPY and phenylephrine in the MCL indicates that ACL deficiency induces major changes in the vascular physiological homeostasis.

  2. Adaptive optics imaging of the retina.

    Science.gov (United States)

    Battu, Rajani; Dabir, Supriya; Khanna, Anjani; Kumar, Anupama Kiran; Roy, Abhijit Sinha

    2014-01-01

    Adaptive optics is a relatively new tool that is available to ophthalmologists for study of cellular level details. In addition to the axial resolution provided by the spectral-domain optical coherence tomography, adaptive optics provides an excellent lateral resolution, enabling visualization of the photoreceptors, blood vessels and details of the optic nerve head. We attempt a mini review of the current role of adaptive optics in retinal imaging. PubMed search was performed with key words Adaptive optics OR Retina OR Retinal imaging. Conference abstracts were searched from the Association for Research in Vision and Ophthalmology (ARVO) and American Academy of Ophthalmology (AAO) meetings. In total, 261 relevant publications and 389 conference abstracts were identified.

  3. Adaptive optics imaging of the retina

    Directory of Open Access Journals (Sweden)

    Rajani Battu

    2014-01-01

    Full Text Available Adaptive optics is a relatively new tool that is available to ophthalmologists for study of cellular level details. In addition to the axial resolution provided by the spectral-domain optical coherence tomography, adaptive optics provides an excellent lateral resolution, enabling visualization of the photoreceptors, blood vessels and details of the optic nerve head. We attempt a mini review of the current role of adaptive optics in retinal imaging. PubMed search was performed with key words Adaptive optics OR Retina OR Retinal imaging. Conference abstracts were searched from the Association for Research in Vision and Ophthalmology (ARVO and American Academy of Ophthalmology (AAO meetings. In total, 261 relevant publications and 389 conference abstracts were identified.

  4. Stochastic parallel gradient descent based adaptive optics used for high contrast imaging coronagraph

    CERN Document Server

    Dong, Bing; Zhang, Xi

    2011-01-01

    An adaptive optics (AO) system based on stochastic parallel gradient descent (SPGD) algorithm is proposed to reduce the speckle noises in the optical system of stellar coronagraph in order to further improve the contrast. The principle of SPGD algorithm is described briefly and a metric suitable for point source imaging optimization is given. The feasibility and good performance of SPGD algorithm is demonstrated by experimental system featured with a 140-actuators deformable mirror (DM) and a Hartmann- Shark wavefront sensor. Then the SPGD based AO is applied to a liquid crystal array (LCA) based coronagraph. The LCA can modulate the incoming light to generate a pupil apodization mask in any pattern. A circular stepped pattern is used in our preliminary experiment and the image contrast shows improvement from 10^-3 to 10^-4.5 at angular distance of 2{\\lambda}/D after corrected by SPGD based AO.

  5. Very low rate compression of speckled SAR imagery

    Energy Technology Data Exchange (ETDEWEB)

    Eichel, P.H. [Sandia National Labs., Albuquerque, NM (United States); Ives, R.W. [Navy (United States)

    1998-01-01

    Synthetic aperture radars produce coherent, and speckled, high resolution images of the ground. Because modern systems can generate large amounts of imagery, there is substantial interest in applying image compression techniques to these products. In this paper, the authors examine the properties of speckled imagery relevant to the task of data compression. In particular, they demonstrate the advisability of compressing the speckle mean function rather than the literal image. The theory, methodology, and an example are presented.

  6. The use of digital image speckle correlation to measure the mechanical properties of skin and facial muscular activity

    Science.gov (United States)

    Staloff, Isabelle Afriat

    Skin mechanical properties have been extensively studied and have led to an understanding of the structure and role of the collagen and elastin fibers network in the dermis and their changes due to aging. All these techniques have either isolated the skin from its natural environment (in vitro), or, when studied in vivo, attempted to minimize the effect of the underlying tissues and muscles. The human facial region is unique compared to the other parts of the body in that the underlying musculature runs through the subcutaneous tissue and is directly connected to the dermis with collagen based fibrous tissues. These fibrous tissues comprise the superficial musculoaponeurotic system, commonly referred to as the SMAS layer. Retaining ligaments anchor the skin to the periosteum, and hold the dermis to the SMAS. In addition, traditional techniques generally collect an average response of the skin. Data gathered in this manner is incomplete as the skin is anisotropic and under constant tension. We therefore introduce the Digital Image Speckle Correlation (DISC) method that maps in two dimensions the skin deformation under the complex set of forces involved during muscular activity. DISC, a non-contact in vivo technique, generates spatial resolved information. By observing the detailed motion of the facial skin we can infer the manner in which the complex ensemble of forces induced by movement of the muscles distribute and dissipate on the skin. By analyzing the effect of aging on the distribution of these complex forces we can measure its impact on skin elasticity and quantify the efficacy of skin care products. In addition, we speculate on the mechanism of wrinkle formation. Furthermore, we investigate the use of DISC to map the mechanism of film formation on skin of various polymers. Finally, we show that DISC can detect the involuntary facial muscular activity induced by various fragrances.

  7. Reproducibility of non-invasive assessment of skin endothelial function using laser Doppler flowmetry and laser speckle contrast imaging.

    Directory of Open Access Journals (Sweden)

    Cyril Puissant

    Full Text Available BACKGROUND: Endothelial dysfunction precedes atherosclerosis. Vasodilation induced by acetylcholine (ACh is a specific test of endothelial function. Reproducibility of laser techniques such as laser-Doppler-flowmetry (LDF and Laser-speckle-contrast-imaging (LSCI to detect ACh vasodilation is debated and results expressions lack standardization. We aimed to study at a 7-day interval (i the inter-subject reproducibility, (ii the intra-subjects reproducibility, and (iii the effect of the results expressions over variability. METHODS AND RESULTS: Using LDF and LSCI simultaneously, we performed two different ACh-iontophoresis protocols. The maximal ACh vasodilation (peak-ACh was expressed as absolute or normalized flow or conductance values. Inter-subject reproducibility was expressed as coefficient of variation (inter-CV,%. Intra-subject reproducibility was expressed as within subject coefficients of variation (intra-CV,%, and intra-class correlation coefficients (ICC. Fifteen healthy subjects were included. The inter-subject reproducibility of peak-ACh depended upon the expression of the results and ranged from 55% to 162% for LDF and from 17% to 83% for LSCI. The intra-subject reproducibility (intra-CV/ICC of peak-ACh was reduced when assessed with LSCI compared to LDF no matter how the results were expressed and whatever the protocol used. The highest intra-subject reproducibility was found using LSCI. It was 18.7%/0.87 for a single current stimulation (expressed as cutaneous vascular conductance and 11.4%/0.61 for multiple current stimulations (expressed as absolute value. CONCLUSION: ACh-iontophoresis coupled with LSCI is a promising test to assess endothelial function because it is reproducible, safe, and non-invasive. N°: NCT01664572.

  8. Laser speckle contrast imaging of blood flow from anesthetized mice: correcting drifts in measurements due to breathing movements

    Science.gov (United States)

    Nogueira, Gesse E. C.; Ribeiro, Márcio A. C.; Campos, Juliane C.; Ferreira, Julio C. B.

    2015-06-01

    Background: Laser speckle contrast imaging allows non-invasive assessment of cutaneous blood flow. Although the technique is attractive to measure a quantity related to the skin blood flow (SBF) in anesthetized animal models, movements from breathing can mask the SBF signal. As a consequence, the measurement is overestimated because a variable amount of a DC component due to the breathing movements is added to the SBF signal. Objective: To evaluate a method for estimating the background level of the SBF signal, rejecting artefacts from breathing. Methods: A baseline correction method used for accurate DNA sequencing was evaluated, based on estimating the background level of a signal in small temporal sliding-windows. The method was applied to evaluate a mouse model of hindlimb ischemia. SBF signals from hindlimbs of anesthetized C57BL/6 mice (n=13) were registered. The mean SBF (Fi and Fc from ischemic and control hindlimbs) were computed from the registers and from the corresponding estimated background levels (Fib and Fcb from ischemic and control hindlimbs). Results: The mean values of the percentages (a measure of ischemia) MI = (Fi/Fc).100 and MIb = (Fib/Fcb).100 were computed to be 30+/-4% and 23+/-3% respectively (mean +/- SE). Evidences of statistical differences between both, ischemic and control hindlimbs, were obtained (p<0.05, paired student-t). The mean error [(MI-MIb)/MIb].100 obtained was 45+/-14% (mean+/-SE). Conclusion: The recovery of a corrupted SBF signal by breathing artefacts is feasible, allowing more accurate measurements.

  9. Speckle disturbance limit in laser-based cinema projection systems

    Science.gov (United States)

    Verschaffelt, Guy; Roelandt, Stijn; Meuret, Youri; van den Broeck, Wendy; Kilpi, Katriina; Lievens, Bram; Jacobs, An; Janssens, Peter; Thienpont, Hugo

    2015-09-01

    In a multi-disciplinary effort, we investigate the level of speckle that can be tolerated in a laser cinema projector based on a quality of experience experiment with movie clips shown to a test audience in a real-life movie theatre setting. We identify a speckle disturbance threshold by statistically analyzing the observers’ responses for different values of the amount of speckle, which was monitored using a well-defined speckle measurement method. The analysis shows that the speckle perception of a human observer is not only dependent on the objectively measured amount of speckle, but it is also strongly influenced by the image content. The speckle disturbance limit for movies turns out to be substantially larger than that for still images, and hence is easier to attain.

  10. Quantitative long term measurements of burns in a rat model using spatial frequency domain imaging and laser speckle imaging (Conference Presentation)

    Science.gov (United States)

    Ponticorvo, Adrien; Rowland, Rebecca A.; Baldado, Melissa L.; Kennedy, Gordon T.; Saager, Rolf B.; Choi, Bernard; Durkin, Anthony J.

    2016-04-01

    The ability to accurately assess burn wound severity in a timely manner is a critical component of wound management as it dictates the course of treatment. While full thickness and superficial burns can be easily diagnosed through visual inspection, burns that fall in between these categories are difficult to classify. Additionally, the ability to better quantify different stages of wound healing from a burn of any severity would be important for evaluating the efficacy of different treatment options. Here we present a longitudinal (28 day) study that employs spatial frequency domain imaging (SFDI) and laser speckle imaging (LSI) as non-invasive technologies to characterize in-vivo burn wounds and healing in a murine model. Burn wounds were created using an established technique of a brass comb heated to a given temperature and applied for a set amount of time. They were imaged immediately after the initial injury and then at 2, 4, 7, 14, 21, and 28 days following the injury. Biopsies were taken on the day of the injury in order to verify the extent of the burn damage as well as at different time points after the injury in order to visualize different stages of inflammation and healing. The results of this study suggest that the reduced scattering coefficient measured using SFDI and blood flow as measured using LSI have the potential to provide useful metrics for quantifying the severity of burn injuries as well as track the different stages associated with wound healing progression.

  11. Laser speckle and related phenomena

    CERN Document Server

    Dainty, John Christopher; Françon, Maurice; Goodman, Joseph Wilfred; McKechnie, Thomas Stewart; Parry, Gareth

    1975-01-01

    Contents: Dainty, J. C.: Introduction. - Goodman, J. W.: Statistical Properties of Laser Speckle Patterns. - Parry, G.: Speckle Patterns in Partially Coherent Light. - McKechnie, T. S.: Speckle Reduction. - Francon, M.: Information Processing Using Speckle Patterns. - Ennos, A. E.: Speckle Interferometry. - Dainty, J. C.: Stellar Speckle Interferometry. - Dainty, J. C.: Recent Developments. - Subject Index.

  12. Performance of the low light level CCD camera for speckle imaging

    CERN Document Server

    Saha, S K

    2002-01-01

    A new generation CCD detector called low light level CCD (L3CCD) that performs like an intensified CCD without incorporating a micro channel plate (MCP) for light amplification was procured and tested. A series of short exposure images with millisecond integration time has been obtained. The L3CCD is cooled to about $-80^\\circ$ C by Peltier cooling.

  13. Image registration using adaptive polar transform.

    Science.gov (United States)

    Matungka, Rittavee; Zheng, Yuan F; Ewing, Robert L

    2009-10-01

    Image registration is an essential step in many image processing applications that need visual information from multiple images for comparison, integration, or analysis. Recently, researchers have introduced image registration techniques using the log-polar transform (LPT) for its rotation and scale invariant properties. However, it suffers from nonuniform sampling which makes it not suitable for applications in which the registered images are altered or occluded. Inspired by LPT, this paper presents a new registration algorithm that addresses the problems of the conventional LPT while maintaining the robustness to scale and rotation. We introduce a novel adaptive polar transform (APT) technique that evenly and effectively samples the image in the Cartesian coordinates. Combining APT with an innovative projection transform along with a matching mechanism, the proposed method yields less computational load and more accurate registration than that of the conventional LPT. Translation between the registered images is recovered with the new search scheme using Gabor feature extraction to accelerate the localization procedure. Moreover an image comparison scheme is proposed for locating the area where the image pairs differ. Experiments on real images demonstrate the effectiveness and robustness of the proposed approach for registering images that are subjected to occlusion and alteration in addition to scale, rotation, and translation.

  14. Evaluation of Right Ventricular Global Longitudinal Function in Patients with Tetralogy of Fallot by Two-dimensional Ultrasound Speckle Tracking Imaging

    Institute of Scientific and Technical Information of China (English)

    李玉曼; 谢明星; 王新房; 吕清; 卢晓芳; 杨亚利; 马红; 方凌云; 张静; 李卫芹

    2010-01-01

    Quantification of right ventricular(RV)volume and function remains a challenge because of RV complex geometry by conventional echocardiography.The purpose of this study was to assess RV global longitudinal function in patients with tetralogy of Fallot(TOF)by 2-dimensional ultrasound speckle tracking imaging(STI).Thirty-eight patients with TOF were enrolled in this study and divided into child group(n=25)and adult group(n=13)according to age.Thirty-eight age-and sex-matched normal subjects were selected as c...

  15. An efficient adaptive arithmetic coding image compression technology

    Institute of Scientific and Technical Information of China (English)

    Wang Xing-Yuan; Yun Jiao-Jiao; Zhang Yong-Lei

    2011-01-01

    This paper proposes an efficient lossless image compression scheme for still images based on an adaptive arithmetic coding compression algorithm.The algorithm increases the image coding compression rate and ensures the quality of the decoded image combined with the adaptive probability model and predictive coding.The use of adaptive models for each encoded image block dynamically estimates the probability of the relevant image block.The decoded image block can accurately recover the encoded image according to the code book information.We adopt an adaptive arithmetic coding algorithm for image compression that greatly improves the image compression rate.The results show that it is an effective compression technology.

  16. Investigations of High Resolution Imaging through the Earth’s Atmosphere Using Speckle Interferometry.

    Science.gov (United States)

    1987-03-15

    8217, Proc. SPIE, 556-27,1985. 11. Freeman,J.U.,E.Ribak,J.C.Christou & E.K.Hege, ’Statistical Analysis of the Weighted Shift-and-Add Imaje Reconstruction...MM" is an limaginj optical interferometer. Understandinj differential images It is imnortant to appreciate that a differential imaje is n:t 3n imJe in...8217-’," peaked, whi, :n can so mistaken Is many sp2ckles, ’wi I .m, itl ;L:;ult [trSmbl i) g n auto-correlation instead of an Imaje . .&1, ’! 1 3 i i t1

  17. In vivo imaging of hemodynamics and oxygen metabolism in acute focal cerebral ischemic rats with laser speckle imaging and functional photoacoustic microscopy

    Science.gov (United States)

    Deng, Zilin; Wang, Zhen; Yang, Xiaoquan; Luo, Qingming; Gong, Hui

    2012-08-01

    Stroke is a devastating disease. The changes in cerebral hemodynamics and oxygen metabolism associated with stroke play an important role in pathophysiology study. But the changes were difficult to describe with a single imaging modality. Here the changes in cerebral blood flow (CBF), cerebral blood volume (CBV), and oxygen saturation (SO2) were yielded with laser speckle imaging (LSI) and photoacoustic microscopy (PAM) during and after 3-h acute focal ischemic rats. These hemodynamic measures were further synthesized to deduce the changes in oxygen extraction fraction (OEF). The results indicate that all the hemodynamics except CBV had rapid declines within 40-min occlusion of middle cerebral artery (MCAO). CBV in arteries and veins first increased to the maximum value of 112.42±36.69% and 130.58±31.01% by 15 min MCAO; then all the hemodynamics had a persistent reduction with small fluctuations during the ischemic. When ischemia lasted for 3 h, CBF in arteries, veins decreased to 17±14.65%, 24.52±20.66%, respectively, CBV dropped to 62±18.56% and 59±18.48%. And the absolute SO2 decreased by 40.52±22.42% and 54.24±11.77%. After 180-min MCAO, the changes in hemodynamics and oxygen metabolism were also quantified. The study suggested that combining LSI and PAM provides an attractive approach for stroke detection in small animal studies.

  18. Follow-up of cortical activity and structure after lesion with laser speckle imaging and magnetic resonance imaging in nonhuman primates

    Science.gov (United States)

    Peuser, Jörn; Belhaj-Saif, Abderraouf; Hamadjida, Adjia; Schmidlin, Eric; Gindrat, Anne-Dominique; Völker, Andreas Charles; Zakharov, Pavel; Hoogewoud, Henri-Marcel; Rouiller, Eric M.; Scheffold, Frank

    2011-09-01

    The nonhuman primate model is suitable to study mechanisms of functional recovery following lesion of the cerebral cortex (motor cortex), on which therapeutic strategies can be tested. To interpret behavioral data (time course and extent of functional recovery), it is crucial to monitor the properties of the experimental cortical lesion, induced by infusion of the excitotoxin ibotenic acid. In two adult macaque monkeys, ibotenic acid infusions produced a restricted, permanent lesion of the motor cortex. In one monkey, the lesion was monitored over 3.5 weeks, combining laser speckle imaging (LSI) as metabolic readout (cerebral blood flow) and anatomical assessment with magnetic resonance imaging (T2-weighted MRI). The cerebral blood flow, measured online during subsequent injections of the ibotenic acid in the motor cortex, exhibited a dramatic increase, still present after one week, in parallel to a MRI hypersignal. After 3.5 weeks, the cerebral blood flow was strongly reduced (below reference level) and the hypersignal disappeared from the MRI scan, although the lesion was permanent as histologically assessed post-mortem. The MRI data were similar in the second monkey. Our experiments suggest that LSI and MRI, although they reflect different features, vary in parallel during a few weeks following an excitotoxic cortical lesion.

  19. One dimensional speckle fields generated by three phase level diffusers

    Science.gov (United States)

    Cabezas, L.; Amaya, D.; Bolognini, N.; Lencina, A.

    2015-02-01

    Speckle patterns have usually been obtained by using ground glass as random diffusers. Liquid-crystal spatial light modulators have opened the possibility of engineering tailored speckle fields obtained from designed diffusers. In this work, one-dimensional Gaussian speckle fields with fully controllable features are generated. By employing a low-cost liquid-crystal spatial light modulator, one-dimensional three phase level diffusers are implemented. These diffusers make it possible to control average intensity distribution and statistical independence among the generated patterns. The average speckle size is governed by an external slit pupil. A theoretical model to describe the generated speckle patterns is developed. Experimental and theoretical results confirming the generation of one-dimensional speckle fields are presented. Some possible applications of these speckles, such as atom trapping and super-resolution imaging, are briefly envisaged.

  20. Assessment of left ventricular torsion in patients with anterior wall myocardial infarction before and after revascularization using speckle tracking imaging

    Institute of Scientific and Technical Information of China (English)

    HAN Wei; XIE Ming-xing; WANG Xin-fang; L(U) Qing; WANG Jing; ZHANG li; ZHANG Jing

    2008-01-01

    Background Rotation of the left ventricular(LV)apex to the base,or LV torsion,is related to myocardial contractility and structure and has recently been recognized as a sensitive indicator of cardiac performance,but it has been difficult to measure.The recent development of 2-dimensional(2D)speckle tracking imaging(STI)may provide a powerful means of assessing LV torsion.This study was conducted to evaluate the global and regional LV twist in patients with anterior wall myocardial infarction(AMI)disease before and after revascularization by STI.Methods 2D STI was performed in 35 AMI patients before and one month after revascularization,as well as in 32 normal controls.Left ventricular global and regional rotations were obtained at basal and apical short-axis levels;LV torsion was defined as apical rotation relative to the base.The time sequences were normalized to the percentage of systolic and diastolic duration.Results Before revascularization,LV peak regional and global torsion in patients with Aml were significantly reduced as the result of reduced apical and basal rotation relative to those of normal control group(all P<0.001):most significantly in the anterior and anterior-septal regions(P<0.001);one month after revascularization,there were significant changes in peak rotation at either the base or apex relative to pre-revascularization values(all P<0.001).Similarly,peak regional and global LV torsion were increased significantly(all P<0.001).Global torsion inversely correlated with EDV(r=0.605,P=0.028)and ESV(r=-0.638,P=-0.019):and positively correlated with LVEF(r=0.630,P=0.021).tlght relations were also found between torsion and.LV longitudinal and short axis function.Conclusions Systolic torsion was decreased in AMI patients.Revascularization therapy can improve the LV function of the AMI patients.STI has a potential to quantify left ventricular global and segment torsion in patients with AMI,and may make the assessment more available in clinical and

  1. Multi-scale Adaptive Computational Ghost Imaging

    Science.gov (United States)

    Sun, Shuai; Liu, Wei-Tao; Lin, Hui-Zu; Zhang, Er-Feng; Liu, Ji-Ying; Li, Quan; Chen, Ping-Xing

    2016-11-01

    In some cases of imaging, wide spatial range and high spatial resolution are both required, which requests high performance of detection devices and huge resource consumption for data processing. We propose and demonstrate a multi-scale adaptive imaging method based on the idea of computational ghost imaging, which can obtain a rough outline of the whole scene with a wide range then accordingly find out the interested parts and achieve high-resolution details of those parts, by controlling the field of view and the transverse coherence width of the pseudo-thermal field illuminated on the scene with a spatial light modulator. Compared to typical ghost imaging, the resource consumption can be dramatically reduced using our scheme.

  2. Adaptive image segmentation applied to plant reproduction by tissue culture

    Science.gov (United States)

    Vazquez Rueda, Martin G.; Hahn, Federico; Zapata, Jose L.

    1997-04-01

    This paper presents that experimental results obtained on indoor tissue culture using the adaptive image segmentation system. The performance of the adaptive technique is contrasted with different non-adaptive techniques commonly used in the computer vision field to demonstrate the improvement provided by the adaptive image segmentation system.

  3. Ultrasound speckle reduction using modified Gabor filters.

    Science.gov (United States)

    Dantas, Ricardo G; Costa, Eduardo T

    2007-03-01

    B-mode ultrasound images are characterized by speckle artifact, which may make the interpretation of images difficult. One widely used method for ultrasound speckle reduction is the split spectrum processing (SSP), but the use of one-dimensional (1-D), narrow-band filters makes the resultant image experience a significant resolution loss. In order to overcome this critical drawback, we propose a novel method for speckle reduction in ultrasound medical imaging, which uses a bank of wideband 2-D directive filters, based on modified Gabor functions. Each filter is applied to the 2-D radio-frequency (RF) data, resulting in a B-mode image filtered in a given direction. The compounding of the filters outputs give rise to a final image in which speckle is reduced and the structure is enhanced. We have denoted this method as directive filtering (DF). Because the proposed filters have effectively the same bandwidth as the original image, it is possible to avoid the resolution loss caused by the use of narrow-band filters, as with SSP. The tests were carried out with both simulated and real clinical data. Using the signal-to-noise ratio (SNR) to quantify the amount of speckle of the ultrasound images, we have achieved an average SNR enhancement of 2.26 times with simulated data and 1.18 times with real clinical data.

  4. Adaptive nonlinear microscopy for whole tissue imaging

    Science.gov (United States)

    Müllenbroich, M. Caroline; McGhee, Ewan J.; Wright, Amanda J.; Anderson, Kurt I.; Mathieson, Keith

    2013-02-01

    Nonlinear microscopy is capable of imaging biological tissue non-invasively with sub-cellular resolution in three dimensions. For efficient multiphoton signal generation, it is necessary to focus high power, ultra-fast laser pulses into a volume of femtolitres. Aberrations introduced either by the system's optical setup or the sample under investigation cause a broadening of the diffraction limited focal spot which leads to loss of image intensity and resolution. Adaptive optics provides a means to compensate for these aberrations and is capable of restoring resolution and signal strength when imaging at depth. We describe the use of a micro-electro-mechanical systems (MEMS) deformable membrane mirror in a multiphoton adaptive microscope. The aberration correction is determined in a wavefront sensorless approach by rapidly altering the mirror shape with a random search algorithm until the fluorescence or second harmonic signal intensity is improved. We demonstrate the benefits of wavefront correction in a wide-variety of samples, including urea crystals, convallaria and organotypic tissue cultures. We show how the optimization algorithm can be adjusted, for example by including a bleaching compensation, to allow the user to switch between different imaging modalities, producing a versatile approach to aberration correction.

  5. Adaptive Marginal Median Filter for Colour Images

    Directory of Open Access Journals (Sweden)

    Almanzor Sapena

    2011-03-01

    Full Text Available This paper describes a new filter for impulse noise reduction in colour images which is aimed at improving the noise reduction capability of the classical vector median filter. The filter is inspired by the application of a vector marginal median filtering process over a selected group of pixels in each filtering window. This selection, which is based on the vector median, along with the application of the marginal median operation constitutes an adaptive process that leads to a more robust filter design. Also, the proposed method is able to process colour images without introducing colour artifacts. Experimental results show that the images filtered with the proposed method contain less noisy pixels than those obtained through the vector median filter.

  6. Speckle Image Reconstruction.

    Science.gov (United States)

    2014-09-26

    semiminor axes and o* an orientation angle of the ellipse projected by a triaxial ellipsoid (an asteroid) and of the ellipse segment cast by a terminator...Hege We are using contemporaneous measurements of seeing at the Steward Observatory 2.3m telescope with a pupil shearing interferometer and a convential

  7. Adaptive dispersion compensation for guided wave imaging

    Science.gov (United States)

    Hall, James S.; Michaels, Jennifer E.

    2012-05-01

    Ultrasonic guided waves offer the promise of fast and reliable methods for interrogating large, plate-like structures. Distributed arrays of permanently attached, inexpensive piezoelectric transducers have thus been proposed as a cost-effective means to excite and measure ultrasonic guided waves for structural health monitoring (SHM) applications. Guided wave data recorded from a distributed array of transducers are often analyzed and interpreted through the use of guided wave imaging algorithms, such as conventional delay-and-sum imaging or the more recently applied minimum variance imaging. Both imaging algorithms perform reasonably well using signal envelopes, but can exhibit significant performance improvements when phase information is used. However, the use of phase information inherently requires knowledge of the dispersion relations, which are often not known to a sufficient degree of accuracy for high quality imaging since they are very sensitive to environmental conditions such as temperature, pressure, and loading. This work seeks to perform improved imaging with phase information by leveraging adaptive dispersion estimates obtained from in situ measurements. Experimentally obtained data from a distributed array is used to validate the proposed approach.

  8. Spatially Adaptive Intensity Bounds for Image Restoration

    Directory of Open Access Journals (Sweden)

    Kaaren L. May

    2003-11-01

    Full Text Available Spatially-adaptive intensity bounds on the image estimate are shown to be an effective means of regularising the ill-posed image restoration problem. For blind restoration, the local intensity constraints also help to further define the solution, thereby reducing the number of multiple solutions and local minima. The bounds are defined in terms of the local statistics of the image estimate and a control parameter which determines the scale of the bounds. Guidelines for choosing this parameter are developed in the context of classical (nonblind image restoration. The intensity bounds are applied by means of the gradient projection method, and conditions for convergence are derived when the bounds are refined using the current image estimate. Based on this method, a new alternating constrained minimisation approach is proposed for blind image restoration. On the basis of the experimental results provided, it is found that local intensity bounds offer a simple, flexible method of constraining both the nonblind and blind restoration problems.

  9. Highly porous nanoberyllium for X-ray beam speckle suppression

    Energy Technology Data Exchange (ETDEWEB)

    Goikhman, Alexander, E-mail: agoikhman@ymail.com; Lyatun, Ivan; Ershov, Petr [Immanuel Kant Baltic Federal University, Nevskogo str. 14, Kaliningrad 236041 (Russian Federation); Snigireva, Irina [European Synchrotron Radiation Facility, BP 220, 38043 Grenoble (France); Wojda, Pawel [Immanuel Kant Baltic Federal University, Nevskogo str. 14, Kaliningrad 236041 (Russian Federation); Gdańsk University of Technology, 11/12 G. Narutowicza, Gdańsk 80-233 (Poland); Gorlevsky, Vladimir; Semenov, Alexander; Sheverdyaev, Maksim; Koletskiy, Viktor [A. A. Bochvar High-Technology Scientific Research Institute for Inorganic Materials, Rogova str. 5a, Moscow 123098 (Russian Federation); Snigirev, Anatoly [Immanuel Kant Baltic Federal University, Nevskogo str. 14, Kaliningrad 236041 (Russian Federation); European Synchrotron Radiation Facility, BP 220, 38043 Grenoble (France)

    2015-04-09

    A speckle suppression device containing highly porous nanoberyllium is proposed for manipulating the spatial coherence length and removing undesirable speckle structure during imaging experiments. This paper reports a special device called a ‘speckle suppressor’, which contains a highly porous nanoberyllium plate squeezed between two beryllium windows. The insertion of the speckle suppressor in an X-ray beam allows manipulation of the spatial coherence length, thus changing the effective source size and removing the undesirable speckle structure in X-ray imaging experiments almost without beam attenuation. The absorption of the nanoberyllium plate is below 1% for 1 mm thickness at 12 keV. The speckle suppressor was tested on the ID06 ESRF beamline with X-rays in the energy range from 9 to 15 keV. It was applied for the transformation of the phase–amplitude contrast to the pure amplitude contrast in full-field microscopy.

  10. Object localization using the statistical behavior of volume speckle fields

    Science.gov (United States)

    Abregana, Timothy Joseph T.; Almoro, Percival F.

    2016-12-01

    Speckle noise presents challenges in object localization using reconstructed wavefronts. Here, a technique for axial localization of rough test objects based on a statistical algorithm that processes volume speckle fields is demonstrated numerically and experimentally. The algorithm utilizes the standard deviation of phase difference maps as a metric to characterize the object wavefront at different axial locations. Compared with an amplitude-based localization method utilizing energy of image gradient, the technique is shown to be robust against speckle noise.

  11. Image Denoising using Adaptive Thresholding in Framelet Transform Domain

    Directory of Open Access Journals (Sweden)

    R.Vidhya

    2012-09-01

    Full Text Available Noise will be unavoidable during image acquisition process and denosing is an essential step to improve the image quality. Image denoising involves the manipulation of the image data to produce a visually high quality image. Finding efficient image denoising methods is still valid challenge in image processing. Wavelet denoising attempts to remove the noise present in the imagery while preserving the image characteristics, regardless of its frequency content. Many of the wavelet based denoising algorithms use DWT (Discrete Wavelet Transform in the decomposition stage which is suffering from shift variance. To overcome this, in this paper we proposed the denoising method which uses Framelet transform to decompose the image and performed shrinkage operation to eliminate the noise .The framework describes a comparative study of different thresholding techniques for image denoising in Framelet transform domain. The idea is to transform the data into the Framelet basis, example shrinkage followed by the inverse transform. In this work different shrinkage rules such as universal shrink(US,Visu shrink (VS, Minmax shrink(MS, Sure shrink(SS , Bayes shrink(BS and Normal shrink(NS were incorporated . Results based on different noise such as Gausssian noise, Poission noise , Salt and pepper noise and Speckle noise at (??=10,20 performed in this paper and peak signal to noise ratio (PSNR and Structural similarity index measure(SSIM as a measure of the quality of denoising was performed.

  12. Generation of speckle vortices by Archimedes' spiral micro-holes

    Science.gov (United States)

    Sun, Haibin; Liu, Tingting; Chen, Jun; Sun, Ping

    2016-10-01

    Speckle plays an important role in the optical field. Optical vortices which exist in random speckle fields usually contain useful phase information. The distribution of speckle field is determined by these optical vortices. In order to study speckle vortices quantitatively, we established a micro-holes array model based on the law of Archimedes' spiral arrangement. Speckle vortices can be generated by the random diffuse reflection points (spiral micro-holes). In the experiments, the gray image of Archimedes' spiral micro-holes are displayed on the screen of liquid crystal spatial light modulator (LC-SLM), and the output optical field is captured by a CCD camera. The numerical simulations and experimental results show that the model can be used to generate speckle vortices.

  13. An effective method for reducing speckle noise in digital holography

    Institute of Scientific and Technical Information of China (English)

    Xin Kang

    2008-01-01

    An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.

  14. Three-dimensional speckle tracking imaging assessment of left ventricular change in patient with coronary heart disease and its correlation with serum indexes

    Institute of Scientific and Technical Information of China (English)

    Jian-Li Fu; Jian-Mei Peng; Ya-Mei Shen; Xiao-Yong Zhang; Yu-Zeng Ding

    2016-01-01

    Objective:To analyze the three-dimensional speckle tracking imaging assessment of left ventricular change in patient with coronary heart disease and its correlation with serum indexes.Methods:A total of 152 patients first diagnosed with coronary heart disease were the observation group of the study and 117 healthy subjects were the control group. Three-dimensional speckle tracking imaging (3D-STI) was used to evaluate the left ventricular function parameters of two groups, the serum content of endothelial function indexes and platelet function indexes were detected, and the correlation between left ventricular function parameters under 3D-STI and serum indexes was further analyzed.Results: Absolute values of left ventricular function parameters LVGLS, LVGRS, LVGCS and LVGAS from 3D-STI of observation group were significantly less than those of control group while Ptw and Torsion levels were greater than those of control group; endothelial function indexes vWF, sICAM-1, sVCAM-1 and ET-1 content in serum were significantly higher than those of control group while vWF-cp and NO content were significantly lower than those of control group; platelet function indexes CD62P, GMP-140, CD63, sP-selectin, sCD40L and PAC-1 content in serum were significantly higher than those of control group. The levels of left ventricular function parameters from 3D-STI in patients with coronary heart disease were directly correlated with serum indexes.Conclusion:3D-STI can accurately assess the left ventricular function and the overall disease severity in patients with coronary heart disease, and it is expected to become an effective method for early diagnosis of diseases and guidance of clinical treatment.

  15. Dynamical properties of speckled speckles

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner; Iversen, Theis Faber Quist; Hansen, Rene Skov

    2010-01-01

    the static diffuser and the plane of observation consist of an optical system that can be characterized by a complex-valued ABCD-matrix (e.g. simple and complex imaging systems, free space propagation in both the near-and far-field, and Fourier transform systems). The use of the complex ABCD-method means...

  16. Speckle-based spectrometer

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Jakobsen, Michael Linde; Hanson, Steen Grüner

    2015-01-01

    A novel spectrometer concept is analyzed and experimentally verified. The method relies on probing the speckle displacement due to a change in the incident wavelength. A rough surface is illuminated at an oblique angle, and the peak position of the covariance between the speckle patterns observed...

  17. Speckle-based wavemeter

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner; Jakobsen, Michael Linde; Chakrabarti, Maumita

    2015-01-01

    A spectrometer based on the application of dynamic speckles will be disclosed. The method relies on scattering of primarily coherent radiation from a slanted rough surface. The scattered radiation is collected on a detector array and the speckle displacement is monitored during a change in the in...

  18. Adaptive Real Time Imaging Synthesis Telescopes

    CERN Document Server

    Wright, Melvyn

    2012-01-01

    The digital revolution is transforming astronomy from a data-starved to a data-submerged science. Instruments such as the Atacama Large Millimeter Array (ALMA), the Large Synoptic Survey Telescope (LSST), and the Square Kilometer Array (SKA) will measure their accumulated data in petabytes. The capacity to produce enormous volumes of data must be matched with the computing power to process that data and produce meaningful results. In addition to handling huge data rates, we need adaptive calibration and beamforming to handle atmospheric fluctuations and radio frequency interference, and to provide a user environment which makes the full power of large telescope arrays accessible to both expert and non-expert users. Delayed calibration and analysis limit the science which can be done. To make the best use of both telescope and human resources we must reduce the burden of data reduction. Our instrumentation comprises of a flexible correlator, beam former and imager with digital signal processing closely coupled...

  19. A new method for adaptive color image filtering

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An adaptive color image filter (ACIF) is proposed in this note. Through analyzing noise corruption of color image, efficient locally adaptive filters are chosen for image enhancement. The proposed adaptive color image filter combines advantages of both nonlinear vector filters and linear filters, it attenuates noise and preserves edges and details very well. Experimental results show that the proposed filter performs better than vector median filter, directional-distance filter, directional-magnitude vector filter, adaptive nearest-neighbor filter, and -trimmed mean filter.

  20. Filter for speckle noise reduction based on compressive sensing

    Science.gov (United States)

    Leportier, Thibault; Park, Min-Chul

    2016-12-01

    In holographic reconstruction, speckle noise is a serious factor that may degrade the image quality greatly. Several methods have been proposed, so far, to filter speckle from hologram reconstruction. The first approach is based on averaging several speckle patterns. The second solution is to apply a filter on the reconstructed image. In the first case, several holograms should be acquired, while compromise between speckle reduction and edge preservation is usually a challenge in the case of digital filtering. We propose a method to filter speckle noise based on compressive sensing (CS). CS is a method that has been demonstrated recently to reconstruct images with a sampling inferior to the Nyquist rate. By applying several times the CS algorithm on the hologram reconstruction with different initial downsampling, several versions of the same images can be reconstructed with slightly different speckle patterns. Then, speckle noise can be greatly decreased while preserving sharpness of the image. We demonstrate the effectiveness of our proposed method with simulations as well as with holograms acquired by phase-shifting method.

  1. Utility of comprehensive assessment of strain dyssynchrony index by speckle tracking imaging for predicting response to cardiac resynchronization therapy.

    Science.gov (United States)

    Tatsumi, Kazuhiro; Tanaka, Hidekazu; Yamawaki, Kouhei; Ryo, Keiko; Omar, Alaa Mabrouk Salem; Fukuda, Yuko; Norisada, Kazuko; Matsumoto, Kensuke; Onishi, Tetsuari; Gorcsan, John; Yoshida, Akihiro; Kawai, Hiroya; Hirata, Ken-ichi

    2011-02-01

    The strain delay index is reportedly a marker of dyssynchrony and residual myocardial contractility. The aim of this study was to test the hypothesis that a relatively simple version of the strain dyssynchrony index (SDI) can predict response to cardiac resynchronization therapy (CRT) and that combining assessment of radial, circumferential, and longitudinal SDI can further improve the prediction of responders. A total of 52 patients who underwent CRT were studied. The SDI was calculated as the average difference between peak and end-systolic strain from 6 segments for radial and circumferential SDI and 18 segments for longitudinal SDI. Conventional dyssynchrony measures were assessed by interventricular mechanical delay, the Yu index, and radial dyssynchrony by speckle tracking strain. Response was defined as a ≥15% decrease in end-systolic volume after 3 months. Of the individual parameters, radial SDI ≥6.5% was the best predictor of response to CRT, with sensitivity of 81%, specificity of 81%, and an area under the curve of 0.87 (p SDIs was 100%. In contrast, rates in patients with either 1 or no positive SDIs were 42% and 22%, respectively (p SDIs). In conclusion, the SDI can successfully predict response to CRT, and the combined approach leads to more accurate prediction than using individual parameters.

  2. Preliminary clinical study of left ventricular myocardial strain in patients with non-ischemic dilated cardiomyopathy by three-dimensional speckle tracking imaging

    Directory of Open Access Journals (Sweden)

    Duan Fengxia

    2012-03-01

    Full Text Available Abstract Background Non-ischemic dilated cardiomyopathy (DCM is the most common cardiomyopathy worldwide, with significant mortality. Correct evaluation of the patient's myocardial function has important clinical significance in the diagnosis, therapeutic effect assessment and prognosis in non-ischemic DCM patients. This study evaluated the feasibility of three-dimensional speckle tracking imaging (3D-STE for assessment of the left ventricular myocardial strain in patients with non-ischemic dilated cardiomyopathy (DCM. Methods Apical full-volume images were acquired from 65 patients with non-ischemic DCM (DCM group and 59 age-matched normal controls (NC group, respectively. The following parameters were measured by 3D-STE: the peak systolic radial strain (RS, circumferential strain (CS, longitudinal strain (LS of each segment. Then all the parameters were compared between the two groups. Results The peak systolic strain in different planes had certain regularities in normal groups, radial strain (RS was the largest in the mid region, the smallest in the apical region, while circumferential strain (CS and longitudinal strain (LS increased from the basal to the apical region. In contrast, the regularity could not be applied to the DCM group. RS, CS, LS were significantly decreased in DCM group as compared with NC group (P Conclusions 3D-STE is a reliable tool for evaluation of left ventricular myocardial strain in patients with non-ischemic DCM, with huge advantage in clinical application.

  3. Discrete Anderson Speckle

    CERN Document Server

    Kondakci, H Esat; Saleh, Bahaa E A

    2016-01-01

    When a disordered array of coupled waveguides is illuminated with an extended coherent optical field, discrete speckle develops: partially coherent light with a granular intensity distribution on the lattice sites. The same paradigm applies to a variety of other settings in photonics, such as imperfectly coupled resonators or fibers with randomly coupled cores. Through numerical simulations and analytical modeling, we uncover a set of surprising features that characterize discrete speckle in one- and two-dimensional lattices known to exhibit transverse Anderson localization. Firstly, the fingerprint of localization is embedded in the fluctuations of the discrete speckle and is revealed in the narrowing of the spatial coherence function. Secondly, the transverse coherence length (or speckle grain size) is frozen during propagation. Thirdly, the axial coherence depth is independent of the axial position, thereby resulting in a coherence voxel of fixed volume independently of position. We take these unique featu...

  4. Assessment value of 3-dimensional speckle tracking imaging for changes of early left ventricular longitudinal systolic function in patients with primary hypertension

    Institute of Scientific and Technical Information of China (English)

    Jing Yu; Yun-Jian Huang

    2016-01-01

    Objective:To study the assessment value of 3-dimensional speckle tracking imaging for changes of early left ventricular longitudinal systolic function in patients with primary hypertension.Methods:Patients with primary hypertension who were treated in our hospital from May 2012 to October 2015 were selected, and 40 patients with left ventricular normal (LVN) primary hypertension and 40 patients with left ventricular remodeling (LVR) primary hypertension were screened according to Ganau typing and enrolled in the LVN group and LVR group of the study respectively; 40 cases of healthy volunteers who received physical examination in our hospital during the same period were selected as control group. Ultrasonic testing was conducted to determine conventional ultrasonic indicators and 3D-STI parameters, and serum was collected to determine AngII, ALD, TGF-β1 and Ang1-7 levels.Results:LVEDd, LVPWT and LVEF of LVN group were not significantly different from those of control group, LVEF of LVR group was not significantly different from those of LVN group and control group, and LVEDd and LVPWT of LVR group were significantly higher than those of LVN group and control group; absolute values of GLS, GCS, GRS and GAS as well as serum Ang1-7 level of LVN group was significantly lower than those of control group, serum AngII, ALD and TGF-β1 levels were higher than those of control group, absolute values of GLS, GCS, GRS and GAS as well as serum Ang1-7 level of LVR group was significantly lower than those of LVN group and control group, and serum AngII, ALD and TGF-β1 levels were higher than those of LVN group and control group; absolute values of GLS, GCS, GRS and GAS were negatively correlated with serum AngII, ALD and TGF-β1 levels, and positively correlated with serum Ang1-7 level.Conclusion:3-dimensional speckle tracking imaging can be used for early evaluation of left ventricular longitudinal systolic function in patients with primary hypertension, and it also has high

  5. In vivo optical imaging of human retinal capillary networks using speckle variance optical coherence tomography with quantitative clinico-histological correlation.

    Science.gov (United States)

    Chan, Geoffrey; Balaratnasingam, Chandrakumar; Xu, Jing; Mammo, Zaid; Han, Sherry; Mackenzie, Paul; Merkur, Andrew; Kirker, Andrew; Albiani, David; Sarunic, Marinko V; Yu, Dao-Yi

    2015-07-01

    Retinal capillary networks are critically linked to neuronal health and disease. The ability to perform accurate in vivo examination of human retinal capillary networks is therefore valuable for studying mechanisms that govern retinal homeostasis and retinal vascular diseases. Speckle variance optical coherence tomography (svOCT) is a non-invasive imaging technique that has the capacity to provide angiographic information about the retinal circulation. The application of this technology for studying human retinal capillary networks however has not been validated in a quantifiable manner. We use a custom-built svOCT device to qualitatively and quantitatively study the various capillary networks in the human perifovea. Capillary networks corresponding to the nerve fibre layer (NFL), the retinal ganglion cell/superficial inner plexiform layer (RGC/sIPL), the deep inner plexiform layer/superficial inner nuclear layer (dIPL/sINL) and the deep inner nuclear layer (dINL) are imaged in 9 normal human subjects. Measurements of capillary diameter and capillary density are made from each of these networks and results are compared to post-mortem histological data acquired with confocal scanning laser microscopy. Additionally, retinal capillary measurements from high-resolution fundus fluorescein angiogram (FA) are directly compared with svOCT images from 6 eyes. We demonstrate that svOCT images of capillary networks are morphologically comparable to microscopic images of histological specimens. Similar to histological images in svOCT images, the capillaries in the NFL network run parallel to the direction of RGC axons while capillaries in the dINL network comprise a planar configuration with multiple closed loops. Capillaries in remaining networks are convoluted with a complex three-dimensional architecture. We demonstrate that there is no significant difference in capillary density measurements between svOCT and histology images for all networks. Capillary diameter was

  6. Advanced Speckle Sensing for Internal Coronagraphs

    Science.gov (United States)

    Noecker, Charley; Shaklan, Stuart B.; Wallace, James K.; Kern, Brian D.; Give'on, Amir; Kasdin, Jeremy; Belikov, Ruslan; Kendrick, Steve

    2011-01-01

    A 4-8m telescope carrying a coronagraph instrument is a leading candidate for an anticipated flagship mission to detect and characterize Earth-size exoplanets in the 2020s. Many candidate coronagraph instruments have been proposed, and one has met many of the principal requirements for that mission. But the telescope and instrument will need exquisite stability and precise control of the incoming wavefront to enable detection of faint companions (10(exp -10) of the star) at an angular separation of 2-4 Airy radii. In particular, wavefront errors cause speckles in the image, and variations in those speckles can confound the exoplanet detection. This challenge is compounded by the background light from zodiacal dust around our Sun and the target star, which limits the speed with which we can estimate and correct the speckles. We are working on developing coherent speckle detection techniques that will allow rapid calibration of speckles on the science detector, allowing subtraction in post-processing or correction with deformable mirrors. The expected speed improvement allows a much quicker timeline for measurement & calibration, which reduces the required telescope stability requirement and eases both the flight system design and the challenge of ground testing. We will describe the experiments and summarize progress to date.

  7. Escherichia coli activity characterization using a laser dynamic speckle technique

    CERN Document Server

    Ramírez-Miquet, Evelio E; Contreras-Alarcón, Orestes R

    2012-01-01

    The results of applying a laser dynamic speckle technique to characterize bacterial activity are presented. The speckle activity was detected in two-compartment Petri dishes. One compartment was inoculated and the other one was left as a control blank. The speckled images were processed by the recently reported temporal difference method. Three inoculums of 0.3, 0.5, and 0.7 McFarland units of cell concentration were tested; each inoculum was tested twice for a total of six experiments. The dependences on time of the mean activity, the standard deviation of activity and other descriptors of the speckle pattern evolution were calculated for both the inoculated compartment and the blank. In conclusion the proposed dynamic speckle technique allows characterizing the activity of Escherichia coli bacteria in solid medium.

  8. Adaptive feature-specific imaging: a face recognition example.

    Science.gov (United States)

    Baheti, Pawan K; Neifeld, Mark A

    2008-04-01

    We present an adaptive feature-specific imaging (AFSI) system and consider its application to a face recognition task. The proposed system makes use of previous measurements to adapt the projection basis at each step. Using sequential hypothesis testing, we compare AFSI with static-FSI (SFSI) and static or adaptive conventional imaging in terms of the number of measurements required to achieve a specified probability of misclassification (Pe). The AFSI system exhibits significant improvement compared to SFSI and conventional imaging at low signal-to-noise ratio (SNR). It is shown that for M=4 hypotheses and desired Pe=10(-2), AFSI requires 100 times fewer measurements than the adaptive conventional imager at SNR= -20 dB. We also show a trade-off, in terms of average detection time, between measurement SNR and adaptation advantage, resulting in an optimal value of integration time (equivalent to SNR) per measurement.

  9. Scene estimation from speckled synthetic aperture radar imagery: Markov-random-field approach.

    Science.gov (United States)

    Lankoande, Ousseini; Hayat, Majeed M; Santhanam, Balu

    2006-06-01

    A novel Markov-random-field model for speckled synthetic aperture radar (SAR) imagery is derived according to the physical, spatial statistical properties of speckle noise in coherent imaging. A convex Gibbs energy function for speckled images is derived and utilized to perform speckle-compensating image estimation. The image estimation is formed by computing the conditional expectation of the noisy image at each pixel given its neighbors, which is further expressed in terms of the derived Gibbs energy function. The efficacy of the proposed technique, in terms of reducing speckle noise while preserving spatial resolution, is studied by using both real and simulated SAR imagery. Using a number of commonly used metrics, the performance of the proposed technique is shown to surpass that of existing speckle-noise-filtering methods such as the Gamma MAP, the modified Lee, and the enhanced Frost.

  10. DIGITAL SPECKLE CORRELATION METHOD IMPROVED BY GENETIC ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    MaShaopeng; JillGuanchang

    2003-01-01

    The digital speckle correlation method is an important optical metrology for surface displacement and strain measurement. With this technique, the whole field deformation information can be obtained by tracking the geometric points on the speckle images based on a correlation-matching search technique. However, general search techniques suffer from great computational complexity in the processing of speckle images with large deformation and the large random errors in the processing of images of bad quality. In this paper, an advanced approach based on genetic algorithms (GA) for correlation-matching search is developed. Benefiting from the abilities of global optimum and parallelism searching of GA, this new approach can complete the correlation-matching search with less computational consumption and at high accuracy. Two experimental results from the simulated speckle images have proved the efficiency of the new approach.

  11. Adaptive image ray-tracing for astrophysical simulations

    CERN Document Server

    Parkin, E R

    2010-01-01

    A technique is presented for producing synthetic images from numerical simulations whereby the image resolution is adapted around prominent features. In so doing, adaptive image ray-tracing (AIR) improves the efficiency of a calculation by focusing computational effort where it is needed most. The results of test calculations show that a factor of >~ 4 speed-up, and a commensurate reduction in the number of pixels required in the final image, can be achieved compared to an equivalent calculation with a fixed resolution image.

  12. Adaptive Local Image Registration: Analysis on Filter Size

    OpenAIRE

    Vishnukumar S; M.Wilscy

    2012-01-01

    Adaptive Local Image Registration is a Local Image Registration based on an Adaptive Filtering frame work. A filter of appropriate size convolves with reference image and gives the pixel values corresponding to the distorted image and the filter is updated in each stage of the convolution. When the filter converges to the system model, it provides the registered image. The filter size plays an important role in this method. The analysis on the filter size is done using Peak Signal-to-Noise Ra...

  13. Monitoring hypoxia induced changes in cochlear blood flow and hemoglobin concentration using a combined dual-wavelength laser speckle contrast imaging and Doppler optical microangiography system.

    Directory of Open Access Journals (Sweden)

    Roberto Reif

    Full Text Available A synchronized dual-wavelength laser speckle contrast imaging (DWLSCI system and a Doppler optical microangiography (DOMAG system was developed to determine several ischemic parameters in the cochlea due to a systemic hypoxic challenge. DWLSCI can obtain two-dimensional data, and was used to determine the relative changes in cochlear blood flow, and change in the concentrations of oxyhemoglobin (HbO, deoxyhemoglobin (Hb and total hemoglobin (HbT in mice. DOMAG can obtain three-dimensional data, and was used to determine the changes in cochlear blood flow with single vessel resolution. It was demonstrated that during a hypoxic challenge there was an increase in the concentrations of Hb, a decrease in the concentrations of HbO and cochlear blood flow, and a slight decrease in the concentration of HbT. Also, the rate of change in the concentrations of Hb and HbO was quantified during and after the hypoxic challenge. The ability to simultaneously measure these ischemic parameters with high spatio-temporal resolution will allow the detailed quantitative analysis of several hearing disorders, and will be useful for diagnosing and developing treatments.

  14. Evaluation of Laser Speckle Contrast Imaging for the Assessment of Oral Mucosal Blood Flow following Periodontal Plastic Surgery: An Exploratory Study

    Science.gov (United States)

    Molnár, Eszter; Molnár, Bálint; Lohinai, Zsolt; Tóth, Zsuzsanna; Benyó, Zoltán; Hricisák, Laszló; Windisch, Péter

    2017-01-01

    The laser speckle contrast imaging (LSCI) is proved to be a reliable tool in flap monitoring in general surgery; however, it has not been evaluated in oral surgery yet. We applied the LSCI to compare the effect of a xenogeneic collagen matrix (Geistlich Mucograft®) to connective tissue grafts (CTG) on the microcirculation of the modified coronally advanced tunnel technique (MCAT) for gingival recession coverage. Gingival microcirculation and wound fluid were measured before and after surgery for six months at twenty-seven treated teeth. In males, the flap microcirculation was restored within 3 days for both grafts followed by a hyperemic response. During the first 8 days the blood flow was higher at xenogeneic graft comparing to the CTG. In females, the ischemic period lasted for 7–12 days depending on the graft and no hyperemic response was observed. Females had more intense and prolonged wound fluid production. The LSCI method is suitable to capture the microcirculatory effect of the surgical intervention in human oral mucosa. The application of xenogeneic collagen matrices as a CTG substitute does not seem to restrain the recovery of graft bed circulation. Gender may have an effect on postoperative circulation and inflammation. PMID:28232940

  15. Evaluation of Laser Speckle Contrast Imaging for the Assessment of Oral Mucosal Blood Flow following Periodontal Plastic Surgery: An Exploratory Study

    Directory of Open Access Journals (Sweden)

    Eszter Molnár

    2017-01-01

    Full Text Available The laser speckle contrast imaging (LSCI is proved to be a reliable tool in flap monitoring in general surgery; however, it has not been evaluated in oral surgery yet. We applied the LSCI to compare the effect of a xenogeneic collagen matrix (Geistlich Mucograft® to connective tissue grafts (CTG on the microcirculation of the modified coronally advanced tunnel technique (MCAT for gingival recession coverage. Gingival microcirculation and wound fluid were measured before and after surgery for six months at twenty-seven treated teeth. In males, the flap microcirculation was restored within 3 days for both grafts followed by a hyperemic response. During the first 8 days the blood flow was higher at xenogeneic graft comparing to the CTG. In females, the ischemic period lasted for 7–12 days depending on the graft and no hyperemic response was observed. Females had more intense and prolonged wound fluid production. The LSCI method is suitable to capture the microcirculatory effect of the surgical intervention in human oral mucosa. The application of xenogeneic collagen matrices as a CTG substitute does not seem to restrain the recovery of graft bed circulation. Gender may have an effect on postoperative circulation and inflammation.

  16. Evaluation of Laser Speckle Contrast Imaging for the Assessment of Oral Mucosal Blood Flow following Periodontal Plastic Surgery: An Exploratory Study.

    Science.gov (United States)

    Molnár, Eszter; Molnár, Bálint; Lohinai, Zsolt; Tóth, Zsuzsanna; Benyó, Zoltán; Hricisák, Laszló; Windisch, Péter; Vág, János

    2017-01-01

    The laser speckle contrast imaging (LSCI) is proved to be a reliable tool in flap monitoring in general surgery; however, it has not been evaluated in oral surgery yet. We applied the LSCI to compare the effect of a xenogeneic collagen matrix (Geistlich Mucograft®) to connective tissue grafts (CTG) on the microcirculation of the modified coronally advanced tunnel technique (MCAT) for gingival recession coverage. Gingival microcirculation and wound fluid were measured before and after surgery for six months at twenty-seven treated teeth. In males, the flap microcirculation was restored within 3 days for both grafts followed by a hyperemic response. During the first 8 days the blood flow was higher at xenogeneic graft comparing to the CTG. In females, the ischemic period lasted for 7-12 days depending on the graft and no hyperemic response was observed. Females had more intense and prolonged wound fluid production. The LSCI method is suitable to capture the microcirculatory effect of the surgical intervention in human oral mucosa. The application of xenogeneic collagen matrices as a CTG substitute does not seem to restrain the recovery of graft bed circulation. Gender may have an effect on postoperative circulation and inflammation.

  17. Ultrasound Speckle Tracking Imaging Contributes to Early Diagnosis of Impaired Left Ventricular Systolic Function in Patients with Type 2 Diabetes Mellitus

    Institute of Scientific and Technical Information of China (English)

    Hong MA; Mingxing XIE; Jing WANG; Qing LU; Xinfang WANG; Xiaofang LU; Yali YANG; Lijun HU

    2008-01-01

    To investigate the value of ultrasound speckle tracking imaging (STI) in the assessment of the short-axis and long-axis systolic function of the left ventricle (LV) in patients with type 2 diabetes mellitus (DM), 100 subjects with normal ejection fraction were studied, including 41 patients with DM only (DM group), 22 patients with both DM and left ventricular hypertrophy (DH group),and 37 healthy subjects (control group). Left ventricle systolic function in the long axis defined as longitudinal strain, and that in the short axis defined as radial strain, apical and basal LV rotations,and LV twist were assessed respectively. The results showed that average peak strain in the long axis at basal, middle and apical levels, and global peak strain were significantly decreased in the patient groups when compared with the control group (P0.05). Apical and basal LV rotations, and LV twist were greater in the patient groups than in the control group (P<0.01 for each). Basal LV rotation and LV twist were greater in DH group than those in DM group (P<0.01). It was concluded that STI may be used to identify early abnormalities in patients with type 2 DM that have normal left ventricular systolic function.

  18. X-Ray Multimodal Tomography Using Speckle-Vector Tracking

    OpenAIRE

    Berujon, Sebastien; Ziegler, Eric

    2015-01-01

    We demonstrate computerized tomography (CT) reconstructions from absorption, phase and dark-field signals obtained from scans acquired when the x-ray probe light is modulated with speckle. Two different interlaced schemes are proposed to reduce the number of sample exposures. First, the already demonstrated x-ray speckle-vector tracking (XSVT) concept for projection imaging allows the three signal CT reconstructions from multiple images per projection. Second, a modified XSVT approach is show...

  19. Adaptation aftereffects in the perception of radiological images.

    Directory of Open Access Journals (Sweden)

    Elysse Kompaniez

    Full Text Available Radiologists must classify and interpret medical images on the basis of visual inspection. We examined how the perception of radiological scans might be affected by common processes of adaptation in the visual system. Adaptation selectively adjusts sensitivity to the properties of the stimulus in current view, inducing an aftereffect in the appearance of stimuli viewed subsequently. These perceptual changes have been found to affect many visual attributes, but whether they are relevant to medical image perception is not well understood. To examine this we tested whether aftereffects could be generated by the characteristic spatial structure of radiological scans, and whether this could bias their appearance along dimensions that are routinely used to classify them. Measurements were focused on the effects of adaptation to images of normal mammograms, and were tested in observers who were not radiologists. Tissue density in mammograms is evaluated visually and ranges from "dense" to "fatty." Arrays of images varying in intermediate levels between these categories were created by blending dense and fatty images with different weights. Observers first adapted by viewing image samples of dense or fatty tissue, and then judged the appearance of the intermediate images by using a texture matching task. This revealed pronounced perceptual aftereffects - prior exposure to dense images caused an intermediate image to appear more fatty and vice versa. Moreover, the appearance of the adapting images themselves changed with prolonged viewing, so that they became less distinctive as textures. These aftereffects could not be accounted for by the contrast differences or power spectra of the images, and instead tended to follow from the phase spectrum. Our results suggest that observers can selectively adapt to the properties of radiological images, and that this selectivity could strongly impact the perceived textural characteristics of the images.

  20. Image Deblurring and Super-resolution by Adaptive Sparse Domain Selection and Adaptive Regularization

    CERN Document Server

    Dong, Weisheng; Shi, Guangming; Wu, Xiaolin

    2010-01-01

    As a powerful statistical image modeling technique, sparse representation has been successfully used in various image restoration applications. The success of sparse representation owes to the development of l1-norm optimization techniques, and the fact that natural images are intrinsically sparse in some domain. The image restoration quality largely depends on whether the employed sparse domain can represent well the underlying image. Considering that the contents can vary significantly across different images or different patches in a single image, we propose to learn various sets of bases from a pre-collected dataset of example image patches, and then for a given patch to be processed, one set of bases are adaptively selected to characterize the local sparse domain. We further introduce two adaptive regularization terms into the sparse representation framework. First, a set of autoregressive (AR) models are learned from the dataset of example image patches. The best fitted AR models to a given patch are ad...

  1. Poor man's adaptive optics with high Strehl and low anisoplanatic effects: holographic imaging in crowded fields

    CERN Document Server

    Schoedel, R; Ghez, A; Girard, J H V; Labadie, L; Rebolo, R; Perez-Garrido, A

    2011-01-01

    We present an algorithm for speckle holography that is optimised for crowded fields. The key features of this algorithm are an iterative approach, the possibility to use several guide stars simultaneously, and cleaning of the instantaneous PSFs of the reference stars from faint secondary sources. High signal-to-noise and accuracy can in this way be reached on the PSFs extracted from the speckle frames. We find that relatively faint (K~12) reference stars are sufficient to reconstruct images with Strehl ratios. If the instrumental FOV is larger than the isoplanatic angle, then the algorithm can be used to reconstruct small sub-fields if the density of reference sources is sufficiently high. The reconstructed sub-images can then be combined to a final mosaic that is largely free of anisoplanatic effects. We have performed experiments with near-infrared and optical speckle data that show the excellent performance of the algorithm. A Strehl ratio of almost 20% was reached on I-band speckle data under average seei...

  2. Content- and disparity-adaptive stereoscopic image retargeting

    Science.gov (United States)

    Yan, Weiqing; Hou, Chunping; Zhou, Yuan; Xiang, Wei

    2016-02-01

    The paper proposes a content- and disparity-adaptive stereoscopic image retargeting. To simultaneously avoid the saliency content and disparity distortion, firstly, we calculate the image saliency region distortion difference, and conclude the factors causing visual distortion. Then, the proposed method via a convex quadratic programming can simultaneously avoid the distortion of the salient region and adjust disparity to a target area, by considering the relationship of the scaling factor of salient region and the disparity scaling factor. The experimental results show that the proposed method is able to successfully adapt the image disparity to the target display screen, while the salient objects remain undistorted in the retargeted stereoscopic image.

  3. Plane Wave Medical Ultrasound Imaging Using Adaptive Beamforming

    DEFF Research Database (Denmark)

    Holfort, Iben Kraglund; Gran, Fredrik; Jensen, Jørgen Arendt

    2008-01-01

    In this paper, the adaptive, minimum variance (MV) beamformer is applied to medical ultrasound imaging. The Significant resolution and contrast gain provided by the adaptive, minimum variance (MV) beamformer, introduces the possibility of plane wave (PW) ultrasound imaging. Data is obtained using...... Field H and a 7 MHz, 128-elements, linear array transducer with lambda/2-spacing. MV is compared to the conventional delay-and-sum (DS) beamformer with Boxcar and Hanning weights. Furthermore, the PW images are compared to the a conventional ultrasound image, obtained from a linear scan sequence...

  4. Image edge detection based on adaptive weighted morphology

    Institute of Scientific and Technical Information of China (English)

    Lihui Jiang; Yanying Guo

    2007-01-01

    A novel morphological edge detector based on adaptive weighted morphological operators is presented. It judges image edge and direction by adaptive weighted morphological structuring elements (SEs). If the edge direction exists, a big weight factor in SE is put; if it does not exist, a small weight factor in SE is put. Thus we can achieve an intensified edge detector. Experimental results prove that the new operator's performance dominates those of classical operators for images in edge detection, and obtains superbly detail edges.

  5. Coherent Image Layout using an Adaptive Visual Vocabulary

    Energy Technology Data Exchange (ETDEWEB)

    Dillard, Scott E.; Henry, Michael J.; Bohn, Shawn J.; Gosink, Luke J.

    2013-03-06

    When querying a huge image database containing millions of images, the result of the query may still contain many thousands of images that need to be presented to the user. We consider the problem of arranging such a large set of images into a visually coherent layout, one that places similar images next to each other. Image similarity is determined using a bag-of-features model, and the layout is constructed from a hierarchical clustering of the image set by mapping an in-order traversal of the hierarchy tree into a space-filling curve. This layout method provides strong locality guarantees so we are able to quantitatively evaluate performance using standard image retrieval benchmarks. Performance of the bag-of-features method is best when the vocabulary is learned on the image set being clustered. Because learning a large, discriminative vocabulary is a computationally demanding task, we present a novel method for efficiently adapting a generic visual vocabulary to a particular dataset. We evaluate our clustering and vocabulary adaptation methods on a variety of image datasets and show that adapting a generic vocabulary to a particular set of images improves performance on both hierarchical clustering and image retrieval tasks.

  6. Elimination of Speckle and Target Orientation Requirements in Millimeter-Wave Active Imaging by Modulated Multimode Mixing Illumination

    Science.gov (United States)

    2012-12-01

    hair in the passive image is not. While there has been considerable discussion of terahertz time domain spectroscopy and other proximate imaging ap...for example along the terminator line of the Moon illuminated by the Sun. A number of prominent features are associated with the open staircase in the

  7. Adaptive and non-adaptive data hiding methods for grayscale images based on modulus function

    Directory of Open Access Journals (Sweden)

    Najme Maleki

    2014-07-01

    Full Text Available This paper presents two adaptive and non-adaptive data hiding methods for grayscale images based on modulus function. Our adaptive scheme is based on the concept of human vision sensitivity, so the pixels in edge areas than to smooth areas can tolerate much more changes without making visible distortion for human eyes. In our adaptive scheme, the average differencing value of four neighborhood pixels into a block via a threshold secret key determines whether current block is located in edge or smooth area. Pixels in the edge areas are embedded by Q-bit of secret data with a larger value of Q than that of pixels placed in smooth areas. Also in this scholar, we represent one non-adaptive data hiding algorithm. Our non-adaptive scheme, via an error reduction procedure, produces a high visual quality for stego-image. The proposed schemes present several advantages. 1-of aspects the embedding capacity and visual quality of stego-image are scalable. In other words, the embedding rate as well as the image quality can be scaled for practical applications 2-the high embedding capacity with minimal visual distortion can be achieved, 3-our methods require little memory space for secret data embedding and extracting phases, 4-secret keys have used to protect of the embedded secret data. Thus, level of security is high, 5-the problem of overflow or underflow does not occur. Experimental results indicated that the proposed adaptive scheme significantly is superior to the currently existing scheme, in terms of stego-image visual quality, embedding capacity and level of security and also our non-adaptive method is better than other non-adaptive methods, in view of stego-image quality. Results show which our adaptive algorithm can resist against the RS steganalysis attack.

  8. Variational denoising method for electronic speckle pattern interferometry

    Institute of Scientific and Technical Information of China (English)

    Fang Zhang; Wenyao Liu; Chen Tang; Jinjiang Wang; Li Ren

    2008-01-01

    Traditional speckle fringe patterns by electronic speckle pattern interferometry (ESPI) are inherently noisy and of limited visibility, so denoising is the key problem in ESPI. We present the variational denoising method for ESPI. This method transforms the image denosing to minimizing an appropriate penalized energy function and solving a partial differential equation. We test the proposed method on computer-simulated and experimental speckle correlation fringes, respectively. The results show that this technique is capable of significantly improving the quality of fringe patterns. It works well as a pre-processing for the fringe patterns by ESPI.

  9. Towards Adaptive High-Resolution Images Retrieval Schemes

    Science.gov (United States)

    Kourgli, A.; Sebai, H.; Bouteldja, S.; Oukil, Y.

    2016-10-01

    Nowadays, content-based image-retrieval techniques constitute powerful tools for archiving and mining of large remote sensing image databases. High spatial resolution images are complex and differ widely in their content, even in the same category. All images are more or less textured and structured. During the last decade, different approaches for the retrieval of this type of images have been proposed. They differ mainly in the type of features extracted. As these features are supposed to efficiently represent the query image, they should be adapted to all kind of images contained in the database. However, if the image to recognize is somewhat or very structured, a shape feature will be somewhat or very effective. While if the image is composed of a single texture, a parameter reflecting the texture of the image will reveal more efficient. This yields to use adaptive schemes. For this purpose, we propose to investigate this idea to adapt the retrieval scheme to image nature. This is achieved by making some preliminary analysis so that indexing stage becomes supervised. First results obtained show that by this way, simple methods can give equal performances to those obtained using complex methods such as the ones based on the creation of bag of visual word using SIFT (Scale Invariant Feature Transform) descriptors and those based on multi scale features extraction using wavelets and steerable pyramids.

  10. Towards Adaptive High-Resolution Images Retrieval Schemes

    Science.gov (United States)

    Kourgli, A.; Sebai, H.; Bouteldja, S.; Oukil, Y.

    2016-06-01

    Nowadays, content-based image-retrieval techniques constitute powerful tools for archiving and mining of large remote sensing image databases. High spatial resolution images are complex and differ widely in their content, even in the same category. All images are more or less textured and structured. During the last decade, different approaches for the retrieval of this type of images have been proposed. They differ mainly in the type of features extracted. As these features are supposed to efficiently represent the query image, they should be adapted to all kind of images contained in the database. However, if the image to recognize is somewhat or very structured, a shape feature will be somewhat or very effective. While if the image is composed of a single texture, a parameter reflecting the texture of the image will reveal more efficient. This yields to use adaptive schemes. For this purpose, we propose to investigate this idea to adapt the retrieval scheme to image nature. This is achieved by making some preliminary analysis so that indexing stage becomes supervised. First results obtained show that by this way, simple methods can give equal performances to those obtained using complex methods such as the ones based on the creation of bag of visual word using SIFT (Scale Invariant Feature Transform) descriptors and those based on multi scale features extraction using wavelets and steerable pyramids.

  11. Spatially adaptive regularized iterative high-resolution image reconstruction algorithm

    Science.gov (United States)

    Lim, Won Bae; Park, Min K.; Kang, Moon Gi

    2000-12-01

    High resolution images are often required in applications such as remote sensing, frame freeze in video, military and medical imaging. Digital image sensor arrays, which are used for image acquisition in many imaging systems, are not dense enough to prevent aliasing, so the acquired images will be degraded by aliasing effects. To prevent aliasing without loss of resolution, a dense detector array is required. But it may be very costly or unavailable, thus, many imaging systems are designed to allow some level of aliasing during image acquisition. The purpose of our work is to reconstruct an unaliased high resolution image from the acquired aliased image sequence. In this paper, we propose a spatially adaptive regularized iterative high resolution image reconstruction algorithm for blurred, noisy and down-sampled image sequences. The proposed approach is based on a Constrained Least Squares (CLS) high resolution reconstruction algorithm, with spatially adaptive regularization operators and parameters. These regularization terms are shown to improve the reconstructed image quality by forcing smoothness, while preserving edges in the reconstructed high resolution image. Accurate sub-pixel motion registration is the key of the success of the high resolution image reconstruction algorithm. However, sub-pixel motion registration may have some level of registration error. Therefore, a reconstruction algorithm which is robust against the registration error is required. The registration algorithm uses a gradient based sub-pixel motion estimator which provides shift information for each of the recorded frames. The proposed algorithm is based on a technique of high resolution image reconstruction, and it solves spatially adaptive regularized constrained least square minimization functionals. In this paper, we show that the reconstruction algorithm gives dramatic improvements in the resolution of the reconstructed image and is effective in handling the aliased information. The

  12. Block-based adaptive lifting schemes for multiband image compression

    Science.gov (United States)

    Masmoudi, Hela; Benazza-Benyahia, Amel; Pesquet, Jean-Christophe

    2004-02-01

    In this paper, we are interested in designing lifting schemes adapted to the statistics of the wavelet coefficients of multiband images for compression applications. More precisely, nonseparable vector lifting schemes are used in order to capture simultaneously the spatial and the spectral redundancies. The underlying operators are then computed in order to minimize the entropy of the resulting multiresolution representation. To this respect, we have developed a new iterative block-based classification algorithm. Simulation tests carried out on remotely sensed multispectral images indicate that a substantial gain in terms of bit-rate is achieved by the proposed adaptive coding method w.r.t the non-adaptive one.

  13. Adaptive ladar receiver for multispectral imaging

    Science.gov (United States)

    Johnson, Kenneth; Vaidyanathan, Mohan; Xue, Song; Tennant, William E.; Kozlowski, Lester J.; Hughes, Gary W.; Smith, Duane D.

    2001-09-01

    We are developing a novel 2D focal plane array (FPA) with read-out integrated circuit (ROIC) on a single chip for 3D laser radar imaging. The ladar will provide high-resolution range and range-resolved intensity images for detection and identification of difficult targets. The initial full imaging-camera-on-a-chip system will be a 64 by 64 element, 100-micrometers pixel-size detector array that is directly bump bonded to a low-noise 64 by 64 array silicon CMOS-based ROIC. The architecture is scalable to 256 by 256 or higher arrays depending on the system application. The system will provide all the required electronic processing at pixel level and the smart FPA enables directly producing the 3D or 4D format data to be captured with a single laser pulse. The detector arrays are made of uncooled InGaAs PIN device for SWIR imaging at 1.5 micrometers wavelength and cooled HgCdTe PIN device for MWIR imaging at 3.8 micrometers wavelength. We are also investigating concepts using multi-color detector arrays for simultaneous imaging at multiple wavelengths that would provide additional spectral dimension capability for enhanced detection and identification of deep-hide targets. The system is suited for flash ladar imaging, for combat identification of ground targets from airborne platforms, flash-ladar imaging seekers, and autonomous robotic/automotive vehicle navigation and collision avoidance applications.

  14. Adaptive filters for color image processing

    Directory of Open Access Journals (Sweden)

    Papanikolaou V.

    1998-01-01

    Full Text Available The color filters that are used to attenuate noise are usually optimized to perform extremely well when dealing with certain noise distributions. Unfortunately it is often the case that the noise corrupting the image is not known. It is thus beneficial to know a priori the type of noise corrupting the image in order to select the optimal filter. A method of extracting and characterizing the noise within a digital color image using the generalized Gaussian probability density function (pdf (B.D. Jeffs and W.H. Pun, IEEE Transactions on Image Processing, 4(10, 1451–1456, 1995 and Proceedings of the Int. Conference on Image Processing, 465–468, 1996, is presented. In this paper simulation results are included to demonstrate the effectiveness of the proposed methodology.

  15. Adaptive filters for color image processing

    Directory of Open Access Journals (Sweden)

    V. Papanikolaou

    1999-01-01

    Full Text Available The color filters that are used to attenuate noise are usually optimized to perform extremely well when dealing with certain noise distributions. Unfortunately it is often the case that the noise corrupting the image is not known. It is thus beneficial to know a priori the type of noise corrupting the image in order to select the optimal filter. A method of extracting and characterizing the noise within a digital color image using the generalized Gaussian probability density function (pdf (B.D. Jeffs and W.H. Pun, IEEE Transactions on Image Processing, 4(10, 1451–1456, 1995 and Proceedings of the Int. Conference on Image Processing, 465–468, 1996, is presented. In this paper simulation results are included to demonstrate the effectiveness of the proposed methodology.

  16. Measuring Close Binary Stars with Speckle Interferometry

    Science.gov (United States)

    2014-09-01

    telescope has access to an adaptive optics system, and those telescopes utilize a prior method developed in 1970 by Antoine Labeyrie [2]. This method...23019+4220. a) b) c) 3. SPECKLE INTERFEROMETRY In 1970, Antoine Labeyrie [2] developed a technique to detect double stars that are closer than the...resulting in a simple product of cosine squared with no additive constant . The effects of a non- zero additive constant will become apparent in section 5

  17. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    Science.gov (United States)

    Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.

    2016-09-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  18. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging.

    Science.gov (United States)

    Cua, Michelle; Wahl, Daniel J; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J; Jian, Yifan; Sarunic, Marinko V

    2016-09-07

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  19. MICADO : The E-ELT adaptive optics imaging camera

    NARCIS (Netherlands)

    Davies, Richard; Ageorges, N.; Barl, L.; Bedin, L. R.; Bender, R.; Bernardi, P.; Chapron, F.; Clenet, Y.; Deep, A.; Deul, E.; Drost, M.; Eisenhauer, F.; Falomo, R.; Fiorentino, G.; Förster Schreiber, N. M.; Gendron, E.; Genzel, R.; Gratadour, D.; Greggio, L.; Grupp, F.; Held, E.; Herbst, T.; Hess, H.-J.; Hubert, Z.; Jahnke, K.; Kuijken, K.; Lutz, D.; Magrin, D.; Muschielok, B.; Navarro, R.; Noyola, E.; Paumard, T.; Piotto, G.; Ragazzoni, R.; Renzini, A.; Rousset, G.; Rix, H.-W.; Saglia, R.; Tacconi, L.; Thiel, M.; Tolstoy, E.; Trippe, S.; Tromp, N.; Valentijn, E. A.; Verdoes Kleijn, G.; Wegner, M.; McLean, I.S.; Ramsay, S.K.; Takami, H.

    2010-01-01

    MICADO is the adaptive optics imaging camera for the E-ELT. It has been designed and optimised to be mounted to the LGS-MCAO system MAORY, and will provide diffraction limited imaging over a wide (~1 arcmin) field of view. For initial operations, it can also be used with its own simpler AO module th

  20. Efficient active depth sensing by laser speckle projection system

    Science.gov (United States)

    Yin, Xuanwu; Wang, Guijin; Shi, Chenbo; Liao, Qingmin

    2014-01-01

    An active depth sensing approach by laser speckle projection system is proposed. After capturing the speckle pattern with an infrared digital camera, we extract the pure speckle pattern using a direct-global separation method. Then the pure speckles are represented by Census binary features. By evaluating the matching cost and uniqueness between the real-time image and the reference image, robust correspondences are selected as support points. After that, we build a disparity grid and propose a generative graphical model to compute disparities. An iterative approach is designed to propagate the messages between blocks and update the model. Finally, a dense depth map can be obtained by subpixel interpolation and transformation. The experimental evaluations demonstrate the effectiveness and efficiency of our approach.

  1. Speckle-Free Coherence Tomography of Turbid Media

    CERN Document Server

    Liba, Orly; SoRelle, Elliott D; Dutta, Rebecca; Sen, Debasish; Moshfeghi, Darius M; Chu, Steven; de la Zerda, Adam

    2016-01-01

    Optical coherence tomography (OCT) is a powerful biomedical imaging technology that relies on the coherent detection of backscattered light to image tissue morphology in vivo. As a consequence, OCT is susceptible to coherent noise (speckle noise), which imposes significant limitations on its diagnostic capabilities. Here we show a method based purely on light manipulation that is able to entirely remove the speckle noise originating from turbid samples without any compromise in resolution. We refer to this method as Speckle-Free OCT (SFOCT). Using SFOCT, we succeeded in revealing small structures that are otherwise hidden by speckle noise when using conventional OCT, including the inner stromal structure of a live mouse cornea, the fine structures inside the mouse pinna, sweat ducts, and Meissners corpuscle in the human fingertip skin. SFOCT has the potential to markedly increase OCTs diagnostic capabilities of various human diseases by revealing minute features that correlate with early pathology.

  2. Fractal image encoding based on adaptive search

    Institute of Scientific and Technical Information of China (English)

    Kya Berthe; Yang Yang; Huifang Bi

    2003-01-01

    Finding the optimal algorithm between an efficient encoding process and the rate distortion is the main research in fractal image compression theory. A new method has been proposed based on the optimization of the Least-Square Error and the orthogonal projection. A large number of domain blocks can be eliminated in order to speed-up fractal image compression. Moreover, since the rate-distortion performance of most fractal image coders is not satisfactory, an efficient bit allocation algorithm to improve the rate distortion is also proposed. The implementation and comparison have been done with the feature extraction method to prove the efficiency of the proposed method.

  3. 基于广义似然比的小波域 SAR 图像相干斑抑制算法%Generalized Likelihood Ratio Based SAR Image Speckle Suppression Algorithm in Wavelet Domain

    Institute of Scientific and Technical Information of China (English)

    侯建华; 刘欣达; 陈稳; 陈少波

    2015-01-01

    A Bayes shrinkage formula is derived under the framework of joint detection and estimation theory, and a wavelet SAR image despeckling algorithm is realized based on generalized likelihood ratio.Firstly, redundant wavelet transform is performed directly to the original speckled SAR images, and binary mask is obtained for each wavelet coefficient.We use scale exponential distribution and Gamma distribution, respectively, to model the likelihood conditional probability of speckle noise and useful signal.According to the mask, the parameters of the two modes are estimated by maximum likelihood estimation method, and thus the likelihood conditional probability ratio is calculated.Experiment results show that the proposed method can effectively filter the speckle noise, and at the same time preserve the image details as possible.Satisfactory results are achieved on both synthetically speckled images and real SAR images.%在联合检测与估计理论框架下推导出了Bayes萎缩函数表达式,并提出了一种基于广义似然比的小波域SAR图像去斑算法。该算法对含斑SAR图像直接做冗余小波变换,求出小波系数所对应的二值掩模;对相干斑噪声和有用信号的似然条件概率分别建模为尺度指数分布和Gamma分布,根据二值掩模信息,采用最大似然估计得到两种模型的参数并计算似然条件概率比。实验结果表明:文中所给算法在有效滤除斑点噪声的同时,也较好地保持了图像的细节信息,在对人工加斑图像和多幅实际SAR图像的处理中获得了令人满意的结果。

  4. Adaptive enhancement method of infrared image based on scene feature

    Science.gov (United States)

    Zhang, Xiao; Bai, Tingzhu; Shang, Fei

    2008-12-01

    All objects emit radiation in amounts related to their temperature and their ability to emit radiation. The infrared image shows the invisible infrared radiation emitted directly. Because of the advantages, the technology of infrared imaging is applied to many kinds of fields. But compared with visible image, the disadvantages of infrared image are obvious. The characteristics of low luminance, low contrast and the inconspicuous difference target and background are the main disadvantages of infrared image. The aim of infrared image enhancement is to improve the interpretability or perception of information in infrared image for human viewers, or to provide 'better' input for other automated image processing techniques. Most of the adaptive algorithm for image enhancement is mainly based on the gray-scale distribution of infrared image, and is not associated with the actual image scene of the features. So the pertinence of infrared image enhancement is not strong, and the infrared image is not conducive to the application of infrared surveillance. In this paper we have developed a scene feature-based algorithm to enhance the contrast of infrared image adaptively. At first, after analyzing the scene feature of different infrared image, we have chosen the feasible parameters to describe the infrared image. In the second place, we have constructed the new histogram distributing base on the chosen parameters by using Gaussian function. In the last place, the infrared image is enhanced by constructing a new form of histogram. Experimental results show that the algorithm has better performance than other methods mentioned in this paper for infrared scene images.

  5. Adaptive textural segmentation of medical images

    Science.gov (United States)

    Kuklinski, Walter S.; Frost, Gordon S.; MacLaughlin, Thomas

    1992-06-01

    A number of important problems in medical imaging can be described as segmentation problems. Previous fractal-based image segmentation algorithms have used either the local fractal dimension alone or the local fractal dimension and the corresponding image intensity as features for subsequent pattern recognition algorithms. An image segmentation algorithm that utilized the local fractal dimension, image intensity, and the correlation coefficient of the local fractal dimension regression analysis computation, to produce a three-dimension feature space that was partitioned to identify specific pixels of dental radiographs as being either bone, teeth, or a boundary between bone and teeth also has been reported. In this work we formulated the segmentation process as a configurational optimization problem and discuss the application of simulated annealing optimization methods to the solution of this specific optimization problem. The configurational optimization method allows information about both, the degree of correspondence between a candidate segment and an assumed textural model, and morphological information about the candidate segment to be used in the segmentation process. To apply this configurational optimization technique with a fractal textural model however, requires the estimation of the fractal dimension of an irregularly shaped candidate segment. The potential utility of a discrete Gerchberg-Papoulis bandlimited extrapolation algorithm to the estimation of the fractal dimension of an irregularly shaped candidate segment is also discussed.

  6. Improving the axial and lateral resolution of three-dimensional fluorescence microscopy using random speckle illuminations.

    Science.gov (United States)

    Negash, Awoke; Labouesse, Simon; Sandeau, Nicolas; Allain, Marc; Giovannini, Hugues; Idier, Jérôme; Heintzmann, Rainer; Chaumet, Patrick C; Belkebir, Kamal; Sentenac, Anne

    2016-06-01

    We consider a fluorescence microscope in which several three-dimensional images of a sample are recorded for different speckle illuminations. We show, on synthetic data, that by summing the positive deconvolution of each speckle image, one obtains a sample reconstruction with axial and transverse resolutions that compare favorably to that of an ideal confocal microscope.

  7. Adaptive Weighting in Radio Interferometric Imaging

    CERN Document Server

    Yatawatta, Sarod

    2014-01-01

    Radio interferometers observe the Fourier space of the sky, at locations determined by the array geometry. Before a real space image is constructed by a Fourier transform, the data is weighted to improve the quality of reconstruction. Two criteria for calculation of weights are maximizing sensitivity and minimizing point spread function (PSF) sidelobe levels. In this paper, we propose a novel weighting scheme suitable for ultra deep imaging experiments. The proposed weighting scheme is used to maximize sensitivity while minimizing PSF sidelobe variation across frequency and multiple epochs. We give simulation results that show the superiority of the proposed scheme compared with commonly used weighting schemes in achieving these objectives.

  8. Image segmentation by EM-based adaptive pulse coupled neural networks in brain magnetic resonance imaging.

    Science.gov (United States)

    Fu, J C; Chen, C C; Chai, J W; Wong, S T C; Li, I C

    2010-06-01

    We propose an automatic hybrid image segmentation model that integrates the statistical expectation maximization (EM) model and the spatial pulse coupled neural network (PCNN) for brain magnetic resonance imaging (MRI) segmentation. In addition, an adaptive mechanism is developed to fine tune the PCNN parameters. The EM model serves two functions: evaluation of the PCNN image segmentation and adaptive adjustment of the PCNN parameters for optimal segmentation. To evaluate the performance of the adaptive EM-PCNN, we use it to segment MR brain image into gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF). The performance of the adaptive EM-PCNN is compared with that of the non-adaptive EM-PCNN, EM, and Bias Corrected Fuzzy C-Means (BCFCM) algorithms. The result is four sets of boundaries for the GM and the brain parenchyma (GM+WM), the two regions of most interest in medical research and clinical applications. Each set of boundaries is compared with the golden standard to evaluate the segmentation performance. The adaptive EM-PCNN significantly outperforms the non-adaptive EM-PCNN, EM, and BCFCM algorithms in gray mater segmentation. In brain parenchyma segmentation, the adaptive EM-PCNN significantly outperforms the BCFCM only. However, the adaptive EM-PCNN is better than the non-adaptive EM-PCNN and EM on average. We conclude that of the three approaches, the adaptive EM-PCNN yields the best results for gray matter and brain parenchyma segmentation.

  9. Adaptive fingerprint image enhancement with emphasis on preprocessing of data.

    Science.gov (United States)

    Bartůnek, Josef Ström; Nilsson, Mikael; Sällberg, Benny; Claesson, Ingvar

    2013-02-01

    This article proposes several improvements to an adaptive fingerprint enhancement method that is based on contextual filtering. The term adaptive implies that parameters of the method are automatically adjusted based on the input fingerprint image. Five processing blocks comprise the adaptive fingerprint enhancement method, where four of these blocks are updated in our proposed system. Hence, the proposed overall system is novel. The four updated processing blocks are: 1) preprocessing; 2) global analysis; 3) local analysis; and 4) matched filtering. In the preprocessing and local analysis blocks, a nonlinear dynamic range adjustment method is used. In the global analysis and matched filtering blocks, different forms of order statistical filters are applied. These processing blocks yield an improved and new adaptive fingerprint image processing method. The performance of the updated processing blocks is presented in the evaluation part of this paper. The algorithm is evaluated toward the NIST developed NBIS software for fingerprint recognition on FVC databases.

  10. Adaptive optics and phase diversity imaging for responsive space applications.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Mark William; Wick, David Victor

    2004-11-01

    The combination of phase diversity and adaptive optics offers great flexibility. Phase diverse images can be used to diagnose aberrations and then provide feedback control to the optics to correct the aberrations. Alternatively, phase diversity can be used to partially compensate for aberrations during post-detection image processing. The adaptive optic can produce simple defocus or more complex types of phase diversity. This report presents an analysis, based on numerical simulations, of the efficiency of different modes of phase diversity with respect to compensating for specific aberrations during post-processing. It also comments on the efficiency of post-processing versus direct aberration correction. The construction of a bench top optical system that uses a membrane mirror as an active optic is described. The results of characterization tests performed on the bench top optical system are presented. The work described in this report was conducted to explore the use of adaptive optics and phase diversity imaging for responsive space applications.

  11. Application of Speckle Tracking Imaging in Evaluating Left Ventricular Function%二维斑点追踪显像技术评价左心室功能的研究进展

    Institute of Scientific and Technical Information of China (English)

    战金营; 赵可辉

    2011-01-01

    Speckle tracking imaging is the latest technology, which can obtain the myocardial tissue velocity, displacement, strain and strain rate by tracking the spots on two-dimensional ultrasound images for analyzing myocardial velocity and detecting the part and holistic myocardial function without angle dependence. It plays a significant role in diagnosing the changes of heart structure and function causing by hypertension, coronary heart disease and diabetes mellitus and so on.%二维斑点追踪显像(Speckle Tracking Imaging,STI)技术是最新发展的技术,它通过追踪二维超声图像上的斑点获得心肌的组织速度、位移、应变、应变率来分析心肌的运动,检测局部和整体心肌的功能,无角度依赖性.它可以早期诊断高血压、冠心病、糖尿病等疾病所引起的心脏功能及结构的改变,在临床上具有重要的意义.

  12. An Improved Adaptive Deconvolution Algorithm for Single Image Deblurring

    Directory of Open Access Journals (Sweden)

    Hsin-Che Tsai

    2014-01-01

    Full Text Available One of the most common defects in digital photography is motion blur caused by camera shake. Shift-invariant motion blur can be modeled as a convolution of the true latent image and a point spread function (PSF with additive noise. The goal of image deconvolution is to reconstruct a latent image from a degraded image. However, ringing is inevitable artifacts arising in the deconvolution stage. To suppress undesirable artifacts, regularization based methods have been proposed using natural image priors to overcome the ill-posedness of deconvolution problem. When the estimated PSF is erroneous to some extent or the PSF size is large, conventional regularization to reduce ringing would lead to loss of image details. This paper focuses on the nonblind deconvolution by adaptive regularization which preserves image details, while suppressing ringing artifacts. The way is to control the regularization weight adaptively according to the image local characteristics. We adopt elaborated reference maps that indicate the edge strength so that textured and smooth regions can be distinguished. Then we impose an appropriate constraint on the optimization process. The experiments’ results on both synthesized and real images show that our method can restore latent image with much fewer ringing and favors the sharp edges.

  13. Assessment of Fevicol (adhesive Drying Process through Dynamic Speckle Techniques

    Directory of Open Access Journals (Sweden)

    Mohammad Z. Ansari

    2015-04-01

    Full Text Available Dynamic laser speckle (or biospeckle analysis is a useful measurement tool to analyze micro-motion on a sample surface via temporal statistics based on a sequence of speckle images. The aim of this work was to evaluate the use of dynamic speckles as an alternative tool to monitoring Fevicol drying process. Experimental demonstration of intensity-based algorithm to monitor Fevicol drying process is reported. The experiment was explored with the technique called Inertia Moment of co-occurrence matrix. The results allowed verifying the drying process and it was possible to observe different activity stages during the drying process. Statistical Tukey test at 5% significance level allowed differentiating different stages of drying. In conclusion, speckle activity, measured by the Inertia Moment, can be used to monitor drying processes of the Fevicol.

  14. Temporal adaptation enhances efficient contrast gain control on natural images.

    Directory of Open Access Journals (Sweden)

    Fabian Sinz

    Full Text Available Divisive normalization in primary visual cortex has been linked to adaptation to natural image statistics in accordance to Barlow's redundancy reduction hypothesis. Using recent advances in natural image modeling, we show that the previously studied static model of divisive normalization is rather inefficient in reducing local contrast correlations, but that a simple temporal contrast adaptation mechanism of the half-saturation constant can substantially increase its efficiency. Our findings reveal the experimentally observed temporal dynamics of divisive normalization to be critical for redundancy reduction.

  15. An adaptive nonlocal means scheme for medical image denoising

    Science.gov (United States)

    Thaipanich, Tanaphol; Kuo, C.-C. Jay

    2010-03-01

    Medical images often consist of low-contrast objects corrupted by random noise arising in the image acquisition process. Thus, image denoising is one of the fundamental tasks required by medical imaging analysis. In this work, we investigate an adaptive denoising scheme based on the nonlocal (NL)-means algorithm for medical imaging applications. In contrast with the traditional NL-means algorithm, the proposed adaptive NL-means (ANL-means) denoising scheme has three unique features. First, it employs the singular value decomposition (SVD) method and the K-means clustering (K-means) technique for robust classification of blocks in noisy images. Second, the local window is adaptively adjusted to match the local property of a block. Finally, a rotated block matching algorithm is adopted for better similarity matching. Experimental results from both additive white Gaussian noise (AWGN) and Rician noise are given to demonstrate the superior performance of the proposed ANL denoising technique over various image denoising benchmarks in term of both PSNR and perceptual quality comparison.

  16. Spectrally Adaptable Compressive Sensing Imaging System

    Science.gov (United States)

    2014-05-01

    viewed by a Stingray F-033C CCD Color Camera. The desired bands are depicted in (g). The original desired bands are shown in (a). Reconstructed images...would be viewed by a Stingray F-033C CCD Color Camera. The desired bands are indicated in (e). The original desired bands are shown in (a). Reconstructed...times and the mean PSNR is estimated. The resulting spectral data cubes are shown as they would be viewed by a Stingray F-033C CCD Color Camera. Figure

  17. Fusion and speckle reduction of multi-polarization SAR images based on nonsubsampled Contourlet transform%GPS单频精密单点定位的研究实现

    Institute of Scientific and Technical Information of China (English)

    涂锐; 黄观文; 凌晴

    2011-01-01

    Nonsubsampled Contourlet Transform(NSCT) is a newly improved multiresolution geometry analysis technique based on Contourlet Transform.NSCT can represent images more effectively because of its flexible multi-resolution,multi-direction and shift invariance,and has been approved to be very suitable for noisy images,such as SAR images.A method of fusing and reducing the speckles of multi-polarization SAR images based on NSCT was proposed in the paper.The images were firstly decomposed by NSCT,and the different fusion rules of decomposed coefficients were chosen with the consideration of denoising and information enhancing.Finally, the fused NSCT coefficients were reconstructed to obtain fusion result .In this paper, HH and VV co-polarization images were fused using the proposed method, and the entropy ,correlation coefficient and Equivalent Number of Looks(ENL) were calculated to evaluate the results.Experiments showed that the proposed algorithm could obtain a good fused image with the improved spatial information, at the same time the speckle noises could be reduced to some extent.%本文研究建立了电离层参数估计的单频精密单点定位的数学模型,并综合考虑各项误差模型改正,运用卡尔曼滤波算法,开发了单频精密单点定位程序,最后利用实测数据进行实验.实验结果表明:静态平面、高程方向精度均优于0.15m,动态精度优于0.3m.

  18. Adaptive optics technology for high-resolution retinal imaging.

    Science.gov (United States)

    Lombardo, Marco; Serrao, Sebastiano; Devaney, Nicholas; Parravano, Mariacristina; Lombardo, Giuseppe

    2012-12-27

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging.

  19. Adaptive Optics Technology for High-Resolution Retinal Imaging

    Directory of Open Access Journals (Sweden)

    Giuseppe Lombardo

    2012-12-01

    Full Text Available Adaptive optics (AO is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging.

  20. Adaptive FEC coding and cooperative relayed wireless image transmission

    Directory of Open Access Journals (Sweden)

    Hansong Xu

    2015-08-01

    Full Text Available High quality image transmission through smart devices requires high transmission rate, throughput and low Bit Error Rate (BER. At the same time, energy efficiency is always the top issue for the battery-based smart devices such as smart phone, tablets, etc. In this paper, an adaptive Forward Error Correction (FEC coding and cooperative relayed image transmission system is proposed, through which both transmission quality and energy efficiency could be promised under complex mobile communication channel environment. There are four steps in the proposed scheme: (1 Discrete Wavelet Transform (DWT and wavelet based Decomposition, (2 Pixel-Position (PP information and Pixel-Value (PV information split based unequal image resource allocation, (3 transmission through channel fading and AWGN communication environment, (4 multiple-relays and adaptive channel coding. Comparing to traditional methods, our proposed method is more practical to transmit high quality images through battery-limited smart phone platforms.

  1. Dual-wavelength laser speckle imaging for monitoring brain metabolic and hemodynamic response to closed head traumatic brain injury in mice

    Science.gov (United States)

    Kofman, Itamar; Abookasis, David

    2015-10-01

    The measurement of dynamic changes in brain hemodynamic and metabolism events following head trauma could be valuable for injury prognosis and for planning of optimal medical treatment. Specifically, variations in blood flow and oxygenation levels serve as important biomarkers of numerous pathophysiological processes. We employed the dual-wavelength laser speckle imaging (DW-LSI) technique for simultaneous monitoring of changes in brain hemodynamics and cerebral blood flow (CBF) at early stages of head trauma in a mouse model of intact head injury (n=10). For induction of head injury, we used a weight-drop device involving a metal mass (˜50 g) striking the mouse's head in a regulated manner from a height of ˜90 cm. In comparison to baseline measurements, noticeable dynamic variations were revealed immediately and up to 1 h postinjury, which indicate the severity of brain damage and highlight the ability of the DW-LSI arrangement to track brain pathophysiology induced by injury. To validate the monitoring of CBF by DW-LSI, measurements with laser Doppler flowmetry (LDF) were also performed (n=5), which confirmed reduction in CBF following injury. A secondary focus of the study was to investigate the effectiveness of hypertonic saline as a neuroprotective agent, inhibiting the development of complications after brain injury in a subgroup of injured mice (n=5), further demonstrating the ability of DW-LSI to monitor the effects upon brain dynamics of drug treatment. Overall, our findings further support the use of DW-LSI as a noninvasive, cost-effective tool to assess changes in hemodynamics under a variety of pathological conditions, suggesting its potential contribution to the biomedical field. To the best of our knowledge, this work is the first to make use of the DW-LSI modality in a small animal model to (1) investigate brain function during the critical first hour of closed head injury trauma, (2) correlate between injury parameters of LDF measurements, and (3

  2. Clinical application of speckle tracking imaging in evaluating left ventricular torsion and untwisting parameters%斑点追踪技术评价左室扭转及解旋运动的临床应用

    Institute of Scientific and Technical Information of China (English)

    董瑞庆; 王如兴

    2012-01-01

    Speckle tracking imaging has been initially used in clinic, which has made some achievement in the clinical practice, such as evaluating heart function and guiding the implantation of pacemaker or cardiac resynchro-nization therapy, especially useful in the diagnosis or treatment of coronary artery disease, cardiomyopathy, valvular heart disease and so on. To facilitate the application and development of speckle tracking imaging in clinical practice, I wrote this review in the aspects of the clinical diseases which mentioned above.%近几年,斑点追踪技术在国内已初步应用于临床,且取得了一定的成果,如评价心功能、心脏再同步化治疗及起搏治疗前后指导以及冠心病、心肌病、瓣膜性心脏病等疾病的诊断与治疗效果.本文从上述几方面做一综述,以促进其在临床工作中的进一步应用及发展.

  3. Adaptive Depth Imaging with Single-Photon Detectors

    CERN Document Server

    He, Weiji; Lin, Jie; Shen, Shanshan; Chen, Qian; Gu, Guohua; Zhou, Beibei; Zhang, Ping

    2016-01-01

    For active optical imaging, the use of single-photon detectors could greatly improve the detection sensitivity of the system. However in low light-level, traditional maximum-likelihood based imaging method needs long acquisition time to capture clear three-dimensional (3D) image. To tackle this problem, we present a novel imaging method for depth estimate, which can obtain the accurate depth image in a short acquisition time. We exploit the temporal correlations of signal and avoid building the photon-count histogram of the maximum likelihood depth estimate. Our method can efficiently distinguish signal from noise and adaptively change the dwell time of each pixel. The experiment results demonstrate that we can fast obtain the accurate depth image despite the existence of strong background noise.

  4. Adaptive edge image enhancement based on maximum fuzzy entropy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiu-hua; YANG Kun-tao

    2006-01-01

    Based on the maximum fuzzy entropy principle,the edge image with low contrast is optimally classified into two classes adaptively,under the condition of probability partition and fuzzy partition.The optimal threshold is used as the classified threshold value,and a local parametric gray-level transformation is applied to the obtained classes.By means of two parameters representing,the homogeneity of the regions in edge image is improved.The excellent performance of the proposed technique is exercisable through simulation results on a set of test images.It is shown how the extracted and enhanced edges provide an efficient edge-representation of images.It is shown that the proposed technique possesses excellent performance in homogeneity through simulations on a set of test images,and the extracted and enhanced edges provide an efficient edge-representation of images.

  5. Adaptive lifting scheme of wavelet transforms for image compression

    Science.gov (United States)

    Wu, Yu; Wang, Guoyin; Nie, Neng

    2001-03-01

    Aiming at the demand of adaptive wavelet transforms via lifting, a three-stage lifting scheme (predict-update-adapt) is proposed according to common two-stage lifting scheme (predict-update) in this paper. The second stage is updating stage. The third is adaptive predicting stage. Our scheme is an update-then-predict scheme that can detect jumps in image from the updated data and it needs not any more additional information. The first stage is the key in our scheme. It is the interim of updating. Its coefficient can be adjusted to adapt to data to achieve a better result. In the adaptive predicting stage, we use symmetric prediction filters in the smooth area of image, while asymmetric prediction filters at the edge of jumps to reduce predicting errors. We design these filters using spatial method directly. The inherent relationships between the coefficients of the first stage and the other stages are found and presented by equations. Thus, the design result is a class of filters with coefficient that are no longer invariant. Simulation result of image coding with our scheme is good.

  6. Adaptive Multi-Lag for Synthetic Aperture Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando; Stuart, Matthias Bo; Jensen, Jørgen Arendt

    2014-01-01

    The range of detectable velocities in ultrasound flow imaging is linked to the user selection of pulse repetiti on frequency. Whenever a region with large differences in velo city magnitude is visualized, a trade-off has to be made. This work suggests an adaptive spatio-temporaly independent, m...

  7. Adaptive wavelet transform algorithm for lossy image compression

    Science.gov (United States)

    Pogrebnyak, Oleksiy B.; Ramirez, Pablo M.; Acevedo Mosqueda, Marco Antonio

    2004-11-01

    A new algorithm of locally adaptive wavelet transform based on the modified lifting scheme is presented. It performs an adaptation of the wavelet high-pass filter at the prediction stage to the local image data activity. The proposed algorithm uses the generalized framework for the lifting scheme that permits to obtain easily different wavelet filter coefficients in the case of the (~N, N) lifting. Changing wavelet filter order and different control parameters, one can obtain the desired filter frequency response. It is proposed to perform the hard switching between different wavelet lifting filter outputs according to the local data activity estimate. The proposed adaptive transform possesses a good energy compaction. The designed algorithm was tested on different images. The obtained simulation results show that the visual and quantitative quality of the restored images is high. The distortions are less in the vicinity of high spatial activity details comparing to the non-adaptive transform, which introduces ringing artifacts. The designed algorithm can be used for lossy image compression and in the noise suppression applications.

  8. Denoising in electronic speckle pattern interferometry fringes by the filtering method based on partial differential equations

    Science.gov (United States)

    Tang, Chen; Zhang, Fang; Yan, Haiqing; Chen, Zhanqing

    2006-04-01

    Denoising in electronic speckle pattern interferometry fringes is the key problem in electronic speckle pattern interferometry. We present the new filtering method based on partial differential equations (called PDE filtering method) to electronic speckle pattern interferometry fringes. The PDE filtering method transforms the image processing to solving the partial differential equations. We test the proposed method on experimentally obtained electronic speckle pattern interferometry fringes, and compare with traditional mean filtering and low-pass Fourier filtering methods. The experimental results show that the technique is capable of effectively removing noise. The PDE filtering method is flexible and has fast computational speed and stable results.

  9. Speckle-free digital holographic recording of a diffusely reflecting object.

    Science.gov (United States)

    Kim, You Seok; Kim, Taegeun; Woo, Sung Soo; Kang, Hoonjong; Poon, Ting-Chung; Zhou, Changhe

    2013-04-08

    We demonstrate holographic recording without speckle noise using the digital holographic technique called optical scanning holography (OSH). First, we record a complex hologram of a diffusely reflecting (DR) object using OSH. The incoherent mode of OSH makes it possible to record the complex hologram without speckle noise. Second, we convert the complex hologram to an off-axis real hologram digitally and finally we reconstruct the real hologram using an amplitude-only spatial light modulator (SLM) without twin-image noise and speckle noise. To the best of our knowledge, this is the first time demonstrating digital holographic recording of a DR object without speckle noise.

  10. [An adaptive threshloding segmentation method for urinary sediment image].

    Science.gov (United States)

    Li, Yongming; Zeng, Xiaoping; Qin, Jian; Han, Liang

    2009-02-01

    In this paper is proposed a new method to solve the segmentation of the complicated defocusing urinary sediment image. The main points of the method are: (1) using wavelet transforms and morphology to erase the effect of defocusing and realize the first segmentation, (2) using adaptive threshold processing in accordance to the subimages after wavelet processing, and (3) using 'peel off' algorithm to deal with the overlapped cells' segmentations. The experimental results showed that this method was not affected by the defocusing, and it made good use of many kinds of characteristics of the images. So this new mehtod can get very precise segmentation; it is effective for defocusing urinary sediment image segmentation.

  11. Adaptive optics optical coherence tomography for retina imaging

    Institute of Scientific and Technical Information of China (English)

    Guohua Shi; Yun Dai; Ling Wang; Zhihua Ding; Xuejun Rao; Yudong Zhang

    2008-01-01

    When optical coherence tomography (OCT) is used for human retina imaging, its transverse resolution is limited by the aberrations of human eyes. To overcome this disadvantage, a high resolution imaging system for living human retina, which consists of a time domain OCT system and a 37-elements adaptive optics (AO) system, has been developed. The AO closed loop rate is 20 frames per second, and the OCT has a 6.7-μm axial resolution. In this paper, this system is introduced and the high resolution imaging results for retina are presented.

  12. Adaptive optics with pupil tracking for high resolution retinal imaging.

    Science.gov (United States)

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

    2012-02-01

    Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics.

  13. Normalized iterative denoising ghost imaging based on the adaptive threshold

    Science.gov (United States)

    Li, Gaoliang; Yang, Zhaohua; Zhao, Yan; Yan, Ruitao; Liu, Xia; Liu, Baolei

    2017-02-01

    An approach for improving ghost imaging (GI) quality is proposed. In this paper, an iteration model based on normalized GI is built through theoretical analysis. An adaptive threshold value is selected in the iteration model. The initial value of the iteration model is estimated as a step to remove the correlated noise. The simulation and experimental results reveal that the proposed strategy reconstructs a better image than traditional and normalized GI, without adding complexity. The NIDGI-AT scheme does not require prior information regarding the object, and can also choose the threshold adaptively. More importantly, the signal-to-noise ratio (SNR) of the reconstructed image is greatly improved. Therefore, this methodology represents another step towards practical real-world applications.

  14. An adaptive multi-feature segmentation model for infrared image

    Science.gov (United States)

    Zhang, Tingting; Han, Jin; Zhang, Yi; Bai, Lianfa

    2016-04-01

    Active contour models (ACM) have been extensively applied to image segmentation, conventional region-based active contour models only utilize global or local single feature information to minimize the energy functional to drive the contour evolution. Considering the limitations of original ACMs, an adaptive multi-feature segmentation model is proposed to handle infrared images with blurred boundaries and low contrast. In the proposed model, several essential local statistic features are introduced to construct a multi-feature signed pressure function (MFSPF). In addition, we draw upon the adaptive weight coefficient to modify the level set formulation, which is formed by integrating MFSPF with local statistic features and signed pressure function with global information. Experimental results demonstrate that the proposed method can make up for the inadequacy of the original method and get desirable results in segmenting infrared images.

  15. Effective Image Restorations Using a Novel Spatial Adaptive Prior

    Directory of Open Access Journals (Sweden)

    Limin Luo

    2010-01-01

    Full Text Available Bayesian or Maximum a posteriori (MAP approaches can effectively overcome the ill-posed problems of image restoration or deconvolution through incorporating a priori image information. Many restoration methods, such as nonquadratic prior Bayesian restoration and total variation regularization, have been proposed with edge-preserving and noise-removing properties. However, these methods are often inefficient in restoring continuous variation region and suppressing block artifacts. To handle this, this paper proposes a Bayesian restoration approach with a novel spatial adaptive (SA prior. Through selectively and adaptively incorporating the nonlocal image information into the SA prior model, the proposed method effectively suppress the negative disturbance from irrelevant neighbor pixels, and utilizes the positive regularization from the relevant ones. A two-step restoration algorithm for the proposed approach is also given. Comparative experimentation and analysis demonstrate that, bearing high-quality edge-preserving and noise-removing properties, the proposed restoration also has good deblocking property.

  16. Laser-induced speckle scatter patterns in Bacillus colonies

    Directory of Open Access Journals (Sweden)

    Huisung eKim

    2014-10-01

    Full Text Available Label-free bacterial colony phenotyping technology called BARDOT (BActerial Rapid Detection using Optical scattering Technology provided successful classification of several different bacteria at the genus, species, and serovar level. Recent experiments with colonies of Bacillus species provided strikingly different characteristics of elastic light scatter (ELS patterns, which were comprised of random speckles compared to other bacteria, which are dominated by concentric rings and spokes. Since this laser-based optical sensor interrogates the whole volume of the colony, 3-D information of micro- and macro-structures are all encoded in the far-field scatter patterns. Here, we present a theoretical model explaining the underlying mechanism of the speckle formation by the colonies from Bacillus species. Except for Bacillus polymyxa, all Bacillus spp. produced random bright spots on the imaging plane, which presumably dependent on the cellular and molecular organization and content within the colony. Our scatter model-based analysis revealed that colony spread resulting in variable surface roughness can modify the wavefront of the scatter field. As the center diameter of the Bacillus spp. colony grew from 500 μm to 900 μm, average speckles area decreased 2-fold and the number of small speckles increased 7-fold. In conclusion, as Bacillus colony grows, the average speckle size in the scatter pattern decreases and the number of smaller speckle increases due to the swarming growth characteristics of bacteria within the colony.

  17. Adaptive texture filtering for defect inspection in ultrasound images

    Science.gov (United States)

    Zmola, Carl; Segal, Andrew C.; Lovewell, Brian; Nash, Charles

    1993-05-01

    The use of ultrasonic imaging to analyze defects and characterize materials is critical in the development of non-destructive testing and non-destructive evaluation (NDT/NDE) tools for manufacturing. To develop better quality control and reliability in the manufacturing environment advanced image processing techniques are useful. For example, through the use of texture filtering on ultrasound images, we have been able to filter characteristic textures from highly-textured C-scan images of materials. The materials have highly regular characteristic textures which are of the same resolution and dynamic range as other important features within the image. By applying texture filters and adaptively modifying their filter response, we have examined a family of filters for removing these textures.

  18. Adaptive Image Digital Watermarking with DCT and FCM

    Institute of Scientific and Technical Information of China (English)

    SU Liyun; MA Hong; TANG Shifu

    2006-01-01

    A novel adaptive digital image watermark algorithm is proposed. Fuzzy c-means clustering (FCM) is used to classify the original image blocks into two classes based on several characteristic parameters of human visual system (HVS). One is suited for embedding a digital watermark, the other is not. So the appropriate blocks in an image are selected to embed the watermark. The watermark is embedded in the middle-frequency part of the host image in conjunction with HVS and discrete cosine transform (DCT). The maximal watermark strength is fixed according to the frequency masking. In the same time, for the good performance, the watermark is modulated into a fractal modulation array. The simulation results show that we can remarkably extract the hiding watermark and the algorithm can achieve good robustness with common signal distortion or geometric distortion and the quality of the watermarked image is guaranteed.

  19. Image Understanding by Image-Seeking Adaptive Networks (ISAN).

    Science.gov (United States)

    1987-08-10

    from the start. Given that objets of interest are first far away then very near, with consequent major changes in image size, size constancy and...rotations, size changes, spectral variations etc. Irrelevant detail is not eliminated however-- it is only a posteriory that relevance is estabilished ...explain how grouping principles come about. Estabilishing the existence of such a set of functions is left for the future work. If this endeavor were

  20. Speckle Suppression with the Project 1640 Integral Field Spectrograph

    CERN Document Server

    Crepp, Justin R; Brenner, Douglas; Oppenheimer, Ben R; Zimmerman, Neil; Hinkley, Sasha; Parry, Ian; King, David; Vasisht, Gautam; Beichman, Charles; Hillenbrand, Lynne; Dekany, Richard; Shao, Mike; Burruss, Rick; Roberts, Lewis C; Bouchez, Antonin; Roberts, Jenny; Soummer, Remi

    2010-01-01

    Project 1640 is a high-contrast imaging instrument recently commissioned at Palomar observatory. A combination of a coronagraph with an integral field spectrograph (IFS), Project 1640 is designed to detect and characterize extrasolar planets, brown dwarfs, and circumstellar material orbiting nearby stars. In this paper, we present our data processing techniques for improving upon instrument raw sensitivity via the removal of quasi-static speckles. Our approach utilizes the chromatic image diversity provided by the IFS in combination with the locally-optimized combination of images (LOCI) algorithm to suppress the intensity of residual contaminating light in close angular proximity to target stars. We describe the Project 1640 speckle suppression pipeline (PSSP) and demonstrate the ability to detect companions with brightness comparable to and below that of initial speckle intensities using on-sky commissioning data. Our preliminary results indicate that suppression factors of at least one order of magnitude a...

  1. Adaptive wavelet transform algorithm for image compression applications

    Science.gov (United States)

    Pogrebnyak, Oleksiy B.; Manrique Ramirez, Pablo

    2003-11-01

    A new algorithm of locally adaptive wavelet transform is presented. The algorithm implements the integer-to-integer lifting scheme. It performs an adaptation of the wavelet function at the prediction stage to the local image data activity. The proposed algorithm is based on the generalized framework for the lifting scheme that permits to obtain easily different wavelet coefficients in the case of the (N~,N) lifting. It is proposed to perform the hard switching between (2, 4) and (4, 4) lifting filter outputs according to an estimate of the local data activity. When the data activity is high, i.e., in the vicinity of edges, the (4, 4) lifting is performed. Otherwise, in the plain areas, the (2,4) decomposition coefficients are calculated. The calculations are rather simples that permit the implementation of the designed algorithm in fixed point DSP processors. The proposed adaptive transform possesses the perfect restoration of the processed data and possesses good energy compactation. The designed algorithm was tested on different images. The proposed adaptive transform algorithm can be used for image/signal lossless compression.

  2. Automated Image-Based Procedures for Adaptive Radiotherapy

    DEFF Research Database (Denmark)

    Bjerre, Troels

    -tissue complication probability (NTCP), margins used to account for interfraction and intrafraction anatomical changes and motion need to be reduced. This can only be achieved through proper treatment plan adaptations and intrafraction motion management. This thesis describes methods in support of image...... to encourage bone rigidity and local tissue volume change only in the gross tumour volume and the lungs. This is highly relevant in adaptive radiotherapy when modelling significant tumour volume changes. - It is described how cone beam CT reconstruction can be modelled as a deformation of a planning CT scan...

  3. Image Super-Resolution via Adaptive Regularization and Sparse Representation.

    Science.gov (United States)

    Cao, Feilong; Cai, Miaomiao; Tan, Yuanpeng; Zhao, Jianwei

    2016-07-01

    Previous studies have shown that image patches can be well represented as a sparse linear combination of elements from an appropriately selected over-complete dictionary. Recently, single-image super-resolution (SISR) via sparse representation using blurred and downsampled low-resolution images has attracted increasing interest, where the aim is to obtain the coefficients for sparse representation by solving an l0 or l1 norm optimization problem. The l0 optimization is a nonconvex and NP-hard problem, while the l1 optimization usually requires many more measurements and presents new challenges even when the image is the usual size, so we propose a new approach for SISR recovery based on regularization nonconvex optimization. The proposed approach is potentially a powerful method for recovering SISR via sparse representations, and it can yield a sparser solution than the l1 regularization method. We also consider the best choice for lp regularization with all p in (0, 1), where we propose a scheme that adaptively selects the norm value for each image patch. In addition, we provide a method for estimating the best value of the regularization parameter λ adaptively, and we discuss an alternate iteration method for selecting p and λ . We perform experiments, which demonstrates that the proposed regularization nonconvex optimization method can outperform the convex optimization method and generate higher quality images.

  4. Adapting smartphones for low-cost optical medical imaging

    Science.gov (United States)

    Pratavieira, Sebastião.; Vollet-Filho, José D.; Carbinatto, Fernanda M.; Blanco, Kate; Inada, Natalia M.; Bagnato, Vanderlei S.; Kurachi, Cristina

    2015-06-01

    Optical images have been used in several medical situations to improve diagnosis of lesions or to monitor treatments. However, most systems employ expensive scientific (CCD or CMOS) cameras and need computers to display and save the images, usually resulting in a high final cost for the system. Additionally, this sort of apparatus operation usually becomes more complex, requiring more and more specialized technical knowledge from the operator. Currently, the number of people using smartphone-like devices with built-in high quality cameras is increasing, which might allow using such devices as an efficient, lower cost, portable imaging system for medical applications. Thus, we aim to develop methods of adaptation of those devices to optical medical imaging techniques, such as fluorescence. Particularly, smartphones covers were adapted to connect a smartphone-like device to widefield fluorescence imaging systems. These systems were used to detect lesions in different tissues, such as cervix and mouth/throat mucosa, and to monitor ALA-induced protoporphyrin-IX formation for photodynamic treatment of Cervical Intraepithelial Neoplasia. This approach may contribute significantly to low-cost, portable and simple clinical optical imaging collection.

  5. ADAPTIVE TCHEBICHEF MOMENT TRANSFORM IMAGE COMPRESSION USING PSYCHOVISUAL MODEL

    Directory of Open Access Journals (Sweden)

    Ferda Ernawan

    2013-01-01

    Full Text Available An extension of the standard JPEG image compression known as JPEG-3 allows rescaling of the quantization matrix to achieve a certain image output quality. Recently, Tchebichef Moment Transform (TMT has been introduced in the field of image compression. TMT has been shown to perform better than the standard JPEG image compression. This study presents an adaptive TMT image compression. This task is obtained by generating custom quantization tables for low, medium and high image output quality levels based on a psychovisual model. A psychovisual model is developed to approximate visual threshold on Tchebichef moment from image reconstruction error. The contribution of each moment will be investigated and analyzed in a quantitative experiment. The sensitivity of TMT basis functions can be measured by evaluating their contributions to image reconstruction for each moment order. The psychovisual threshold model allows a developer to design several custom TMT quantization tables for a user to choose from according to his or her target output preference. Consequently, these quantization tables produce lower average bit length of Huffman code while still retaining higher image quality than the extended JPEG scaling scheme.

  6. Adaptive Intuitionistic Fuzzy Enhancement of Brain Tumor MR Images.

    Science.gov (United States)

    Deng, He; Deng, Wankai; Sun, Xianping; Ye, Chaohui; Zhou, Xin

    2016-10-27

    Image enhancement techniques are able to improve the contrast and visual quality of magnetic resonance (MR) images. However, conventional methods cannot make up some deficiencies encountered by respective brain tumor MR imaging modes. In this paper, we propose an adaptive intuitionistic fuzzy sets-based scheme, called as AIFE, which takes information provided from different MR acquisitions and tries to enhance the normal and abnormal structural regions of the brain while displaying the enhanced results as a single image. The AIFE scheme firstly separates an input image into several sub images, then divides each sub image into object and background areas. After that, different novel fuzzification, hyperbolization and defuzzification operations are implemented on each object/background area, and finally an enhanced result is achieved via nonlinear fusion operators. The fuzzy implementations can be processed in parallel. Real data experiments demonstrate that the AIFE scheme is not only effectively useful to have information from images acquired with different MR sequences fused in a single image, but also has better enhancement performance when compared to conventional baseline algorithms. This indicates that the proposed AIFE scheme has potential for improving the detection and diagnosis of brain tumors.

  7. Laser speckle analysis of retinal vascular dynamics

    DEFF Research Database (Denmark)

    Neganova, Anastasiia Y.; Postnov, Dmitry D.; Jacobsen, Jens Christian B.;

    2016-01-01

    Studies of vascular responses are usually performed on isolated vessels or on single vessels in vivo. This allows for precise measurements of diameter or blood flow. However, dynamical responses of the whole microvascular network are difficult to access experimentally. We suggest to use full......-field laser speckle imaging to evaluate vascular responses of the retinal network. Image segmentation and vessel recognition algorithms together with response mapping allow us to analyze diameter changes and blood flow responses in the intact retinal network upon systemic administration of the vasoconstrictor...

  8. An adaptive optics imaging system designed for clinical use.

    Science.gov (United States)

    Zhang, Jie; Yang, Qiang; Saito, Kenichi; Nozato, Koji; Williams, David R; Rossi, Ethan A

    2015-06-01

    Here we demonstrate a new imaging system that addresses several major problems limiting the clinical utility of conventional adaptive optics scanning light ophthalmoscopy (AOSLO), including its small field of view (FOV), reliance on patient fixation for targeting imaging, and substantial post-processing time. We previously showed an efficient image based eye tracking method for real-time optical stabilization and image registration in AOSLO. However, in patients with poor fixation, eye motion causes the FOV to drift substantially, causing this approach to fail. We solve that problem here by tracking eye motion at multiple spatial scales simultaneously by optically and electronically integrating a wide FOV SLO (WFSLO) with an AOSLO. This multi-scale approach, implemented with fast tip/tilt mirrors, has a large stabilization range of ± 5.6°. Our method consists of three stages implemented in parallel: 1) coarse optical stabilization driven by a WFSLO image, 2) fine optical stabilization driven by an AOSLO image, and 3) sub-pixel digital registration of the AOSLO image. We evaluated system performance in normal eyes and diseased eyes with poor fixation. Residual image motion with incremental compensation after each stage was: 1) ~2-3 arc minutes, (arcmin) 2) ~0.5-0.8 arcmin and, 3) ~0.05-0.07 arcmin, for normal eyes. Performance in eyes with poor fixation was: 1) ~3-5 arcmin, 2) ~0.7-1.1 arcmin and 3) ~0.07-0.14 arcmin. We demonstrate that this system is capable of reducing image motion by a factor of ~400, on average. This new optical design provides additional benefits for clinical imaging, including a steering subsystem for AOSLO that can be guided by the WFSLO to target specific regions of interest such as retinal pathology and real-time averaging of registered images to eliminate image post-processing.

  9. Adaptive optics imaging of low and intermediate redshift quasars

    CERN Document Server

    Márquez, I; Theodore, B; Bremer, M; Monnet, G; Beuzit, J L

    2001-01-01

    We present the results of adaptive-optics imaging in the H and K bands of 12 low and intermediate redshift (z15.0) themselves as reference for the correction, have typical spatial resolution of FWHM~0.3 arcsec before deconvolution. The deconvolved H-band image of PG1700+514 has a spatial resolution of 0.16 arcsec and reveals a wealth of details on the companion and the host-galaxy. Four out of the twelve quasars have close companions and obvious signs of interactions. The two-dimensional images of three of the host-galaxies unambiguously reveal bars and spiral arms. The morphology of the other objects are difficult to determine from one dimensional surface brightness profile and deeper images are needed. Analysis of mocked data shows that elliptical galaxies are always recognized as such, whereas disk hosts can be missed for small disk scale lengths and large QSO contributions.

  10. Fast Adaptive Wavelet for Remote Sensing Image Compression

    Institute of Scientific and Technical Information of China (English)

    Bo Li; Run-Hai Jiao; Yuan-Cheng Li

    2007-01-01

    Remote sensing images are hard to achieve high compression ratio because of their rich texture. By analyzing the influence of wavelet properties on image compression, this paper proposes wavelet construction rules and builds a new biorthogonal wavelet construction model with parameters. The model parameters are optimized by using genetic algorithm and adopting energy compaction as the optimization object function. In addition, in order to resolve the computation complexity problem of online construction, according to the image classification rule proposed in this paper we construct wavelets for different classes of images and implement the fast adaptive wavelet selection algorithm (FAWS). Experimental results show wavelet bases of FAWS gain better compression performance than Daubechies9/7.

  11. High resolution adaptive imaging of a single atom

    CERN Document Server

    Wong-Campos, J D; Neyenhuis, B; Mizrahi, J; Monroe, C

    2015-01-01

    We report the optical imaging of a single atom with nanometer resolution using an adaptive optical alignment technique that is applicable to general optical microscopy. By decomposing the image of a single laser-cooled atom, we identify and correct optical aberrations in the system and realize an atomic position sensitivity of $\\approx$ 0.5 nm/$\\sqrt{\\text{Hz}}$ with a minimum uncertainty of 1.7 nm, allowing the direct imaging of atomic motion. This is the highest position sensitivity ever measured for an isolated atom, and opens up the possibility of performing out-of-focus 3D particle tracking, imaging of atoms in 3D optical lattices or sensing forces at the yoctonewton (10$^{-24}$ N) scale.

  12. Context adaptive coding of bi-level images

    DEFF Research Database (Denmark)

    Forchhammer, Søren

    2008-01-01

    With the advent of sequential arithmetic coding, the focus of highly efficient lossless data compression is placed on modelling the data. Rissanen's Algorithm Context provided an elegant solution to universal coding with optimal convergence rate. Context based arithmetic coding laid the grounds...... for the modern paradigm of data compression based on a modelling and a coding stage. One advantage of contexts is their flexibility, e.g. choosing a two-dimensional ("-D) context facilitates efficient image coding. The area of image coding has greatly been influenced by context adaptive coding, applied e.......g. in the lossless JBIG bi-level image coding standard, and in the entropy coding of contemporary lossless and lossy image and video coding standards and schemes. The theoretical work and analysis of universal context based coding has addressed sequences of data and finite memory models as Markov chains and sources...

  13. Image segmentation on adaptive edge-preserving smoothing

    Science.gov (United States)

    He, Kun; Wang, Dan; Zheng, Xiuqing

    2016-09-01

    Nowadays, typical active contour models are widely applied in image segmentation. However, they perform badly on real images with inhomogeneous subregions. In order to overcome the drawback, this paper proposes an edge-preserving smoothing image segmentation algorithm. At first, this paper analyzes the edge-preserving smoothing conditions for image segmentation and constructs an edge-preserving smoothing model inspired by total variation. The proposed model has the ability to smooth inhomogeneous subregions and preserve edges. Then, a kind of clustering algorithm, which reasonably trades off edge-preserving and subregion-smoothing according to the local information, is employed to learn the edge-preserving parameter adaptively. At last, according to the confidence level of segmentation subregions, this paper constructs a smoothing convergence condition to avoid oversmoothing. Experiments indicate that the proposed algorithm has superior performance in precision, recall, and F-measure compared with other segmentation algorithms, and it is insensitive to noise and inhomogeneous-regions.

  14. ADAPTATIVE IMAGE WATERMARKING SCHEME BASED ON NEURAL NETWORK

    Directory of Open Access Journals (Sweden)

    BASSEL SOLAIMANE

    2011-01-01

    Full Text Available Digital image watermarking has been proposed as a method to enhance medical data security, confidentiality and integrity. Medical image watermarking requires extreme care when embedding additional data, given their importance to clinical diagnosis, treatment, and research. In this paper, a novel image watermarking approach based on the human visual system (HVS model and neural network technique is proposed. The watermark was inserted into the middle frequency coefficients of the cover image’s blocked DCT based transform domain. In order to make the watermark stronger and less susceptible to different types of attacks, it is essential to find the maximum amount of interested watermark before the watermark becomes visible. In this paper, neural networks are used to implement an automated system of creating maximum-strength watermarks. The experimental results show that such method can survive of common image processing operations and has good adaptability for automated watermark embedding.

  15. Adaptive Image Transmission Scheme over Wavelet-Based OFDM System

    Institute of Scientific and Technical Information of China (English)

    GAOXinying; YUANDongfeng; ZHANGHaixia

    2005-01-01

    In this paper an adaptive image transmission scheme is proposed over Wavelet-based OFDM (WOFDM) system with Unequal error protection (UEP) by the design of non-uniform signal constellation in MLC. Two different data division schemes: byte-based and bitbased, are analyzed and compared. Different bits are protected unequally according to their different contribution to the image quality in bit-based data division scheme, which causes UEP combined with this scheme more powerful than that with byte-based scheme. Simulation results demonstrate that image transmission by UEP with bit-based data division scheme presents much higher PSNR values and surprisingly better image quality. Furthermore, by considering the tradeoff of complexity and BER performance, Haar wavelet with the shortest compactly supported filter length is the most suitable one among orthogonal Daubechies wavelet series in our proposed system.

  16. An edge-adaptive demosaicking method based on image correlation

    Institute of Scientific and Technical Information of China (English)

    贾晓芬; 赵佰亭; 周孟然; 陈兆权

    2015-01-01

    To reduce the cost, size and complexity, a consumer digital camera usually uses a single sensor overlaid with a color filter array (CFA) to sample one of the red−green−blue primary color values, and uses demosaicking algorithm to estimate the missing color values at each pixel. A novel image correlation and support vector machine (SVM) based edge-adaptive algorithm was proposed, which can reduce edge artifacts and false color artifacts, effectively. Firstly, image pixels were separated into edge region and smooth region with an edge detection algorithm. Then, a hybrid approach switching between a simple demosaicking algorithm on the smooth region and SVM based demosaicking algorithm on the edge region was performed. Image spatial and spectral correlations were employed to create middle planes for the interpolation. Experimental result shows that the proposed approach produced visually pleasing full-color result images and obtained higher CPSNR and smaller S-CIELAB *abDE than other conventional demosaicking algorithms.

  17. Adaptive Deep Supervised Autoencoder Based Image Reconstruction for Face Recognition

    Directory of Open Access Journals (Sweden)

    Rongbing Huang

    2016-01-01

    Full Text Available Based on a special type of denoising autoencoder (DAE and image reconstruction, we present a novel supervised deep learning framework for face recognition (FR. Unlike existing deep autoencoder which is unsupervised face recognition method, the proposed method takes class label information from training samples into account in the deep learning procedure and can automatically discover the underlying nonlinear manifold structures. Specifically, we define an Adaptive Deep Supervised Network Template (ADSNT with the supervised autoencoder which is trained to extract characteristic features from corrupted/clean facial images and reconstruct the corresponding similar facial images. The reconstruction is realized by a so-called “bottleneck” neural network that learns to map face images into a low-dimensional vector and reconstruct the respective corresponding face images from the mapping vectors. Having trained the ADSNT, a new face image can then be recognized by comparing its reconstruction image with individual gallery images, respectively. Extensive experiments on three databases including AR, PubFig, and Extended Yale B demonstrate that the proposed method can significantly improve the accuracy of face recognition under enormous illumination, pose change, and a fraction of occlusion.

  18. Studies of an Adaptive Kaczmarz Method for Electrical Impedance Imaging

    Science.gov (United States)

    Li, Taoran; Isaacson, David; Newell, Jonathan C.; Saulnier, Gary J.

    2013-04-01

    We present an adaptive Kaczmarz method for solving the inverse problem in electrical impedance tomography and determining the conductivity distribution inside an object from electrical measurements made on the surface. To best characterize an unknown conductivity distribution and avoid inverting the Jacobian-related term JTJ which could be expensive in terms of memory storage in large scale problems, we propose to solve the inverse problem by adaptively updating both the optimal current pattern with improved distinguishability and the conductivity estimate at each iteration. With a novel subset scheme, the memory-efficient reconstruction algorithm which appropriately combines the optimal current pattern generation and the Kaczmarz method can produce accurate and stable solutions adaptively compared to traditional Kaczmarz and Gauss-Newton type methods. Several reconstruction image metrics are used to quantitatively evaluate the performance of the simulation results.

  19. Shape-adaptable hyperlens for acoustic magnifying imaging

    Science.gov (United States)

    Zhang, Hongkuan; Zhou, Xiaoming; Hu, Gengkai

    2016-11-01

    Previous prototypes of acoustic hyperlens consist of rigid channels, which are unable to adapt in shape to the object under detection. We propose to overcome this limitation by employing soft plastic tubes that could guide acoustics with robustness against bending deformation. Based on the idea of soft-tube acoustics, acoustic magnifying hyperlens with planar input and output surfaces has been fabricated and validated experimentally. The shape-adaption capability of the soft-tube hyperlens is demonstrated by a controlled experiment, in which the magnifying super-resolution images remain stable when the lens input surface is curved. Our study suggests a feasible route toward constructing the flexible channel-structured acoustic metamaterials with the shape-adaption capability, opening then an additional degree of freedom for full control of sound.

  20. Image compression with QM-AYA adaptive binary arithmetic coder

    Science.gov (United States)

    Cheng, Joe-Ming; Langdon, Glen G., Jr.

    1993-01-01

    The Q-coder has been reported in the literature, and is a renorm-driven binary adaptive arithmetic coder. A similar renorm-driven coder, the QM coder, uses the same approach with an initial attack to more rapidly estimate the statistics in the beginning, and with a different state table. The QM coder is the adaptive binary arithmetic coder employed in the JBIG and JPEG image compression algorithms. The QM-AYA arithmetic coder is similar to the QM coder, with a different state table, that offers balanced improvements to the QM probability estimation for the less skewed distributions. The QM-AYA performs better when the probability estimate is near 0.5 for each binary symbol. An approach for constructing effective index change tables for Q-coder type adaptation is discussed.

  1. 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.

  2. Adaptive Receive and Transmit Apodization for Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Holfort, Iben Kraglund; Austeng, Andreas; Synnevåg, Johan-Fredrik

    2009-01-01

    This paper suggests a framework for utilizing adaptive, data-dependent apodization weights on both the receiving and transmitting aperture for Synthetic Aperture (SA) ultrasound imaging. The suggested approach is based on the Minimum Variance (MV) beamformer and consists of two steps. A set...... emission images before summation. The method is investigated using simulated SA ultrasound data obtained using Field II. Data of 13 point targets distributed at depths from 40 mm to 70 mm, and a 5.5 MHz, 64-element linear array transducer have been used. The investigation has shown that the introduction...

  3. Development of an optimized algorithm for the characterization of microflow using speckle patterns present in optical coherence tomography signal; Desenvolvimento de um algoritimo otimizado para caracterizacao de fluxos microfluidicos utilizando padroes de speckle presentes no sinal de tomografia por coerencia optica

    Energy Technology Data Exchange (ETDEWEB)

    Pretto, Lucas Ramos de

    2015-07-01

    This work discusses the Optical Coherence Tomography system (OCT) and its application to the microfluidics area. To this end, physical characterization of microfluidic circuits were performed using 3D (three-dimensional) models constructed from OCT images of such circuits. The technique was thus evaluated as a potential tool to aid in the inspection of microchannels. Going further, this work paper studies and develops analytical techniques for microfluidic flow, in particular techniques based on speckle pattern. In the first instance, existing methods were studied and improved, such as Speckle Variance - OCT, where a gain of 31% was obtained in processing time. Other methods, such as LASCA (Laser Speckle Contrast Analysis), based on speckle autocorrelation, are adapted to OCT images. Derived from LASCA, the developed analysis technique based on intensity autocorrelation motivated the development of a custom OCT system as well as an optimized acquisition software, with a sampling rate of 8 kHz. The proposed method was, then, able to distinguish different flow rates, and limits of detection were tested, proving its feasibility for implementation on Brownian motion analysis and flow rates below 10 μl/min. (author)

  4. Adaptive zero-tree structure for curved wavelet image coding

    Science.gov (United States)

    Zhang, Liang; Wang, Demin; Vincent, André

    2006-02-01

    We investigate the issue of efficient data organization and representation of the curved wavelet coefficients [curved wavelet transform (WT)]. We present an adaptive zero-tree structure that exploits the cross-subband similarity of the curved wavelet transform. In the embedded zero-tree wavelet (EZW) and the set partitioning in hierarchical trees (SPIHT), the parent-child relationship is defined in such a way that a parent has four children, restricted to a square of 2×2 pixels, the parent-child relationship in the adaptive zero-tree structure varies according to the curves along which the curved WT is performed. Five child patterns were determined based on different combinations of curve orientation. A new image coder was then developed based on this adaptive zero-tree structure and the set-partitioning technique. Experimental results using synthetic and natural images showed the effectiveness of the proposed adaptive zero-tree structure for encoding of the curved wavelet coefficients. The coding gain of the proposed coder can be up to 1.2 dB in terms of peak SNR (PSNR) compared to the SPIHT coder. Subjective evaluation shows that the proposed coder preserves lines and edges better than the SPIHT coder.

  5. Adaptive fusion of infrared and visible images in dynamic scene

    Science.gov (United States)

    Yang, Guang; Yin, Yafeng; Man, Hong; Desai, Sachi

    2011-11-01

    Multiple modalities sensor fusion has been widely employed in various surveillance and military applications. A variety of image fusion techniques including PCA, wavelet, curvelet and HSV has been proposed in recent years to improve human visual perception for object detection. One of the main challenges for visible and infrared image fusion is to automatically determine an optimal fusion strategy for different input scenes along with an acceptable computational cost. This paper, we propose a fast and adaptive feature selection based image fusion method to obtain high a contrast image from visible and infrared sensors for targets detection. At first, fuzzy c-means clustering is applied on the infrared image to highlight possible hotspot regions, which will be considered as potential targets' locations. After that, the region surrounding the target area is segmented as the background regions. Then image fusion is locally applied on the selected target and background regions by computing different linear combination of color components from registered visible and infrared images. After obtaining different fused images, histogram distributions are computed on these local fusion images as the fusion feature set. The variance ratio which is based on Linear Discriminative Analysis (LDA) measure is employed to sort the feature set and the most discriminative one is selected for the whole image fusion. As the feature selection is performed over time, the process will dynamically determine the most suitable feature for the image fusion in different scenes. Experiment is conducted on the OSU Color-Thermal database, and TNO Human Factor dataset. The fusion results indicate that our proposed method achieved a competitive performance compared with other fusion algorithms at a relatively low computational cost.

  6. Ocular microtremor laser speckle metrology

    Science.gov (United States)

    Al-Kalbani, M.; Mihaylova, E.; Collins, N.; Toal, V.; Coakley, D.; Boyle, G.

    2009-02-01

    Ocular Microtremor (OMT) is a continual, high frequency physiological tremor of the eye present in all subjects even when the eye is apparently at rest. OMT causes a peak to peak displacement of around 150nm-2500nm with a broadband frequency spectrum between 30Hz to 120Hz; with a peak at about 83Hz. OMT carries useful clinical information on depth of consciousness and on some neurological disorders. Nearly all quantitative clinical investigations have been based on OMT measurements using an eye contacting piezoelectric probe which has low clinical acceptability. Laser speckle metrology is a candidate for a high resolution, non-contacting, compact, portable OMT measurement technique. However, tear flow and biospeckle might be expected to interfere with the displacement information carried by the speckle. The paper investigates the properties of the scattered speckle of laser light (λ = 632.8nm) from the eye sclera to assess the feasibility of using speckle techniques to measure OMT such as the speckle correlation. The investigation is carried using a high speed CMOS video camera adequate to capture the high frequency of the tremor. The investigation is supported by studies using an eye movement simulator (a bovine sclera driven by piezoelectric bimorphs). The speckle contrast and the frame to frame spatiotemporal variations are analyzed to determine if the OMT characteristics are detectable within speckle changes induced by the biospeckle or other movements.

  7. Synchronized renal blood flow dynamics mapped with wavelet analysis of laser speckle flowmetry data

    DEFF Research Database (Denmark)

    Brazhe, Alexey R; Marsh, Donald J; von Holstein-Rathlou, Niels-Henrik;

    2014-01-01

    Full-field laser speckle microscopy provides real-time imaging of superficial blood flow rate. Here we apply continuous wavelet transform to time series of speckle-estimated blood flow from each pixel of the images to map synchronous patterns in instantaneous frequency and phase on the surface...... of rat kidneys. The regulatory mechanism in the renal microcirculation generates oscillations in arterial blood flow at several characteristic frequencies. Our approach to laser speckle image processing allows detection of frequency and phase entrainments, visualization of their patterns, and estimation...

  8. 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.

  9. Multimodal Medical Image Fusion by Adaptive Manifold Filter

    Directory of Open Access Journals (Sweden)

    Peng Geng

    2015-01-01

    Full Text Available Medical image fusion plays an important role in diagnosis and treatment of diseases such as image-guided radiotherapy and surgery. The modified local contrast information is proposed to fuse multimodal medical images. Firstly, the adaptive manifold filter is introduced into filtering source images as the low-frequency part in the modified local contrast. Secondly, the modified spatial frequency of the source images is adopted as the high-frequency part in the modified local contrast. Finally, the pixel with larger modified local contrast is selected into the fused image. The presented scheme outperforms the guided filter method in spatial domain, the dual-tree complex wavelet transform-based method, nonsubsampled contourlet transform-based method, and four classic fusion methods in terms of visual quality. Furthermore, the mutual information values by the presented method are averagely 55%, 41%, and 62% higher than the three methods and those values of edge based similarity measure by the presented method are averagely 13%, 33%, and 14% higher than the three methods for the six pairs of source images.

  10. 二维斑点追踪成像技术在心脏疾病中的临床应用进展%Clinical application progress of two - dimensional speckle tracking imaging in cardiac diseases

    Institute of Scientific and Technical Information of China (English)

    李子卓; 方理刚

    2011-01-01

    目的 斑点追踪成像技术(STI)是新近发展起来的一项超声技术,其无角度依赖性,可以定量评价心肌的长轴、短轴、圆周的运动以及扭转运动,本文对STI技术在心脏疾病中的临床应用进展进行综述.%Speckle tracking imaging ( STI ) is a new ultrasonic technique in recent years, it takes the advantage of independency on the angle of insonation, and it can quantitatively assess the longitudinal, radial, circumferential and torsional function of left ventricle. This paper reviews the clinical application progress of STI in cardiac diseases.

  11. Spatially Adaptive Image Restoration Using Fuzzy Punctual Kriging

    Institute of Scientific and Technical Information of China (English)

    Anwar M. Mirza; Asmatullah Chaudhry; Badre Munir

    2007-01-01

    We present a general formulation based on punctual kriging and fuzzy concepts for image restoration in spatial domain. Gray-level images degraded with Gaussian white noise have been considered. Based on the pixel local neighborhood, fuzzy logic has been employed intelligently to avoid unnecessary estimation of a pixel. The intensity estimation of the selected pixels is then carried out by employing punctual kriging in conjunction with the method of Lagrange multipliers and estimates of local semi-variances. Application of such a hybrid technique performing both selection and intensity estimation of a pixel demonstrates substantial improvement in the image quality as compared to the adaptive Wiener filter and existing fuzzy- kriging approaches. It has been found that these filters achieve noise reduction without loss of structural detail information, as indicated by their higher structure similarity indices, peak signal to noise ratios and the new variogram based quality measures.

  12. Adaptively wavelet-based image denoising algorithm with edge preserving

    Institute of Scientific and Technical Information of China (English)

    Yihua Tan; Jinwen Tian; Jian Liu

    2006-01-01

    @@ A new wavelet-based image denoising algorithm, which exploits the edge information hidden in the corrupted image, is presented. Firstly, a canny-like edge detector identifies the edges in each subband.Secondly, multiplying the wavelet coefficients in neighboring scales is implemented to suppress the noise while magnifying the edge information, and the result is utilized to exclude the fake edges. The isolated edge pixel is also identified as noise. Unlike the thresholding method, after that we use local window filter in the wavelet domain to remove noise in which the variance estimation is elaborated to utilize the edge information. This method is adaptive to local image details, and can achieve better performance than the methods of state of the art.

  13. Fast Source Camera Identification Using Content Adaptive Guided Image Filter.

    Science.gov (United States)

    Zeng, Hui; Kang, Xiangui

    2016-03-01

    Source camera identification (SCI) is an important topic in image forensics. One of the most effective fingerprints for linking an image to its source camera is the sensor pattern noise, which is estimated as the difference between the content and its denoised version. It is widely believed that the performance of the sensor-based SCI heavily relies on the denoising filter used. This study proposes a novel sensor-based SCI method using content adaptive guided image filter (CAGIF). Thanks to the low complexity nature of the CAGIF, the proposed method is much faster than the state-of-the-art methods, which is a big advantage considering the potential real-time application of SCI. Despite the advantage of speed, experimental results also show that the proposed method can achieve comparable or better performance than the state-of-the-art methods in terms of accuracy.

  14. Adaptive interference hyperspectral image compression with spectrum distortion control

    Institute of Scientific and Technical Information of China (English)

    Jing Ma; Yunsong Li; Chengke Wu; Dong Chen

    2009-01-01

    As one of the next generation imaging spectrometers,interferential spectrometer has been paid much attention.With traditional spectrum compression methods,the hyperspectral images generated by interferential spectrometer can only be protected with better visual quality in spatial domain,but its optical applications in Fourier domain are often ignored.So the relation between the distortion in Fourier domain and the compression in spatial domain is analyzed in this letter.Based on this analysis,a novel coding scheme is proposed,which can compress data in spatial domain while reducing the distortion in Fourier domain.The bitstream of set partitioning in hierarchical trees (SPIHT) is truncated by adaptively lifting the rate-distortion slopes of zerotrees according to the priorities of optical path difference (OPD) based on rate-distortion optimization theory.Experimental results show that the proposed scheme can achieve better performance in Fourier domain while maintaining the image quality in spatial domain.

  15. A Markov random field-based approach to speckle reduction

    Science.gov (United States)

    Lankoande, Ousseini

    One of the major factors plaguing the performance of any coherent imaging system in general, and synthetic-aperture-radar (SAR) and ultrasound-medical-imaging systems in particular, is the presence of signal-dependent speckle noise. Grainy in appearance, speckle noise is primarily due to the phase fluctuations of the electromagnetic returned signals. Existing multiplicative models for speckle noise do not possess the level of generality required to capture and exploit the inherent spatial-correlation characteristics of speckle noise. The capability of Markov random fields (MRFs) to model spatially correlated and signal-dependent phenomena makes them an excellent choice for modeling speckled images without the need to adopt a multiplicative-noise model. In addition, a MRF framework can lend itself to many image-processing strategies that are not predicated on any multiplicative- or additive-noise assumptions. We propose a new mathematical framework for modeling and mitigating speckle noise that combines the flexibility and generality of a MRF with the physical properties of speckle noise drawn from the statistical optics principles. In particular, Goodman's conditional probability density function (cpdf) of the intensity of any two points in the speckled image and the associated correlation function are used to derive the cpdf of any center pixel intensity given its four neighbors. An important parameter of the cpdf, the coherence factor, characterizes the spatial correlation between two given pixels. For the first-order MRF model used in this dissertation, the coherence factor is restricted to only one value, which is estimated from the data using a pseudo-likelihood method. Equipped with the cpdf, the Hammersley-Clifford theorem is utilized to derive a convex Gibbs energy function that characterizes the MRF. Based on the proposed model, we introduce two speckle-reduction algorithms. The first algorithm, termed the simulated-annealing-MRF (SAMRF), is based on

  16. Adaptive codebook selection schemes for image classification in correlated channels

    Science.gov (United States)

    Hu, Chia Chang; Liu, Xiang Lian; Liu, Kuan-Fu

    2015-09-01

    The multiple-input multiple-output (MIMO) system with the use of transmit and receive antenna arrays achieves diversity and array gains via transmit beamforming. Due to the absence of full channel state information (CSI) at the transmitter, the transmit beamforming vector can be quantized at the receiver and sent back to the transmitter by a low-rate feedback channel, called limited feedback beamforming. One of the key roles of Vector Quantization (VQ) is how to generate a good codebook such that the distortion between the original image and the reconstructed image is the minimized. In this paper, a novel adaptive codebook selection scheme for image classification is proposed with taking both spatial and temporal correlation inherent in the channel into consideration. The new codebook selection algorithm is developed to select two codebooks from the discrete Fourier transform (DFT) codebook, the generalized Lloyd algorithm (GLA) codebook and the Grassmannian codebook to be combined and used as candidates of the original image and the reconstructed image for image transmission. The channel is estimated and divided into four regions based on the spatial and temporal correlation of the channel and an appropriate codebook is assigned to each region. The proposed method can efficiently reduce the required information of feedback under the spatially and temporally correlated channels, where each region is adaptively. Simulation results show that in the case of temporally and spatially correlated channels, the bit-error-rate (BER) performance can be improved substantially by the proposed algorithm compared to the one with only single codebook.

  17. Phase-preserving speckle reduction based on soft thresholding in quaternion wavelet domain

    Science.gov (United States)

    Liu, Yipeng; Jin, Jing; Wang, Qiang; Shen, Yi

    2012-10-01

    Speckle reduction is a difficult task for ultrasound image processing because of low resolution and contrast. As a novel tool of image analysis, quaternion wavelet (QW) has some superior properties compared to discrete wavelets, such as nearly shift-invariant wavelet coefficients and phase-based texture presentation. We aim to exploit the excellent performance of speckle reduction in quaternion wavelet domain based on the soft thresholding method. First, we exploit the characteristics of magnitude and phases in quaternion wavelet transform (QWT) to the denoising application, and find that the QWT phases of the images are little influenced by the noises. Then we model the QWT magnitude using the Rayleigh distribution, and derive the thresholding criterion. Furthermore, we conduct several experiments on synthetic speckle images and real ultrasound images. The performance of the proposed speckle reduction algorithm, using QWT with soft thresholding, demonstrates superiority to those using discrete wavelet transform and classical algorithms.

  18. An adaptive filtered back-projection for photoacoustic image reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Huang, He; Bustamante, Gilbert; Peterson, Ralph; Ye, Jing Yong, E-mail: jingyong.ye@utsa.edu [Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, Texas 78249 (United States)

    2015-05-15

    Purpose: The purpose of this study is to develop an improved filtered-back-projection (FBP) algorithm for photoacoustic tomography (PAT), which allows image reconstruction with higher quality compared to images reconstructed through traditional algorithms. Methods: A rigorous expression of a weighting function has been derived directly from a photoacoustic wave equation and used as a ramp filter in Fourier domain. The authors’ new algorithm utilizes this weighting function to precisely calculate each photoacoustic signal’s contribution and then reconstructs the image based on the retarded potential generated from the photoacoustic sources. In addition, an adaptive criterion has been derived for selecting the cutoff frequency of a low pass filter. Two computational phantoms were created to test the algorithm. The first phantom contained five spheres with each sphere having different absorbances. The phantom was used to test the capability for correctly representing both the geometry and the relative absorbed energy in a planar measurement system. The authors also used another phantom containing absorbers of different sizes with overlapping geometry to evaluate the performance of the new method for complicated geometry. In addition, random noise background was added to the simulated data, which were obtained by using an arc-shaped array of 50 evenly distributed transducers that spanned 160° over a circle with a radius of 65 mm. A normalized factor between the neighbored transducers was applied for correcting measurement signals in PAT simulations. The authors assumed that the scanned object was mounted on a holder that rotated over the full 360° and the scans were set to a sampling rate of 20.48 MHz. Results: The authors have obtained reconstructed images of the computerized phantoms by utilizing the new FBP algorithm. From the reconstructed image of the first phantom, one can see that this new approach allows not only obtaining a sharp image but also showing

  19. Fusion and speckle reduction or multi-polarization SAR images based on nonsubsompled Contourlet transform%基于非下采样Contourlet变换的极化SAR图像融合与去噪

    Institute of Scientific and Technical Information of China (English)

    孙晓霞; 张继贤; 燕琴

    2011-01-01

    针对非下采样Comourlet变换(NSCT)在处理噪声影像中具有的优势,以及同极化SAR图像(HH、VV)之间的相关性与互补性,本文实验了一种基于非下采样Contourlet变换的极化图像融合方法.该方法首先对每个极化图像进行多尺度、多方向分解,然后对不同分解子带系数分别采用有利于斑点噪声去除和信息增强的融合规则进行融合,最终通过NSCT反变换得到融合图像.通过信息熵、相关系数以及等效视数等指标的评价,验证了该方法可以有效地实现信息增强,同时该方法也在一定程度上降低了斑点噪声的负面影响.%Nonsubsampled Contourlet Tramform ( NSCT) is a newly improved multiresulution geometry analysis technique based on Contourlet Transform. NSCT can represent images more effectively because of its flexible multi-resolution, multi-direction and shift invariance, and has been approved to be very suitable for noisy images, souch as SAR images. A method of fusing and reducing the speckles of multi-polarization SAR images based on NSCT was proposed in the paper. The images were firstly decomposed by NSCT, and then different fusion rules of decomposed coefficients were chosen with the consideration of denoising and information enhaneing. Finally, the fused NSCT coefficients were reconstructed to obtain fusion result. In this paper, IIH and VV co-polarization images were fused using the propoed method, and the entropy, correlation coefficient and Equivalent Number of looks (ENL) were calculated to evaluate the results. Experiments showed that the proposed algorithm could obtain a good fused image with the improved spatial infor mation, at the same time thE speckle noises could be reduced to some extent.

  20. Speckle statistics of entangled photons

    CERN Document Server

    Klein, Avraham; Spivak, Boris

    2016-01-01

    We consider the propagation of several entangled photons through an elastically scattering medium and study statistical properties of their speckle patterns. We find the spatial correlations of multiphoton speckles and their sensitivity to changes of system parameters. Our analysis covers both the directed-wave regime, where rays propagate almost ballistically while experiencing small-angle diffusion, and the real-space diffusive regime. We demonstrate that long-range correlations of the speckle patterns dominate experimental signatures for large-aperture photon detectors. We also show that speckle sensitivity depends strongly on the number of photons $N$ in the incoming beam, increasing as $\\sqrt{N}$ in the directed-wave regime and as $N$ in the diffusive regime.

  1. Adaptive geodesic transform for segmentation of vertebrae on CT images

    Science.gov (United States)

    Gaonkar, Bilwaj; Shu, Liao; Hermosillo, Gerardo; Zhan, Yiqiang

    2014-03-01

    Vertebral segmentation is a critical first step in any quantitative evaluation of vertebral pathology using CT images. This is especially challenging because bone marrow tissue has the same intensity profile as the muscle surrounding the bone. Thus simple methods such as thresholding or adaptive k-means fail to accurately segment vertebrae. While several other algorithms such as level sets may be used for segmentation any algorithm that is clinically deployable has to work in under a few seconds. To address these dual challenges we present here, a new algorithm based on the geodesic distance transform that is capable of segmenting the spinal vertebrae in under one second. To achieve this we extend the theory of the geodesic distance transforms proposed in1 to incorporate high level anatomical knowledge through adaptive weighting of image gradients. Such knowledge may be provided by the user directly or may be automatically generated by another algorithm. We incorporate information 'learnt' using a previously published machine learning algorithm2 to segment the L1 to L5 vertebrae. While we present a particular application here, the adaptive geodesic transform is a generic concept which can be applied to segmentation of other organs as well.

  2. Adaptive Semi-linear Inversion of Strong Gravitational Lens Imaging

    CERN Document Server

    Nightingale, James

    2014-01-01

    We present a new pixelized method for the inversion of gravitationally lensed extended source images which we term adaptive semi-linear inversion (SLI). At the heart of the method is an h-means clustering algorithm which is used to derive a source plane pixelization that adapts to the lens model magnification. The distinguishing feature of adaptive SLI is that every pixelization is derived from a random initialization, ensuring that data discretization is performed in a completely different and unique way for every lens model parameter set. We compare standard SLI on a fixed source pixel grid with the new method and demonstrate the shortcomings of the former when modeling singular power law ellipsoid (SPLE) lens profiles. In particular, we demonstrate the superior reliability and efficiency of adaptive SLI which, by design, fixes the number of degrees of freedom (NDOF) of the optimization and thereby removes biases present with other methods that allow the NDOF to vary. In addition, we highlight the importanc...

  3. Adaptive Fusion of Stochastic Information for Imaging Fractured Vadose Zones

    Science.gov (United States)

    Daniels, J.; Yeh, J.; Illman, W.; Harri, S.; Kruger, A.; Parashar, M.

    2004-12-01

    A stochastic information fusion methodology is developed to assimilate electrical resistivity tomography, high-frequency ground penetrating radar, mid-range-frequency radar, pneumatic/gas tracer tomography, and hydraulic/tracer tomography to image fractures, characterize hydrogeophysical properties, and monitor natural processes in the vadose zone. The information technology research will develop: 1) mechanisms and algorithms for fusion of large data volumes ; 2) parallel adaptive computational engines supporting parallel adaptive algorithms and multi-physics/multi-model computations; 3) adaptive runtime mechanisms for proactive and reactive runtime adaptation and optimization of geophysical and hydrological models of the subsurface; and 4) technologies and infrastructure for remote (pervasive) and collaborative access to computational capabilities for monitoring subsurface processes through interactive visualization tools. The combination of the stochastic fusion approach and information technology can lead to a new level of capability for both hydrologists and geophysicists enabling them to "see" into the earth at greater depths and resolutions than is possible today. Furthermore, the new computing strategies will make high resolution and large-scale hydrological and geophysical modeling feasible for the private sector, scientists, and engineers who are unable to access supercomputers, i.e., an effective paradigm for technology transfer.

  4. Nonlocal means filter-based speckle tracking.

    Science.gov (United States)

    Afsham, Narges; Rasoulian, Abtin; Najafi, Mohammad; Abolmaesumi, Purang; Rohling, Robert

    2015-08-01

    The objective of sensorless freehand 3-D ultrasound imaging is to eliminate the need for additional tracking hardware and reduce cost and complexity. However, the accuracy of current out-of-plane pose estimation is main obstacle for full 6-degree-of-freedom (DoF) tracking. We propose a new filter-based speckle tracking framework to increase the accuracy of out-of-plane displacement estimation. In this framework, we use the displacement estimation not only for the specific speckle pattern, but for the entire image. We develop a nonlocal means (NLM) filter based on a probabilistic normal variance mixture model of ultrasound, known as Rician-inverse Gaussian (RiIG). To aggregate the local displacement estimations, Stein's unbiased risk estimate (SURE) is used as a quality measure of the estimations. We derive an explicit analytical form of SURE for the RiIG model and use it as a weight factor. The proposed filter-based speckle tracking framework is formulated and evaluated for three commonly used noise models, including the RiIG model. The out-of-plane estimations are compared with our previously proposed model-based algorithm in a set of ex vivo experiments for different tissue types. We show that the proposed RiIG filter-based method is more accurate and less tissue-dependent than the other methods. The proposed method is also evaluated in vivo on the spines of five different subjects to assess the feasibility of a clinical application. The 6-DoF transform parameters are estimated and compared with the electromagnetic tracker measurements. The results show higher tracking accuracy for typical small lateral displacements and tilt rotations between image pairs.

  5. Adaptive Bayesian-based speck-reduction in SAR images using complex wavelet transform

    Science.gov (United States)

    Ma, Ning; Yan, Wei; Zhang, Peng

    2005-10-01

    In this paper, an improved adaptive speckle reduction method is presented based on dual tree complex wavelet transform (CWT). It combines the characteristics of additive noise reduction of soft thresholding with the CWT's directional selectivity, being its main contribution to adapt the effective threshold to preserve the edge detail. A Bayesian estimator is applied to the decomposed data also to estimate the best value for the noise-free complex wavelet coefficients. This estimation is based on alpha-stable and Gaussian distribution hypotheses for complex wavelet coefficients of the signal and noise, respectively. Experimental results show that the denoising performance is among the state-of-the-art techniques based on real discrete wavelet transform (DWT).

  6. Adaptive image contrast enhancement algorithm for point-based rendering

    Science.gov (United States)

    Xu, Shaoping; Liu, Xiaoping P.

    2015-03-01

    Surgical simulation is a major application in computer graphics and virtual reality, and most of the existing work indicates that interactive real-time cutting simulation of soft tissue is a fundamental but challenging research problem in virtual surgery simulation systems. More specifically, it is difficult to achieve a fast enough graphic update rate (at least 30 Hz) on commodity PC hardware by utilizing traditional triangle-based rendering algorithms. In recent years, point-based rendering (PBR) has been shown to offer the potential to outperform the traditional triangle-based rendering in speed when it is applied to highly complex soft tissue cutting models. Nevertheless, the PBR algorithms are still limited in visual quality due to inherent contrast distortion. We propose an adaptive image contrast enhancement algorithm as a postprocessing module for PBR, providing high visual rendering quality as well as acceptable rendering efficiency. Our approach is based on a perceptible image quality technique with automatic parameter selection, resulting in a visual quality comparable to existing conventional PBR algorithms. Experimental results show that our adaptive image contrast enhancement algorithm produces encouraging results both visually and numerically compared to representative algorithms, and experiments conducted on the latest hardware demonstrate that the proposed PBR framework with the postprocessing module is superior to the conventional PBR algorithm and that the proposed contrast enhancement algorithm can be utilized in (or compatible with) various variants of the conventional PBR algorithm.

  7. Classification in medical images using adaptive metric k-NN

    Science.gov (United States)

    Chen, C.; Chernoff, K.; Karemore, G.; Lo, P.; Nielsen, M.; Lauze, F.

    2010-03-01

    The performance of the k-nearest neighborhoods (k-NN) classifier is highly dependent on the distance metric used to identify the k nearest neighbors of the query points. The standard Euclidean distance is commonly used in practice. This paper investigates the performance of k-NN classifier with respect to different adaptive metrics in the context of medical imaging. We propose using adaptive metrics such that the structure of the data is better described, introducing some unsupervised learning knowledge in k-NN. We investigated four different metrics are estimated: a theoretical metric based on the assumption that images are drawn from Brownian Image Model (BIM), the normalized metric based on variance of the data, the empirical metric is based on the empirical covariance matrix of the unlabeled data, and an optimized metric obtained by minimizing the classification error. The spectral structure of the empirical covariance also leads to Principal Component Analysis (PCA) performed on it which results the subspace metrics. The metrics are evaluated on two data sets: lateral X-rays of the lumbar aortic/spine region, where we use k-NN for performing abdominal aorta calcification detection; and mammograms, where we use k-NN for breast cancer risk assessment. The results show that appropriate choice of metric can improve classification.

  8. Adaptive clutter rejection for ultrasound color Doppler imaging

    Science.gov (United States)

    Yoo, Yang Mo; Managuli, Ravi; Kim, Yongmin

    2005-04-01

    We have developed a new adaptive clutter rejection technique where an optimum clutter filter is dynamically selected according to the varying clutter characteristics in ultrasound color Doppler imaging. The selection criteria have been established based on the underlying clutter characteristics (i.e., the maximum instantaneous clutter velocity and the clutter power) and the properties of various candidate clutter filters (e.g., projection-initialized infinite impulse response and polynomial regression). We obtained an average improvement of 3.97 dB and 3.27 dB in flow signal-to-clutter-ratio (SCR) compared to the conventional and down-mixing methods, respectively. These preliminary results indicate that the proposed adaptive clutter rejection method could improve the sensitivity and accuracy in flow velocity estimation for ultrasound color Doppler imaging. For a 192 x 256 color Doppler image with an ensemble size of 10, the proposed method takes only 57.2 ms, which is less than the acquisition time. Thus, the proposed method could be implemented in modern ultrasound systems, while providing improved clutter rejection and more accurate velocity estimation in real time.

  9. Speckle interferometric observations of close binary stars

    CERN Document Server

    Saha, S K; Yeswanth, L; Anbazhagan, P

    2002-01-01

    Speckle interferometric technique is employed to record a series of hundreds of short-exposure images of several close binary stars with sub-arcsecond separation through a narrow band filter at the Cassegrain focus of the 2.34 meter (m) Vainu Bappu telescope (VBT), situated at Vainu Bappu Observatory (VBO), Kavalur, India. The data are recorded sequentially by a Peltier-cooled intensified CCD camera with 10 ms exposure. The auto-correlation method is applied to determine the angular separations and position angles of these binary systems.

  10. Analysis of strawberry ripening by dynamic speckle measurements

    Science.gov (United States)

    Mulone, C.; Budini, N.; Vincitorio, F. M.; Freyre, C.; López Díaz, A. J.; Ramil Rego, A.

    2013-11-01

    This work seeks to determine the age of a fruit from observation of its dynamic speckle pattern. A mobile speckle pattern originates on the fruit's surface due to the interference of the wavefronts reflected from moving scatterers. For this work we analyzed two series of photographs of a strawberry speckle pattern, at different stages of ripening, acquired with a CMOS camera. The first day, we took ten photographs at an interval of one second. The same procedure was repeated the next day. From each series of images we extracted several statistical descriptors of pixel-to-pixel gray level variation during the observation time. By comparing these values from the first to the second day we noticed a diminution of the speckle activity. This decay demonstrated that after only one day the ripening process of the strawberry can be detected by dynamic speckle pattern analysis. For this study we employed a simple new algorithm to process the data obtained from the photographs. This algorithm allows defining a global mobility index that indicates the evolution of the fruit's ripening.

  11. Adaptive optics scanning laser ophthalmoscope imaging: technology update

    Directory of Open Access Journals (Sweden)

    Merino D

    2016-04-01

    Full Text Available David Merino, Pablo Loza-Alvarez The Institute of Photonic Sciences (ICFO, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain Abstract: Adaptive optics (AO retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it. Keywords: high-resolution, in vivo retinal imaging, AOSLO

  12. Robust image registration using adaptive coherent point drift method

    Science.gov (United States)

    Yang, Lijuan; Tian, Zheng; Zhao, Wei; Wen, Jinhuan; Yan, Weidong

    2016-04-01

    Coherent point drift (CPD) method is a powerful registration tool under the framework of the Gaussian mixture model (GMM). However, the global spatial structure of point sets is considered only without other forms of additional attribute information. The equivalent simplification of mixing parameters and the manual setting of the weight parameter in GMM make the CPD method less robust to outlier and have less flexibility. An adaptive CPD method is proposed to automatically determine the mixing parameters by embedding the local attribute information of features into the construction of GMM. In addition, the weight parameter is treated as an unknown parameter and automatically determined in the expectation-maximization algorithm. In image registration applications, the block-divided salient image disk extraction method is designed to detect sparse salient image features and local self-similarity is used as attribute information to describe the local neighborhood structure of each feature. The experimental results on optical images and remote sensing images show that the proposed method can significantly improve the matching performance.

  13. Sparse diffraction imaging method using an adaptive reweighting homotopy algorithm

    Science.gov (United States)

    Yu, Caixia; Zhao, Jingtao; Wang, Yanfei; Qiu, Zhen

    2017-02-01

    Seismic diffractions carry valuable information from subsurface small-scale geologic discontinuities, such as faults, cavities and other features associated with hydrocarbon reservoirs. However, seismic imaging methods mainly use reflection theory for constructing imaging models, which means a smooth constraint on imaging conditions. In fact, diffractors occupy a small account of distributions in an imaging model and possess discontinuous characteristics. In mathematics, this kind of phenomena can be described by the sparse optimization theory. Therefore, we propose a diffraction imaging method based on a sparsity-constraint model for studying diffractors. A reweighted L 2-norm and L 1-norm minimization model is investigated, where the L 2 term requests a least-square error between modeled diffractions and observed diffractions and the L 1 term imposes sparsity on the solution. In order to efficiently solve this model, we use an adaptive reweighting homotopy algorithm that updates the solutions by tracking a path along inexpensive homotopy steps. Numerical examples and field data application demonstrate the feasibility of the proposed method and show its significance for detecting small-scale discontinuities in a seismic section. The proposed method has an advantage in improving the focusing ability of diffractions and reducing the migration artifacts.

  14. Characterization of Holmes in The Adventure of Speckled Band

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-ling

    2015-01-01

    Sherlock Holmes is the fictional creation of Sir Arthur Conan Doyle. In The Adventure of the Speckled Band, Sir Arthur Conan Doyle has succeeded in creating the image of Sherlock Holmes. He is not only an excellent detective who is skillful in as⁃tute observation and deductive reasoning, but also the symbol of justice and wisdom.

  15. Satellite Imaging with Adaptive Optics on a 1 M Telescope

    Science.gov (United States)

    Bennet, F.; Price, I.; Rigaut, F.; Copeland, M.

    2016-09-01

    The Research School of Astronomy and Astrophysics at the Mount Stromlo Observatory in Canberra, Australia, have been developing adaptive optic (AO) systems for space situational awareness applications. We report on the development and demonstration of an AO system for satellite imaging using a 1 m telescope. The system uses the orbiting object as a natural guide star to measure atmospheric turbulence, and a deformable mirror to provide an optical correction. The AO system utilised modern, high speed and low noise EMCCD technology on both the wavefront sensor and imaging camera to achieve high performance, achieving a Strehl ratio in excess of 30% at 870 nm. Images are post processed with lucky imaging algorithms to further improve the final image quality. We demonstrate the AO system on stellar targets and Iridium satellites, achieving a near diffraction limited full width at half maximum. A specialised realtime controller allows our system to achieve a bandwidth above 100 Hz, with the wavefront sensor and control loop running at 2 kHz. The AO systems we are developing show how ground-based optical sensors can be used to manage the space environment. AO imaging systems can be used for satellite surveillance, while laser ranging can be used to determine precise orbital data used in the critical conjunction analysis required to maintain a safe space environment. We have focused on making this system compact, expandable, and versatile. We are continuing to develop this platform for other space situational awareness applications such as geosynchronous satellite astrometry, space debris characterisation, satellite imaging, and ground-to-space laser communication.

  16. An Adaptive Watermarking Technique for Copyright Protection of Digital Images

    Energy Technology Data Exchange (ETDEWEB)

    Park, K.S.; Lee, B.Y.; Park, S.H. [Yonsei University, Seoul (Korea); Chung, T.Y. [Kangnung National University, Kangnung (Korea)

    2002-03-01

    This paper proposes a new watermark embedding and extraction technique which extends the direct sequence spread spectrum technique. The proposed technique approximates the complexity of image and block in spatial domain using Laplacian filtering and watermark is adaptively embeded in the mid-frequency DCT components. Local parity bits are attached to higher-frequency DCT components and they are used to detect extraction errors and correct those errors. In extraction process, the proposed method boosts the higher frequency components of image and extracts the watermark by demodulation and this information is verified and adjusted by parity bits. Experimental results show it is invisible and robust to several external attacks. (author). 7 refs., 5 figs., 2 tabs.

  17. Image adaptive RST invariant watermark using pseudo-Zernike moments

    Institute of Scientific and Technical Information of China (English)

    Leida LI; Baolong GUO

    2008-01-01

    Rotation, scaling and translation (RST) attacks can desynchronize watermark detection, which causes failure in many watermarking systems. In this paper, an image adaptive RST invariant watermark (AWPZM) is proposed by using the rotation invariant property of pseudo-Zernike moments (PZM) and odd-even quantization. PZM of the original image is computed first, and then those suitable for watermark generation are selected. Then, magnitudes of them are odd-even quantized to generate the watermark. In detection, a normalized hamming function is employed to determine the similarity of the watermark. Experimental results show its robustness to rotation and scaling. For traditional attacks, such as JPEG compression, added noise and filtering, the similarities are all above 0.95.

  18. Adaptive stereo medical image watermarking using non-corresponding blocks.

    Science.gov (United States)

    Mohaghegh, H; Karimi, N; Soroushmehr, S M R; Samavi, S; Najarian, K

    2015-01-01

    Today with the advent of technology in different medical imaging fields, the use of stereoscopic images has increased. Furthermore, with the rapid growth in telemedicine for remote diagnosis, treatment, and surgery, there is a need for watermarking. This is for copyright protection and tracking of digital media. Also, the efficient use of bandwidth for transmission of such data is another concern. In this paper an adaptive watermarking scheme is proposed that considers human visual system in depth perception. Our proposed scheme modifies maximum singular values of wavelet coefficients of stereo pair for embedding watermark bits. Experimental results show high 3D visual quality of watermarked video frames. Moreover, comparison with a compatible state of the art method shows that the proposed method is highly robust against attacks such as AWGN, salt and pepper noise, and JPEG compression.

  19. Image denoising using a directional adaptive diffusion filter

    Science.gov (United States)

    Zhao, Cuifang; Shi, Caicheng; He, Peikun

    2006-11-01

    Partial differential equations (PDEs) are well-known due to their good processing results which it can not only smooth the noise but also preserve the edges. But the shortcomings of these processes came to being noticed by people. In some sense, PDE filter is called "cartoon model" as it produces an approximation of the input image, use the same diffusion model and parameters to process noise and signal because it can not differentiate them, therefore, the image is naturally modified toward piecewise constant functions. A new method called a directional adaptive diffusion filter is proposed in the paper, which combines PDE mode with wavelet transform. The undecimated discrete wavelet transform (UDWT) is carried out to get different frequency bands which have obviously directional selectivity and more redundancy details. Experimental results show that the proposed method provides a performance better to preserve textures, small details and global information.

  20. MICADO: the E-ELT Adaptive Optics Imaging Camera

    CERN Document Server

    Davies, R

    2010-01-01

    MICADO is the adaptive optics imaging camera for the E-ELT. It has been designed and optimised to be mounted to the LGS-MCAO system MAORY, and will provide diffraction limited imaging over a wide (about 1 arcmin) field of view. For initial operations, it can also be used with its own simpler AO module that provides on-axis diffraction limited performance using natural guide stars. We discuss the instrument's key capabilities and expected performance, and show how the science drivers have shaped its design. We outline the technical concept, from the opto-mechanical design to operations and data processing. We describe the AO module, summarise the instrument performance, and indicate some possible future developments.

  1. FILTERING OF MEDICAL ULTRASONIC IMAGES BASED ON A MODIFIED ANISTROPIC DIFFUSION EQUATION

    Institute of Scientific and Technical Information of China (English)

    Wang Ling; Li Deyu; Wang Tianfu; Lin Jiangli; Peng Yun; Rao Li; Zheng Yi

    2007-01-01

    Speckle noise reduction is a key problem of the image analysis of medical UltraSound images. In this paper, two important improvements have been developed to a fast anisotropic diffusion algorithm for speckle noise reduction. The Gaussian filter is firstly used before gradient calculation, and then the adaptive algorithm of the factor k is proposed. Numerous experimental results show that the proposed model is superior to other methods in noise removal, fidelity and edge preservation. It is suitable for the preprocessing of a great number of medical UltraSound images, such as three dimensional reconstruction.

  2. 斑点追踪成像技术在心肌梗死左室心肌应变能力中的应用%Application of Speckle Tracking Imaging in Left Ventricular Strain Capacity of Myocardial Infarction

    Institute of Scientific and Technical Information of China (English)

    喻丽华; 赵季红; 蔡伟; 李学文

    2012-01-01

    目的:探讨超声斑点追踪成像(speckle tracking imaging,STI)技术评价心肌梗死患者左室心肌整体和局部应变的价值.方法:收集医院60例确诊为前壁心肌梗死患者,将同期体检健康志愿者60例作为正常对照.分别收集2组心尖位左室长轴3个切面高帧频二维动态图像,以自动功能成像软件(automated functional imaging,AFI)测量左室18节段峰值收缩期应变(S)、切面峰值收缩应变(GLS)及左室长轴平均总应变(GLS-Avg),分析GLS-Avg与左室射血分数(left ventricular ejection fraction,LVEF)的相关性;比较2组患者GLS-Avg.结果:前壁心肌梗死患者左室18节段S值自基底段向心尖段逐渐增加,各壁间差异无统计学意义(P>0.05);前壁心肌梗死患者各节段壁应变绝对值低于正常对照组(P<0.05).GLS-Avg与LVEF具有良好相关性(r=0.93,P<0.05).结论:斑点追踪成像技术能定量测定心肌梗死患者左室和整体心肌的变化.%Objective To study the application of speckle tracking imaging(STI) technology in myocardial infarction patients with left ventricular global and local strain. Methods Sixty cases of myocardial infarction patients were selected, and another sixty healthy patients were in control group. Left ventricular apical long-axis positions were recorded in three two-dimensional slices of high frame rate dynamic images. Left ventricular peak systolic strain in paragraph 18(S), the section peak systolic strain(GLS) and left ventricular long axis of the average total strain(GLS-Avg) of all cases were measured by automated functional imaging(AFI). The relationship of GLS-Avg and left ventricular ejection fraction(LVEF) was analyzed. Results Paragraph 18(S) values of left ventricle from the basal to apical segments gradually increased in control group. The intramural difference was not statistically significant(P>0.05), and strain of the wall segment in myocardial infarction group was lower than that of the control

  3. Towards real time speckle controlled retinal photocoagulation

    Science.gov (United States)

    Bliedtner, Katharina; Seifert, Eric; Stockmann, Leoni; Effe, Lisa; Brinkmann, Ralf

    2016-03-01

    Photocoagulation is a laser treatment widely used for the therapy of several retinal diseases. Intra- and inter-individual variations of the ocular transmission, light scattering and the retinal absorption makes it impossible to achieve a uniform effective exposure and hence a uniform damage throughout the therapy. A real-time monitoring and control of the induced damage is highly requested. Here, an approach to realize a real time optical feedback using dynamic speckle analysis is presented. A 532 nm continuous wave Nd:YAG laser is used for coagulation. During coagulation, speckle dynamics are monitored by a coherent object illumination using a 633nm HeNe laser and analyzed by a CMOS camera with a frame rate up to 1 kHz. It is obvious that a control system needs to determine whether the desired damage is achieved to shut down the system in a fraction of the exposure time. Here we use a fast and simple adaption of the generalized difference algorithm to analyze the speckle movements. This algorithm runs on a FPGA and is able to calculate a feedback value which is correlated to the thermal and coagulation induced tissue motion and thus the achieved damage. For different spot sizes (50-200 μm) and different exposure times (50-500 ms) the algorithm shows the ability to discriminate between different categories of retinal pigment epithelial damage ex-vivo in enucleated porcine eyes. Furthermore in-vivo experiments in rabbits show the ability of the system to determine tissue changes in living tissue during coagulation.

  4. Adaptive optics scanning laser ophthalmoscope imaging: technology update.

    Science.gov (United States)

    Merino, David; Loza-Alvarez, Pablo

    2016-01-01

    Adaptive optics (AO) retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it.

  5. Extreme learning machine and adaptive sparse representation for image classification.

    Science.gov (United States)

    Cao, Jiuwen; Zhang, Kai; Luo, Minxia; Yin, Chun; Lai, Xiaoping

    2016-09-01

    Recent research has shown the speed advantage of extreme learning machine (ELM) and the accuracy advantage of sparse representation classification (SRC) in the area of image classification. Those two methods, however, have their respective drawbacks, e.g., in general, ELM is known to be less robust to noise while SRC is known to be time-consuming. Consequently, ELM and SRC complement each other in computational complexity and classification accuracy. In order to unify such mutual complementarity and thus further enhance the classification performance, we propose an efficient hybrid classifier to exploit the advantages of ELM and SRC in this paper. More precisely, the proposed classifier consists of two stages: first, an ELM network is trained by supervised learning. Second, a discriminative criterion about the reliability of the obtained ELM output is adopted to decide whether the query image can be correctly classified or not. If the output is reliable, the classification will be performed by ELM; otherwise the query image will be fed to SRC. Meanwhile, in the stage of SRC, a sub-dictionary that is adaptive to the query image instead of the entire dictionary is extracted via the ELM output. The computational burden of SRC thus can be reduced. Extensive experiments on handwritten digit classification, landmark recognition and face recognition demonstrate that the proposed hybrid classifier outperforms ELM and SRC in classification accuracy with outstanding computational efficiency.

  6. Block Compressed Sensing of Images Using Adaptive Granular Reconstruction

    Directory of Open Access Journals (Sweden)

    Ran Li

    2016-01-01

    Full Text Available In the framework of block Compressed Sensing (CS, the reconstruction algorithm based on the Smoothed Projected Landweber (SPL iteration can achieve the better rate-distortion performance with a low computational complexity, especially for using the Principle Components Analysis (PCA to perform the adaptive hard-thresholding shrinkage. However, during learning the PCA matrix, it affects the reconstruction performance of Landweber iteration to neglect the stationary local structural characteristic of image. To solve the above problem, this paper firstly uses the Granular Computing (GrC to decompose an image into several granules depending on the structural features of patches. Then, we perform the PCA to learn the sparse representation basis corresponding to each granule. Finally, the hard-thresholding shrinkage is employed to remove the noises in patches. The patches in granule have the stationary local structural characteristic, so that our method can effectively improve the performance of hard-thresholding shrinkage. Experimental results indicate that the reconstructed image by the proposed algorithm has better objective quality when compared with several traditional ones. The edge and texture details in the reconstructed image are better preserved, which guarantees the better visual quality. Besides, our method has still a low computational complexity of reconstruction.

  7. Optical design of the comet Shoemaker-Levy speckle camera

    Energy Technology Data Exchange (ETDEWEB)

    Bissinger, H. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    An optical design is presented in which the Lick 3 meter telescope and a bare CCD speckle camera system was used to image the collision sites of the Shoemaker-Levy 9 comet with the Planet Jupiter. The brief overview includes of the optical constraints and system layout. The choice of a Risley prism combination to compensate for the time dependent atmospheric chromatic changes are described. Plate scale and signal-to-noise ratio curves resulting from imaging reference stars are compared with theory. Comparisons between un-corrected and reconstructed images of Jupiter`s impact sites. The results confirm that speckle imaging techniques can be used over an extended time period to provide a method to image large extended objects.

  8. Shape Adaptive, Robust Iris Feature Extraction from Noisy Iris Images

    Science.gov (United States)

    Ghodrati, Hamed; Dehghani, Mohammad Javad; Danyali, Habibolah

    2013-01-01

    In the current iris recognition systems, noise removing step is only used to detect noisy parts of the iris region and features extracted from there will be excluded in matching step. Whereas depending on the filter structure used in feature extraction, the noisy parts may influence relevant features. To the best of our knowledge, the effect of noise factors on feature extraction has not been considered in the previous works. This paper investigates the effect of shape adaptive wavelet transform and shape adaptive Gabor-wavelet for feature extraction on the iris recognition performance. In addition, an effective noise-removing approach is proposed in this paper. The contribution is to detect eyelashes and reflections by calculating appropriate thresholds by a procedure called statistical decision making. The eyelids are segmented by parabolic Hough transform in normalized iris image to decrease computational burden through omitting rotation term. The iris is localized by an accurate and fast algorithm based on coarse-to-fine strategy. The principle of mask code generation is to assign the noisy bits in an iris code in order to exclude them in matching step is presented in details. An experimental result shows that by using the shape adaptive Gabor-wavelet technique there is an improvement on the accuracy of recognition rate. PMID:24696801

  9. Adaptive Optics and Lucky Imager (AOLI): presentation and first light

    CERN Document Server

    Velasco, S; Mackay, C; Oscoz, A; King, D L; Crass, J; Díaz-Sánchez, A; Femenía, B; González-Escalera, V; Labadie, L; López, R L; Garrido, A Pérez; Puga, M; Rodríguez-Ramos, L F; Zuther, J

    2015-01-01

    In this paper we present the Adaptive Optics Lucky Imager (AOLI), a state-of-the-art instrument which makes use of two well proved techniques for extremely high spatial resolution with ground-based telescopes: Lucky Imaging (LI) and Adaptive Optics (AO). AOLI comprises an AO system, including a low order non-linear curvature wavefront sensor together with a 241 actuators deformable mirror, a science array of four 1024x1024 EMCCDs, allowing a 120x120 down to 36x36 arcseconds field of view, a calibration subsystem and a powerful LI software. Thanks to the revolutionary WFS, AOLI shall have the capability of using faint reference stars ({\\it I\\/} $\\sim$ 16.5-17.5), enabling it to be used over a much wider part of the sky than with common Shack-Hartmann AO systems. This instrument saw first light in September 2013 at William Herschel Telescope. Although the instrument was not complete, these commissioning demonstrated its feasibility, obtaining a FWHM for the best PSF of 0.151$\\pm$0.005 arcsec and a plate scale o...

  10. Progress and Prospect of Application Research of Three-dimensional Speckle Tracking Imaging%超声三维斑点追踪技术应用研究的进展及前景

    Institute of Scientific and Technical Information of China (English)

    冉红

    2013-01-01

    超声三维斑点追踪成像技术是一种评估心肌功能的新技术,该技术是基于二维灰阶组织成像基础上发展起来的非角度依赖性实用新技术,可通过识别图像的心肌回声斑点信号来追踪心肌运动轨迹,从多个方向对心肌节段应变进行评价,获取局部心肌径向、纵向及环向心肌形变信息,并实现三维空间的立体定位,可精确定量并定性评价心肌的局部及整体心肌应变力学改变,有效完成评价心肌的功能研究.斑点跟踪的应变和应变率对及早发现心肌功能障碍具有很高的敏感性及特异性,前瞻性检测心肌功能对冠状动脉粥样硬化性心脏病患者临床治疗决策上起着积极的指导作用,对患者实现阶段性疗效评估及长期预后预测均有着重要意义.综述阐述了斑点追踪二维及三维应变成像技术的基本概念,讨论了新的超声方法主要的临床应用价值及其存在的局限性和发展应用前景,这些都是目前国内外心血管超声研究的热点方向.%Three-dimensional speckle tracking is a new technology to evaluate myocardial function. It is a new imaging with angle independence which is based on gray-scale imaging. The spot signal myocardial echo with recognition image can track myocardial motion to e-valuate the segmental myocardial strain from multiple directions. Assessment of the echocardiography images has been recently described in radial peak strain, longitudinal peak strain and circumferential peak strain. It has been validated as methods to quantify regional myocardial function. To realize the space positioning of three-dimensional, strain can achieve precise quantitative and qualitative evaluation of myocardial changes. It can complete the function of effective evaluation of myocardium. Strain and strain rate of speckle tracking for the early detection of myocardial dysfunction which has higher sensitivity and specificity. Positive prospective detection of

  11. Speckle analysis in laser scanning display system

    Institute of Scientific and Technical Information of China (English)

    Hong Chang; Wei Huang; Fugui Yang; Hai Ming; Jianping Xie

    2009-01-01

    The theory of speckle formation in laser scanning display system is established based on the averaging effect of eye response as laser beam scanning through an eye resolution spot.It is analyzed that speckle reduction can be obtained by averaging states of speckle during scanning.The theoretical results show that a smaller correlation length of screen surface and the narrowing of laser beam in scanning direction can reduce speckle contrast for this system.

  12. Color digital holography using speckle illumination by means of a multi-mode fiber

    Science.gov (United States)

    Funamizu, Hideki; Shimoma, Shohei; Aizu, Yoshihisa

    2014-02-01

    We present color digital holography using speckle illumination by means of a multi-mode fiber. In this technique, speckle fields emitted from the fiber are used as both a reference wave and a wavefront illuminating an object. For three wavelengths, the interference patterns of two coherent waves are recorded as digital holograms on a CCD camera. A speckle method is used for suppressing DC terms and reducing a twin image in an in-line color digital holography. The speckle fields are changed by vibrating the multi-mode fiber using a vibrator, and a number of holograms are acquired to average reconstructed images. The dependence of the averaged number of holograms on color quality of reconstructed images is evaluated by chromaticity coordinates and color differences in colorimetry.

  13. Experimental Characterization of Correlation-Functions of Random Surfaces by Speckle Measurement and Complementary Algorithm

    Institute of Scientific and Technical Information of China (English)

    程传福; 刘曼; 滕树云; 宋洪胜; 陈建平; 徐至展

    2003-01-01

    A method for the extracting the correlation functions of random surfaces is proposed by using the image speckle intensity. Theoretically, we analyse the integral expression of average intensity of the image speckles, and compare it with the pair of Fourier-Bessel-transform-and-the-inversion of the exponential function of the height-height correlation function of the random surfaces. Then the algorithm is proposed numerically to complement the lacking Bessel function factor in the expression of the average speckle intensity, which changes the intensity data into the pair of the Fourier-Bessel-transform. Experimentally, we measure the average image speckle intensities versus the radius of the filtering aperture in the 4 f system and extract the height-height correlation function by using the proposed algorithm. The results of the practical measurements for three surface samples and the comparison with those by atomic force microscopy validate the feasibility of this method.

  14. 反远距成像相移剪切散斑干涉检测系统%Phase shifting and shearing speckle interferometry system with retro-focus imaging

    Institute of Scientific and Technical Information of China (English)

    朱猛; 李翔宇; 李秀明; 黄战华

    2014-01-01

    A retro-focus Michelson type shearing speckle interferometry imaging system was proposed to extend the field of view (FOV)for a speckle shearing interferometer.The retro-focus imaging system includes negative lens group and television lens.Analysis of the optical setup was taken out and the simulation was demonstrated by ZEMAX software.The phase shifting unit was a plane mirror attached with a piezo,the non-uniform phase difference caused by the tilted mirror was discussed.The equal-step Carre algorithm was used to calculate the phase map so that the non-uniform phase error was avoided.The experiment results of center loaded metal plane show this method can achieve large FOV detection system.A 70°FOV imaging system can be implemented by using three plano-concave lenses with -75mm focus length and the FOV can be adjusted by changing the focus length and number of lenses.%为了扩大传统剪切散斑干涉仪的检测视场,设计了一种反远距成像迈克尔逊式剪切散斑干涉系统。采用负透镜组与标准成像镜头组成反远距成像系统,分析了光路的成像参量,并利用 ZEMAX 软件进行了模拟;讨论了发散光路时间相移的非均匀性,采用等步长相移算法进行相位解算可以弥补非均匀误差;并对中心加载的橡胶平板进行了测量。结果表明,该系统能有效地扩大成像视场,采用3片焦距为-75mm 的平凹镜片可以实现70°视场角的散斑干涉检测,通过调整平凹镜片的焦距和数量可以实时调整成像视场。

  15. Adaptive image fusion based on nonsubsampled contourlet transform

    Science.gov (United States)

    Zhang, Xiongmei; Li, Junshan; Yi, Zhaoxiang; Yang, Wei

    2007-11-01

    Multiresolution-based image fusion has been the focus of considerable research attention in recent years with a number of algorithms proposed. In most of the algorithms, however, the parameter configuration is usually based on experience. This paper proposes an adaptive image fusion algorithm based on the nonsubsampled contourlet transform (NSCT), which realizes automatic parameter adjustment and gets rid of the adverse effect caused by artificial factors. The algorithm incorporates the quality metric of structural similarity (SSIM) into the NSCT fusion framework. The SSIM value is calculated to assess the fused image quality, and then it is fed back to the fusion algorithm to achieve a better fusion by directing parameters (level of decomposition and flag of decomposition direction) adjustment. Based on the cross entropy, the local cross entropy (LCE) is constructed and used to determine an optimal choice of information source for the fused coefficients at each scale and direction. Experimental results show that the proposed method achieves the best fusion compared to three other methods judged on both the objective metrics and visual inspection and exhibits robust against varying noises.

  16. Fast-adaptive near-lossless image compression

    Science.gov (United States)

    He, Kejing

    2016-05-01

    The purpose of image compression is to store or transmit image data efficiently. However, most compression methods emphasize the compression ratio rather than the throughput. We propose an encoding process and rules, and consequently a fast-adaptive near-lossless image compression method (FAIC) with good compression ratio. FAIC is a single-pass method, which removes bits from each codeword, then predicts the next pixel value through localized edge detection techniques, and finally uses Golomb-Rice codes to encode the residuals. FAIC uses only logical operations, bitwise operations, additions, and subtractions. Meanwhile, it eliminates the slow operations (e.g., multiplication, division, and logarithm) and the complex entropy coder, which can be a bottleneck in hardware implementations. Besides, FAIC does not depend on any precomputed tables or parameters. Experimental results demonstrate that FAIC achieves good balance between compression ratio and computational complexity in certain range (e.g., peak signal-to-noise ratio >35 dB, bits per pixel>2). It is suitable for applications in which the amount of data is huge or the computation power is limited.

  17. In vivo lateral blood flow velocity measurement using speckle size estimation.

    Science.gov (United States)

    Xu, Tiantian; Hozan, Mohsen; Bashford, Gregory R

    2014-05-01

    In previous studies, we proposed blood measurement using speckle size estimation, which estimates the lateral component of blood flow within a single image frame based on the observation that the speckle pattern corresponding to blood reflectors (typically red blood cells) stretches (i.e., is "smeared") if blood flow is in the same direction as the electronically controlled transducer line selection in a 2-D image. In this observational study, the clinical viability of ultrasound blood flow velocity measurement using speckle size estimation was investigated and compared with that of conventional spectral Doppler of carotid artery blood flow data collected from human patients in vivo. Ten patients (six male, four female) were recruited. Right carotid artery blood flow data were collected in an interleaved fashion (alternating Doppler and B-mode A-lines) with an Antares Ultrasound Imaging System and transferred to a PC via the Axius Ultrasound Research Interface. The scanning velocity was 77 cm/s, and a 4-s interval of flow data were collected from each subject to cover three to five complete cardiac cycles. Conventional spectral Doppler data were collected simultaneously to compare with estimates made by speckle size estimation. The results indicate that the peak systolic velocities measured with the two methods are comparable (within ±10%) if the scan velocity is greater than or equal to the flow velocity. When scan velocity is slower than peak systolic velocity, the speckle stretch method asymptotes to the scan velocity. Thus, the speckle stretch method is able to accurately measure pure lateral flow, which conventional Doppler cannot do. In addition, an initial comparison of the speckle size estimation and color Doppler methods with respect to computational complexity and data acquisition time indicated potential time savings in blood flow velocity estimation using speckle size estimation. Further studies are needed for calculation of the speckle stretch method

  18. 斑点追踪技术评价肥厚性心肌病左室收缩功能%Assessment of Left Ventricular Systolic Function in Hypertrophic Cardiomyopathy Using Speckle Tracking Imaging

    Institute of Scientific and Technical Information of China (English)

    尹丽; 郭丽苹; 薛炜

    2012-01-01

    目的 探讨斑点追踪技术(STI)评价肥厚性心肌病(HCM)患者左室心肌收缩功能的价值.资料与方法 选择无左室流出道梗阻、无明显临床症状、尚未接受临床干预性治疗的31例室间隔中上部肥厚性心肌病患者,同时采用随机数字表法选择30例健康成人作为对照组,采用Philips iE33彩色多普勒超声诊断仪,连接心电图,X3-1探头于心尖四腔切面采集实时三维超声图像,测量各组左室射血分数(LVEF);S5-1探头于短轴切面乳头肌水平采集二维灰阶图像,利用斑点追踪技术测量中段前间隔和间隔的局部收缩功能参数:心肌运动速率(S)、环向应变率(CSR)、径向应变率(RSR)、角速度(AV)、角位移(AE),测量该层面整体旋转角度峰值(BR).对两组间各参数进行比较.结果 HCM组与对照组LVEF比较,差异无统计学意义(P>0.05).与对照组比较,HCM组中段前间隔与间隔的S、CSR、RSR、AV减低,BR增加,AE增加,差异均有统计学意义(P<0.05).结论 斑点追踪技术能够无创、准确地评价肥厚性心肌病患者的局部心肌功能,为临床早期诊治提供有价值的信息.%Purpose To evaluate left ventricular systolic function of patients with hypertrophic cardiomyopathy (HCM) using speckle tracking imaging. Materials and Methods Thirty-one asymptomatic HCM patients with upper interventricular septum hypertrophy, but no left ventricular outflow obstruction was selected as HCM group before treatment. Thirty health persons were selected at random as control group. Left ventricular ejection fraction (LVEF) was detected by X3-1 probe at 4 chamber apex view using real time three-dimensional echocardiography. Regional systolic function parameters, including speed (S), circumferential strain rate (CSR), radial strain rate (RSR), angle velocity (AV), angle excursion (AE), and bulk rotation (BR), were detected by S5-1 probe at short axis view papillary muscle level using speckle tracking

  19. X-ray pulse wavefront metrology using speckle tracking.

    Science.gov (United States)

    Berujon, Sebastien; Ziegler, Eric; Cloetens, Peter

    2015-07-01

    An instrument allowing the quantitative analysis of X-ray pulsed wavefronts is presented and its processing method explained. The system relies on the X-ray speckle tracking principle to accurately measure the phase gradient of the X-ray beam from which beam optical aberrations can be deduced. The key component of this instrument, a semi-transparent scintillator emitting visible light while transmitting X-rays, allows simultaneous recording of two speckle images at two different propagation distances from the X-ray source. The speckle tracking procedure for a reference-less metrology mode is described with a detailed account on the advanced processing schemes used. A method to characterize and compensate for the imaging detector distortion, whose principle is also based on speckle, is included. The presented instrument is expected to find interest at synchrotrons and at the new X-ray free-electron laser sources under development worldwide where successful exploitation of beams relies on the availability of an accurate wavefront metrology.

  20. THE PROGRESSION OF TWO-DIMNSIONAL SPECKLE TRACKING IMAGING ON DIAGNOSTING VALUE OF CORONARY HEART DISEASE%二维斑点追踪成像技术在冠心病诊断中的研究进展

    Institute of Scientific and Technical Information of China (English)

    李淑玲; 张小杉; 皇甫卫忠; 张蕾

    2014-01-01

    Two dimensional speckle tracking automatic functional imaging techniques may obtain myocardial motion trajectory by identifying two-dimensional images of myocardial echo tracking. The technology not only can determine local myocardial longitudinal,axial and radial deformation capacity, but also assess global left ventricular torsion. This paper reviewed the technique for left ventricular regional,global cardiac function assessment and project of treatment with patients of coronary heart dis-ease.%二维斑点追踪自动功能成像技术通过识别二维图像的心肌回声斑点来追踪心肌的运动轨迹。我们通过该技术不仅能够判断心肌纵向、径向、轴向的变形能力,而且能够评价左室整体的运动状态,现就该技术对冠心病病人左室局部及整体心功能的评估、治疗方案选择等作一综述。

  1. Pattern matching and adaptive image segmentation applied to plant reproduction by tissue culture

    Science.gov (United States)

    Vazquez Rueda, Martin G.; Hahn, Federico

    1999-03-01

    This paper shows the results obtained in a system vision applied to plant reproduction by tissue culture using adaptive image segmentation and pattern matching algorithms, this analysis improves the number of tissue obtained and minimize errors, the image features of tissue are considered join to statistical analysis to determine the best match and results. Tests make on potato plants are used to present comparative results with original images processed with adaptive segmentation algorithm and non adaptive algorithms and pattern matching.

  2. A new optical pressure sensor interrogated by speckles pattern for oil industry

    Science.gov (United States)

    Sperandio, Vinicius M.; Pontes, Maria J.; Neto, Anselmo F.; Webster, Lucas G.

    2015-09-01

    A new optical pressure control concept in petroleum industry based on laser speckle analysis, with inherent safety light, is investigated in this work. A plastic optical fiber (POF) utilized to instrument a conventional manometer enabled pressure monitoring of a system that is interrogated by speckle photography technique. Specklegrams were imaged on a CCD camera and then analyzed, after Mathematical Morphology Filter, regarding its movement. Tests demonstrated that the speckle pattern movement is radial towards the center of pressure and accordingly reverse during depressurization within 5% maximum error.

  3. Photometric Calibration of the Gemini South Adaptive Optics Imager

    Science.gov (United States)

    Stevenson, Sarah Anne; Rodrigo Carrasco Damele, Eleazar; Thomas-Osip, Joanna

    2017-01-01

    The Gemini South Adaptive Optics Imager (GSAOI) is an instrument available on the Gemini South telescope at Cerro Pachon, Chile, utilizing the Gemini Multi-Conjugate Adaptive Optics System (GeMS). In order to allow users to easily perform photometry with this instrument and to monitor any changes in the instrument in the future, we seek to set up a process for performing photometric calibration with standard star observations taken across the time of the instrument’s operation. We construct a Python-based pipeline that includes IRAF wrappers for reduction and combines the AstroPy photutils package and original Python scripts with the IRAF apphot and photcal packages to carry out photometry and linear regression fitting. Using the pipeline, we examine standard star observations made with GSAOI on 68 nights between 2013 and 2015 in order to determine the nightly photometric zero points in the J, H, Kshort, and K bands. This work is based on observations obtained at the Gemini Observatory, processed using the Gemini IRAF and gemini_python packages, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).

  4. Adaptive optics retinal imaging in the living mouse eye.

    Science.gov (United States)

    Geng, Ying; Dubra, Alfredo; Yin, Lu; Merigan, William H; Sharma, Robin; Libby, Richard T; Williams, David R

    2012-04-01

    Correction of the eye's monochromatic aberrations using adaptive optics (AO) can improve the resolution of in vivo mouse retinal images [Biss et al., Opt. Lett. 32(6), 659 (2007) and Alt et al., Proc. SPIE 7550, 755019 (2010)], but previous attempts have been limited by poor spot quality in the Shack-Hartmann wavefront sensor (SHWS). Recent advances in mouse eye wavefront sensing using an adjustable focus beacon with an annular beam profile have improved the wavefront sensor spot quality [Geng et al., Biomed. Opt. Express 2(4), 717 (2011)], and we have incorporated them into a fluorescence adaptive optics scanning laser ophthalmoscope (AOSLO). The performance of the instrument was tested on the living mouse eye, and images of multiple retinal structures, including the photoreceptor mosaic, nerve fiber bundles, fine capillaries and fluorescently labeled ganglion cells were obtained. The in vivo transverse and axial resolutions of the fluorescence channel of the AOSLO were estimated from the full width half maximum (FWHM) of the line and point spread functions (LSF and PSF), and were found to be better than 0.79 μm ± 0.03 μm (STD)(45% wider than the diffraction limit) and 10.8 μm ± 0.7 μm (STD)(two times the diffraction limit), respectively. The axial positional accuracy was estimated to be 0.36 μm. This resolution and positional accuracy has allowed us to classify many ganglion cell types, such as bistratified ganglion cells, in vivo.

  5. Region-based retrieval of remote sensing image patches with adaptive image segmentation

    Science.gov (United States)

    Li, Shijin; Zhu, Jiali; Zhu, Yuelong; Feng, Jun

    2012-06-01

    Over the past four decades, the satellite imaging sensors have acquired huge quantities of Earth- observation data. Content-based image retrieval allows for fast and effective queries of remote sensing images. Here, we take the following two issues into consideration. Firstly, different features and their combination should be chosen for different land covers. Secondly, for the block dividing strategy and the complexities of the remote sensing images, it can not effectively retrieve some small target areas scattered in multiple nontarget blocks. Aiming at the above two issues, a new region-based retrieval method with adaptive image segmentation is proposed. In order to improve the accuracy of remote sensing image segmentation, feature selection and weighing is performed by two-stage clustering, and image segmentation is accomplished based on the chosen features and mean shift procedure. Meanwhile, for the homogeneous characteristics of remote sensing land covers, a new regional representation and matching scheme are adopted to perform image retrieval. Experimental results on retrieving various land covers show that the method can avoid the impact of traditional blocking strategies, and can achieve an average percentage of 19% higher precision with the same level of recall rate, than the relevance feedback method for small target areas.

  6. Evaluation of regional left ventricular function in patients with myocardial infarction by speckle tracking imaging%斑点追踪显像技术定量评价心肌梗死局部室壁运动异常

    Institute of Scientific and Technical Information of China (English)

    李胜; 汪太平; 徐岩; 史学功; 王其海; 金朝龙

    2009-01-01

    Objective To evaluate the clinical value of speckle tracking imaging in the measurement of two-dimensional strain in patients with myocardial infarction. Methods High frame rate two-dimensional echocardiography were performed in 30 healthy subjects,21patients with anterior myocardial infarction and 15 patients with inferior myocardial infarction. Longitudinal strain (LS), radial velocity (Vs), regional shortening fraction (RFS),radial strain (RS) were measured in the apical two-chamber view and short-axis view(the level of papillary muscle) using two-dimensional strain software. Results Compared with healthy subjects, LS, Vs, RFS, RS decreased in the segments with infarction(P<0.05). LS, Vs, RFS, RS of the two myocardial infarction groups had partly differences(P<0.05). Conclusions Regional wall motion of left ventricle in patients with myocardial infarction can be evaluated accurately with speckle tracking imaging.%目的 应用超声斑点追踪显像技术测量心肌梗死患者各节段室壁的二维应变,探讨其诊断局部室壁运动异常的临床应用价值.方法 30例正常人、21例前壁心肌梗死患者和15例下壁心肌梗死患者分别记录心尖位两腔观及左室乳头肌水平短轴观的高帧频图像,应用二维应变软件测量各节段的纵向应变(LS)、径向收缩期峰值速度(Vs)、局部短轴缩短分数(RFS)、径向应变(RS).结果 与正常组相比,心肌梗死各组心尖位节段LS、Vs、RFS、RS明显减低(P<0.05).心肌梗死组间比较,部分节段的LS、Vs、RFS、RS存在明显差异(P<0.05).结论 超声斑点追踪显像技术可准确评价节段性室壁运动异常,为临床评价心肌梗死患者左室收缩功能提供了无创性新方法.

  7. Edge Preserved Speckle Noise Reduction Using Integrated Fuzzy Filters.

    Science.gov (United States)

    Biradar, Nagashettappa; Dewal, M L; Rohit, Manoj Kumar

    2014-01-01

    Echocardiographic images are inherent with speckle noise which makes visual reading and analysis quite difficult. The multiplicative speckle noise masks finer details, necessary for diagnosis of abnormalities. A novel speckle reduction technique based on integration of geometric, wiener, and fuzzy filters is proposed and analyzed in this paper. The denoising applications of fuzzy filters are studied and analyzed along with 26 denoising techniques. It is observed that geometric filter retains noise and, to address this issue, wiener filter is embedded into the geometric filter during iteration process. The performance of geometric-wiener filter is further enhanced using fuzzy filters and the proposed despeckling techniques are called integrated fuzzy filters. Fuzzy filters based on moving average and median value are employed in the integrated fuzzy filters. The performances of integrated fuzzy filters are tested on echocardiographic images and synthetic images in terms of image quality metrics. It is observed that the performance parameters are highest in case of integrated fuzzy filters in comparison to fuzzy and geometric-fuzzy filters. The clinical validation reveals that the output images obtained using geometric-wiener, integrated fuzzy, nonlocal means, and details preserving anisotropic diffusion filters are acceptable. The necessary finer details are retained in the denoised echocardiographic images.

  8. Digital Speckle Technique Applied to Flow Visualization

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Digital speckle technique uses a laser, a CCD camera, and digital processing to generate interference fringes at the television framing rate. Its most obvious advantage is that neither darkroom facilities nor photographic wet chemical processing is required. In addition, it can be used in harsh engineering environments. This paper discusses the strengths and weaknesses of three digital speckle methodologies. (1) Digital speckle pattern interferometry (DSPI) uses an optical polarization phase shifter for visualization and measurement of the density field in a flow field. (2) Digital shearing speckle interferometry (DSSI) utilizes speckle-shearing interferometry in addition to optical polarization phase shifting. (3) Digital speckle photography (DSP) with computer reconstruction. The discussion describes the concepts, the principles and the experimental arrangements with some experimental results. The investigation shows that these three digital speckle techniques provide an excellent method for visualizing flow fields and for measuring density distributions in fluid mechanics and thermal flows.

  9. Improvement of speckle noise suppression in digital holography by rotating linear polarization state

    Institute of Scientific and Technical Information of China (English)

    Wen Xiao; Jing Zhang; Lu Rong; Feng Pan; Shuo Liu; Fanjing Wang; Aga He

    2011-01-01

    An improved polarization recording approach to reduce speckle noise in digital holography is proposed.Multiple off-axis holograms are obtained by rotating the linear polarization state of both illumination and reference wave simultaneously. By averaging the intensity fields, the speckle noise in the reconstructed images is well suppressed. Statistical evaluation of the experimental results shows the effectiveness and improvement of the proposed method.%@@ An improved polarization recording approach to reduce speckle noise in digital holography is proposed.Multiple off-axis holograms are obtained by rotating the linear polarization state of both illumination and reference wave simultaneously.By averaging the intensity fields, the speckle noise in the reconstructed images is well suppressed.Statistical evaluation of the experimental results shows the effectiveness and improvement of the proposed method.

  10. Progressive image data compression with adaptive scale-space quantization

    Science.gov (United States)

    Przelaskowski, Artur

    1999-12-01

    Some improvements of embedded zerotree wavelet algorithm are considere. Compression methods tested here are based on dyadic wavelet image decomposition, scalar quantization and coding in progressive fashion. Profitable coders with embedded form of code and rate fixing abilities like Shapiro EZW and Said nad Pearlman SPIHT are modified to improve compression efficiency. We explore the modifications of the initial threshold value, reconstruction levels and quantization scheme in SPIHT algorithm. Additionally, we present the result of the best filter bank selection. The most efficient biorthogonal filter banks are tested. Significant efficiency improvement of SPIHT coder was finally noticed even up to 0.9dB of PSNR in some cases. Because of the problems with optimization of quantization scheme in embedded coder we propose another solution: adaptive threshold selection of wavelet coefficients in progressive coding scheme. Two versions of this coder are tested: progressive in quality and resolution. As a result, improved compression effectiveness is achieved - close to 1.3 dB in comparison to SPIHT for image Barbara. All proposed algorithms are optimized automatically and are not time-consuming. But sometimes the most efficient solution must be found in iterative way. Final results are competitive across the most efficient wavelet coders.

  11. AN APPROACH TO SUPPRESS SPECKLE NOISE AND ENHANCE EDGE

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Anisotropic diffusion has good effect on reducing noise and preserving edge, but it may lose some details due to the blocky effect and can not suppress speckle effectively. The Laplacian factor is used to process the observed image which is considered as a piecewise planar image, so the Fourth Order Anisotropic Diffusion (FOAD) can avoid the blocky effect. The edge is preserved and enhanced by the Line Edge Detector (LED) based on stick technique and hypothesis test optimizing method. An approach called the Fourth Order Anisotropic Diffusion and Edge Enhancing (FOADEE), where the LED is combined with the FOAD, is presented. For quantitative evaluation and comparison with the LED, the FOAD and the FOADEE, two parameters as measure of the noise suppression and edge preservation are introduced. It is proved that the novel method can not only suppress speckle prominently but also preserve even enhance edge and useful details effectively by applying it to the phantoms and tissue images.

  12. Relation between strain dyssynchrony index determined by comprehensive assessment using speckle-tracking imaging and long-term outcome after cardiac resynchronization therapy for patients with heart failure.

    Science.gov (United States)

    Tatsumi, Kazuhiro; Tanaka, Hidekazu; Matsumoto, Kensuke; Kaneko, Akihiro; Tsuji, Takayuki; Ryo, Keiko; Fukuda, Yuko; Norisada, Kazuko; Onishi, Tetsuari; Yoshida, Akihiro; Kawai, Hiroya; Hirata, Ken-Ichi

    2012-04-15

    Strain dyssynchrony index (SDI), which was a marker of dyssynchrony and residual myocardial contractility, can predict left ventricular reverse remodeling short-term after cardiac resynchronization therapy (CRT). We investigated SDI-predicted long-term outcome after CRT in patients with heart failure (HF). We studied 74 patients with HF who underwent CRT. SDI was calculated as the average difference between peak and end-systolic strain from 6 segments for radial and circumferential SDIs and 18 segments for longitudinal SDI using 2-dimensional speckle-tracking strain. Based on our previous findings, the predefined cutoff for significant dyssynchrony and residual myocardial contractility was a radial SDI ≥6.5%, a circumferential SDI ≥3.2%, and a longitudinal SDI ≥3.6%. The predefined principal outcome variable was the combined end point of death or hospitalization owing to deteriorating HF. Long-term follow-up after CRT was tracked over 4 years. The primary end point of prespecified events occurred in 14 patients (19%). An association with a favorable long-term outcome after CRT was observed in patients with significant radial, circumferential, and longitudinal SDIs (p SDIs, respectively). Furthermore, cardiovascular event-free rate after CRT in patients with positivity of 3 for the 3 SDIs was 100% better than that in patients with positivity of 1 (52%, p SDIs. In conclusion, SDIs can successfully predict long-term outcome after CRT in patients with HF. Moreover, the approach combining the 3 types of SDI leads to a more accurate prediction than the use of individual parameters. These findings may have clinical implications in patients with CRT.

  13. Surface estimation methods with phased-arrays for adaptive ultrasonic imaging in complex components

    Science.gov (United States)

    Robert, S.; Calmon, P.; Calvo, M.; Le Jeune, L.; Iakovleva, E.

    2015-03-01

    Immersion ultrasonic testing of structures with complex geometries may be significantly improved by using phased-arrays and specific adaptive algorithms that allow to image flaws under a complex and unknown interface. In this context, this paper presents a comparative study of different Surface Estimation Methods (SEM) available in the CIVA software and used for adaptive imaging. These methods are based either on time-of-flight measurements or on image processing. We also introduce a generalized adaptive method where flaws may be fully imaged with half-skip modes. In this method, both the surface and the back-wall of a complex structure are estimated before imaging flaws.

  14. Penapisan Derau Gaussian, Speckle dan Salt&Pepper Pada Citra Warna

    OpenAIRE

    Purwanti Ningrum, Ika; Eko Putra, Agfianto; Nursantika, Dian

    2011-01-01

    Quality of digital image can decrease becouse some noises. Noise can come from lower quality of image recorder, disturb when transmission data process and weather. Noise filtering can make image better becouse will filtering that noise from the image and can improve quality of digital image. This research have aim to improve color image quality with filtering noise. Noise (Gaussian, Speckle, Salt&Pepper) will apply to original image, noise from image will filtering use Bilateral Filter method...

  15. AN ADAPTIVE DIGITAL IMAGE WATERMARK ALGORITHM BASED ON GRAY-SCALE MORPHOLOGY

    Institute of Scientific and Technical Information of China (English)

    Tong Ming; Hu Jia; Ji Hongbing

    2009-01-01

    An adaptive digital image watermark algorithm with strong robustness based on gray-scale morphology is proposed in this paper.The embedded strategies include:The algorithm seeks and extracts adaptively the image strong texture regions.The algorithm maps the image strong texture region to the wavelet tree structures,and embeds adaptively watermark into the wavelet coefficients corresponding to the image's strong texture regions.According to the visual masking features,the algorithm adjusts adaptively the watermark-embedding intensity.Experimental results show the algorithm is robust to compression,filtering,noise as well as strong shear attacks.The algorithm is blind watermark scheme.The image strong texture region extraction method based on morphology in this algorithm is simple and effective and adaptive to various images.

  16. Dynamic speckle interferometry of high-cycle material fatigue: Theory and some experiments

    Science.gov (United States)

    Vladimirov, A. P.

    2016-06-01

    The objective of this paper was theoretical analysis of speckle dynamics in the image plane of a thin transparent object. It was suggested that speckle dynamics develops in simultaneous periodic motion of the sample, micro- and macro-variations of its refraction index and its translational motion. The results of the theory were contrasted with the data obtained in the fatigue tests with transparent object.

  17. Speckle-based three-dimensional velocity measurement using spatial filtering velocimetry

    DEFF Research Database (Denmark)

    Iversen, Theis Faber Quist; Jakobsen, Michael Linde; Hanson, Steen Grüner

    2011-01-01

    We present an optical method for measuring the real-time three-dimensional (3D) translational velocity of a diffusely scattering rigid object observed through an imaging system. The method is based on a combination of the motion of random speckle patterns and regular fringe patterns. The speckle...... spatial filters designed to measure the three components of the object’s translational velocity. Furthermore, experimental data are presented that demonstrate full 3D velocity measurement....

  18. Acousto-electrical speckle pattern in Lorentz force electrical impedance tomography

    CERN Document Server

    Grasland-Mongrain, Pol; Mari, Jean-Martial; Souchon, Remi; Catheline, Stefan; Chapelon, Jean-Yves; Lafon, Cyril; Cloutier, Guy

    2015-01-01

    Ultrasound speckle is a granular texture pattern appearing in ultrasound imaging. It can be used to distinguish tissues and identify pathologies. Lorentz force electrical impedance tomography is an ultrasound-based medical imaging technique of the tissue electrical conductivity. It is based on the application of an ultrasound wave in a medium placed in a magnetic field and on the measurement of the induced electric current due to Lorentz force. Similarly to ultrasound imaging, we hypothesized that a speckle could be observed with Lorentz force electrical impedance tomography imaging. In this study, we first assessed the theoretical similarity between the measured signals in Lorentz force electrical impedance tomography and in ultrasound imaging modalities. We then compared experimentally the signal measured in both methods using an acoustic and electrical impedance interface. Finally, a bovine muscle sample was imaged using the two methods. Similar speckle patterns were observed. This indicates the existence ...

  19. Image-based adaptive optics for in vivo imaging in the hippocampus

    Science.gov (United States)

    Champelovier, D.; Teixeira, J.; Conan, J.-M.; Balla, N.; Mugnier, L. M.; Tressard, T.; Reichinnek, S.; Meimon, S.; Cossart, R.; Rigneault, H.; Monneret, S.; Malvache, A.

    2017-01-01

    Adaptive optics is a promising technique for the improvement of microscopy in tissues. A large palette of indirect and direct wavefront sensing methods has been proposed for in vivo imaging in experimental animal models. Application of most of these methods to complex samples suffers from either intrinsic and/or practical difficulties. Here we show a theoretically optimized wavefront correction method for inhomogeneously labeled biological samples. We demonstrate its performance at a depth of 200 μm in brain tissue within a sparsely labeled region such as the pyramidal cell layer of the hippocampus, with cells expressing GCamP6. This method is designed to be sample-independent thanks to an automatic axial locking on objects of interest through the use of an image-based metric that we designed. Using this method, we show an increase of in vivo imaging quality in the hippocampus. PMID:28220868

  20. Image-based adaptive optics for in vivo imaging in the hippocampus

    Science.gov (United States)

    Champelovier, D.; Teixeira, J.; Conan, J.-M.; Balla, N.; Mugnier, L. M.; Tressard, T.; Reichinnek, S.; Meimon, S.; Cossart, R.; Rigneault, H.; Monneret, S.; Malvache, A.

    2017-02-01

    Adaptive optics is a promising technique for the improvement of microscopy in tissues. A large palette of indirect and direct wavefront sensing methods has been proposed for in vivo imaging in experimental animal models. Application of most of these methods to complex samples suffers from either intrinsic and/or practical difficulties. Here we show a theoretically optimized wavefront correction method for inhomogeneously labeled biological samples. We demonstrate its performance at a depth of 200 μm in brain tissue within a sparsely labeled region such as the pyramidal cell layer of the hippocampus, with cells expressing GCamP6. This method is designed to be sample-independent thanks to an automatic axial locking on objects of interest through the use of an image-based metric that we designed. Using this method, we show an increase of in vivo imaging quality in the hippocampus.

  1. Speckle contrast diffuse correlation tomography of complex turbid medium flow

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chong; Irwin, Daniel; Lin, Yu; Shang, Yu; He, Lian; Kong, Weikai; Yu, Guoqiang [Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506 (United States); Luo, Jia [Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky 40506 (United States)

    2015-07-15

    Purpose: Developed herein is a three-dimensional (3D) flow contrast imaging system leveraging advancements in the extension of laser speckle contrast imaging theories to deep tissues along with our recently developed finite-element diffuse correlation tomography (DCT) reconstruction scheme. This technique, termed speckle contrast diffuse correlation tomography (scDCT), enables incorporation of complex optical property heterogeneities and sample boundaries. When combined with a reflectance-based design, this system facilitates a rapid segue into flow contrast imaging of larger, in vivo applications such as humans. Methods: A highly sensitive CCD camera was integrated into a reflectance-based optical system. Four long-coherence laser source positions were coupled to an optical switch for sequencing of tomographic data acquisition providing multiple projections through the sample. This system was investigated through incorporation of liquid and solid tissue-like phantoms exhibiting optical properties and flow characteristics typical of human tissues. Computer simulations were also performed for comparisons. A uniquely encountered smear correction algorithm was employed to correct point-source illumination contributions during image capture with the frame-transfer CCD and reflectance setup. Results: Measurements with scDCT on a homogeneous liquid phantom showed that speckle contrast-based deep flow indices were within 12% of those from standard DCT. Inclusion of a solid phantom submerged below the liquid phantom surface allowed for heterogeneity detection and validation. The heterogeneity was identified successfully by reconstructed 3D flow contrast tomography with scDCT. The heterogeneity center and dimensions and averaged relative flow (within 3%) and localization were in agreement with actuality and computer simulations, respectively. Conclusions: A custom cost-effective CCD-based reflectance 3D flow imaging system demonstrated rapid acquisition of dense boundary

  2. Gold-Speckled Multimodal Nanoparticles for Noninvasive Bioimaging

    Science.gov (United States)

    2008-01-01

    In this report the synthesis, characterization, and functional evaluation of a multimodal nanoparticulate contrast agent for noninvasive imaging through both magnetic resonance imaging (MRI) and photoacoustic tomography (PAT) is presented. The nanoparticles described herein enable high resolution and highly sensitive three-dimensional diagnostic imaging through the synergistic coupling of MRI and PAT capabilities. Gadolinium (Gd)-doped gold-speckled silica (GSS) nanoparticles, ranging from 50 to 200 nm, have been prepared in a simple one-pot synthesis using nonionic microemulsions. The photoacoustic signal is generated from a nonuniform, discontinuous gold nanodomains speckled across the silica surface, whereas the MR contrast is provided through Gd incorporated in the silica matrix. The presence of a discontinuous speckled surface, as opposed to a continuous gold shell, allows sufficient bulk water exchange with the Gd ions to generate a strong MR contrast. The dual imaging capabilities of the particles have been demonstrated through in silicio and in vitro methods. The described particles also have the capacity for therapeutic applications including the thermal ablation of tumors through the absorption of irradiated light. PMID:19466201

  3. Body Image Distortion and Exposure to Extreme Body Types: Contingent Adaptation and Cross Adaptation for Self and Other.

    Science.gov (United States)

    Brooks, Kevin R; Mond, Jonathan M; Stevenson, Richard J; Stephen, Ian D

    2016-01-01

    Body size misperception is common amongst the general public and is a core component of eating disorders and related conditions. While perennial media exposure to the "thin ideal" has been blamed for this misperception, relatively little research has examined visual adaptation as a potential mechanism. We examined the extent to which the bodies of "self" and "other" are processed by common or separate mechanisms in young women. Using a contingent adaptation paradigm, experiment 1 gave participants prolonged exposure to images both of the self and of another female that had been distorted in opposite directions (e.g., expanded other/contracted self), and assessed the aftereffects using test images both of the self and other. The directions of the resulting perceptual biases were contingent on the test stimulus, establishing at least some separation between the mechanisms encoding these body types. Experiment 2 used a cross adaptation paradigm to further investigate the extent to which these mechanisms are independent. Participants were adapted either to expanded or to contracted images of their own body or that of another female. While adaptation effects were largest when adapting and testing with the same body type, confirming the separation of mechanisms reported in experiment 1, substantial misperceptions were also demonstrated for cross adaptation conditions, demonstrating a degree of overlap in the encoding of self and other. In addition, the evidence of misperception of one's own body following exposure to "thin" and to "fat" others demonstrates the viability of visual adaptation as a model of body image disturbance both for those who underestimate and those who overestimate their own size.

  4. Body Image Distortion and Exposure to Extreme Body Types: Contingent Adaptation and Cross Adaptation for Self and Other

    Directory of Open Access Journals (Sweden)

    Kevin R. Brooks

    2016-07-01

    Full Text Available Body size misperception is common amongst the general public and is a core component of eating disorders and related conditions. While perennial media exposure to the thin ideal has been blamed for this misperception, relatively little research has examined visual adaptation as a potential mechanism. We examined the extent to which the bodies of self and other are processed by common or separate mechanisms in young women. Using a contingent adaptation paradigm, experiment 1 gave participants prolonged exposure to images both of the self and of another female that had been distorted in opposite directions (e.g. expanded other/contracted self, and assessed the aftereffects using test images both of the self and other. The directions of the resulting perceptual biases were contingent on the test stimulus, establishing at least some separation between the mechanisms encoding these body types. Experiment 2 used a cross adaptation paradigm to further investigate the extent to which these mechanisms are independent. Participants were adapted either to expanded or to contracted images of their own body or that of another female. While adaptation effects were largest when adapting and testing with the same body type, confirming the separation of mechanisms reported in experiment 1, substantial misperceptions were also demonstrated for cross adaptation conditions, demonstrating a degree of overlap in the encoding of self and other. In addition, the evidence of misperception of one’s own body following exposure to thin and to fat others demonstrates the viability of visual adaptation as a model of body image disturbance both for those who underestimate and those who overestimate their own size.

  5. Speckle reference beam holographic and speckle photographic interferometry in non-destructive test systems

    Science.gov (United States)

    Liu, H. K.

    1976-01-01

    The techniques of speckle beam holographic interferometry and speckle photographic interferometry are described. In particular, their practical limitations and their applications to the existing holographic nondestructive test system are discussed.

  6. Restoration and enhancement of textural properties in SAR images using second-order statistics

    Science.gov (United States)

    Nezry, Edmond; Kohl, Hans-Guenther; De Groof, Hugo

    1994-12-01

    Local second order properties, describing spatial relations between pixels are introduced into the single-point speckle adaptive filtering processes, in order to account for the effects of speckle spatial correlation and to enhance scene textural properties in the restored image. To this end, texture measures originating, first from local grey level co-occurrence matrices (GLCM), and second from the local autocorrelation functions (ACF) are used. Results obtained on 3-look processed ERS-1 FDC and PRI spaceborne images illustrate the performance allowed by the introduction of these texture measures in the structure retaining speckle adaptive filters. The observable texture in remote sensing images is related to the physical spatial resolution of the sensor. For this reason, other spatial speckle decorrelation methods, more simple and easier to implement, for example post-filtering and linear image resampling, are also presented in this paper. In the particular case of spaceborne SAR imagery, all these methods lead to visually similar results. They produce filtered (radar reflectivity) images visually comparable to optical images.

  7. Laser speckle reduction by phase range limited computer generated hologram in laser projection display system.

    Science.gov (United States)

    Chang, Yan-Shuo; Lin, Chia-Hsin; Hsu, Ku-Hui; Hsu, Wei-Feng; Hsiao, Li-Jen; Lin, Hoang Yan

    2014-09-20

    The speckle phenomenon is an annoyance in laser projection display systems. We propose a novel speckle suppression method that utilizes the interference concept on a pixel point, which reduces the speckle contrast (SC) of the project image by limiting the phase distribution range in the optical field. The SC formula is derived in the uniform interval phase range for partially developed speckle conditions, showing that the SC can be lowered by lessening the phase range limitation. In the ideal simulation model, the SC can be reduced from 98.77% to 0% as the phase range limitation varies from 2π to 0. The phase range limitation model is a novel method using a computer generated hologram to provide beam shaping and phase limitation. In a more realistic simulation model, the SC is reduced from 99.18% to 16.68%.

  8. Fabrication of nanoscale speckle using broad ion beam milling on polymers for deformation analysis

    Directory of Open Access Journals (Sweden)

    Qinghua Wang

    2016-07-01

    Full Text Available We first report a fabrication technique of nanoscale speckle patterns on polymers using broad ion beam milling. The proposed technique is simple and low-cost to produce speckles ranging from dozens of nanometers to less than three micrometers in a large area of several millimeters. Random patterns were successfully produced with an argon (Ar ion beam on the surfaces of four kinds of polymers: the epoxy matrix of carbon fiber reinforced plastic, polyester, polyvinyl formal-acetal, and polyimide. The speckle morphologies slightly vary with different polymers. The fabricated speckle patterns have good time stability and are promising to be used to measure the nanoscale deformations of polymers using the digital image correlation method.

  9. Adaptive field-of-view imaging for efficient receive beamforming in medical ultrasound imaging systems.

    Science.gov (United States)

    Agarwal, Anup; Yoo, Yang Mo; Schneider, Fabio Kurt; Kim, Yongmin

    2008-09-01

    Quadrature demodulation-based phase rotation beamforming (QD-PRBF) is commonly used to support dynamic receive focusing in medical ultrasound systems. However, it is computationally demanding since it requires two demodulation filters for each receive channel. To reduce the computational requirements of QD-PRBF, we have previously developed two-stage demodulation (TSD), which reduces the number of lowpass filters by performing demodulation filtering on summation signals. However, it suffers from image quality degradation due to aliasing at lower beamforming frequencies. To improve the performance of TSD-PRBF with reduced number of beamforming points, we propose a new adaptive field-of-view (AFOV) imaging method. In AFOV imaging, the beamforming frequency is adjusted depending on displayed FOV size and the center frequency of received signals. To study its impact on image quality, simulation was conducted using Field II, phantom data were acquired from a commercial ultrasound machine, and the image quality was quantified using spatial (i.e., axial and lateral) and contrast resolution. The developed beamformer (i.e., TSD-AFOV-PRBF) with 1024 beamforming points provided comparable image resolution to QD-PRBF for typical FOV sizes (e.g., 4.6% and 1.3% degradation in contrast resolution for 160 mm and 112 mm, respectively for a 3.5 MHz transducer). Furthermore, it reduced the number of operations by 86.8% compared to QD-PRBF. These results indicate that the developed TSD-AFOV-PRBF can lower the computational requirement for receive beamforming without significant image quality degradation.

  10. Rician noise reduction in magnetic resonance images using adaptive non-local mean and guided image filtering

    Science.gov (United States)

    Mahmood, Muhammad Tariq; Chu, Yeon-Ho; Choi, Young-Kyu

    2016-06-01

    This paper proposes a Rician noise reduction method for magnetic resonance (MR) images. The proposed method is based on adaptive non-local mean and guided image filtering techniques. In the first phase, a guidance image is obtained from the noisy image through an adaptive non-local mean filter. Sobel operators are applied to compute the strength of edges which is further used to control the spread of the kernel in non-local mean filtering. In the second phase, the noisy and the guidance images are provided to the guided image filter as input to restore the noise-free image. The improved performance of the proposed method is investigated using the simulated and real data sets of MR images. Its performance is also compared with the previously proposed state-of-the art methods. Comparative analysis demonstrates the superiority of the proposed scheme over the existing approaches.

  11. Statistics of spatially integrated speckle intensity difference

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner; Yura, Harold

    2009-01-01

    We consider the statistics of the spatially integrated speckle intensity difference obtained from two separated finite collecting apertures. For fully developed speckle, closed-form analytic solutions for both the probability density function and the cumulative distribution function are derived...... here for both arbitrary values of the mean number of speckles contained within an aperture and the degree of coherence of the optical field. Additionally, closed-form expressions are obtained for the corresponding nth statistical moments....

  12. 斑点追踪技术评价缺血心肌短轴缩短率和圆周应变%Evaluation of Regional Shortening Fraction and Circumferential Strain in Patients with Myocardial Ischemia by Speckle Tracking Imaging

    Institute of Scientific and Technical Information of China (English)

    何艳; 王东平; 陈金国; 张娜; 杨体霞; 张军; 周利民

    2012-01-01

    目的 运用斑点追踪技术(STI)测量缺血心肌的短轴缩短率和圆周应变值,探讨其在诊断心肌缺血,评价心肌功能中的应用价值.方法 对29例心肌缺血患者(冠状动脉狭窄≥75%)和28例正常对照组(冠状动脉没有狭窄)分别行超声心动图检查,采集并记录左室短轴观(二尖瓣水平)的高帧频动态二维灰阶图像,应用二维应变分析软件进行脱机分析,系统自动将左室短轴分为前间隔、前壁、侧壁、后壁、下壁、后间隔6个节段,并给出应变曲线,分别测量各节段心肌的短轴缩短率和圆周应变值.结果 正常对照组的圆周应变曲线是负向峰值曲线,短轴缩短率曲线是正向峰值曲线,整组曲线排列较整齐;而心肌缺血组的应变曲线形态不规则.心肌缺血组圆周应变和短轴缩短率均低于正常对照组,差异有统计学意义(P<0.05).结论 斑点追踪技术能对心肌的二维应变进行定量分析,为临床诊断心肌缺血,评价心肌功能提供了无创性新方法.%Objective To evaluate the clinical value of speckle tracking imaging in the measurement of regional shortening fraction and circumferential strain in patients with myocardial ischemia. Methods Twenty-nine patients with myocardial ischemia and twenty-eight healthy subjects underwent echocardiography,high frame rate two-dimensional images were recorded from the left ventricular short-axis views at the levels of mitral annulus, regional shortening fraction and circumferential strain were measured in the left ventricular short-axis views using two-dimensional strain software. Results Circumferential strain curve, regional shortening fraction curve in healthy group changed regularly, while in myocardial ischemia patients, the curve changed irregularly. Regional shortening fraction and circumferential strain in myocardial ischemia patients showed significant reduction compared with normal myocardium(P<0.05). Conclusion Speckle

  13. Tracking speckle displacement by double Kalman filtering

    Institute of Scientific and Technical Information of China (English)

    Donghui Li; Li Guo

    2006-01-01

    @@ A tracking technique using two sequentially-connected Kalman filter for tracking laser speckle displacement is presented. One Kalman filter tracks temporal speckle displacement, while another Kalman filter tracks spatial speckle displacement. The temporal Kalman filter provides a prior for the spatial Kalman filter, and the spatial Kalman filter provides measurements for the temporal Kalman filter. The contribution of a prior to estimations of the spatial Kalman filter is analyzed. An optical analysis system was set up to verify the double-Kalman-filter tracker's ability of tracking laser speckle's constant displacement.

  14. Wavelength-Adaptive Dehazing Using Histogram Merging-Based Classification for UAV Images

    Directory of Open Access Journals (Sweden)

    Inhye Yoon

    2015-03-01

    Full Text Available Since incoming light to an unmanned aerial vehicle (UAV platform can be scattered by haze and dust in the atmosphere, the acquired image loses the original color and brightness of the subject. Enhancement of hazy images is an important task in improving the visibility of various UAV images. This paper presents a spatially-adaptive dehazing algorithm that merges color histograms with consideration of the wavelength-dependent atmospheric turbidity. Based on the wavelength-adaptive hazy image acquisition model, the proposed dehazing algorithm consists of three steps: (i image segmentation based on geometric classes; (ii generation of the context-adaptive transmission map; and (iii intensity transformation for enhancing a hazy UAV image. The major contribution of the research is a novel hazy UAV image degradation model by considering the wavelength of light sources. In addition, the proposed transmission map provides a theoretical basis to differentiate visually important regions from others based on the turbidity and merged classification results.

  15. Color Histograms Adapted to Query-Target Images for Object Recognition across Illumination Changes

    Directory of Open Access Journals (Sweden)

    Jack-Gérard Postaire

    2005-08-01

    Full Text Available Most object recognition schemes fail in case of illumination changes between the color image acquisitions. One of the most widely used solutions to cope with this problem is to compare the images by means of the intersection between invariant color histograms. The main originality of our approach is to cope with the problem of illumination changes by analyzing each pair of query and target images constructed during the retrieval, instead of considering each image of the database independently from each other. In this paper, we propose a new approach which determines color histograms adapted to each pair of images. These adapted color histograms are obtained so that their intersection is higher when the two images are similar than when they are different. The adapted color histograms processing is based on an original model of illumination changes based on rank measures of the pixels within the color component images.

  16. Wavelength-adaptive dehazing using histogram merging-based classification for UAV images.

    Science.gov (United States)

    Yoon, Inhye; Jeong, Seokhwa; Jeong, Jaeheon; Seo, Doochun; Paik, Joonki

    2015-03-19

    Since incoming light to an unmanned aerial vehicle (UAV) platform can be scattered by haze and dust in the atmosphere, the acquired image loses the original color and brightness of the subject. Enhancement of hazy images is an important task in improving the visibility of various UAV images. This paper presents a spatially-adaptive dehazing algorithm that merges color histograms with consideration of the wavelength-dependent atmospheric turbidity. Based on the wavelength-adaptive hazy image acquisition model, the proposed dehazing algorithm consists of three steps: (i) image segmentation based on geometric classes; (ii) generation of the context-adaptive transmission map; and (iii) intensity transformation for enhancing a hazy UAV image. The major contribution of the research is a novel hazy UAV image degradation model by considering the wavelength of light sources. In addition, the proposed transmission map provides a theoretical basis to differentiate visually important regions from others based on the turbidity and merged classification results.

  17. Blood Vessels Extraction in Retinal Image Using New Generation Curvelet Transform and Adaptive Weighted Morphology Operators

    Directory of Open Access Journals (Sweden)

    Saleh Shahbeig

    2013-02-01

    Full Text Available According to many medical and biometric applications of retinal images, the automatic and accurate extraction of the retinal blood vessels is very important. In this paper, an effective method is introduced to extract the blood vessels from the background of colored images of retina. In this algorithm, by applying the equalizer function on the retinal images, the brightness of the images is considerably uniformed. Because of high ability of Curvelet transform in introducing image borders in various scale and directions, borders and, consequently the contrast of retinal images can be enhanced. Therefore, the enhanced retinal image can be prepared for the extraction of blood vessels by improving Curvelet coefficients of the retinal images, adaptively and locally. Since the blood vessels in retinal images are distributed in various directions, we use the adaptive weighted morphology operators to extract the blood vessels from retinal images. Morphology operators based on reconstruction are used to refine the appeared frills with the size of smaller than arterioles in images properly. Finally, by analyzing the connected component in the images and applying adaptive filter on the components locally, all residual frills are refined from the images. The proposed algorithm in this paper has been evaluated by the images in the DRIVE database. The results how that the blood vessels are extracted from background of the retinal images of DRIVE database with the high accuracy of 96.15%, which in turn shows the high ability of the proposed algorithm in extracting the retinal blood vessels.

  18. A mobile communication device adapted to provide a dynamic display arrangement

    DEFF Research Database (Denmark)

    2011-01-01

    The invention relates to a mobile communication device comprising a light projector adapted to project a multi-coloured image onto a surface; a hinged mirror comprising a first mirror part adapted to be tilted around the hinge into the light path of the light projector; wherein the first mirror...... part comprises means for correcting a skew angle in the multi-coloured image projected onto a surface. Thereby is achieved that the mobile communication device is able to provide RGB full colour dynamic image projection which is preferred over monochromatic laser projection because it is a speckle free...

  19. 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.

  20. Application of adaptive wavelet transforms via lifting in image data compression

    Science.gov (United States)

    Ye, Shujiang; Zhang, Ye; Liu, Baisen

    2008-10-01

    The adaptive wavelet transforms via lifting is proposed. In the transform, update filter is selected by the signal's character. Perfect reconstruction is possible without any overhead cost. To make sure the system's stability, in the lifting scheme of adaptive wavelet, update step is placed before prediction step. The Adaptive wavelet transforms via lifting is benefit for the image compression, because of the high stability, the small coefficients of high frequency parts, and the perfect reconstruction. With the adaptive wavelet transforms via lifting and the SPIHT, the image compression is realized in this paper, and the result is pleasant.

  1. Spatiotonal adaptivity in super-resolution of under-sampled image sequences

    NARCIS (Netherlands)

    Pham, T.Q.

    2006-01-01

    This thesis concerns the use of spatial and tonal adaptivity in improving the resolution of aliased image sequences under scene or camera motion. Each of the five content chapters focuses on a different subtopic of super-resolution: image registration (chapter 2), image fusion (chapter 3 and 4), sup

  2. High contrast imaging of exoplanets on ELTs using a super-Nyquist wavefront control scheme

    CERN Document Server

    Gerard, Benjamin L

    2016-01-01

    One of the key science goals for extremely large telescopes (ELTs) is the detailed characterization of already known directly imaged exoplanets. The typical adaptive optics (AO) Nyquist control region for ELTs is ~0.4 arcseconds, placing many already known directly imaged planets outside the DM control region and not allowing any standard wavefront control scheme to remove speckles that would allow higher SNR images/spectra to be acquired. This can be fixed with super-Nyquist wavefront control (SNWFC), using a sine wave phase plate to allow for wavefront control outside the central DM Nyquist region. We demonstrate that SNWFC is feasible through a simple, deterministic, non-coronagraphic, super-Nyquist speckle nulling technique in the adaptive optics laboratory at the National Research Council of Canada. We also present results in simulation of how SNWFC using the self coherent camera (SCC) can be used for high contrast imaging. This technique could be implemented on future high contrast imaging instruments t...

  3. Block-Based Adaptive Vector Lifting Schemes for Multichannel Image Coding

    Directory of Open Access Journals (Sweden)

    Amel Benazza-Benyahia

    2007-04-01

    Full Text Available We are interested in lossless and progressive coding of multispectral images. To this respect, nonseparable vector lifting schemes are used in order to exploit simultaneously the spatial and the interchannel similarities. The involved operators are adapted to the image contents thanks to block-based procedures grounded on an entropy optimization criterion. A vector encoding technique derived from EZW allows us to further improve the efficiency of the proposed approach. Simulation tests performed on remote sensing images show that a significant gain in terms of bit rate is achieved by the resulting adaptive coding method with respect to the non-adaptive one.

  4. Block-Based Adaptive Vector Lifting Schemes for Multichannel Image Coding

    Directory of Open Access Journals (Sweden)

    Pesquet Jean-Christophe

    2007-01-01

    Full Text Available We are interested in lossless and progressive coding of multispectral images. To this respect, nonseparable vector lifting schemes are used in order to exploit simultaneously the spatial and the interchannel similarities. The involved operators are adapted to the image contents thanks to block-based procedures grounded on an entropy optimization criterion. A vector encoding technique derived from EZW allows us to further improve the efficiency of the proposed approach. Simulation tests performed on remote sensing images show that a significant gain in terms of bit rate is achieved by the resulting adaptive coding method with respect to the non-adaptive one.

  5. Spatially adaptive migration tomography for multistatic GPR imaging

    Science.gov (United States)

    Paglieroni, David W; Beer, N. Reginald

    2013-08-13

    A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

  6. In vivo burn diagnosis by camera-phone diffuse reflectance laser speckle detection.

    Science.gov (United States)

    Ragol, S; Remer, I; Shoham, Y; Hazan, S; Willenz, U; Sinelnikov, I; Dronov, V; Rosenberg, L; Bilenca, A

    2016-01-01

    Burn diagnosis using laser speckle light typically employs widefield illumination of the burn region to produce two-dimensional speckle patterns from light backscattered from the entire irradiated tissue volume. Analysis of speckle contrast in these time-integrated patterns can then provide information on burn severity. Here, by contrast, we use point illumination to generate diffuse reflectance laser speckle patterns of the burn. By examining spatiotemporal fluctuations in these time-integrated patterns along the radial direction from the incident point beam, we show the ability to distinguish partial-thickness burns in a porcine model in vivo within the first 24 hours post-burn. Furthermore, our findings suggest that time-integrated diffuse reflectance laser speckle can be useful for monitoring burn healing over time post-burn. Unlike conventional diffuse reflectance laser speckle detection systems that utilize scientific or industrial-grade cameras, our system is designed with a camera-phone, demonstrating the potential for burn diagnosis with a simple imager.

  7. An Image Enhancement Method Using the Quantum-Behaved Particle Swarm Optimization with an Adaptive Strategy

    Directory of Open Access Journals (Sweden)

    Xiaoping Su

    2013-01-01

    Full Text Available Image enhancement techniques are very important to image processing, which are used to improve image quality or extract the fine details in degraded images. In this paper, two novel objective functions based on the normalized incomplete Beta transform function are proposed to evaluate the effectiveness of grayscale image enhancement and color image enhancement, respectively. Using these objective functions, the parameters of transform functions are estimated by the quantum-behaved particle swarm optimization (QPSO. We also propose an improved QPSO with an adaptive parameter control strategy. The QPSO and the AQPSO algorithms, along with genetic algorithm (GA and particle swarm optimization (PSO, are tested on several benchmark grayscale and color images. The results show that the QPSO and AQPSO perform better than GA and PSO for the enhancement of these images, and the AQPSO has some advantages over QPSO due to its adaptive parameter control strategy.

  8. Numerical simulation package for speckle metrology

    Science.gov (United States)

    Kornis, Janos; Bokor, Nandor; Nemeth, Attila

    1998-09-01

    A computer program package for numerical simulation of speckle phenomena has been developed. It is suitable for simulating both objective and subjective speckle effects in various optical setups. Several simulation results are presented in this paper. The simulations was made in UNIX and Windows NT environment.

  9. Adaptive mesh generation for image registration and segmentation

    DEFF Research Database (Denmark)

    Fogtmann, Mads; Larsen, Rasmus

    2013-01-01

    This paper deals with the problem of generating quality tetrahedral meshes for image registration. From an initial coarse mesh the approach matches the mesh to the image volume by combining red-green subdivision and mesh evolution through mesh-to-image matching regularized with a mesh quality...

  10. Demonstration Of Synthetic Exo-earth Detection In The Lab With Speckle Subtraction Techniques

    Science.gov (United States)

    Belikov, Ruslan; Give'on, A.; Savransky, D.; Pueyo, L.; Kern, B.; Kasdin, J.

    2007-12-01

    The problem of detecting and imaging earth-like exoplanets is hampered by the fact that wavefront error in the optics of a space telescope creates a speckle pattern that can swamp the exoplanet. The standard approach for dealing with speckles is to suppress them below the planet level by a deformable mirror using a wavefront control algorithm. However, such wavefront control may take a long time to achieve speckle suppression of 1010, the nominal contrast necessary for exo-earths, especially if the target star is dim. Furthermore, a very precise deformable mirror and electronics are required. In this paper, we present and demonstrate in the lab a method to detect planet light from amidst a brighter speckle pattern (as long as that pattern is stable), thus relaxing the requirement of 1010 speckle suppression. Furthermore, our detection is simultaneous with wavefront control and uses all the images taken in the course of wavefront control, saving valuable mission time. The method consists of (a) using the wavefront control estimate of the coherent speckle field to separate the speckles from the incoherent planet light, and (b) using a matched filter to reduce noise. No motion or rotation of the telescope is required for this method. The experiment was conducted on the High Contrast Imaging Testbed at the Jet Propulsion Lab using the Shaped Pupil coronagraph under 10% optical bandwidth. This work was funded in part by JPL contract 1254357 and the Michelson Science Center, and carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  11. The role of the microprocessor in onboard image processing for the information adaptive system

    Science.gov (United States)

    Kelly, W. L., IV; Meredith, B. D.

    1980-01-01

    The preliminary design of the Information Adaptive System is presented. The role of the microprocessor in the implementation of the individual processing elements is discussed. Particular emphasis is placed on multispectral image data processing.

  12. AVES-IMCO: an adaptive optics visible spectrograph and imager/coronograph for NAOS

    Science.gov (United States)

    Beuzit, Jean-Luc; Lagrange, A.-M.; Mouillet, D.; Chauvin, G.; Stadler, E.; Charton, J.; Lacombe, F.; AVES-IMCO Team

    2001-05-01

    The NAOS adaptive optics system will very soon provide diffraction-limited images on the VLT, down to the visible wavelengths (0.020 arcseconds at 0.83 micron for instance). At the moment, the only instrument dedicated to NAOS is the CONICA spectro-imager, operating in the near-infrared from 1 to 5 microns. We are now proposing to ESO, in collaboration with an Italian group, the development of a visible spectrograph/imager/coronograph, AVES-IMCO (Adaptive Optics Visual Echelle Spectrograph and IMager/COronograph). We present here the general concept of the new instrument as well as its expected performances in the different modes.

  13. Adaptive optics OCT using 1060nm swept source and dual deformable lenses for human retinal imaging

    Science.gov (United States)

    Jian, Yifan; Lee, Sujin; Cua, Michelle; Miao, Dongkai; Bonora, Stefano; Zawadzki, Robert J.; Sarunic, Marinko V.

    2016-03-01

    Adaptive optics concepts have been applied to the advancement of biological imaging and microscopy. In particular, AO has also been very successfully applied to cellular resolution imaging of the retina, enabling visualization of the characteristic mosaic patterns of the outer retinal layers using flood illumination fundus photography, Scanning Laser Ophthalmoscopy (SLO), and Optical Coherence Tomography (OCT). Despite the high quality of the in vivo images, there has been a limited uptake of AO imaging into the clinical environment. The high resolution afforded by AO comes at the price of limited field of view and specialized equipment. The implementation of a typical adaptive optics imaging system results in a relatively large and complex optical setup. The wavefront measurement is commonly performed using a Hartmann-Shack Wavefront Sensor (HS-WFS) placed at an image plane that is optically conjugated to the eye's pupil. The deformable mirror is also placed at a conjugate plane, relaying the wavefront corrections to the pupil. Due to the sensitivity of the HS-WFS to back-reflections, the imaging system is commonly constructed from spherical mirrors. In this project, we present a novel adaptive optics OCT retinal imaging system with significant potential to overcome many of the barriers to integration with a clinical environment. We describe in detail the implementation of a compact lens based wavefront sensorless adaptive optics (WSAO) 1060nm swept source OCT human retinal imaging system with dual deformable lenses, and present retinal images acquired in vivo from research volunteers.

  14. Overcoming turbulence-induced space-variant blur by using phase-diverse speckle.

    Science.gov (United States)

    Thelen, Brian J; Paxman, Richard G; Carrara, David A; Seldin, John H

    2009-01-01

    Space-variant blur occurs when imaging through volume turbulence over sufficiently large fields of view. Space-variant effects are particularly severe in horizontal-path imaging, slant-path (air-to-ground or ground-to-air) geometries, and ground-based imaging of low-elevation satellites or astronomical objects. In these geometries, the isoplanatic angle can be comparable to or even smaller than the diffraction-limited resolution angle. We report on a postdetection correction method that seeks to correct for the effects of space-variant aberrations, with the goal of reconstructing near-diffraction-limited imagery. Our approach has been to generalize the method of phase-diverse speckle (PDS) by using a physically motivated distributed-phase-screen model. Simulation results are presented that demonstrate the reconstruction of near-diffraction-limited imagery under both matched and mismatched model assumptions. In addition, we present evidence that PDS could be used as a beaconless wavefront sensor in a multiconjugate adaptive optics system when imaging extended scenes.

  15. An adaptive fusion strategy of polarization image based on NSCT

    Science.gov (United States)

    Zhao, Chang-xia; Duan, Jin; Mo, Chun-he; Chen, Guang-qiu; Fu, Qiang

    2015-03-01

    An improved image fusion algorithm based on the NSCT is proposed in this paper. After decomposition NSCT method of multi-scale and multiple directions, polarization image was decomposed into two parts: low frequency sub-band and high frequency band-pass images. The fusion strategy of combining local regional energy and gradient structure similarity were used in low-frequency coefficients. While in the high-frequency band-pass coefficients part, the fusion strategy of the location spatial frequency as the correlation coefficient was used. The intensity image and polarization degree image are fused for improving the sharpness and contrast of the image. The experiments show that the algorithm is effective to improve the imaging quality in the turbid medium.

  16. Probing the functions of contextual modulation by adapting images rather than observers.

    Science.gov (United States)

    Webster, Michael A

    2014-11-01

    Countless visual aftereffects have illustrated how visual sensitivity and perception can be biased by adaptation to the recent temporal context. This contextual modulation has been proposed to serve a variety of functions, but the actual benefits of adaptation remain uncertain. We describe an approach we have recently developed for exploring these benefits by adapting images instead of observers, to simulate how images should appear under theoretically optimal states of adaptation. This allows the long-term consequences of adaptation to be evaluated in ways that are difficult to probe by adapting observers, and provides a common framework for understanding how visual coding changes when the environment or the observer changes, or for evaluating how the effects of temporal context depend on different models of visual coding or the adaptation processes. The approach is illustrated for the specific case of adaptation to color, for which the initial neural coding and adaptation processes are relatively well understood, but can in principle be applied to examine the consequences of adaptation for any stimulus dimension. A simple calibration that adjusts each neuron's sensitivity according to the stimulus level it is exposed to is sufficient to normalize visual coding and generate a host of benefits, from increased efficiency to perceptual constancy to enhanced discrimination. This temporal normalization may also provide an important precursor for the effective operation of contextual mechanisms operating across space or feature dimensions. To the extent that the effects of adaptation can be predicted, images from new environments could be "pre-adapted" to match them to the observer, eliminating the need for observers to adapt.

  17. SOAR Adaptive Module (SAM): Seeing Improvement with a UV Laser

    Science.gov (United States)

    Tokovinin, Andrei; Cantarutti, Rolando; Tighe, Roberto; Schurter, Patricio; Martinez, Manuel; Thomas, Sandrine; van der Bliek, Nicole

    2016-12-01

    The adaptive module of the 4.1 m SOAR telescope, SOAR Adaptive Module (SAM), corrects ground-layer turbulence using an ultraviolet laser guide star. It has been commissioned in 2013 and it is in regular science operation since 2014. SAM works with the CCD imager covering a 3‧ field or with the speckle camera. It operates routinely and stably, delivering resolution in the I band equal to the free-atmosphere seeing. This paper describes the SAM system as a whole, providing essential reference for its users and technical information of interest to instrumentalists. Operation of the instrument, its performance, and science projects done with SAM so far are reviewed.

  18. An improved adaptive wavelet shrinkage for ultrasound despeckling

    Indian Academy of Sciences (India)

    P Nirmala Devi; R Asokan

    2014-08-01

    Ultrasound imaging is the most widely used medical diagnostic technique for clinical decision making, due to its ability to make real time imaging for moving structures, low cost and safety. However, its usefulness is degraded by the presence of signal dependent speckle noise. Several wavelet-based denoising schemes have been reported in the literature for the removal of speckle noise. This study proposes a new and improved adaptive wavelet shrinkage in the translational invariant domain. It exploits the knowledge of the correlation of the wavelet coefficients within and across the resolution scales. A preliminary coefficient classification representing useful image information and noise is performed with a novel inter-scale dependency measure. The spatial context adaptation of the wavelet coefficients within a subband is achieved by a local spatial adaptivity indicator, determined by using a truncation threshold. A weighted signal variance is estimated based on this measure and used in the determination of a subband adaptive threshold. The proposed thresholding function aims to reduce the fixed bias of the soft thresholding approach. Experiments conducted with the proposed filter are compared with the existing filtering algorithms in terms of Peak-Signal to Noise Ratio (PSNR), Mean Square Error (MSE), Structural Similarity IndexMeasure (SSIM), Equivalent Number of Looks (ENL) and Edge Preservation Index (EPI). A comparison of the results shows that the proposed filter achieves an improvement in terms of quantitative measures and in terms of visual quality of the images.

  19. Low-Light Image Enhancement Using Adaptive Digital Pixel Binning

    Directory of Open Access Journals (Sweden)

    Yoonjong Yoo

    2015-06-01

    Full Text Available This paper presents an image enhancement algorithm for low-light scenes in an environment with insufficient illumination. Simple amplification of intensity exhibits various undesired artifacts: noise amplification, intensity saturation, and loss of resolution. In order to enhance low-light images without undesired artifacts, a novel digital binning algorithm is proposed that considers brightness, context, noise level, and anti-saturation of a local region in the image. The proposed algorithm does not require any modification of the image sensor or additional frame-memory; it needs only two line-memories in the image signal processor (ISP. Since the proposed algorithm does not use an iterative computation, it can be easily embedded in an existing digital camera ISP pipeline containing a high-resolution image sensor.

  20. On the Adaptability of Neural Network Image Super-Resolution

    OpenAIRE

    Chua, Kah Keong; Tay, Yong Haur

    2012-01-01

    In this paper, we described and developed a framework for Multilayer Perceptron (MLP) to work on low level image processing, where MLP will be used to perform image super-resolution. Meanwhile, MLP are trained with different types of images from various categories, hence analyse the behaviour and performance of the neural network. The tests are carried out using qualitative test, in which Mean Squared Error (MSE), Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity Index (SSIM). The r...

  1. The effect of retinal image error update rate on human vestibulo-ocular reflex gain adaptation.

    Science.gov (United States)

    Fadaee, Shannon B; Migliaccio, Americo A

    2016-04-01

    The primary function of the angular vestibulo-ocular reflex (VOR) is to stabilise images on the retina during head movements. Retinal image movement is the likely feedback signal that drives VOR modification/adaptation for different viewing contexts. However, it is not clear whether a retinal image position or velocity error is used primarily as the feedback signal. Recent studies examining this signal are limited because they used near viewing to modify the VOR. However, it is not known whether near viewing drives VOR adaptation or is a pre-programmed contextual cue that modifies the VOR. Our study is based on analysis of the VOR evoked by horizontal head impulses during an established adaptation task. Fourteen human subjects underwent incremental unilateral VOR adaptation training and were tested using the scleral search coil technique over three separate sessions. The update rate of the laser target position (source of the retinal image error signal) used to drive VOR adaptation was different for each session [50 (once every 20 ms), 20 and 15/35 Hz]. Our results show unilateral VOR adaptation occurred at 50 and 20 Hz for both the active (23.0 ± 9.6 and 11.9 ± 9.1% increase on adapting side, respectively) and passive VOR (13.5 ± 14.9, 10.4 ± 12.2%). At 15 Hz, unilateral adaptation no longer occurred in the subject group for both the active and passive VOR, whereas individually, 4/9 subjects tested at 15 Hz had significant adaptation. Our findings suggest that 1-2 retinal image position error signals every 100 ms (i.e. target position update rate 15-20 Hz) are sufficient to drive VOR adaptation.

  2. Evaluation of Left Ventricular Function in Patients with Apex-hypertrophy Using Speckle Tracking Imaging%斑点追踪显像对心尖肥厚型心肌病左室功能的评价分析

    Institute of Scientific and Technical Information of China (English)

    王春梅; 唐琪; 穆玉明; 李艳红

    2011-01-01

    Objective To evaluate the left ventricular function in patients with apex - hypertrophy using speckle tracking imaging.Methods A total of 18 patinents with apex - hypertrophy ( HCM ) and 20 normal controls were enrolled in this study.Images of apacial 4-chamber, 2 - chamber and ventricular short - axises ( anular, papillary - muscle, apex ) were obtained ; the peak - systolic longitudinal strain ( SL ), circumfrencial strain ( SC ) and radial strain ( SR ) of all segments were analyzed.Results SL, SC, and SR of all segments in the HCM group were lower than those in normal controls ( P <0.05 ).Compared with normal controls, SL was lower in all segments in HCM group.SR was lower in most segments in the angular and the papillary - muscle views; SC was lower in several segments in the angular and the papillary - muscle views.Conclusion The longitudinal and radial systolic function among HCM patients is decreased, especially for the longitudinal systolic function.Changes of regional SL, SR and SC are promising indices that reflect these changes.%目的 探讨斑点追踪显像评价心尖肥厚型心肌病左室收缩功能的改变.方法 记录18例心尖肥厚型心肌病患者(HCM组)和20例健康对照者(对照组),获取二维灰阶图像,分析各个心肌节段收缩期峰值的纵向应变(SL)、径向应变(SR)和周向应变(SC).结果 HCM组心肌整体SL、SR及SC收缩期峰值应变均明显低于对照组(P<0.05).HCM组所有节段的收缩期峰值SL均明显低于对照组;与对照组相比,左房室瓣及乳头肌水平大多数节段的SR降低,左房室瓣及乳头肌水平个别节段的SC降低,心尖水平所有节段的SC及SR均明显降低(P<0.05).结论 HCM患者左室长轴和短轴收缩功能均降低,以长轴功能减弱明显,局部心肌SL、SR及SC的变化可反映心肌的功能改变.

  3. Left Ventricular Myocardial Strain in Patients with Cardiac Amyloidosis Using Speckle Tracking Imaging%斑点追踪成像评价心脏淀粉样变性患者左心室心肌分层应变

    Institute of Scientific and Technical Information of China (English)

    张晶; 肖杨杰; 任卫东; 刘爽; 孙菲菲; 乔伟

    2013-01-01

    Purpose To evaluate the systolic function of left ventricular subendocardial and subepicardial myocardium using speckle tracking imaging (STI) in patients with cardiac amyloidosis. Materials and Methods Twenty patients with cardiac amyloidosis (CA group ) and thirty healthy subjects (control group) were examined using two-dimensional echocardiography. High frame rate two-dimensional images were recorded at left ventricular short-axis views during three consecutive cardiac cycles on basal, papillary muscle and apical planes. Peak systolic circumferential strain (CS) and radial strain (RS) were measured in subendocardial, subepicardial and transmural myocardium. The mean CS and RS were calculated in subendocardial and subepicardial myocardium. Results Compared with control group, IVSd, LVPWDd, LAESd, E/A and E/e of CA group were significantly increased (P0.05). In three short-axis and global views, CS of subendocardial myocardium was higher than that of subepicardial myocardium in both CA group and control group (P0.05)。CA组和对照组左心室短轴二尖瓣水平、乳头肌水平、心尖水平及左心室整体内膜下心肌收缩期CS峰值高于外膜下心肌(P<0.001)。对照组内膜下心肌收缩期RS峰值高于外膜下心肌(P<0.001),CA组内膜下心肌收缩期RS值均低于外膜下心肌(P<0.05)。与对照组比较,CA组左心室二尖瓣水平、乳头肌水平、心尖水平内膜下、外膜下及平面整体心肌收缩期CS峰值和RS峰值均减低(P<0.001),左心室整体内膜下、外膜下心肌收缩期CS峰值和RS峰值均减低(P<0.001),且内膜下心肌减低更明显。结论STI可以评价CA患者左心室圆周及径向心肌收缩功能,可作为临床早期诊断CA和评价病变程度的无创性检查方法。

  4. Image Denoising via Bandwise Adaptive Modeling and Regularization Exploiting Nonlocal Similarity.

    Science.gov (United States)

    Xiong, Ruiqin; Liu, Hangfan; Zhang, Xinfeng; Zhang, Jian; Ma, Siwei; Wu, Feng; Gao, Wen

    2016-09-27

    This paper proposes a new image denoising algorithm based on adaptive signal modeling and regularization. It improves the quality of images by regularizing each image patch using bandwise distribution modeling in transform domain. Instead of using a global model for all the patches in an image, it employs content-dependent adaptive models to address the non-stationarity of image signals and also the diversity among different transform bands. The distribution model is adaptively estimated for each patch individually. It varies from one patch location to another and also varies for different bands. In particular, we consider the estimated distribution to have non-zero expectation. To estimate the expectation and variance parameters for every band of a particular patch, we exploit the nonlocal correlation in image to collect a set of highly similar patches as the data samples to form the distribution. Irrelevant patches are excluded so that such adaptively-learned model is more accurate than a global one. The image is ultimately restored via bandwise adaptive soft-thresholding, based on a Laplacian approximation of the distribution of similar-patch group transform coefficients. Experimental results demonstrate that the proposed scheme outperforms several state-of-the-art denoising methods in both the objective and the perceptual qualities.

  5. Determining the imaging plane of a retinal capillary layer in adaptive optical imaging

    Science.gov (United States)

    Yang, Le-Bao; Hu, Li-Fa; Li, Da-Yu; Cao, Zhao-Liang; Mu, Quan-Quan; Ma, Ji; Xuan, Li

    2016-09-01

    Even in the early stage, endocrine metabolism disease may lead to micro aneurysms in retinal capillaries whose diameters are less than 10 μm. However, the fundus cameras used in clinic diagnosis can only obtain images of vessels larger than 20 μm in diameter. The human retina is a thin and multiple layer tissue, and the layer of capillaries less than 10 μm in diameter only exists in the inner nuclear layer. The layer thickness of capillaries less than 10 μm in diameter is about 40 μm and the distance range to rod&cone cell surface is tens of micrometers, which varies from person to person. Therefore, determining reasonable capillary layer (CL) position in different human eyes is very difficult. In this paper, we propose a method to determine the position of retinal CL based on the rod&cone cell layer. The public positions of CL are recognized with 15 subjects from 40 to 59 years old, and the imaging planes of CL are calculated by the effective focal length of the human eye. High resolution retinal capillary imaging results obtained from 17 subjects with a liquid crystal adaptive optics system (LCAOS) validate our method. All of the subjects’ CLs have public positions from 127 μm to 147 μm from the rod&cone cell layer, which is influenced by the depth of focus. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174274, 11174279, 61205021, 11204299, 61475152, and 61405194).

  6. High-resolution adaptive imaging of a single atom

    Science.gov (United States)

    Wong-Campos, J. D.; Johnson, K. G.; Neyenhuis, B.; Mizrahi, J.; Monroe, C.

    2016-09-01

    Optical imaging systems are used extensively in the life and physical sciences because of their ability to non-invasively capture details on the microscopic and nanoscopic scales. Such systems are often limited by source or detector noise, image distortions and human operator misjudgement. Here, we report a general, quantitative method to analyse and correct these errors. We use this method to identify and correct optical aberrations in an imaging system for single atoms and realize an atomic position sensitivity of ˜0.5 nm Hz-1/2 with a minimum uncertainty of 1.7 nm, allowing the direct imaging of atomic motion. This is the highest position sensitivity ever measured for an isolated atom and opens up the possibility of performing out-of-focus three-dimensional particle tracking, imaging of atoms in three-dimensional optical lattices or sensing forces at the yoctonewton (10-24 N) scale.

  7. S4: A Spatial-Spectral model for Speckle Suppression

    CERN Document Server

    Fergus, Rob; Oppenheimer, Rebecca; Brenner, Douglas; Pueyo, Laurent

    2014-01-01

    High dynamic-range imagers aim to block out or null light from a very bright primary star to make it possible to detect and measure far fainter companions; in real systems a small fraction of the primary light is scattered, diffracted, and unocculted. We introduce S4, a flexible data-driven model for the unocculted (and highly speckled) light in the P1640 spectroscopic coronograph. The model uses Principal Components Analysis (PCA) to capture the spatial structure and wavelength dependence of the speckles but not the signal produced by any companion. Consequently, the residual typically includes the companion signal. The companion can thus be found by filtering this error signal with a fixed companion model. The approach is sensitive to companions that are of order a percent of the brightness of the speckles, or up to $10^{-7}$ times the brightness of the primary star. This outperforms existing methods by a factor of 2-3 and is close to the shot-noise physical limit.

  8. S4: A spatial-spectral model for speckle suppression

    Energy Technology Data Exchange (ETDEWEB)

    Fergus, Rob [Department of Computer Science, New York University, New York, NY 10003 (United States); Hogg, David W. [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003 (United States); Oppenheimer, Rebecca; Brenner, Douglas [Department of Astrophysics, American Museum of Natural History, New York, NY 10024-5192 (United States); Pueyo, Laurent, E-mail: fergus@cs.nyu.edu [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2014-10-20

    High dynamic range imagers aim to block or eliminate light from a very bright primary star in order to make it possible to detect and measure far fainter companions; in real systems, a small fraction of the primary light is scattered, diffracted, and unocculted. We introduce S4, a flexible data-driven model for the unocculted (and highly speckled) light in the P1640 spectroscopic coronagraph. The model uses principal components analysis (PCA) to capture the spatial structure and wavelength dependence of the speckles, but not the signal produced by any companion. Consequently, the residual typically includes the companion signal. The companion can thus be found by filtering this error signal with a fixed companion model. The approach is sensitive to companions that are of the order of a percent of the brightness of the speckles, or up to 10{sup –7} times the brightness of the primary star. This outperforms existing methods by a factor of two to three and is close to the shot-noise physical limit.

  9. From amorphous speckle pattern to reconfigurable Bessel beam via wavefront shaping

    CERN Document Server

    Di Battista, Diego; Leonetti, Marco; Zacharakis, Giannis

    2015-01-01

    Bessel beams are non-diffracting light structures, which can be produced with simple tabletop optical elements such as axicon lenses or ring spatial filters and coherent laser beams. One of their main characteristic is that Bessel beams maintain their spatial characteristics after meters of propagation. In this paper we demonstrate a system and method for generating Bessel beams from amorphous speckle patterns, exploiting adaptive optimization by a spatial light modulator. These speckles are generated by light modes transmitted through a scattering curtain and selected by a ring shaped filter. With the proposed strategy it is possible to produce at user defined positions, reconfigurable, non-diffracting Bessel beams through a disordered medium.

  10. Adaptive beaming and imaging in the turbulent atmosphere

    CERN Document Server

    Lukin, Vladimir P

    2002-01-01

    Due to the wide application of adaptive optical systems, an understanding of optical wave propagation in randomly inhomogeneous media has become essential, and several numerical models of individual AOS components and of efficient correction algorithms have been developed. This monograph contains detailed descriptions of the mathematical experiments that were designed and carried out during more than a decade's worth of research.

  11. Imaging-Based Treatment Adaptation in Radiation Oncology

    NARCIS (Netherlands)

    Troost, E.G.; Thorwarth, D.; Oyen, W.J.G.

    2015-01-01

    In many tumor types, significant effort is being put into patient-tailored adaptation of treatment to improve outcome and preferably reduce toxicity. These opportunities first arose with the introduction of modern irradiation techniques (e.g., intensity-modulated radiotherapy) combined with function

  12. Darkfield adapter for whole slide imaging: adapting a darkfield internal reflection illumination system to extend WSI applications.

    Directory of Open Access Journals (Sweden)

    Yoshihiro Kawano

    Full Text Available We present a new method for whole slide darkfield imaging. Whole Slide Imaging (WSI, also sometimes called virtual slide or virtual microscopy technology, produces images that simultaneously provide high resolution and a wide field of observation that can encompass the entire section, extending far beyond any single field of view. For example, a brain slice can be imaged so that both overall morphology and individual neuronal detail can be seen. We extended the capabilities of traditional whole slide systems and developed a prototype system for darkfield internal reflection illumination (DIRI. Our darkfield system uses an ultra-thin light-emitting diode (LED light source to illuminate slide specimens from the edge of the slide. We used a new type of side illumination, a variation on the internal reflection method, to illuminate the specimen and create a darkfield image. This system has four main advantages over traditional darkfield: (1 no oil condenser is required for high resolution imaging (2 there is less scatter from dust and dirt on the slide specimen (3 there is less halo, providing a more natural darkfield contrast image, and (4 the motorized system produces darkfield, brightfield and fluorescence images. The WSI method sometimes allows us to image using fewer stains. For instance, diaminobenzidine (DAB and fluorescent staining are helpful tools for observing protein localization and volume in tissues. However, these methods usually require counter-staining in order to visualize tissue structure, limiting the accuracy of localization of labeled cells within the complex multiple regions of typical neurohistological preparations. Darkfield imaging works on the basis of light scattering from refractive index mismatches in the sample. It is a label-free method of producing contrast in a sample. We propose that adapting darkfield imaging to WSI is very useful, particularly when researchers require additional structural information without the

  13. Improved SMB speckle filtering of polarimetric SAR data with synergistic use of orientation angle compensation and spatial majority rule

    Institute of Scientific and Technical Information of China (English)

    柳林; 江利明; 李洪忠

    2016-01-01

    The scattering-model-based (SMB) speckle filtering for polarimetric SAR (PolSAR) data is reasonably effective in preserving dominant scattering mechanisms. However, the efficiency strongly depends on the accuracies of both the decomposition and classification of the scattering properties. In addition, a relatively weak speckle reduction particularly in distributed media was reported in the related literatures. In this work, an improved SMB filtering strategy is proposed considering the aforementioned deficiencies. First, the orientation angle compensation is incorporated into the SMB filtering process to remedy the overestimation of the volume scattering contribution in the Freeman-Durden decomposition. In addition, an algorithm to select the homogenous pixels is developed based on the spatial majority rule for adaptive speckle reduction. We demonstrate the superiority of the proposed methods in terms of scattering property preservation and speckle noise reduction using L-band PolSAR data sets of San Francisco that were acquired by the NASA/JPL airborne SAR (AIRSAR) system.

  14. The EMCCD-Based Speckle Interferometer of the BTA 6-m Telescope: Description and First Results

    CERN Document Server

    Maksimov, A F; Dyachenko, V V; Malogolovets, E V; Rastegaev, D A; Semernikov, E A

    2009-01-01

    The description is given for the speckle interferometer of the BTA 6-m telescope of the SAO RAS based on a new detector with an electron multiplication CCD. The main components of the instrument are microscope objectives, interference filters and atmospheric dispersion correction prisms. The PhotonMAX-512B CCD camera using a back-illuminated CCD97 allows up to 20 speckle images (with 512$\\times$512 pix resolution) per second storage on the hard drive. Due to high quantum efficiency (93% in the maximum at 550 nm), and high transmission of its optical elements, the new camera can be used for diffraction-limited (0.02$''$) image reconstruction of $15^{m}$ stars under good seeing conditions. The main advantages of the new system over the previous generation BTA speckle interferometer are examined.

  15. En face speckle reduction in optical coherence microscopy by frequency compounding

    Science.gov (United States)

    Magnain, Caroline; Wang, Hui; Sakadžić, Sava; Fischl, Bruce; Boas, David A.

    2017-01-01

    We report the use of frequency compounding to significantly reduce speckle noise in optical coherence microscopy, more specifically on the en face images. This method relies on the fact that the speckle patterns recorded from different wavelengths simultaneously are independent; hence their summation yields significant reduction in noise, with only a single acquisition. The results of our experiments with microbeads show that the narrow confocal parameter, due to a high numerical aperture objective, restricts the axial resolution loss that would otherwise theoretically broaden linearly with the number of optical frequency bands used. This speckle reduction scheme preserves the lateral resolution since it is performed on individual A-scans. Finally, we apply this technique to images of fixed human brain tissue, showing significant improvements in contrast-to-noise ratio with only moderate loss of axial resolution, in an effort to improve automatic three-dimensional detection of cells and fibers in the cortex. PMID:27128040

  16. A Markov-random-field-based filter for speckle reduction in ultrasound imagery

    Science.gov (United States)

    Lankoande, Ousseini; Hayat, Majeed M.; Santhanam, Balu

    2009-02-01

    The coherent nature of ultrasound imaging inherently produces the notorious signal-dependent speckle noise. Recently, a novel approach based upon embedding the statistical and physical properties of speckle patterns into a Markov-random-field (MRF) framework was developed and demonstrated by the authors in the context of synthetic-aperture radar imaging. The contributions of this work are twofold. First, the MRF approach is extended to include a pseudo maximum-likelihood estimator of a key model parameter, making the approach fully autonomous. Second, the capability of the extended approach, called the modified MRF-based conditional-expectation approach (MRFCEA), in denoising real ultrasound imagery is demonstrated. The proposed MRFCEA approach offers superior performance over existing methods by reducing speckle noise without compromising the spatial resolution. In addition, MRFCEA is autonomous, contrary to existing methods such as the enhanced-Frost or the modified-Lee, which require user's input.

  17. Adaptive light-sheet microscopy for long-term, high-resolution imaging in living organisms.

    Science.gov (United States)

    Royer, Loïc A; Lemon, William C; Chhetri, Raghav K; Wan, Yinan; Coleman, Michael; Myers, Eugene W; Keller, Philipp J

    2016-12-01

    Optimal image quality in light-sheet microscopy requires a perfect overlap between the illuminating light sheet and the focal plane of the detection objective. However, mismatches between the light-sheet and detection planes are common owing to the spatiotemporally varying optical properties of living specimens. Here we present the AutoPilot framework, an automated method for spatiotemporally adaptive imaging that integrates (i) a multi-view light-sheet microscope capable of digitally translating and rotating light-sheet and detection planes in three dimensions and (ii) a computational method that continuously optimizes spatial resolution across the specimen volume in real time. We demonstrate long-term adaptive imaging of entire developing zebrafish (Danio rerio) and Drosophila melanogaster embryos and perform adaptive whole-brain functional imaging in larval zebrafish. Our method improves spatial resolution and signal strength two to five-fold, recovers cellular and sub-cellular structures in many regions that are not resolved by non-adaptive imaging, adapts to spatiotemporal dynamics of genetically encoded fluorescent markers and robustly optimizes imaging performance during large-scale morphogenetic changes in living organisms.

  18. The adaptive-loop-gain adaptive-scale CLEAN deconvolution of radio interferometric images

    CERN Document Server

    Zhang, L; Liu, X

    2016-01-01

    CLEAN algorithms are a class of deconvolution solvers which are widely used to remove the effect of the telescope Point Spread Function (PSF). Loop gain is one important parameter in CLEAN algorithms. Currently the parameter is fixed during deconvolution, which restricts the performance of CLEAN algorithms. In this paper, we propose a new deconvolution algorithm with an adaptive loop gain scheme, which is referred to as the adaptive-loop-gain adaptivescale CLEAN (Algas-Clean) algorithm. The test results show that the new algorithm can give a more accurate model with faster convergence.

  19. A bit-level image encryption algorithm based on spatiotemporal chaotic system and self-adaptive

    Science.gov (United States)

    Teng, Lin; Wang, Xingyuan

    2012-09-01

    This paper proposes a bit-level image encryption algorithm based on spatiotemporal chaotic system which is self-adaptive. We use a bit-level encryption scheme to reduce the volume of data during encryption and decryption in order to reduce the execution time. We also use the adaptive encryption scheme to make the ciphered image dependent on the plain image to improve performance. Simulation results show that the performance and security of the proposed encryption algorithm can encrypt plaintext effectively and resist various typical attacks.

  20. MSTAR图像2D Gabor滤波增强与自适应阈值分割%2D Gabor Filter Enhancing and Adaptive Thresholding for MSTAR Image

    Institute of Scientific and Technical Information of China (English)

    倪维平; 严卫东; 吴俊政; 芦颖; 郑刚; 马心璐

    2013-01-01

    Image segmentation is a hot point in the research field of automatic target recognition of SAR image. In order to segment the MSTAR image automatically, a new adaptive method is proposed. Firstly, 2D Gabor filters with various orientations and scales are used to enhance the original image, which can effectually reduce speckle noise in the background, and smooth the interior of the homogeneous regions. Then the analysis of the statistical characteristics of the enhanced image is made, based on which the adaptive thresholding rules is presented for the automatically segmentation of the images. Experiment results with the MSTAR images indicate that the algorithm presented has advantage of segmentation accuracy, calculation efficiency and noise robustness over the traditional methods, such as OTSU, FCM and MRF.%  为实现MSTAR图像无监督分割,并提高分割精度和计算效率,提出了一种基于Gabor滤波增强的自适应阈值分割算法。首先利用多尺度、多方向的Gabor滤波器组对待分割图像进行滤波处理,抑制目标、阴影和背景区域内部的斑噪起伏,同时增强区域间的差异性;在此基础上,通过对增强图像统计特性的分析,给出了灰度阈值计算形式,实现了MSTAR图像的自适应分割。实验结果表明,本文算法对不同斑噪强度的MSTAR图像均具有良好的处理效果,在分割精度、计算效率等方面优于传统的OTSU,以及FCM、MRF等分割方法。

  1. Tailoring Directive Gain for High-Contrast, Wide-Viewing-Angle Organic Light-Emitting Diodes Using Speckle Image Holograpy Metasurfaces.

    Science.gov (United States)

    Zhou, Lei; Ou, Qing-Dong; Shen, Su; Zhou, Yun; Fan, Yuan-Yuan; Zhang, Jun; Tang, Jian-Xin

    2016-08-31

    Holography metasurfaces have been used to control the propagation of light to an unprecedented level, exhibiting the immense potential for light steering in organic light-emitting diodes (OLEDs). Here, a new approach to tailoring directive gain for high contrast, wide-viewing-angle OLEDs is proposed by implementing a spcekle image holography (SIH) metasurface. The experimental and theoretical results provide the direct proofs that the SIH metasurface can play very important roles not only in releasing the trapped energy flow insides the devices but also in tailoring the wavefronts to the preferred patterns due to its "regional orientation" k-vectors patterns. The resulting power efficiency and external quantum efficiency of the OLEDs using a SIH metasurface are 1.97 and 1.95 times that of the reference device with a standard architecture. Furthermore, the wavefronts of emitted light are delicately modulated in a polarization-independent manner, yielding 2.5 times higher contrast ratio compared to the reference device. This unique engineered directive gain property is also well-retained for the viewing angles varing from normal to titled ±60° without spectral distortion. These results enrich the understanding of light wavefronts control in OLEDs and highlight its potential application in display as well as light steering for other optoelectronics.

  2. An Edge-Preserved Image Denoising Algorithm Based on Local Adaptive Regularization

    Directory of Open Access Journals (Sweden)

    Li Guo

    2016-01-01

    Full Text Available Image denoising methods are often based on the minimization of an appropriately defined energy function. Many gradient dependent energy functions, such as Potts model and total variation denoising, regard image as piecewise constant function. In these methods, some important information such as edge sharpness and location is well preserved, but some detailed image feature like texture is often compromised in the process of denoising. For this reason, an image denoising method based on local adaptive regularization is proposed in this paper, which can adaptively adjust denoising degree of noisy image by adding spatial variable fidelity term, so as to better preserve fine scale features of image. Experimental results show that the proposed denoising method can achieve state-of-the-art subjective visual effect, and the signal-noise-ratio (SNR is also objectively improved by 0.3–0.6 dB.

  3. Viable myocardium evaluation by two dimensional speckle tracking imaging combined with adenosine stress echocardiography%二维斑点追踪技术结合腺苷负荷评价心肌存活性

    Institute of Scientific and Technical Information of China (English)

    冉红; 张平洋; 方玲玲; 马小五; 吴文芳; 冯王飞

    2013-01-01

    Objective Rcgional lcft vcntricular (LV) function could be detected by measuring peak-systolic strain by speckle tracking imaging (STI).We evaluated the value of STI combined with adenosine stress echocardiography on assessing myocardial viability in patients with myocardial infarction (MI).Methods Two dimensional echocardiography was performed at rest and after adenosine stress echocardiography (infused at 140 μg · kg-1 · min-1 over a period of 6 min) in 39 stable patients with previous MI.Peak-systolic (Speak-sys) circumferential strain,radial strain and longitudinal strain were assessed by STI.Radionuclide myocardial perfusion/metabolic imaging served as the “gold standard” to detection of myocardial viability.Results (1) There were 215 viable and 153 non-viable regions among 368abnormal motion segments out of 624 segments in 39 MI patients according to radionuclide imaging results.(2) Speak-sys was similar between viable and nonviable myocardium at rest (all P > 0.05).After adenosine infusion,radial Speak-sys [(37.98 ± 5.45) % vs.(30.22 ± 5.47) %],longitudinal Speak-sys [(-23.71 ±4.53) % vs.(-17.52 ± 4.34) %] increased significantly (P < 0.05) in viable segments compared to baseline levels and were significantly higher than in nonviable segments radial Speak-sys [(37.98 ± 5.45) %vs.(30.12±5.37)%] and longitudinal Speak-sys[(-23.71 ±4.53)% vs.(-16.95±4.62)%](P<0.05),while remained unchanged in nonviable segments before and after adenosine infusion.Circumferential Speak-sys was similar before and after adenosine infusion in both viable and nonviable segments (all P > 0.05).(3) Delta radial strain change > 9.8% has a sensitivity of 82.3% and a specificity of 81.1% whereas a delta change of longitudinal strain > 16.5% has a sensitivity of 83.5% and a specificity of 92.3% for detecting viable segments.Conclusions Speckle tracking imaging combined with adenosine stress echocardiography could serve as a new and

  4. Smart image sensor with adaptive correction of brightness

    Science.gov (United States)

    Paindavoine, Michel; Ngoua, Auguste; Brousse, Olivier; Clerc, Cédric

    2012-03-01

    Today, intelligent image sensors require the integration in the focal plane (or near the focal plane) of complex algorithms for image processing. Such devices must meet the constraints related to the quality of acquired images, speed and performance of embedded processing, as well as low power consumption. To achieve these objectives, analog pre-processing are essential, on the one hand, to improve the quality of the images making them usable whatever the light conditions, and secondly, to detect regions of interest (ROIs) to limit the amount of pixels to be transmitted to a digital processor performing the high-level processing such as feature extraction for pattern recognition. To show that it is possible to implement analog pre-processing in the focal plane, we have designed and implemented in 130nm CMOS technology, a test circuit with groups of 4, 16 and 144 pixels, each incorporating analog average calculations.

  5. Advances in speckle metrology and related techniques

    CERN Document Server

    Kaufmann, Guillermo H

    2010-01-01

    Speckle metrology includes various optical techniques that are based on the speckle fields generated by reflection from a rough surface or by transmission through a rough diffuser. These techniques have proven to be very useful in testing different materials in a non-destructive way. They have changed dramatically during the last years due to the development of modern optical components, with faster and more powerful digital computers, and novel data processing approaches. This most up-to-date overview of the topic describes new techniques developed in the field of speckle metrology over the l

  6. ADAPTIVE LIFTING BASED IMAGE COMPRESSION SCHEME WITH PARTICLE SWARM OPTIMIZATION TECHNIQUE

    Directory of Open Access Journals (Sweden)

    Nishat kanvel

    2010-09-01

    Full Text Available This paper presents an adaptive lifting scheme with Particle Swarm Optimization technique for image compression. Particle swarm Optimization technique is used to improve the accuracy of the predictionfunction used in the lifting scheme. This scheme is applied in Image compression and parameters such as PSNR, Compression Ratio and the visual quality of the image is calculated .The proposed scheme iscompared with the existing methods.

  7. Adaptive hybrid subband image coding with DWT, DCT, and modified DPCM

    Science.gov (United States)

    Kim, Tae W.; Choe, Howard C.; Griswold, Norman C.

    1997-04-01

    Image coding based on subband decomposition with DPCM and PCM has received much attention in the areas of image compression research and industry. In this paper we present a new adaptive image subband coding with discrete wavelet transform, discrete cosine transform, and a modified DPCM. The main contribution of this work is the development of a simple, yet effective image compression and transmission algorithm. An important feature of this algorithm is the hybrid modified DPCM coding scheme which produces both simple, but significant, image compression and transmission coding.

  8. Filtering Based Adaptive Visual Odometry Sensor Framework Robust to Blurred Images

    Directory of Open Access Journals (Sweden)

    Haiying Zhao

    2016-07-01

    Full Text Available Visual odometry (VO estimation from blurred image is a challenging problem in practical robot applications, and the blurred images will severely reduce the estimation accuracy of the VO. In this paper, we address the problem of visual odometry estimation from blurred images, and present an adaptive visual odometry estimation framework robust to blurred images. Our approach employs an objective measure of images, named small image gradient distribution (SIGD, to evaluate the blurring degree of the image, then an adaptive blurred image classification algorithm is proposed to recognize the blurred images, finally we propose an anti-blurred key-frame selection algorithm to enable the VO robust to blurred images. We also carried out varied comparable experiments to evaluate the performance of the VO algorithms with our anti-blur framework under varied blurred images, and the experimental results show that our approach can achieve superior performance comparing to the state-of-the-art methods under the condition with blurred images while not increasing too much computation cost to the original VO algorithms.

  9. 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.

  10. Region-based adaptive anisotropic diffusion for image enhancement and denoising

    Science.gov (United States)

    Wang, Yi; Niu, Ruiqing; Zhang, Liangpei; Shen, Huanfeng

    2010-11-01

    A novel region-based adaptive anisotropic diffusion (RAAD) is presented for image enhancement and denoising. The main idea of this algorithm is to perform the region-based adaptive segmentation. To this end, we use the eigenvalue difference of the structure tensor of each pixel to classify an image into homogeneous detail, and edge regions. According to the different types of regions, a variable weight is incorporated into the anisotropic diffusion partial differential equation for compromising the forward and backward diffusion, so that our algorithm can adaptively encourage strong smoothing in homogeneous regions and suitable sharpening in detail and edge regions. Furthermore, we present an adaptive gradient threshold selection strategy. We suggest that the optimal gradient threshold should be estimated as the mean of local intensity differences on the homogeneous regions. In addition, we modify the anisotropic diffusion discrete scheme by taking into account edge orientations. We believe our algorithm to be a novel mechanism for image enhancement and denoising. Qualitative experiments, based on various general digital images and several T1- and T2-weighted magnetic resonance simulated images, show significant improvements when the RAAD algorithm is used versus the existing anisotropic diffusion and the previous forward and backward diffusion algorithms for enhancing edge features and improving image contrast. Quantitative analyses, based on peak signal-to-noise ratio, the universal image quality index, and the structural similarity confirm the superiority of the proposed algorithm.

  11. An adaptive image enhancement technique by combining cuckoo search and particle swarm optimization algorithm.

    Science.gov (United States)

    Ye, Zhiwei; Wang, Mingwei; Hu, Zhengbing; Liu, Wei

    2015-01-01

    Image enhancement is an important procedure of image processing and analysis. This paper presents a new technique using a modified measure and blending of cuckoo search and particle swarm optimization (CS-PSO) for low contrast images to enhance image adaptively. In this way, contrast enhancement is obtained by global transformation of the input intensities; it employs incomplete Beta function as the transformation function and a novel criterion for measuring image quality considering three factors which are threshold, entropy value, and gray-level probability density of the image. The enhancement process is a nonlinear optimization problem with several constraints. CS-PSO is utilized to maximize the objective fitness criterion in order to enhance the contrast and detail in an image by adapting the parameters of a novel extension to a local enhancement technique. The performance of the proposed method has been compared with other existing techniques such as linear contrast stretching, histogram equalization, and evolutionary computing based image enhancement methods like backtracking search algorithm, differential search algorithm, genetic algorithm, and particle swarm optimization in terms of processing time and image quality. Experimental results demonstrate that the proposed method is robust and adaptive and exhibits the better performance than other methods involved in the paper.

  12. High-speed adaptive optics line scan confocal retinal imaging for human eye

    Science.gov (United States)

    Wang, Xiaolin; Zhang, Yuhua

    2017-01-01

    Purpose Continuous and rapid eye movement causes significant intraframe distortion in adaptive optics high resolution retinal imaging. To minimize this artifact, we developed a high speed adaptive optics line scan confocal retinal imaging system. Methods A high speed line camera was employed to acquire retinal image and custom adaptive optics was developed to compensate the wave aberration of the human eye’s optics. The spatial resolution and signal to noise ratio were assessed in model eye and in living human eye. The improvement of imaging fidelity was estimated by reduction of intra-frame distortion of retinal images acquired in the living human eyes with frame rates at 30 frames/second (FPS), 100 FPS, and 200 FPS. Results The device produced retinal image with cellular level resolution at 200 FPS with a digitization of 512×512 pixels/frame in the living human eye. Cone photoreceptors in the central fovea and rod photoreceptors near the fovea were resolved in three human subjects in normal chorioretinal health. Compared with retinal images acquired at 30 FPS, the intra-frame distortion in images taken at 200 FPS was reduced by 50.9% to 79.7%. Conclusions We demonstrated the feasibility of acquiring high resolution retinal images in the living human eye at a speed that minimizes retinal motion artifact. This device may facilitate research involving subjects with nystagmus or unsteady fixation due to central vision loss. PMID:28257458

  13. Cellular pulse-coupled neural network with adaptive weights for image segmentation and its VLSI implementation

    Science.gov (United States)

    Schreiter, Juerg; Ramacher, Ulrich; Heittmann, Arne; Matolin, Daniel; Schuffny, Rene

    2004-05-01

    We present a cellular pulse coupled neural network with adaptive weights and its analog VLSI implementation. The neural network operates on a scalar image feature, such as grey scale or the output of a spatial filter. It detects segments and marks them with synchronous pulses of the corresponding neurons. The network consists of integrate-and-fire neurons, which are coupled to their nearest neighbors via adaptive synaptic weights. Adaptation follows either one of two empirical rules. Both rules lead to spike grouping in wave like patterns. This synchronous activity binds groups of neurons and labels the corresponding image segments. Applications of the network also include feature preserving noise removal, image smoothing, and detection of bright and dark spots. The adaptation rules are insensitive for parameter deviations, mismatch and non-ideal approximation of the implied functions. That makes an analog VLSI implementation feasible. Simulations showed no significant differences in the synchronization properties between networks using the ideal adaptation rules and networks resembling implementation properties such as randomly distributed parameters and roughly implemented adaptation functions. A prototype is currently being designed and fabricated using an Infineon 130nm technology. It comprises a 128 × 128 neuron array, analog image memory, and an address event representation pulse output.

  14. Implementation of adaptive radiation therapy for urinary bladder carcinoma - Imaging, planning and image guidance

    Energy Technology Data Exchange (ETDEWEB)

    Tuomikoski, Laura; Collan, Juhani; Keyrilaeinen, Jani; Saarilahti, Kauko; Tenhunen, Mikko [Dept. of Oncology, Helsinki Univ. Central Hospital, Helsinki (Finland)], e-mail: laura.tuomikoski@hus.fi; Korhonen, Juha [Dept. of Oncology, Helsinki Univ. Central Hospital, Helsinki (Finland); Clinical Research Inst. Helsinki Univ. Central Hospital Ltd, Helsinki (Finland); Visapaeae, Harri [Dept. of Oncology, Helsinki Univ. Central Hospital, Helsinki (Finland); Dept. of Urology, Helsinki Univ. Central Hospital, Helsinki (Finland); Sairanen, Jukka [Dept. of Urology, Helsinki Univ. Central Hospital, Helsinki (Finland)

    2013-10-15

    Background: Adaptive radiation therapy (ART) for urinary bladder cancer has emerged as a promising alternative to conventional RT with potential to minimize radiation-induced toxicity to healthy tissues. In this work we have studied bladder volume variations and their effect on healthy bladder dose sparing and intra fractional margins, in order to refine our ART strategy. Material and methods: An online ART treatment strategy was followed for five patients with urinary bladder cancer with the tumors demarcated using Lipiodol. A library of 3-4 predefined treatment plans for each patient was created based on four successive computed tomography (CT) scans. Cone beam CT (CBCT) images were acquired before each treatment fraction and after the treatment at least weekly. In partial bladder treatment the sparing of the healthy part of the bladder was investigated. The bladder wall displacements due to bladder filling were determined in three orthogonal directions (CC, AP, DEX-SIN) using the treatment planning CT scans. An ellipsoidal model was applied in order to find the theoretical maximum values for the bladder wall displacements. Moreover, the actual bladder filling rate during treatment was evaluated using the CBCT images. Results: In partial bladder treatment the volume of the bladder receiving high absorbed doses was generally smaller with a full than empty bladder. The estimation of the bladder volume and the upper limit for the intra fractional movement of the bladder wall could be represented with an ellipsoidal model with a reasonable accuracy. Observed maximum growth of bladder dimensions was less than 10 mm in all three orthogonal directions during 15 minute interval. Conclusion: The use of Lipiodol contrast agent enables partial bladder treatment with reduced irradiation of the healthy bladder volume. The ellipsoidal bladder model can be used for the estimation of the bladder volume changes and the upper limit of the bladder wall movement during the treatment

  15. Adaptive compression of slowly varying images transmitted over Wireless Sensor Networks.

    Science.gov (United States)

    Nikolakopoulos, George; Kandris, Dionisis; Tzes, Anthony

    2010-01-01

    In this article a scheme for image transmission over Wireless Sensor Networks (WSN) with an adaptive compression factor is introduced. The proposed control architecture affects the quality of the transmitted images according to: (a) the traffic load within the network and (b) the level of details contained in an image frame. Given an approximate transmission period, the adaptive compression mechanism applies Quad Tree Decomposition (QTD) with a varying decomposition compression factor based on a gradient adaptive approach. For the initialization of the proposed control scheme, the desired a priori maximum bound for the transmission time delay is being set, while a tradeoff among the quality of the decomposed image frame and the time needed for completing the transmission of the frame should be taken under consideration. Based on the proposed control mechanism, the quality of the slowly varying transmitted image frames is adaptively deviated based on the measured time delay in the transmission. The efficacy of the adaptive compression control scheme is validated through extended experimental results.

  16. Adaptive Compression of Slowly Varying Images Transmitted over Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Anthony Tzes

    2010-07-01

    Full Text Available In this article a scheme for image transmission over Wireless Sensor Networks (WSN with an adaptive compression factor is introduced. The proposed control architecture affects the quality of the transmitted images according to: (a the traffic load within the network and (b the level of details contained in an image frame. Given an approximate transmission period, the adaptive compression mechanism applies Quad Tree Decomposition (QTD with a varying decomposition compression factor based on a gradient adaptive approach. For the initialization of the proposed control scheme, the desired a priori maximum bound for the transmission time delay is being set, while a tradeoff among the quality of the decomposed image frame and the time needed for completing the transmission of the frame should be taken under consideration. Based on the proposed control mechanism, the quality of the slowly varying transmitted image frames is adaptively deviated based on the measured time delay in the transmission. The efficacy of the adaptive compression control scheme is validated through extended experimental results.

  17. Detection of respiratory motion in fluoroscopic images for adaptive radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Moser, T; Nill, S; Remmert, G; Bendl, R [German Cancer Research Center, Heidelberg (Germany); Biederer, J [Department of Diagnostic Radiology, University Hospital Schleswig-Holstein, Kiel (Germany)], E-mail: T.Moser@dkfz-heidelberg.de

    2008-06-21

    Respiratory motion limits the potential of modern high-precision radiotherapy techniques such as IMRT and particle therapy. Due to the uncertainty of tumour localization, the ability of achieving dose conformation often cannot be exploited sufficiently, especially in the case of lung tumours. Various methods have been proposed to track the position of tumours using external signals, e.g. with the help of a respiratory belt or by observing external markers. Retrospectively gated time-resolved x-ray computed tomography (4D CT) studies prior to therapy can be used to register the external signals with the tumour motion. However, during treatment the actual motion of internal structures may be different. Direct control of tissue motion by online imaging during treatment promises more precise information. On the other hand, it is more complex, since a larger amount of data must be processed in order to determine the motion. Three major questions arise from this issue. Firstly, can the motion that has occurred be precisely determined in the images? Secondly, how large must, respectively how small can, the observed region be chosen to get a reliable signal? Finally, is it possible to predict the proximate tumour location within sufficiently short acquisition times to make this information available for gating irradiation? Based on multiple studies on a porcine lung phantom, we have tried to examine these questions carefully. We found a basic characteristic of the breathing cycle in images using the image similarity method normalized mutual information. Moreover, we examined the performance of the calculations and proposed an image-based gating technique. In this paper, we present the results and validation performed with a real patient data set. This allows for the conclusion that it is possible to build up a gating system based on image data, solely, or (at least in avoidance of an exceeding exposure dose) to verify gates proposed by the various external systems.

  18. Adaptive polarization image fusion based on regional energy dynamic weighted average

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yong-qiang; PAN Quan; ZHANG Hong-cai

    2005-01-01

    According to the principle of polarization imaging and the relation between Stokes parameters and the degree of linear polarization, there are much redundant and complementary information in polarized images. Since man-made objects and natural objects can be easily distinguished in images of degree of linear polarization and images of Stokes parameters contain rich detailed information of the scene, the clutters in the images can be removed efficiently while the detailed information can be maintained by combining these images. An algorithm of adaptive polarization image fusion based on regional energy dynamic weighted average is proposed in this paper to combine these images. Through an experiment and simulations,most clutters are removed by this algorithm. The fusion method is used for different light conditions in simulation, and the influence of lighting conditions on the fusion results is analyzed.

  19. Automatic Spatially-Adaptive Balancing of Energy Terms for Image Segmentation

    CERN Document Server

    Rao, Josna; Abugharbieh, Rafeef

    2009-01-01

    Image segmentation techniques are predominately based on parameter-laden optimization. The objective function typically involves weights for balancing competing image fidelity and segmentation regularization cost terms. Setting these weights suitably has been a painstaking, empirical process. Even if such ideal weights are found for a novel image, most current approaches fix the weight across the whole image domain, ignoring the spatially-varying properties of object shape and image appearance. We propose a novel technique that autonomously balances these terms in a spatially-adaptive manner through the incorporation of image reliability in a graph-based segmentation framework. We validate on synthetic data achieving a reduction in mean error of 47% (p-value << 0.05) when compared to the best fixed parameter segmentation. We also present results on medical images (including segmentations of the corpus callosum and brain tissue in MRI data) and on natural images.

  20. Uniform and Non-Uniform Single Image Deblurring Based on Sparse Representation and Adaptive Dictionary Learning

    Directory of Open Access Journals (Sweden)

    Ashwini M. Deshpande

    2014-02-01

    Full Text Available Considering the sparseness property of images, a sparse representation based iterative deblurring method is presented for single image deblurring under uniform and non-uniform motion blur. The approach taken is based on sparse and redundant representations over adaptively training dictionaries from single blurred-noisy image itself. Further, the K-SVD algorithm is used to obtain a dictionary that describes the image contents effectively. Comprehensive experimental evaluation demonstrate that the proposed framework integrating the sparseness property of images, adaptive dictionary training and iterative deblurring scheme together significantly improves the deblurring performance and is comparable with the state-of-the art deblurring algorithms and seeks a powerful solution to an ill-conditioned inverse problem.