Sample records for digital color correlation

  1. Digital color imaging

    Fernandez-Maloigne, Christine; Macaire, Ludovic


    This collective work identifies the latest developments in the field of the automatic processing and analysis of digital color images.For researchers and students, it represents a critical state of the art on the scientific issues raised by the various steps constituting the chain of color image processing.It covers a wide range of topics related to computational color imaging, including color filtering and segmentation, color texture characterization, color invariant for object recognition, color and motion analysis, as well as color image and video indexing and retrieval. <

  2. 3D digital image correlation using single color camera pseudo-stereo system

    Li, Junrui; Dan, Xizuo; Xu, Wan; Wang, Yonghong; Yang, Guobiao; Yang, Lianxiang


    Three dimensional digital image correlation (3D-DIC) has been widely used by industry to measure the 3D contour and whole-field displacement/strain. In this paper, a novel single color camera 3D-DIC setup, using a reflection-based pseudo-stereo system, is proposed. Compared to the conventional single camera pseudo-stereo system, which splits the CCD sensor into two halves to capture the stereo views, the proposed system achieves both views using the whole CCD chip and without reducing the spatial resolution. In addition, similarly to the conventional 3D-DIC system, the center of the two views stands in the center of the CCD chip, which minimizes the image distortion relative to the conventional pseudo-stereo system. The two overlapped views in the CCD are separated by the color domain, and the standard 3D-DIC algorithm can be utilized directly to perform the evaluation. The system's principle and experimental setup are described in detail, and multiple tests are performed to validate the system.

  3. A field guide to digital color

    Stone, Maureen


    Maureen Stone's field guide to digital color presents a survey of digital color with special emphasis on those fields important for computer graphics. The book provides the foundation for understanding color and its applications, discusses color media and color management and the use of color in computer graphics, including color design and selection. The book provides a guide for anyone who wants to understand and apply digital color. An annotated bibliography provides in-depth references for further study on each topic.

  4. Full-frame, high-speed 3D shape and deformation measurements using stereo-digital image correlation and a single color high-speed camera

    Yu, Liping; Pan, Bing


    Full-frame, high-speed 3D shape and deformation measurement using stereo-digital image correlation (stereo-DIC) technique and a single high-speed color camera is proposed. With the aid of a skillfully designed pseudo stereo-imaging apparatus, color images of a test object surface, composed of blue and red channel images from two different optical paths, are recorded by a high-speed color CMOS camera. The recorded color images can be separated into red and blue channel sub-images using a simple but effective color crosstalk correction method. These separated blue and red channel sub-images are processed by regular stereo-DIC method to retrieve full-field 3D shape and deformation on the test object surface. Compared with existing two-camera high-speed stereo-DIC or four-mirror-adapter-assisted singe-camera high-speed stereo-DIC, the proposed single-camera high-speed stereo-DIC technique offers prominent advantages of full-frame measurements using a single high-speed camera but without sacrificing its spatial resolution. Two real experiments, including shape measurement of a curved surface and vibration measurement of a Chinese double-side drum, demonstrated the effectiveness and accuracy of the proposed technique.

  5. Automatic color map digitization by spectral classification

    Chu, N. Y.; Anuta, P. E.


    A method of converting polygon map information into a digital form which does not require manual tracing of polygon edges is discussed. The maps must be in color-coded format with a unique color for each category in the map. Color scanning using a microdensitometer is employed and a three-channel color separation digital data set is generated. The digital data are then classified by using a Gaussian maximum likelihood classifier, and the resulting digitized map is evaluated. Very good agreement is observed between the classified and original map.

  6. Digital Jacquard Fabric Design in Colorful Mode



    Digital image design is one of advanced technique in textile design. The investigation into digital Jacquard textile design in the colorful mode is one form of research in digital Jacquard fabric design, which aimed at expanding past and present jacquard design and production methods towards innovative ends. In this paper, the design principles and design methods for unconventional digital Jacquard fabric design in colorful mode have been analyzed based on the new technologies and computer applied color theory. The results of this study will enhance further research in the area of digital textile.

  7. High-performance digital color video camera

    Parulski, Kenneth A.; D'Luna, Lionel J.; Benamati, Brian L.; Shelley, Paul R.


    Typical one-chip color cameras use analog video processing circuits. An improved digital camera architecture has been developed using a dual-slope A/D conversion technique and two full-custom CMOS digital video processing integrated circuits, the color filter array (CFA) processor and the RGB postprocessor. The system used a 768 X 484 active element interline transfer CCD with a new field-staggered 3G color filter pattern and a lenslet overlay, which doubles the sensitivity of the camera. The industrial-quality digital camera design offers improved image quality, reliability, manufacturability, while meeting aggressive size, power, and cost constraints. The CFA processor digital VLSI chip includes color filter interpolation processing, an optical black clamp, defect correction, white balance, and gain control. The RGB postprocessor digital integrated circuit includes a color correction matrix, gamma correction, 2D edge enhancement, and circuits to control the black balance, lens aperture, and focus.

  8. Digital color restoration of old paintings.

    Pappas, M; Pitas, I


    Physical and chemical changes can degrade the visual color appearance of old paintings. Five digital color restoration techniques, which can be used to simulate the original appearance of paintings, are presented. Although a small number of color samples is employed in the restoration procedure, simulation results indicate that good restoration quality can be attained.

  9. Spatial Variation of the Correlated Color Temperature of Lightning Channel

    Shimoji, Nobuaki; Aoyama, Ryoma


    In present work, we propose the analysis method of lightning based on the color analysis. We analyzed the digital still images in which the cloud-to-ground (CG) and intracloud (IC) lightning flashes are shown. Applying some digital image processing techniques, we extracted lightning channels. Then, the correlated color temperature (CCT) of the extracted lightning channels was obtained by mapping digital pixels of the extracted lightning channels to CIE 1931 xy-chromaticity diagram. Our result...

  10. Nonlinear color-image decomposition for image processing of a digital color camera

    Saito, Takahiro; Aizawa, Haruya; Yamada, Daisuke; Komatsu, Takashi


    This paper extends the BV (Bounded Variation) - G and/or the BV-L1 variational nonlinear image-decomposition approaches, which are considered to be useful for image processing of a digital color camera, to genuine color-image decomposition approaches. For utilizing inter-channel color cross-correlations, this paper first introduces TV (Total Variation) norms of color differences and TV norms of color sums into the BV-G and/or BV-L1 energy functionals, and then derives denoising-type decomposition-algorithms with an over-complete wavelet transform, through applying the Besov-norm approximation to the variational problems. Our methods decompose a noisy color image without producing undesirable low-frequency colored artifacts in its separated BV-component, and they achieve desirable high-quality color-image decomposition, which is very robust against colored random noise.

  11. Influence of imaging resolution on color fidelity in digital archiving.

    Zhang, Pengchang; Toque, Jay Arre; Ide-Ektessabi, Ari


    Color fidelity is of paramount importance in digital archiving. In this paper, the relationship between color fidelity and imaging resolution was explored by calculating the color difference of an IT8.7/2 color chart with a CIELAB color difference formula for scanning and simulation images. Microscopic spatial sampling was used in selecting the image pixels for the calculations to highlight the loss of color information. A ratio, called the relative imaging definition (RID), was defined to express the correlation between image resolution and color fidelity. The results show that in order for color differences to remain unrecognizable, the imaging resolution should be at least 10 times higher than the physical dimension of the smallest feature in the object being studied.

  12. Digital devices: big challenge in color management

    Vauderwange, Oliver; Curticapean, Dan; Dreβler, Paul; Wozniak, Peter


    The paper will present how the students learn to find technical solutions in color management by using adequate digital devices and recognize the specific upcoming tasks in this area. Several issues, problems and their solutions will be discussed. The scientific background offer specific didactical solutions in this area of optics. Color management is the major item of this paper. Color management is a crucial responsibility for media engineers and designers. Print, screen and mobile applications must independently display the same colors. Predictability and consistency in the color representation are the aims of a color management system. This is only possible in a standardized and audited production workflow. Nowadays digital media have a fast-paced development process. An increasing number of different digital devices with different display sizes and display technologies are a great challenge for every color management system. The authors will present their experience in the field of color management. The design and development of a suitable learning environment with the required infrastructure is in the focus. The combination of theoretical and practical lectures creates a deeper understanding in the area of the digital color representation.

  13. Frequency correlates in grapheme-color synaesthesia.

    Beeli, Gian; Esslen, Michaela; Jäncke, Lutz


    Individuals with synaesthesia experience certain stimuli in more than one sensory modality. Most common is the linkage of letters and digits (graphemes) to colors. Whereas synaesthesia might be partly genetically determined, the linkages to specific colors are assumed to be learned. We present a systematic statistical analysis of synaesthetic color perception based on subjects' reproduction of individual colors for each grapheme, instead of simple verbal categorizations. The statistical analysis revealed that the color perceptions, measured with the HSL (hue, saturation, and luminance) scale, varied systematically among the different digits and letters. The frequencies of the digits and letters (in the German language) partly explained these systematic variations. However, digit frequency was more strongly related to color perception in the synaesthetes than was letter frequency. The results for digit and letter frequency indicate that experience with graphemes may shape synaesthetic color perception.

  14. WVSAMB Color Digital Orthophotos North Zone

    Federal Emergency Management Agency, Department of Homeland Security — Digital color orthophotography of the State of West Virginia (West Virginia State Plane Coordinate System North Zone). The W.V. state plane system has two...

  15. [True color accuracy in digital forensic photography].

    Ramsthaler, Frank; Birngruber, Christoph G; Kröll, Ann-Katrin; Kettner, Mattias; Verhoff, Marcel A


    Forensic photographs not only need to be unaltered and authentic and capture context-relevant images, along with certain minimum requirements for image sharpness and information density, but color accuracy also plays an important role, for instance, in the assessment of injuries or taphonomic stages, or in the identification and evaluation of traces from photos. The perception of color not only varies subjectively from person to person, but as a discrete property of an image, color in digital photos is also to a considerable extent influenced by technical factors such as lighting, acquisition settings, camera, and output medium (print, monitor). For these reasons, consistent color accuracy has so far been limited in digital photography. Because images usually contain a wealth of color information, especially for complex or composite colors or shades of color, and the wavelength-dependent sensitivity to factors such as light and shadow may vary between cameras, the usefulness of issuing general recommendations for camera capture settings is limited. Our results indicate that true image colors can best and most realistically be captured with the SpyderCheckr technical calibration tool for digital cameras tested in this study. Apart from aspects such as the simplicity and quickness of the calibration procedure, a further advantage of the tool is that the results are independent of the camera used and can also be used for the color management of output devices such as monitors and printers. The SpyderCheckr color-code patches allow true colors to be captured more realistically than with a manual white balance tool or an automatic flash. We therefore recommend that the use of a color management tool should be considered for the acquisition of all images that demand high true color accuracy (in particular in the setting of injury documentation).

  16. Development of digital shade guides for color assessment using a digital camera with ring flashes.

    Tung, Oi-Hong; Lai, Yu-Lin; Ho, Yi-Ching; Chou, I-Chiang; Lee, Shyh-Yuan


    Digital photographs taken with cameras and ring flashes are commonly used for dental documentation. We hypothesized that different illuminants and camera's white balance setups shall influence color rendering of digital images and affect the effectiveness of color matching using digital images. Fifteen ceramic disks of different shades were fabricated and photographed with a digital camera in both automatic white balance (AWB) and custom white balance (CWB) under either light-emitting diode (LED) or electronic ring flash. The Commission Internationale d'Éclairage L*a*b* parameters of the captured images were derived from Photoshop software and served as digital shade guides. We found significantly high correlation coefficients (r² > 0.96) between the respective spectrophotometer standards and those shade guides generated in CWB setups. Moreover, the accuracy of color matching of another set of ceramic disks using digital shade guides, which was verified by ten operators, improved from 67% in AWB to 93% in CWB under LED illuminants. Probably, because of the inconsistent performance of the flashlight and specular reflection, the digital images captured under electronic ring flash in both white balance setups revealed less reliable and relative low-matching ability. In conclusion, the reliability of color matching with digital images is much influenced by the illuminants and camera's white balance setups, while digital shade guides derived under LED illuminants with CWB demonstrate applicable potential in the fields of color assessments.

  17. Non Correlation DWT Based Watermarking Behavior in Different Color Spaces

    Mehdi Khalili


    Full Text Available There are two digital watermarking techniques. Digital watermarking techniques based on correlation and digital watermarking techniques that are not based on correlation. In previous work, we proposed a DWT2 based CDMA image watermarking scheme to study the effects of using eight color spaces RGB, YCbCr, JPEG-YCbCr, YIQ, YUV, HSI, HSV and CIELab, on watermarking algorithms based on correlation techniques. This paper proposes a non correlation based image watermarking scheme in wavelet transform domain and tests it in the same color spaces, to develop studying, reach a comprehensive analysis and focus on satisfying the requirements of based non coloration watermarking algorithms. To achieve more security, imperceptibility and robustness of the proposed scheme, first, the binary watermark image encodes by applying ATM, CCM and exclusive OR. Then, the scrambled watermark embeds into intended quantized approximation coefficients of wavelet transform by LSB insertion technique.

  18. Digital Color in Cellulose Nanocrystal Films

    Dumanli, Ahu Gümrah; van der Kooij, Hanne M.; Kamita, Gen; Reisner, Erwin; Baumberg, Jeremy J.; Steiner, Ullrich; Vignolini, Silvia


    This is the final published version. It first appeared at Cellulose nanocrystals (CNCs) form chiral nematic phases in aqueous suspensions that can be preserved upon evaporation of water. The resulting films show an intense directional coloration determined by their microstructure. Here, microreflection experiments correlated with analysis of the helicoidal nanostructure of the films reveal that the iridescent colors and the ordering of the ind...

  19. A color-communication scheme for digital imagery

    Acosta, Alex


    Color pictures generated from digital images are frequently used by geologists, foresters, range managers, and others. These color products are preferred over black and white pictures because the human eye is more sensitive to color differences than to various shades of gray. Color discrimination is a function of perception, and therefore colors in these color composites are generally described subjectively, which can lead to ambiguous color communication. Numerous color-coordinate systems are available that quantitively relate digital triplets representing amounts of red, free, and blue to the parameters of hue, saturation, and intensity perceived by the eye. Most of these systems implement a complex transformation of the primary colors to a color space that is hard to visualize, thus making it difficult to relate digital triplets to perception parameters. This paper presents a color-communcation scheme that relates colors on a color triangle to corresponding values of "hue" (H), "saturation" (S), and chromaticity coordinates (x,y,z). The scheme simplifies the relation between red, green, and blue (RGB) digital triplets and the color generated by these triplets. Some examples of the use of the color-communication scheme in digital image processing are presented.

  20. Polaroid Graphics Imaging Direct Digital Color Proofing

    King, Patrick F.


    Good morning ladies and gentlemen. I represent Polaroid Graphics Imaging, a wholly owned subsidiary of the Polaroid Corporation. We wish to thank Ken Cloud and the SPIE for the opportunity to speak today. Several criterion are fundamental in the role for Direct Digital Color Proofing (DDCP), First, the DDCP must represent a first generation hardcopy of the exact color information in the production stream. If must, as it's name suggests be an exact, proof (hence the name direct) of the electronic or digital information which would otherwise be directed toward film working. It is after all the most critical means to evaluate the quality of whatever pagination, scanner or color work which has gone be for it. Second, the DDCP must represent an opportunity. That opportunity is to reconvene the production stream and move to film making, optical or magnetic storage, or satellite transmission with the confidence that the DDCP is identical to some conventional counterpart. In the case of film it must match a conventional proof and press sheet, dot for dot. Otherwise it is merely an exercise in interpretation. For magnetic or optical storage and satellite transmission there must be assurance that at any opportunity either a duplicate DDCP or a conventional film/proof could reproduce earlier results. Finally as the printed product is the final goal and direct to press is evolving in direct to plate and direct to gravure printing the DDCP must share the half toner lineage of these products. Thirdly and hardly least, the whole purpose for DDCP is increased productivity. However, our industry struggles to maintain individuality and variety. Somehow DDCP must balance these forces.

  1. Color Correction in Multiple Generation Reproduction Using Digital Watermarking

    Zhigang Fan; Shen-ge Wang; Hui Cheng


    In most existing color reproduction systems, color correction is performed in an open-looped fashion.For multiple generation color copying, color fidelity cannot be guaranteed as the errors introduced in color correction may accumulate. A method of solving the error accumulation problem by embedding color information as invisible digital watermark in hardcopies is proposed. When the hardcopy is scanned, the embedded information can be retrieved to provide real-time calibration. As the method is close-looped in nature, it may reduce error accumulation and improve color fidelity, particularly when copies go through multiple generation reproduction.

  2. Color Calibration for Colorized Vision System with Digital Sensor and LED Array Illuminator

    Zhenmin Zhu


    Full Text Available Color measurement by the colorized vision system is a superior method to achieve the evaluation of color objectively and continuously. However, the accuracy of color measurement is influenced by the spectral responses of digital sensor and the spectral mismatch of illumination. In this paper, two-color vision system illuminated by digital sensor and LED array, respectively, is presented. The Polynomial-Based Regression method is applied to solve the problem of color calibration in the sRGB and CIE  L⁎a⁎b⁎ color spaces. By mapping the tristimulus values from RGB to sRGB color space, color difference between the estimated values and the reference values is less than 3ΔE. Additionally, the mapping matrix ΦRGB→sRGB has proved a better performance in reducing the color difference, and it is introduced subsequently into the colorized vision system proposed for a better color measurement. Necessarily, the printed matter of clothes and the colored ceramic tile are chosen as the application experiment samples of our colorized vision system. As shown in the experimental data, the average color difference of images is less than 6ΔE. It indicates that a better performance of color measurement is obtained via the colorized vision system proposed.

  3. Analysis of color profile quality of digital projector

    Iva Molek


    Full Text Available The aim of the present study was to analyze the display of colors in digital projection. For this purpose the digital projector NEC NP210 was used. The measurements were performed in accordance with the instructions and recommendations of ISO standards. Our goal was to research the creation of color profile of the projector using a EyeOne Pro spectrophotometer and to establish whether the size of color gamut of standardized sRGB color space can be reached by characterization of the digital projector modules. By using the color chart Color Checker Classic, the photometric and colorimetric accuracy of the characterized and uncharacterized projection were evaluated. In the final part of the research, comparison between the colorimetric accuracy of the computer screen and the digital projector was performed. The results showed that by module characterization of the NEC NP210 Movie projector in studio conditions, the same size of the color space could not be achieved as by using the default sRGB module. Evaluation of colorimetric accuracy by using the digitalized color chart Color Checker Classic provides usable results, especially when the display of chromatic colors with emphasis on skin tones, and achromatic colors with emphasis on grey balance or chromaticity respectively, were examined. Based on the obtained results of the computer screen and digital projector comparison, it could be concluded that both compared computer screens match the standards. Overall, the NEC NP210 projector with the sRGB default module without profile could be also used if necessary. Thus, we can sum up that digital projection displaying standardized sRGB color space could not be comparable to a high quality CRT or LCD computer screen.

  4. [Constructing 3-dimensional colorized digital dental model assisted by digital photography].

    Ye, Hong-qiang; Liu, Yu-shu; Liu, Yun-song; Ning, Jing; Zhao, Yi-jiao; Zhou, Yong-sheng


    To explore a method of constructing universal 3-dimensional (3D) colorized digital dental model which can be displayed and edited in common 3D software (such as Geomagic series), in order to improve the visual effect of digital dental model in 3D software. The morphological data of teeth and gingivae were obtained by intra-oral scanning system (3Shape TRIOS), constructing 3D digital dental models. The 3D digital dental models were exported as STL files. Meanwhile, referring to the accredited photography guide of American Academy of Cosmetic Dentistry (AACD), five selected digital photographs of patients'teeth and gingivae were taken by digital single lens reflex camera (DSLR) with the same exposure parameters (except occlusal views) to capture the color data. In Geomagic Studio 2013, after STL file of 3D digital dental model being imported, digital photographs were projected on 3D digital dental model with corresponding position and angle. The junctions of different photos were carefully trimmed to get continuous and natural color transitions. Then the 3D colorized digital dental model was constructed, which was exported as OBJ file or WRP file which was a special file for software of Geomagic series. For the purpose of evaluating the visual effect of the 3D colorized digital model, a rating scale on color simulation effect in views of patients'evaluation was used. Sixteen patients were recruited and their scores on colored and non-colored digital dental models were recorded. The data were analyzed using McNemar-Bowker test in SPSS 20. Universal 3D colorized digital dental model with better color simulation was constructed based on intra-oral scanning and digital photography. For clinical application, the 3D colorized digital dental models, combined with 3D face images, were introduced into 3D smile design of aesthetic rehabilitation, which could improve the patients' cognition for the esthetic digital design and virtual prosthetic effect. Universal 3D colorized

  5. Improved Digital Image Correlation method

    Mudassar, Asloob Ahmad; Butt, Saira


    Digital Image Correlation (DIC) is a powerful technique which is used to correlate two image segments to determine the similarity between them. A correlation image is formed which gives a peak known as correlation peak. If the two image segments are identical the peak is known as auto-correlation peak otherwise it is known as cross correlation peak. The location of the peak in a correlation image gives the relative displacement between the two image segments. Use of DIC for in-plane displacement and deformation measurements in Electronic Speckle Photography (ESP) is well known. In ESP two speckle images are correlated using DIC and relative displacement is measured. We are presenting background review of ESP and disclosing a technique based on DIC for improved relative measurements which we regard as the improved DIC method. Simulation and experimental results reveal that the proposed improved-DIC method is superior to the conventional DIC method in two aspects, in resolution and in the availability of reference position in displacement measurements.

  6. Development of an XYZ Digital Camera with Embedded Color Calibration System for Accurate Color Acquisition

    Kretkowski, Maciej; Jablonski, Ryszard; Shimodaira, Yoshifumi

    Acquisition of accurate colors is important in the modern era of widespread exchange of electronic multimedia. The variety of device-dependent color spaces causes troubles with accurate color reproduction. In this paper we present the outlines of accomplished digital camera system with device-independent output formed from tristimulus XYZ values. The outstanding accuracy and fidelity of acquired color is achieved in our system by employing an embedded color calibration system based on emissive device generating reference calibration colors with user-defined spectral distribution and chromaticity coordinates. The system was tested by calibrating the camera using 24 reference colors spectrally reproduced from 24 color patches of the Macbeth Chart. The average color difference (CIEDE2000) has been found to be ΔE =0.83, which is an outstanding result compared to commercially available digital cameras.

  7. Digital color acquisition, perception, coding and rendering

    Fernandez-Maloigne, Christine; Macaire, Ludovic


    In this book the authors identify the basic concepts and recent advances in the acquisition, perception, coding and rendering of color. The fundamental aspects related to the science of colorimetry in relation to physiology (the human visual system) are addressed, as are constancy and color appearance. It also addresses the more technical aspects related to sensors and the color management screen. Particular attention is paid to the notion of color rendering in computer graphics. Beyond color, the authors also look at coding, compression, protection and quality of color images and videos.

  8. Spatial Variation of the Correlated Color Temperature of Lightning Channel

    Shimoji, Nobuaki; Sakihama, Singo


    In this paper, we studied the spatial variation of the correlated color temperature (CCT) of lightning channel. We also discussed the energy of lightning channels relating to the CCT . First we applied digital image processing techniques to lightning images. In order to reduce the chromatic aberration, we created the reduction technique algorithm of the chromatic aberration on digital still images. We applied the reduction technique of the chromatic aberration to digital still images, and then the obtained results was mapped to the xy-chromaticity diagram. The CCT of the lightning channel was decided on the xy-chromaticity diagram. From results, the spatial variation of the CCT of the lightning channel was confirmed. Then the energy associated with the the CCT was discussed.

  9. Film Recording of Digital Color Images


    physiological evidence indicating that the retina contains three kinds of color receptors. In fact, various kinds of color blindness have been...fundamental sensitivites of the eye. Fortunately, estimates of the s-(X) can be obtained by alternative methods, such as color blindness studies [4]. A...number of fundamental response curves have been proposed. One set which was deduced from color blindness data, and is in good agreement with more

  10. Color-image retrieval based on fuzzy correlation

    ZHAI Hongchen; LIANG Yanmei; MU Guoguang


    We report a method of color-image retrieval based on fuzzy correlation, in which α-cut relations in fuzzy set theory are applied to defining color match and height match of color peaks for synthesizing fuzzy correlation of two color histograms, and RGB space is partitioned into six sub-regions in the experiment for the regional color comparisons. Experimental results show that the efficiency of the color-image retrieval can be effectively improved by this approach.

  11. Black Twin Colors on Topographics Maps in Digital Print

    Maja Matas; Vilko Žiljak


    Spot dyes join the double feature of the INFRAREDESIGN® theory. A large number of planned colors in graphics of topographic maps, are simulated in the press with only four process colorants. Achieved are seperated infromation for the visible and infrared spectrum. This introduces the protection of printed matter, protection of property, reduces the cost of spot printing of large numbers of layers. For the digital print technology simulation of the merge of "topographical colors" is extended t...

  12. Multimodal digital color imaging system for facial skin lesion analysis

    Bae, Youngwoo; Lee, Youn-Heum; Jung, Byungjo


    In dermatology, various digital imaging modalities have been used as an important tool to quantitatively evaluate the treatment effect of skin lesions. Cross-polarization color image was used to evaluate skin chromophores (melanin and hemoglobin) information and parallel-polarization image to evaluate skin texture information. In addition, UV-A induced fluorescent image has been widely used to evaluate various skin conditions such as sebum, keratosis, sun damages, and vitiligo. In order to maximize the evaluation efficacy of various skin lesions, it is necessary to integrate various imaging modalities into an imaging system. In this study, we propose a multimodal digital color imaging system, which provides four different digital color images of standard color image, parallel and cross-polarization color image, and UV-A induced fluorescent color image. Herein, we describe the imaging system and present the examples of image analysis. By analyzing the color information and morphological features of facial skin lesions, we are able to comparably and simultaneously evaluate various skin lesions. In conclusion, we are sure that the multimodal color imaging system can be utilized as an important assistant tool in dermatology.

  13. Black Twin Colors on Topographics Maps in Digital Print

    Maja Matas


    Full Text Available Spot dyes join the double feature of the INFRAREDESIGN® theory. A large number of planned colors in graphics of topographic maps, are simulated in the press with only four process colorants. Achieved are seperated infromation for the visible and infrared spectrum. This introduces the protection of printed matter, protection of property, reduces the cost of spot printing of large numbers of layers. For the digital print technology simulation of the merge of "topographical colors" is extended to achieve Infrared graphics. The black color tone, a typical color in cartography, is associated with two dyes with different compositions and different properties in the infrared spectrum. Black twins are programmed for the digital printing form for the printing with CMYK process components, and according to the IRD® procedure.

  14. Digital color image encoding and decoding using a novel chaotic random generator

    Nien, H.H. [Department of Electrical Engineering, Chienkuo Technology University, Changhua 500, Taiwan (China); Huang, C.K. [Department of Electrical Engineering, Chienkuo Technology University, Changhua 500, Taiwan (China)]. E-mail:; Changchien, S.K. [Department of Electrical Engineering, Chienkuo Technology University, Changhua 500, Taiwan (China); Shieh, H.W. [Department of Electrical Engineering, Chienkuo Technology University, Changhua 500, Taiwan (China); Chen, C.T. [Department of Electrical Engineering, Chienkuo Technology University, Changhua 500, Taiwan (China); Tuan, Y.Y. [Department of Electrical Engineering, Chienkuo Technology University, Changhua 500, Taiwan (China)


    This paper proposes a novel chaotic system, in which variables are treated as encryption keys in order to achieve secure transmission of digital color images. Since the dynamic response of chaotic system is highly sensitive to the initial values of a system and to the variation of a parameter, and chaotic trajectory is so unpredictable, we use elements of variables as encryption keys and apply these to computer internet communication of digital color images. As a result, we obtain much higher communication security. We adopt one statistic method involving correlation coefficient {gamma} and FIPS PUB 140-1 to test on the distribution of distinguished elements of variables for continuous-time chaotic system, and accordingly select optimal encryption keys to use in secure communication of digital color images. At the transmitter end, we conduct RGB level decomposition on digital color images, and encrypt them with chaotic keys, and finally transmit them through computer internet. The same encryption keys are used to decrypt and recover the original images at the receiver end. Even if the encrypted images are stolen in the public channel, an intruder is not able to decrypt and recover the original images because of the lack of adequate encryption keys. Empirical example shows that the chaotic system and encryption keys applied in the encryption, transmission, decryption, and recovery of digital color images can achieve higher communication security and best recovered images.

  15. Combining Digital Watermarks with Two-Color Bitmap Image


    A technology for combining digital watermarks with two-color bitmap image based on the threshold watermarking method is presented. Our technology doesn't add any thing to the digital media, but combines the watermarks in two-color bitmap image by looking for some characteristic values in the bitmap and uses the relationship between the watermarks and the characteristic values to prove the copyright protection. The choice of the characteristic values depends on the choice of a cryptographic key known by the owner of the bitmap. The benefit of using a cryptographic key is to combine the watermarks with the bitmap in a high secure way.

  16. Color estimation of forest-steppe soils by digital photography under laboratory conditions

    Valeeva, A. A.; Aleksandrova, A. B.; Koposov, G. F.


    Numerical values in the RGB, HSB, and L*a*b systems for the colors of structurally differentiated soils (Luvisols) in the Volga-Kama forest-steppe have been obtained using a digital camera. A high correlation has been revealed between the soil color and the content of humus in the range 0.39-6%. When the content of humus exceeds 6%, the color of humus horizon varies only slightly. A regression equation within the RRGB range from 85 to 173 has been calculated for the rapid determination of humus content in low- and medium-humus texturally differentiated soils of the Volga-Kama forest-steppe.

  17. Color space conversion of digital photofinishing by neural network

    Baozhong Mu; Feihong Yu


    @@ A practical neural network model was designed to realize the color space conversion of digital photofinishing. The sampling, network structure and training process were introduced respectively. But in actual training, the networks fall into local minimum in all probability. To solve this problem, evolutionary programming (EP) algorithm was applied and the learning rate was adaptively adjusted. In the experiment, the performance of network was compared with pre-optimizing. Then the color space conversion was evaluated by the simulation error of samples from the point of color difference.

  18. High-speed Digital Color Imaging Pyrometry


    Electrotechnical Commission. IEC, 1999 IEC 61966-2-1: Multimedia Sys- tems and Equipment, Colour Measurements and Management, Part 2-1: Colour Man...Report 790491, SAE Tech. Paper , 1979. 14 [44] Quoc, H. X.; Vignon, J.-M.; Brun, M. A New Approach of the Two-color Method for Determining Local...Instantaneous Soot Concentration and Temperature in a d.i. Diesel Combustion Chamber. Technical Report 910736, SAE Tech. Paper , 1991. 15 16 1 DEFENSE

  19. Correlation evaluation of intensity and color band images

    Carter, J.M.


    The purpose of this project is to determine which of the three color bands--red, green, or blue--to use in providing the best possible correlation and to determine the accuracy with which these color bands correlate in comparison with the correlation of the three color bands with the intensity model. To fulfill this purpose, the correlation technique of template matching is implemented using a correlator. Correlations are implemented with each of the individual color bands and also with the corresponding intensity model. The correlation coefficient resulting from a successful correlation ranges from 0.9 to 1. A coefficient of 1 demonstrates that the feature information varies identically. When analyzing the data collected from the correlations, the following results are obtained. The color band recommended for the most accurate correlation is the green color band. The correlation of the color bands with the intensity model was not as successful in determining the better color band because the correlation coefficients were very low in comparison to the correlation of the individual color bands.

  20. Correlation between three color coordinates of human teeth.

    Lee, Yong-Keun


    The objective was to determine whether there were significant correlations in the three color coordinates within each of two color coordinate systems, such as the Commission Internationale de l’Eclairage (CIE) L*a*b* system, and the lightness, chroma, and hue angle system, of human vital teeth. The color of six maxillary and six mandibular anterior teeth was measured by the Shade Vision System. Pearson correlations between each pair of the color coordinates were determined (α=0.01 ). The influence of two color coordinates on the other color coordinate was determined with a multiple regression analysis (α=0.01 ). Based on correlation analyses, all the color coordinate pairs showed significant correlations except for the chroma and hue angle pair. The CIE L* was negatively correlated with the CIE a*,b*, and chroma, but positively correlated with the hue angle. The CIE a* was positively correlated with the CIE b* and chroma. Tooth color coordinates were correlated each other. Lighter teeth were less chromatic both in the CIE a* and b* coordinates. Therefore, it was postulated that the three color coordinates of human teeth were harmonized within certain color attribute ranges, and a lack of correlations in these coordinates might indicate external/internal discolorations and/or anomalies of teeth.

  1. Single-exposure color digital holography

    Feng, Shaotong; Wang, Yanhui; Zhu, Zhuqing; Nie, Shouping


    In this paper, we report a method for color image reconstruction by recording only one single multi-wavelength hologram. In the recording process, three lasers of different wavelengths emitting in the red, green and blue regions are used for illuminating on the object and the object diffraction fields will arrive at the hologram plane simultaneously. Three reference beams with different spatial angles will interfere with the corresponding object diffraction fields on the hologram plane, respectively. Finally, a series of sub-holograms incoherently overlapped on the CCD to be recorded as a multi-wavelength hologram. Angular division multiplexing is employed to reference beams so that the spatial spectra of the multiple recordings will be separated in the Fourier plane. In the reconstruction process, the multi-wavelength hologram will be Fourier transformed into its Fourier plane, where the spatial spectra of different wavelengths are separated and can be easily extracted by employing frequency filtering. The extracted spectra are used to reconstruct the corresponding monochromatic complex amplitudes, which will be synthesized to reconstruct the color image. For singleexposure recording technique, it is convenient for applications on the real-time image processing fields. However, the quality of the reconstructed images is affected by speckle noise. How to improve the quality of the images needs for further research.

  2. Objective measurement of erythema in psoriasis using digital color photography with color calibration.

    Raina, A; Hennessy, R; Rains, M; Allred, J; Hirshburg, J M; Diven, D G; Markey, M K


    Traditional metrics for evaluating the severity of psoriasis are subjective, which complicates efforts to measure effective treatments in clinical trials. We collected images of psoriasis plaques and calibrated the coloration of the images according to an included color card. Features were extracted from the images and used to train a linear discriminant analysis classifier with cross-validation to automatically classify the degree of erythema. The results were tested against numerical scores obtained by a panel of dermatologists using a standard rating system. Quantitative measures of erythema based on the digital color images showed good agreement with subjective assessment of erythema severity (κ = 0.4203). The color calibration process improved the agreement from κ = 0.2364 to κ = 0.4203. We propose a method for the objective measurement of the psoriasis severity parameter of erythema and show that the calibration process improved the results. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Color gradients of spiral disks in the Sloan Digital Sky Survey

    Cheng-Ze Liu; Shi-Yin Shen; Zheng-Yi Shao; Rui-Xiang Chang; Jin-Liang Hou; Jun Yin; Da-Wei Yang


    We investigate the radial color gradients of galactic disks using a sample of~20000 face-on spiral galaxies selected from the fourth data release of the Sloan Digital Sky Survey (SDSS-DR4).We combine galaxies with similar concentrations,sizes and luminosities to construct composite galaxies,and then measure their color profiles by stacking the azimuthally averaged radial color profiles of all the member galaxies.Except for the smallest galaxies (R50<3 kpc),almost all galaxies show negative disk color gradients with mean g-γgradient (G)_(gr)=-0.006mag kpc-1 andr-z gradient (G)_(rz) =-0.018 mag kpc~(-1).The disk color gradients are independent of the morphological types of galaxies and strongly dependent on the disk surface brightness μd,with lower surface brightness galactic disks having steeper color gradients.We quantify the intrinsic correlation between color gradients and surface brightness as G_(gr) = -0.011μd + 0.233 and G_(rz) = -0.015μd + 0.324.These quantified correlations provide tight observational constraints on the formation and evolution models of spiral galaxies.

  4. A novel quantum representation of color digital images

    Sang, Jianzhi; Wang, Shen; Li, Qiong


    In this paper, we propose a novel quantum representation of color digital images (NCQI) in quantum computer. The freshly proposed quantum image representation uses the basis state of a qubit sequence to store the RGB value of each pixel. All pixels are stored into a normalized superposition state and can be operated simultaneously. Comparison results with the latest multi-channel representation for quantum image reveal that NCQI can achieve a quadratic speedup in quantum image preparation. Meanwhile, some NCQI-based image processing operations are discussed. Analyses and comparisons demonstrate that many color operations can be executed conveniently based on NCQI. Therefore, the proposed NCQI model is more flexible and better suited to carry out color quantum image processing.

  5. Speckle pattern processing by digital image correlation

    Gubarev Fedor


    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.

  6. A Color Image Digital Watermarking Scheme Based on SOFM

    Anitha, J


    Digital watermarking technique has been presented and widely researched to solve some important issues in the digital world, such as copyright protection, copy protection and content authentication. Several robust watermarking schemes based on vector quantization (VQ) have been presented. In this paper, we present a new digital image watermarking method based on SOFM vector quantizer for color images. This method utilizes the codebook partition technique in which the watermark bit is embedded into the selected VQ encoded block. The main feature of this scheme is that the watermark exists both in VQ compressed image and in the reconstructed image. The watermark extraction can be performed without the original image. The watermark is hidden inside the compressed image, so much transmission time and storage space can be saved when the compressed data are transmitted over the Internet. Simulation results demonstrate that the proposed method has robustness against various image processing operations without sacrif...

  7. Digital holographic video service system for natural color scene

    Seo, Young-Ho; Lee, Yoon-Hyuk; Koo, Ja-Myung; Kim, Woo-Youl; Yoo, Ji-Sang; Kim, Dong-Wook


    We propose a new system that can generate digital holograms using natural color information. The system consists of a camera system for capturing images (object points) and software (S/W) for various image processing. The camera system uses a vertical rig, which is equipped with two depth and RGB cameras and a cold mirror, which has different reflectances according to wavelength for obtaining images with the same viewpoint. The S/W is composed of the engines for processing the captured images and executing computer-generated hologram for generating digital holograms using general-purpose graphics processing units. Each algorithm was implemented using C/C++ and CUDA languages, and all engines in the form of library were integrated in LabView environment. The proposed system can generate about 10 digital holographic frames per second using about 6 K object points.

  8. WACODI: A generic algorithm to derive the intrinsic color of natural waters from digital images

    Novoa, S.; Wernand, M.; van der Woerd, H.J.


    This document presents the WAter COlor from Digital Images (WACODI) algorithm, which extracts the color of natural waters from images collected by low-cost digital cameras, in the context of participatory science and water quality monitoring. SRGB images are converted to the CIE XYZ color space, und

  9. Copyright Protection of Color Video Using Digital Watermarking

    Majid Masoumi


    Full Text Available A huge amount of digital multimedia data is broadcasting daily over the internet. Since digital data can be easily duplicated, intellectual property right protection techniques have become an important issue. In this study, a robust algorithm based on DWT for video copyright protection is proposed. Firstly, the RGB video is converted into YUV color component video, then, in order to make the watermark imperceptible, the luminance layer is only used to embed the watermark and the chrominance layer is left unchanged. In this algorithm, DWT is performed on both watermark image and video I-frames. Using a multiplicative hiding method, watermark image is embedded in its corresponding frequency coefficients of DWT in video I-frames. Based on experimental results the presented method maintains the high transparency of video stream meanwhile resist the watermark against a variety of attacks like: noisy attacks, filtering attacks, blurring attack and compression attacks.

  10. Luminance-color correlation is not used to estimate the color of the illumination

    J.J.M. Granzier (Jeroen); E. Brenner (Eli); F.W. Cornelissen (Frans); J.B. Smeets (Jeroen)


    textabstractHumans can identify the colors of objects fairly consistently, despite considerable variations in the spectral composition of the illumination. It has been suggested that the correlation between luminance and color within a scene helps to disentangle the influences of illumination and re

  11. Luminance-color correlation is not used to estimate the color of the illumination

    Granzier, JJM; Brenner, E; Cornelissen, FW; Smeets, JBJ


    Humans can identify the colors of objects fairly consistently, despite considerable variations in the spectral composition of the illumination. It has been suggested that the correlation between luminance and color within a scene helps to disentangle the influences of illumination and reflectance,

  12. JIMWLK evolution: From color charges to rapidity correlations

    Iancu, E. [Institut de Physique Théorique de Saclay, F-91191 Gif-sur-Yvette (France); Triantafyllopoulos, D.N. [ECT* and Fondazione Bruno Kessler, Strada delle Tabarelle 286, I-38123 Villazzano (Italy)


    We study multi-particle production with rapidity correlations in high-energy p+A collisions. In the context of the Color Glass Condensate, the evolution for such correlations is governed by a generalization of the JIMWLK equation which evolves the strong nuclear fields both in the amplitude and in the complex conjugate one. We give the equivalent Langevin formulation, whose main ingredient is the color charge density linked to a projectile parton (a Wilson line)

  13. JIMWLK evolution: From color charges to rapidity correlations

    Iancu, E.; Triantafyllopoulos, D. N.


    We study multi-particle production with rapidity correlations in high-energy p+A collisions. In the context of the Color Glass Condensate, the evolution for such correlations is governed by a generalization of the JIMWLK equation which evolves the strong nuclear fields both in the amplitude and in the complex conjugate one. We give the equivalent Langevin formulation, whose main ingredient is the color charge density linked to a projectile parton (a Wilson line).

  14. JIMWLK evolution: from color charges to rapidity correlations

    Iancu, E


    We study multi-particle production with rapidity correlations in high-energy p+A collisions. In the context of the Color Glass Condensate, the evolution for such correlations is governed by a generalization of the JIMWLK equation which evolves the strong nuclear fields both in the amplitude and in the complex conjugate one. We give the equivalent Langevin formulation, whose main ingredient is the color charge density linked to a projectile parton (a Wilson line).

  15. Nonlinear Dimming and Correlated Color Temperture Control of Bi-Color White LED Systems

    Chen, H; Tan, SC; Hui, SYR


    This paper proposes a nonlinear approach of controlling the luminous intensity and correlated color temperature (CCT) of white light-emitting diode (LED) systems with dual color temperatures. This LED system is made up of a warm color LED source (2700 K) and a cool color LED source (5000 K). The luminous intensity of each of these LED sources is individually controlled by pulsewidth modulation. The overall intensity of the LED system is due to the combined emitted flux of both LED sources. It...

  16. Color object indexing and retrieval in digital libraries.

    Wei, Jie


    In our previous work, illumination invariant object recognition was achieved by normalizing the three color bands. We further employed the compressed histogram of the chromaticity to arrive at a valuable representation of an object which can facilitate high retrieval accuracy. The first shortcoming of this method lies in the usage of a uniform quantization scheme in obtaining the chromaticity, which is not in agreement with the perception of the human vision system. In this paper, we develop an approach using the CIE UCS transform to circumvent this problem. Second, instead of using uncompressed images to achieve the illumination invariant indexing and retrieval, we carry out our indexing process directly in the DCT domain by using several coefficients from each macro-block. Third, in light of the special properties of the normalized chromaticity histogram frames, the foundation of the ensuing low-pass filtering, an additional step is inserted to render this frame smoother thus resulting in a better data reduction. Fourth, in order to facilitate efficient retrieval during the data query phase, which is of utmost importance in digital libraries, the 36-dimensional model vectors as the indices of model images in digital libraries are clustered by use of vector quantization techniques. This clustering strategy reduces the searching space by an order of magnitude. Desirable results have been observed from our experiments using the proposed color-object-indexing/retrieval algorithm.

  17. Evaluation of natural color and color infrared digital cameras as a remote sensing tool for natural resource management

    Bobbe, Thomas J.; McKean, Jim; Zigadlo, Joseph P.


    Digital cameras are a recent development in electronic imaging that provide a unique capability to acquire high resolution digital imagery in near real-time. The USDA Forest Service Nationwide Forestry Applications Program has recently evaluated natural color and color infrared digital camera systems as a remote sensing tool to collect resource information. Digital cameras are well suited for small projects and complement the use of other remote sensing systems to perform environmental monitoring, sample surveys and accuracy assessments, and update geographic information systems (GIS) data bases.

  18. Implicit interactions between number and space in digit-color synesthesia.

    Niessen, Eva; Fink, Gereon R; Schweitzer, Lisa; Kluender, Nora; Weiss, Peter H


    In digit-color synesthesia, a variant of grapheme-color synesthesia, digits trigger an additional color percept. Recent work on number processing in synesthesia suggests that colors can implicitly elicit numerical representations in digit-color synesthetes implying that synesthesia is bidirectional. Furthermore, morphometric investigations revealed structural differences in the parietal cortex of grapheme-color synesthetes, i.e., in the brain region where interactions between number and space occur in non-synesthetic subjects. Based upon these previous findings, we here examined whether implicitly evoked numerical representations interact with spatial representations in synesthesia in such a way that even a non-numerical, visuo-spatial task (here: line bisection) is modulated, i.e., whether synesthetes exhibit a systematic bisection bias for colored lines. Thirteen digit-color synesthetes were asked to bisect two sets of lines which were colored in their individual synesthetic colors associated with a small or a large digit, respectively. For all colored line stimuli combined, digit-color synesthetes showed--like control subjects (n = 13, matched for age, gender, IQ and handedness)--a pseudo-neglect when bisecting colored lines. Measuring the color-induced change of the bisection bias (i.e., comparing the biases when bisecting lines colored according to a small number vs those lines corresponding to a large number) revealed that only digit-color synesthetes were significantly influenced by line color. The results provide further evidence for the bidirectional nature of synesthesia and support the concept of a mental number line. In addition, they extend previous reports on bidirectionality in synesthesia by showing that even non-numerical, visuo-spatial performance can be modulated by implicit bidirectional processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Digital image modification detection using color information and its histograms.

    Zhou, Haoyu; Shen, Yue; Zhu, Xinghui; Liu, Bo; Fu, Zigang; Fan, Na


    The rapid development of many open source and commercial image editing software makes the authenticity of the digital images questionable. Copy-move forgery is one of the most widely used tampering techniques to create desirable objects or conceal undesirable objects in a scene. Existing techniques reported in the literature to detect such tampering aim to improve the robustness of these methods against the use of JPEG compression, blurring, noise, or other types of post processing operations. These post processing operations are frequently used with the intention to conceal tampering and reduce tampering clues. A robust method based on the color moments and other five image descriptors is proposed in this paper. The method divides the image into fixed size overlapping blocks. Clustering operation divides entire search space into smaller pieces with similar color distribution. Blocks from the tampered regions will reside within the same cluster since both copied and moved regions have similar color distributions. Five image descriptors are used to extract block features, which makes the method more robust to post processing operations. An ensemble of deep compositional pattern-producing neural networks are trained with these extracted features. Similarity among feature vectors in clusters indicates possible forged regions. Experimental results show that the proposed method can detect copy-move forgery even if an image was distorted by gamma correction, addictive white Gaussian noise, JPEG compression, or blurring.

  20. New approach to color calibration of high fidelity color digital camera by using unique wide gamut color generator based on LED diodes

    Kretkowski, M.; Shimodaira, Y.; Jabłoński, R.


    Development of a high accuracy color reproduction system requires certain instrumentation and reference for color calibration. Our research led to development of a high fidelity color digital camera with implemented filters that realize the color matching functions. The output signal returns XYZ values which provide absolute description of color. In order to produce XYZ output a mathematical conversion must be applied to CCD output values introducing a conversion matrix. The conversion matrix coefficients are calculated by using a color reference with known XYZ values and corresponding output signals from the CCD sensor under each filter acquisition from a certain amount of color samples. The most important feature of the camera is its ability to acquire colors from the complete theoretically visible color gamut due to implemented filters. However market available color references such as various color checkers are enclosed within HDTV gamut, which is insufficient for calibration in the whole operating color range. This led to development of a unique color reference based on LED diodes called the LED Color Generator (LED CG). It is capable of displaying colors in a wide color gamut estimated by chromaticity coordinates of 12 primary colors. The total amount of colors possible to produce is 25512. The biggest advantage is a possibility of displaying colors with desired spectral distribution (with certain approximations) due to multiple primary colors it consists. The average color difference obtained for test colors was found to be ▵E~0.78 for calibration with LED CG. The result is much better and repetitive in comparison with the Macbeth ColorCheckerTM which typically gives ▵E~1.2 and in the best case ▵E~0.83 with specially developed techniques.

  1. Intensity Correlation Function of a Single-Mode Laser Driven by Two Colored Noises with Colored Cross-Correlation

    HANLi-Bo; CAOLi; WUDa-Jin; WANGJun


    By using the linear approximation method, the intensity correlation function and the intensity correlation time are calculated in a gain-noise model of a single-mode laser driven by colored cross-correlated pump noise and quantum noise, each of which is colored. We detect that, when the cross-correlation between both noises is negative, the behavior of the intensity correlation function C(t) versus time t, in addition to decreasing monotonously, also exhibits several other cases, such as one maximum, one minimum, and two extrema (one maximum and one minimum), i.e., some parameters of the noises can greatly change the dependence of the intensity correlation function upon time. Moreover, we find that there is a minimum Tmin in the curve of the intensity correlation time versus the pump noise intensity, and the depth and position of Train strongly depend on the quantum noise self-correlation time T2 and cross-correlation time T3.

  2. Optical/digital color photography based on white-light information processing

    罗罡; 刘福来; 林列; 方志良; 王肇圻; 母国光; 翁志成


    The achievement in optical/digital color photography based on white-light information processing including the color-encoding camera, the color image decoder, the integral window Fourier algorithm of the Fourier transform in digital decoding, the color correction of the retrieval color image and the fusion of zero order diffraction is reported. This technique has found its important applications in the fields of aerial reconnaissance photography and far-distance ground photography due to its features of large information capacity, convenience in archival storage, the capability of color enhancement, particularly easy transportation by Internet.

  3. Multi-jet correlations and color coherence phenomena

    Lee, Jason


    A study of multi-jet correlations and color coherence effects is performed with data collected with the CMS experiment at the LHC. Multi-jet correlations in the angles between the jets are measured and compared to predictions including higher order corrections via parton showers.

  4. Correlation based efficient face recognition and color change detection

    Elbouz, M.; Alfalou, A.; Brosseau, C.; Alam, M. S.; Qasmi, S.


    Identifying the human face via correlation is a topic attracting widespread interest. At the heart of this technique lies the comparison of an unknown target image to a known reference database of images. However, the color information in the target image remains notoriously difficult to interpret. In this paper, we report a new technique which: (i) is robust against illumination change, (ii) offers discrimination ability to detect color change between faces having similar shape, and (iii) is specifically designed to detect red colored stains (i.e. facial bleeding). We adopt the Vanderlugt correlator (VLC) architecture with a segmented phase filter and we decompose the color target image using normalized red, green, and blue (RGB), and hue, saturation, and value (HSV) scales. We propose a new strategy to effectively utilize color information in signatures for further increasing the discrimination ability. The proposed algorithm has been found to be very efficient for discriminating face subjects with different skin colors, and those having color stains in different areas of the facial image.


    V. L. Kozlov


    Full Text Available The correlation processing of optical digital images of expert research objects is promising to improve the quality, reliability and representativeness of the research. The development of computer algorithms for expert investigations by using correlation analysis methods for solving such problems of criminology, as a comparison of color-tone image parameters impressions of seals and stamps, and measurement of the rifling profile trace of the barrel on the bullet is the purpose of the work. A method and software application for measurement of linear, angular and altitude characteristics of the profile (micro relief of the rifling traces of the barrel on the bullet for judicial-ballistic tests is developed. Experimental results testify to a high overall performance of the developed program application and confirm demanded accuracy of spent measurements. Technique and specialized program application for the comparison of color-tone image parameters impressions of seals and stamps, reflecting degree and character of painting substance distribution in strokes has been developed. It improves presentation and objectivity of tests, and also allows to reduce their carrying out terms. The technique of expert interpretation of correlation analysis results has been offered. Reliability of the received results has been confirmed by experimental researches and has been checked up by means of other methods.

  6. Automatic Microaneurysm Detection and Characterization Through Digital Color Fundus Images

    Martins, Charles; Veras, Rodrigo; Ramalho, Geraldo; Medeiros, Fatima; Ushizima, Daniela


    Ocular fundus images can provide information about retinal, ophthalmic, and even systemic diseases such as diabetes. Microaneurysms (MAs) are the earliest sign of Diabetic Retinopathy, a frequently observed complication in both type 1 and type 2 diabetes. Robust detection of MAs in digital color fundus images is critical in the development of automated screening systems for this kind of disease. Automatic grading of these images is being considered by health boards so that the human grading task is reduced. In this paper we describe segmentation and the feature extraction methods for candidate MAs detection.We show that the candidate MAs detected with the methodology have been successfully classified by a MLP neural network (correct classification of 84percent).

  7. 3D Color Digital Elevation Map of AFM Sample


    This color image is a three dimensional (3D) view of a digital elevation map of a sample collected by NASA's Phoenix Mars Lander's Atomic Force Microscope (AFM). The image shows four round pits, only 5 microns in depth, that were micromachined into the silicon substrate, which is the background plane shown in red. This image has been processed to reflect the levelness of the substrate. A Martian particle only one micrometer, or one millionth of a meter, across is held in the upper left pit. The rounded particle shown at the highest magnification ever seen from another world is a particle of the dust that cloaks Mars. Such dust particles color the Martian sky pink, feed storms that regularly envelop the planet and produce Mars' distinctive red soil. The particle was part of a sample informally called 'Sorceress' delivered to the AFM on the 38th Martian day, or sol, of the mission (July 2, 2008). The AFM is part of Phoenix's microscopic station called MECA, or the Microscopy, Electrochemistry, and Conductivity Analyzer. The AFM was developed by a Swiss-led consortium, with Imperial College London producing the silicon substrate that holds sampled particles. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  8. Experimental color encryption in a joint transform correlator architecture

    Tebaldi, Myrian; Amaya, Dafne; Torroba, Roberto [Centro de Investigaciones Opticas (CONICET La Plata-CIC) and UID OPTIMO, Facultad Ingenieria, Universidad Nacional de La Plata (Argentina); Horrillo, Sergi; Perez-Cabre, Elisabet; Millan, Maria S [Departamento de Optica y Optometria de la Universidad Politecnica de Cataluna, Terrasa (Spain); Bolognini, Nestor, E-mail:


    We present an experimental color image encryption by using a photorefractive crystal and a joint transform correlator (JTC) architecture. We achieve the color storing by changing the illumination wavelength. One JTC aperture has the input image information corresponding to a determined color channel bonded to a random phase mask (object aperture), and the other JTC aperture contains the key code mask. The joint power spectrum is stored in a photorefractive crystal. Each color data is stored as a modulation of birefringence in this photosensitive medium. The adequate wavelength change produces a corresponding power spectrum modification that avoids image encryption cross talk in the read out step. An analysis in terms of the sensitivity of the photorefractive silenite crystal for different recording wavelengths is carried out. It should be highlighted that the multiplexed power spectrum shows neither the multiplexing operation nor the amount of stored information increasing the system security. We present experimental results that support our approach

  9. Quantifying Human Visible Color Variation from High Definition Digital Images of Orb Web Spiders

    Ajuria Ibarra, Helena; Rao, Dinesh


    Digital processing and analysis of high resolution images of 30 individuals of the orb web spider Verrucosa arenata were performed to extract and quantify human visible colors present on the dorsal abdomen of this species. Color extraction was performed with minimal user intervention using an unsupervised algorithm to determine groups of colors on each individual spider, which was then analyzed in order to quantify and classify the colors obtained, both spatially and using energy and entropy measures of the digital images. Analysis shows that the colors cover a small region of the visible spectrum, are not spatially homogeneously distributed over the patterns and from an entropic point of view, colors that cover a smaller region on the whole pattern carry more information than colors covering a larger region. This study demonstrates the use of processing tools to create automatic systems to extract valuable information from digital images that are precise, efficient and helpful for the understanding of the underlying biology. PMID:27902724

  10. Edge Adaptive Color Demosaicking Based on the Spatial Correlation of the Bayer Color Difference

    Oh HyunMook


    Full Text Available An edge adaptive color demosaicking algorithm that classifies the region types and estimates the edge direction on the Bayer color filter array (CFA samples is proposed. In the proposed method, the optimal edge direction is estimated based on the spatial correlation on the Bayer color difference plane, which adopts the local directional correlation of an edge region of the Bayer CFA samples. To improve the image quality with the consistent edge direction, we classify the region of an image into three different types, such as edge, edge pattern, and flat regions. Based on the region types, the proposed method estimates the edge direction adaptive to the regions. As a result, the proposed method reconstructs clear edges with reduced visual distortions in the edge and the edge pattern regions. Experimental results show that the proposed method outperforms conventional edge-directed methods on objective and subjective criteria.

  11. High-performance VGA-resolution digital color CMOS imager

    Agwani, Suhail; Domer, Steve; Rubacha, Ray; Stanley, Scott


    This paper discusses the performance of a new VGA resolution color CMOS imager developed by Motorola on a 0.5micrometers /3.3V CMOS process. This fully integrated, high performance imager has on chip timing, control, and analog signal processing chain for digital imaging applications. The picture elements are based on 7.8micrometers active CMOS pixels that use pinned photodiodes for higher quantum efficiency and low noise performance. The image processing engine includes a bank of programmable gain amplifiers, line rate clamping for dark offset removal, real time auto white balancing, per column gain and offset calibration, and a 10 bit pipelined RSD analog to digital converter with a programmable input range. Post ADC signal processing includes features such as bad pixel replacement based on user defined thresholds levels, 10 to 8 bit companding and 5 tap FIR filtering. The sensor can be programmed via a standard I2C interface that runs on 3.3V clocks. Programmable features include variable frame rates using a constant frequency master clock, electronic exposure control, continuous or single frame capture, progressive or interlace scanning modes. Each pixel is individually addressable allowing region of interest imaging and image subsampling. The sensor operates with master clock frequencies of up to 13.5MHz resulting in 30FPS. A total programmable gain of 27dB is available. The sensor power dissipation is 400mW at full speed of operation. The low noise design yields a measured 'system on a chip' dynamic range of 50dB thus giving over 8 true bits of resolution. Extremely high conversion gain result in an excellent peak sensitivity of 22V/(mu) J/cm2 or 3.3V/lux-sec. This monolithic image capture and processing engine represent a compete imaging solution making it a true 'camera on a chip'. Yet in its operation it remains extremely easy to use requiring only one clock and a 3.3V power supply. Given the available features and performance levels, this sensor will be

  12. Why is digit ratio correlated to sports performance?

    Kim, Tae Beom; Kim, Khae Hawn


    Second to fourth digit ratio is the ratio of second to fourth digit length. It has been known that digit ratio is sexually dimorphic in humans, such that males tend to have lower digit ratio (longer fourth digits relative to second digits) than females. Digit ratio is thought to be a biomarker of the balance between fetal testosterone (FT) and fetal estrogen (FE) in a relatively narrow developmental window at the end of the first trimester of pregnancy. On the contrary, the relationships between digit ratio and levels of sex steroids in adults are not clear. Most correlational studies between digit ratio and adult sex steroids have revealed that this association is statistically not significant. However, for many years, a lot of researches showed negative relationships between digit ratio and sports performance such as rugby, surfing, rowing, sprinting, endurance, and hand grip strength. Here, we discuss possible mechanisms about the relationships between digit ratio and sports performance. PMID:28119871

  13. Digital image correlation: displacement accuracy estimation

    Wattrisse B.


    Full Text Available The aim of this collaborative work is to study the uncertainties associated with Digital Image Correlation techniques (DIC. More specifically, the link between displacement uncertainties and several correlation parameters chosen by the user and relative to the image analysis software and several image characteristics like speckle size and image noise is emphasized. A previous work [1] has been done for situations with spatially fluctuating displacement fields which dealt with mismatch error linked to the discrepancy between the adopted shape function and the real displacement field in the subset. This present work is focused on the ultimate error regime. To ensure that there is no mismatch error, synthetic images of plane rigid body translation have been analysed. DIC softwares developed by or used in the French community were used to study a large number of settings. The first observations are: (a bias amplitude is almost always insensitive to the subset size, (b DIC formulations can be split up into two families. For the first one, the bias amplitude increases with the noise while it remains constant for the second one. For both families, the mean value of the random error increases with the noise level and with the inverse of the subset size. Furthermore, the random error decreases with the radius of the speckle for the first family, while it increases for the second one. These two different behaviours of the tested DIC package are probably due to their underlying DIC formulation (interpolation, correlation criteria, optimisation process.

  14. Digital image fusion systems: color imaging and low-light targets

    Estrera, Joseph P.


    This paper presents digital image fusion (enhanced A+B) systems in color imaging and low light target applications. This paper will discuss first the digital sensors that are utilized in the noted image fusion applications which is a 1900x1086 (high definition format) CMOS imager coupled to a Generation III image intensifier for the visible/near infrared (NIR) digital sensor and 320x240 or 640x480 uncooled microbolometer thermal imager for the long wavelength infrared (LWIR) digital sensor. Performance metrics for these digital imaging sensors will be presented. The digital image fusion (enhanced A+B) process will be presented in context of early fused night vision systems such as the digital image fused system (DIFS) and the digital enhanced night vision goggle and later, the long range digitally fused night vision sighting system. Next, this paper will discuss the effects of user display color in a dual color digital image fusion system. Dual color image fusion schemes such as Green/Red, Cyan/Yellow, and White/Blue for image intensifier and thermal infrared sensor color representation, respectively, are discussed. Finally, this paper will present digitally fused imagery and image analysis of long distance targets in low light from these digital fused systems. The result of this image analysis with enhanced A+B digital image fusion systems is that maximum contrast and spatial resolution is achieved in a digital fusion mode as compared to individual sensor modalities in low light, long distance imaging applications. Paper has been cleared by DoD/OSR for Public Release under Ref: 08-S-2183 on August 8, 2008.

  15. Digital color management in full-color holographic three-dimensional printer.

    Yang, Fei; Murakami, Yuri; Yamaguchi, Masahiro


    We propose a new method of color management for a full-color holographic, three-dimensional (3D) printer, which produces a volume reflection holographic stereogram using red, green, and blue three-color lasers. For natural color management in the holographic 3D printer, we characterize its color reproduction characteristics based on the spectral measurement of reproduced light. Then the color conversion formula, which comprises a one-dimensional lookup table and a 3×3 matrix, was derived from the measurement data. The color reproducibility was evaluated by printing a color chart hologram, and the average CIELAB ΔE=13.19 is fairly small.

  16. Digital Image Correlation with Dynamic Subset Selection

    Hassan, Ghulam Mubashar; MacNish, Cara; Dyskin, Arcady; Shufrin, Igor


    The quality of the surface pattern and selection of subset size play a critical role in achieving high accuracy in Digital Image Correlation (DIC). The subset size in DIC is normally selected by testing different subset sizes across the entire image, which is a laborious procedure. This also leads to the problem that the worst region of the surface pattern influences the performance of DIC across the entire image. In order to avoid these limitations, a Dynamic Subset Selection (DSS) algorithm is proposed in this paper to optimize the subset size for each point in an image before optimizing the correlation parameters. The proposed DSS algorithm uses the local pattern around the point of interest to calculate a parameter called the Intensity Variation Ratio (Λ), which is used to optimize the subset size. The performance of the DSS algorithm is analyzed using numerically generated images and is compared with the results of traditional DIC. Images obtained from laboratory experiments are also used to demonstrate the utility of the DSS algorithm. Results illustrate that the DSS algorithm provides a better alternative to subset size "guessing" and finds an appropriate subset size for each point of interest according to the local pattern.

  17. Quantitative Evaluation of Surface Color of Tomato Fruits Cultivated in Remote Farm Using Digital Camera Images

    Hashimoto, Atsushi; Suehara, Ken-Ichiro; Kameoka, Takaharu

    To measure the quantitative surface color information of agricultural products with the ambient information during cultivation, a color calibration method for digital camera images and a remote monitoring system of color imaging using the Web were developed. Single-lens reflex and web digital cameras were used for the image acquisitions. The tomato images through the post-ripening process were taken by the digital camera in both the standard image acquisition system and in the field conditions from the morning to evening. Several kinds of images were acquired with the standard RGB color chart set up just behind the tomato fruit on a black matte, and a color calibration was carried out. The influence of the sunlight could be experimentally eliminated, and the calibrated color information consistently agreed with the standard ones acquired in the system through the post-ripening process. Furthermore, the surface color change of the tomato on the tree in a greenhouse was remotely monitored during maturation using the digital cameras equipped with the Field Server. The acquired digital color images were sent from the Farm Station to the BIFE Laboratory of Mie University via VPN. The time behavior of the tomato surface color change during the maturing process could be measured using the color parameter calculated based on the obtained and calibrated color images along with the ambient atmospheric record. This study is a very important step in developing the surface color analysis for both the simple and rapid evaluation of the crop vigor in the field and to construct an ambient and networked remote monitoring system for food security, precision agriculture, and agricultural research.

  18. Digital Color Infrared Orthophotos of Great Smoky Mountains National Park Vegetation Mapping Project

    National Park Service, Department of the Interior — This digital color infrared orthophoto was created by the Center for Remote Sensing and Mapping the Science (CRMS) at The University of Georgia to support the...

  19. Marketingová komunikace portálu DigitalColor

    Jelenská, Andrea


    Jelenská, A., Marketing communication of the portal DigitalColor. Bachelor thesis. Brno: 2015. This bachelor thesis is orientated on the proposal of marketing communications of the photographic portal DigitalColor. In its theoretical part the conceptions and implements connected with marketing communication are defined. The practical part concentrates on the proposal of propagation and the connected analysis of contemporary marketing communications of the portal, analysis of competition and s...

  20. Influence of the correlated color temperature of a light source on the color discrimination capacity of the observer.

    Pardo, Pedro J; Cordero, Eduardo M; Suero, María Isabel; Pérez, Ángel L


    It is well known that there are different preferences in correlated color temperature of light sources for daily living activities or for viewing artistic paintings. There are also data relating the capacity of observers to make judgments on color differences with the spectral power distribution of the light source used. The present work describes a visual color discrimination experiment whose results confirm the existence of a relationship between the correlated color temperature of a light source and the color discrimination capacities of the observers.

  1. Digital Image Correlation for Performance Monitoring.

    Palaviccini, Miguel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Turner, Daniel Z. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Herzberg, Michael [National Security Campus, Kansas City, MO (United States)


    Evaluating the health of a mechanism requires more than just a binary evaluation of whether an operation was completed. It requires analyzing more comprehensive, full-field data. Health monitoring is a process of nondestructively identifying characteristics that indicate the fitness of an engineered component. In order to monitor unit health in a production setting, an automated test system must be created to capture the motion of mechanism parts in a real-time and non-intrusive manner. One way to accomplish this is by using high-speed video (HSV) and Digital Image Correlation (DIC). In this approach, individual frames of the video are analyzed to track the motion of mechanism components. The derived performance metrics allow for state-of-health monitoring and improved fidelity of mechanism modeling. The results are in-situ state-of-health identification and performance prediction. This paper introduces basic concepts of this test method, and discusses two main themes: the use of laser marking to add fiducial patterns to mechanism components, and new software developed to track objects with complex shapes, even as they move behind obstructions. Finally, the implementation of these tests into an automated tester is discussed.

  2. Prototype of a pigments color chart for the digital conservation of ancient murals

    Liang, Jinxing; Wan, Xiaoxia


    Digital imaging has become a very important technique in the conservation of cultural art relics because it can nondestructively acquire the color and spectral image of cultural art relics for different applications. Imaging accuracy is one of the key factors in digital protection of cultural art relics. In order to improve the color and spectral accuracy for digital imaging of cultural art relics, the idea of making the specific color charts for different kinds of artworks is presented. Taking ancient Chinese Dunhuang murals as the specific object of study, a prototype pigments color chart of the Dunhuang murals (DCC), containing a six-step grayscale and 30 colored pigment samples, is made to investigate its pigment types and painting techniques. Under the premise of considering the difference in the number of samples in color charts, the DCC is tested and compared with the classic and widely used standard Macbeth colorchecker (CC) in two aspects: color correction for RGB imaging and spectral reconstruction for spectral imaging. The results show that the prototype pigments color chart is more effective and exhibits superior performance to the CC in both aspects for digital conservation of the Dunhuang murals.

  3. Color and stellar population gradients in galaxies. Correlation with mass

    Tortora, C; Cardone, V F; Capaccioli, M; Jetzer, Ph; Molinaro, R


    We analyze the color gradients (CGs) of ~50000 nearby SDSS galaxies. From synthetic spectral models based on a simplified star formation recipe, we derive the mean spectral properties, and explain the observed radial trends of the color as gradients of the stellar population age and metallicity (Z). The most massive ETGs (M_* > 10^{11} Msun) have shallow CGs in correspondence of shallow (negative) Z gradients. In the stellar mass range 10^(10.3-10.5) < M_* < 10^(11) Msun, the Z gradients reach their minimum of ~ -0.5 dex^{-1}. At M_* ~ 10^{10.3-10.5} Msun, color and Z gradient slopes suddenly change. They turn out to anti-correlate with the mass, becoming highly positive at the very low masses. We have also found that age gradients anti-correlate with Z gradients, as predicted by hierarchical cosmological simulations for ETGs. On the other side, LTGs have gradients which systematically decrease with mass (and are always more negative than in ETGs), consistently with the expectation from gas infall and S...

  4. A real-time error-free color-correction facility for digital consumers

    Shaw, Rodney


    It has been well known since the earliest days of color photography that color-balance in general, and facial reproduction (flesh tones) in particular, are of dominant interest to the consumer, and significant research resources have been expended in satisfying this need. The general problem is a difficult one, spanning the factors that govern perception and personal preference, the physics and chemistry of color reproduction, as well as wide field of color measurement specification, and analysis. However, with the advent of digital photography and its widespread acceptance in the consumer market, and with the possibility of a much greater degree of individual control over color reproduction, the field is taking on a new consumer-driven impetus, and the provision of user facilities for preferred color choice now constitutes an intense field of research. In addition, due to the conveniences of digital technology, the collection of large data bases and statistics relating to individual color preferences have now become a relatively straightforward operation. Using a consumer preference approach of this type, we have developed a user-friendly facility whereby unskilled consumers may manipulate the color of their personal digital images according to their preferred choice. By virtue of its ease of operation and the real-time nature of the color-correction transforms, this facility can readily be inserted anywhere a consumer interacts with a digital image, from camera, printer, or scanner, to web or photo-kiosk. Here the underlying scientific principles are explored in detail, and these are related to the practical color-preference outcomes. Examples are given of the application to the correction of images with unsatisfactory color balance, and especially to flesh tones and faces, and the nature of the consumer controls and their corresponding image transformations are explored.

  5. Color digital holography using speckle illumination by means of a multi-mode fiber

    Funamizu, Hideki; Shimoma, Shohei; Aizu, Yoshihisa


    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.

  6. Signal Digitizer and Cross-Correlation Application Specific Integrated Circuit

    Baranauskas, Dalius (Inventor); Baranauskas, Gytis (Inventor); Zelenin, Denis (Inventor); Kangaslahti, Pekka (Inventor); Tanner, Alan B. (Inventor); Lim, Boon H. (Inventor)


    According to one embodiment, a cross-correlator comprises a plurality of analog front ends (AFEs), a cross-correlation circuit and a data serializer. Each of the AFEs comprises a variable gain amplifier (VGA) and a corresponding analog-to-digital converter (ADC) in which the VGA receives and modifies a unique analog signal associates with a measured analog radio frequency (RF) signal and the ADC produces digital data associated with the modified analog signal. Communicatively coupled to the AFEs, the cross-correlation circuit performs a cross-correlation operation on the digital data produced from different measured analog RF signals. The data serializer is communicatively coupled to the summing and cross-correlating matrix and continuously outputs a prescribed amount of the correlated digital data.

  7. Estimation of color modification in digital images by CFA pattern change.

    Choi, Chang-Hee; Lee, Hae-Yeoun; Lee, Heung-Kyu


    Extensive studies have been carried out for detecting image forgery such as copy-move, re-sampling, blurring, and contrast enhancement. Although color modification is a common forgery technique, there is no reported forensic method for detecting this type of manipulation. In this paper, we propose a novel algorithm for estimating color modification in images acquired from digital cameras when the images are modified. Most commercial digital cameras are equipped with a color filter array (CFA) for acquiring the color information of each pixel. As a result, the images acquired from such digital cameras include a trace from the CFA pattern. This pattern is composed of the basic red green blue (RGB) colors, and it is changed when color modification is carried out on the image. We designed an advanced intermediate value counting method for measuring the change in the CFA pattern and estimating the extent of color modification. The proposed method is verified experimentally by using 10,366 test images. The results confirmed the ability of the proposed method to estimate color modification with high accuracy. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  8. Performances on Symbol Digit Modalities Test, Color Trails Test, and modified Stroop test in a healthy, elderly Danish sample

    Vogel, Asmus; Stokholm, Jette; Jørgensen, Kasper


    for different age groups. For SDMT and CTT1, Danish Adult Reading Test (DART) score also had a significant impact on test performances. The incongruent version of the modified Stroop test was significantly correlated to education. Moderate and significant correlations were found between the three tests. Even......This study presents Danish data for the Symbol Digit Modalities Test (SDMT), Color Trails Test (CTT), and a modified Stroop test from 100 subjects aged 60-87 years. Among the included demographic variables, age had the highest impact on test performances. Thus, the study presents separate data...

  9. Large Scale Cross Drive Correlation Of Digital Media


    this new illicit activity , law enforcement agencies, financial institutions, and other private businesses are incorporating digital forensic experts...providing information technology as a service, the digital universe is doubling every two years. It is estimated that by 2020, the amount of data created...response teams in military and business organizations need a way to correlate large amounts of digital media to determine similarity, detect patterns

  10. Non-linearly weighted fuzzy correlation for color-image retrieval

    Guoguang Mu(母国光); Hongchen Zhai(翟宏琛); Siyuan Zhang(张思远)


    An algorithm with non-linear weight factors in the summation process for fuzzy correlation of color his-tograms is presented, in which non-linear weights are assigned to some characteristic colors of interest.Experimental results show that this can improve the retrieval of color images with partial aberrations orwith local color characters.

  11. Normalized intensity correlation function of single-mode laser system driven by colored cross-correlation noises

    Bing Wang; Xiuqing Wu


    @@ Considering a single-mode laser system with cross-correlated additive colored noise and multiplicative colored noise, we study the effects of correlation among noises on the normalized intensity correlation function C(s).C(s) is derived by means of the projection operator method.

  12. Color calibration of a CMOS digital camera for mobile imaging

    Eliasson, Henrik


    As white balance algorithms employed in mobile phone cameras become increasingly sophisticated by using, e.g., elaborate white-point estimation methods, a proper color calibration is necessary. Without such a calibration, the estimation of the light source for a given situation may go wrong, giving rise to large color errors. At the same time, the demands for efficiency in the production environment require the calibration to be as simple as possible. Thus it is important to find the correct balance between image quality and production efficiency requirements. The purpose of this work is to investigate camera color variations using a simple model where the sensor and IR filter are specified in detail. As input to the model, spectral data of the 24-color Macbeth Colorchecker was used. This data was combined with the spectral irradiance of mainly three different light sources: CIE A, D65 and F11. The sensor variations were determined from a very large population from which 6 corner samples were picked out for further analysis. Furthermore, a set of 100 IR filters were picked out and measured. The resulting images generated by the model were then analyzed in the CIELAB space and color errors were calculated using the ΔE94 metric. The results of the analysis show that the maximum deviations from the typical values are small enough to suggest that a white balance calibration is sufficient. Furthermore, it is also demonstrated that the color temperature dependence is small enough to justify the use of only one light source in a production environment.

  13. Digital compositing a full-color holographic animated stereogram

    Diamond, Mark C.


    The paper addresses the use of hybrid cinematography, computer graphics, and electronic imaging to create a full color, animated, holographic stereogram for embossed replication. Several methods of stereoscopic techniques for pre-visualization of holographic stereogram subjects are discussed as well.

  14. D Point Cloud Model Colorization by Dense Registration of Digital Images

    Crombez, N.; Caron, G.; Mouaddib, E.


    Architectural heritage is a historic and artistic property which has to be protected, preserved, restored and must be shown to the public. Modern tools like 3D laser scanners are more and more used in heritage documentation. Most of the time, the 3D laser scanner is completed by a digital camera which is used to enrich the accurate geometric informations with the scanned objects colors. However, the photometric quality of the acquired point clouds is generally rather low because of several problems presented below. We propose an accurate method for registering digital images acquired from any viewpoints on point clouds which is a crucial step for a good colorization by colors projection. We express this image-to-geometry registration as a pose estimation problem. The camera pose is computed using the entire images intensities under a photometric visual and virtual servoing (VVS) framework. The camera extrinsic and intrinsic parameters are automatically estimated. Because we estimates the intrinsic parameters we do not need any informations about the camera which took the used digital image. Finally, when the point cloud model and the digital image are correctly registered, we project the 3D model in the digital image frame and assign new colors to the visible points. The performance of the approach is proven in simulation and real experiments on indoor and outdoor datasets of the cathedral of Amiens, which highlight the success of our method, leading to point clouds with better photometric quality and resolution.

  15. Planning digital artery perforators using color Doppler ultrasonography: A preliminary report.

    Shintani, Kosuke; Takamatsu, Kiyohito; Uemura, Takuya; Onode, Ema; Okada, Mitsuhiro; Kazuki, Kenichi; Nakamura, Hiroaki


    Digital artery perforator (DAP) flaps have been applied for the coverage of finger soft tissue defects. Although an advantage of this method is that there is no scarification of the digital arteries, it is difficult to identify the location of the perforators during intraoperative elevation of the DAP flap. In this study, anatomically reliable locations of DAPs were confirmed using color Doppler ultrasonography (US) in healthy volunteers. A successful case using an adiposal-only DAP flap for the coverage of a released digital nerve using preoperative DAP mapping with color Doppler US is also described. A total of 40 digital arteries in 20 fingers of the right hands of five healthy volunteers (mean age: 32.2 years old) were evaluated. The DAPs were identified using color flow imaging based on the beat of the digital artery in the short axial view. In total, 133 perforators were detected, 76 (an average of 3.8 per finger) arising from the radial digital artery and 57 (an average of 2.9 per finger) arising from ulnar digital artery. Sixty-three perforators (an average of 3.2 per finger) in the middle phalanges and 70 (an average of 3.5 per finger) in the proximal phalanges were found. Overall, an average of 1.7 perforators from each digital artery was detected in the proximal or middle phalanges. Moreover, at least one DAP per phalanx was reliably confirmed using color Doppler US. Preoperative knowledge of DAP mapping could make elevating the DAP flap easier and safer.

  16. Enhancing the Color Set Partitioning in Hierarchical Tree (SPIHT Algorithm Using Correlation Theory

    a a a


    Full Text Available Problem statement: Efficient color image compression algorithm is essential for mass storage and the transmission of the image. The compression efficiency of the Set Partitioning in Hierarchical Tree (SPIHT coding algorithm for color images is improved by using correlation theory. Approach: In this study the correlation between the color channels are used to propose the new algorithm. The correlation between the color channels are analyzed in various color spaces and the color space CIE-UVW in which the color channels are highly correlated is taken. The most correlated U channel is considered as base color and compressed by using the wavelet filter and the SPIHT algorithm. The linear approximation of the two of the color components (V and W based on the primary color component U is used to code subordinate color components. The image is divided into N*N blocks in each color channels. The linear approximation coefficients are calculated for each block of the subordinate colors V and W as functions of the base color. Only these coefficients of each block are coded and send to the receiver along with the SPIHT coding of the base color. Results: By using this algorithm, a significant (4 dB mean value Peak Signal to Noise Ratio (PSNR improvement is obtained compared to the traditional coding scheme for the same compression rate and reduces the coding and decoding time. Also the proposed compression algorithm reduces the complexity in coding and decoding algorithms. Conclusion: This algorithm allows the reduction of complexity for both coding and decoding of color images. It is concluded that a significant PSNR gain and visual quality improvement is obtained. It is found that in color image coding, this algorithm is superior to the traditional de-correlation based methods and reduces the coding and decoding time.

  17. Background interference on the color of dental composite materials with different thickness by digital contrast

    Lins, Emery C.; Florez, Fernando L. E.; Portero, Priscila P.; Lizarelli, Rozane F. Z.; Oliveira, Osmir B., Jr.; Bagnato, Vanderlei S.


    In this work the color dependence of resin composites with the background color was evaluated. The objective was to measure since what thickness the color of the sample stops being influenced by the color of the background over which the resin is placed and the methodology used in experiment was based in analyzing the contrast of digital images of the sample over a black background. The results shown that since 0.8 mm the images contrast becomes almost constant; it prove that since this thickness the color of resin composite depends on the optical resin properties only. The experiment was repeated under three conditions of luminosity to evaluate the influence of it on the image contrast and the results obtained were identical.

  18. Retinopathy online challenge: automatic detection of microaneurysms in digital color fundus photographs.

    Niemeijer, M.; Ginneken, B. van; Cree, M.J.; Mizutani, A.; Quellec, G.; Sanchez, C.I.; Zhang, B.; Hornero, R.; Lamard, M.; Muramatsu, C.; Wu, X.; Cazuguel, G.; You, J.; Mayo, A.; Li, Q.; Hatanaka, Y.; Cochener, B.; Roux, C.; Karray, F.; Garcia, M.; Fujita, H.; Abramoff, M.D.


    The detection of microaneurysms in digital color fundus photographs is a critical first step in automated screening for diabetic retinopathy (DR), a common complication of diabetes. To accomplish this detection numerous methods have been published in the past but none of these was compared with each

  19. Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology

    Drago Strle


    Full Text Available This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode’s current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm2 of silicon area (including three photodiodes and the analog part of the ADC. The DSP is currently implemented on FPGA.

  20. High-speed digital color fringe projection technique for three-dimensional facial measurements

    Liu, Cheng-Yang; Chang, Li-Jen; Wang, Chung-Yi


    Digital fringe projection techniques have been widely studied in industrial applications because of the advantages of high accuracy, fast acquisition and non-contact operation. In this study, a single-shot high-speed digital color fringe projection technique is proposed to measure three-dimensional (3-D) facial features. The light source used in the measurement system is structured light with color fringe patterns. A projector with digital light processing is used as light source to project color structured light onto face. The distorted fringe pattern image is captured by the 3-CCD color camera and encoded into red, green and blue channels. The phase-shifting algorithm and quality guided path unwrapping algorithm are used to calculate absolute phase map. The detecting angle of the color camera is adjusted by using a motorized stage. Finally, a complete 3-D facial feature is obtained by our technique. We have successfully achieved simultaneous 3-D phase acquisition, reconstruction and exhibition at a speed of 0.5 s. The experimental results may provide a novel, high accuracy and real-time 3-D shape measurement for facial recognition system.

  1. Integrated High Resolution Digital Color Light Sensor in 130 nm CMOS Technology

    Strle, Drago; Nahtigal, Uroš; Batistell, Graciele; Zhang, Vincent Chi; Ofner, Erwin; Fant, Andrea; Sturm, Johannes


    This article presents a color light detection system integrated in 130 nm CMOS technology. The sensors and corresponding electronics detect light in a CIE XYZ color luminosity space using on-chip integrated sensors without any additional process steps, high-resolution analog-to-digital converter, and dedicated DSP algorithm. The sensor consists of a set of laterally arranged integrated photodiodes that are partly covered by metal, where color separation between the photodiodes is achieved by lateral carrier diffusion together with wavelength-dependent absorption. A high resolution, hybrid, ∑∆ ADC converts each photo diode’s current into a 22-bit digital result, canceling the dark current of the photo diodes. The digital results are further processed by the DSP, which calculates normalized XYZ or RGB color and intensity parameters using linear transformations of the three photo diode responses by multiplication of the data with a transformation matrix, where the coefficients are extracted by training in combination with a pseudo-inverse operation and the least-mean square approximation. The sensor system detects the color light parameters with 22-bit accuracy, consumes less than 60 μA on average at 10 readings per second, and occupies approx. 0.8 mm2 of silicon area (including three photodiodes and the analog part of the ADC). The DSP is currently implemented on FPGA. PMID:26205275

  2. Correlation of digital health use and chronic pain coping strategies.

    Ranney, Megan L; Duarte, Cassandra; Baird, Janette; Patry, Emily J; Green, Traci C


    Digital health is an increasingly popular tool for patient engagement, having shown great success in arenas such as medication adherence, management of chronic conditions, and patient safety. Given the growth of chronic pain diagnoses, it is imperative to find new technologies to improve care for this particular population. Little research has catalogued the use of digital health in the chronic pain patient population. This manuscript's objective was to describe current patterns of digital health usage among chronic pain patients and how digital health use correlates with health care utilization and health outcomes. A cross-sectional survey was administered to patients with a self-identified chronic pain diagnosis participating in 'Patients Like Me'(®) (PLM), an organization that directly collects data from patients experiencing chronic health conditions, with emphasis on patient-centered outcomes and experiences interacting with the health care system. Validated measures of healthcare utilization, chronic pain management, and digital health use were adapted for the survey. Digital health was defined as the use of online sites, social media, and mobile phone applications before, during, or after healthcare utilization. Descriptive statistics, chi square tests, logistic regression, and linear regression were used as appropriate for analysis. Among 565 respondents (mean age 51.3, 87.2% female, 45.7% publicly insured), most participants (89.5%) reported some digital health use. Females and users below the age of 50 were more likely to use multiple forms of digital health. Healthcare utilization, education level, and race/ethnicity did not correlate with digital health use. Patients using more types of digital health reported significantly higher levels of pain coping skills in the realms of social support, relaxation, and exercise. Digital health use is common among a wide range of patients with chronic pain diagnoses. The use of multiple forms of digital health is

  3. Improving information perception from digital images for users with dichromatic color vision

    Shayeghpour, Omid; Nyström, Daniel; Gooran, Sasan


    Color vision deficiency (CVD) is the inability, or limited ability, to recognize colors and discriminate between them. A person with this condition perceives a narrower range of colors compared to a person with normal color vision. In this study we concentrate on recoloring digital images in such a way that users with CVD, especially dichromats, perceive more details from the recolored images compared to the original ones. During this color transformation process, the goal is to keep the overall contrast of the image constant, while adjusting the colors that might cause confusion for the CVD user. In this method, RGB values at each pixel of the image are first converted into HSV values and, based on pre-defined rules, the problematic colors are adjusted into colors that are perceived better by the user. Comparing the simulation of the original image, as it would be perceived by a dichromat, with the same dichromatic simulation on the recolored image, clearly shows that our method can eliminate a lot of confusion for the user and convey more details. Moreover, an online questionnaire was created and a group of 39 CVD users confirmed that the transformed images allow them to perceive more information compared to the original images.

  4. A Signal Detection Analysis of Digitized and Photographic Image Modes and Color Realism in a Pictorial Recognition Memory Task.

    El-Gazzar, Abdel-Latif I.

    The relative effectiveness of digital versus photographic images was examined with 96 college students as subjects. A 2x2 balanced factorial design was employed to test eight hypotheses. The four groups were (1) digitized black and white; (2) digitized pseudocolor; (3) photographic black and white; and (4) photographic realistic color. Findings…

  5. Colored Digital Image Watermarking using the Wavelet Technique

    Mohammed F. Al-Hunaity


    Full Text Available With the revolution of information technology and Wide Area Networking, data has become less and less private where the access of media as well as the attempts to change and manipulate the contents of media data have become a common case. For that, we need to use a watermarking technique to protect the copyright of the media as well as for digital right management but without leaving a visual effect. We presented a watermarking technique that deals with images where the used technique to embed a wavelet compressed watermark image within the least significant bit (LSB of the cover image pixels in a specific pattern which won't be visible after embedding and will cause the cover image to become copyrighted using the embedded watermark image that can be extracted later.

  6. Digital data storage of core image using high resolution full color core scanner; Kokaizodo full color scanner wo mochiita core image no digital ka

    Takahashi, W.; Ujo, S.; Osato, K.; Takasugi, S. [Geothermal Energy Research and Development Co. Ltd., Tokyo (Japan)


    This paper reports on digitization of core images by using a new type core scanner system. This system consists of a core scanner unit (equipped with a CCD camera), a personal computer and ancillary devices. This is a modification of the old type system, with measurable core length made to 100 cm/3 scans, and resolution enhanced to 5100 pixels/m (1024 pixels/m in the old type). The camera was changed to that of a color specification, and the A/D conversion was improved to 24-bit full color. As a result of carrying out a detail reproduction test on digital images of this core scanner, it was found that objects can be identified at a level of about the size of pixels constituting the image in the case when the best contrast is obtained between the objects and the background, and that in an evaluation test on visibility of concaves and convexes on core surface, reproducibility is not very good in large concaves and convexes. 2 refs., 6 figs.

  7. Correlation function of an optical bistable system with cross-correlated additive white noise and multiplicative colored noise

    Bing Wang; Shaoping Yan


    Considering an optical bistable system with cross-correlated additive white noise and multiplicative colored noise,we study the effects of correlation between the noises on the correlation function C(s)using the unified colored noise approximation and the Stratonovich decoupling ansatz formalism.The effects of the self-correlation time T of the multiplicative colored noise and the correlation intensity A between the two noises are studied with numerical calculation.It is found that C(s)increases with the increase of the self-correlation time r,but decreases with the increase of the correlation intensity A.At large value of T,there is almost no change for C(s)when T changes.

  8. Ultralow-Power Digital Correlator for Microwave Polarimetry

    Piepmeier, Jeffrey R.; Hass, K. Joseph


    A recently developed high-speed digital correlator is especially well suited for processing readings of a passive microwave polarimeter. This circuit computes the autocorrelations of, and the cross-correlations among, data in four digital input streams representing samples of in-phase (I) and quadrature (Q) components of two intermediate-frequency (IF) signals, denoted A and B, that are generated in heterodyne reception of two microwave signals. The IF signals arriving at the correlator input terminals have been digitized to three levels (-1,0,1) at a sampling rate up to 500 MHz. Two bits (representing sign and magnitude) are needed to represent the instantaneous datum in each input channel; hence, eight bits are needed to represent the four input signals during any given cycle of the sampling clock. The accumulation (integration) time for the correlation is programmable in increments of 2(exp 8) cycles of the sampling clock, up to a maximum of 2(exp 24) cycles. The basic functionality of the correlator is embodied in 16 correlation slices, each of which contains identical logic circuits and counters (see figure). The first stage of each correlation slice is a logic gate that computes one of the desired correlations (for example, the autocorrelation of the I component of A or the negative of the cross-correlation of the I component of A and the Q component of B). The sampling of the output of the logic gate output is controlled by the sampling-clock signal, and an 8-bit counter increments in every clock cycle when the logic gate generates output. The most significant bit of the 8-bit counter is sampled by a 16-bit counter with a clock signal at 2(exp 8) the frequency of the sampling clock. The 16-bit counter is incremented every time the 8-bit counter rolls over.

  9. A novel blinding digital watermark algorithm based on lab color space

    Dong, Bing-feng; Qiu, Yun-jie; Lu, Hong-tao


    It is necessary for blinding digital image watermark algorithm to extract watermark information without any extra information except the watermarked image itself. But most of the current blinding watermark algorithms have the same disadvantage: besides the watermarked image, they also need the size and other information about the original image when extracting the watermark. This paper presents an innovative blinding color image watermark algorithm based on Lab color space, which does not have the disadvantages mentioned above. This algorithm first marks the watermark region size and position through embedding some regular blocks called anchor points in image spatial domain, and then embeds the watermark into the image. In doing so, the watermark information can be easily extracted after doing cropping and scale change to the image. Experimental results show that the algorithm is particularly robust against the color adjusting and geometry transformation. This algorithm has already been used in a copyright protecting project and works very well.

  10. Optimal CCD readout by digital correlated double sampling

    Alessandri, Cristobal; Guzman, Dani; Passalacqua, Ignacio; Alvarez-Fontecilla, Enrique; Guarini, Marcelo


    Digital correlated double sampling (DCDS), a readout technique for charge-coupled devices (CCD), is gaining popularity in astronomical applications. By using an oversampling ADC and a digital filter, a DCDS system can achieve a better performance than traditional analogue readout techniques at the expense of a more complex system analysis. Several attempts to analyse and optimize a DCDS system have been reported, but most of the work presented in the literature has been experimental. Some approximate analytical tools have been presented for independent parameters of the system, but the overall performance and trade-offs have not been yet modelled. Furthermore, there is disagreement among experimental results that cannot be explained by the analytical tools available. In this work, a theoretical analysis of a generic DCDS readout system is presented, including key aspects such as the signal conditioning stage, the ADC resolution, the sampling frequency and the digital filter implementation. By using a time-dom...

  11. Stationary Intensity Distribution of Single-Mode Laser Driven by Additive and Multiplicative Colored Noises with Colored Cross-Correlation

    LIANG Gui-Yun; CAO Li; WANG Jun; Wu Da-Jin


    Applying the approximate Fokker-Planck equation we derived, we obtain the analytic expression of thestationary laser intensity distribution Pst(Ⅰ) by studying the single-mode laser cubic model subject to colored cross-correlation additive and multiplicative noise, each of which is colored. Based on it, we discuss the effects on the stationarylaser intensity distribution Pst(Ⅰ) by cross-correlation between noises and "color" of noises (non-Markovian effect) whenthe laser system is above the threshold. In detail, we analyze two cases: One is that the three correlation-times (i.e.the self-correlation and cross-correlation times of the additive and multiplicative noise) are chosen to be the same value(τ1 = τ2 = τ3 = τ). For this case, the effect of noise cross-correlation is investigated emphatically, and we detect thatonly when λ≠ 0 can the noise-induced transition occur in the Pst(Ⅰ) curve, and only when τ≠ 0 and λ≠ 0, can the"reentrant noise-induced transition" occur. The other case is that the three correlation times are not the same value,τ1 ≠τ2 ≠τ3. For this case, we find that the noise-induced transition occurring in the Pst (Ⅰ) curve is entirely differentwhen the values of τ1, τ2, and τ3 are changed respectively. In particular, when τ2 (self-correlation time of additivenoise) is changing, the ratio of the two maximums of the Pst(Ⅰ) curve R exhibits an interesting phenomenon, "reentrantnoise-induced transition", which demonstrates the effect of noise "color" (non-Markovian effect).

  12. Stationary Intensity Distribution of Single-Mode Laser Driven by Additive and Multiplicative Colored Noises with Colored Cross-Correlation

    CAOLi; WANGJun; WuDa-Jin; LIANGGui-Yun


    Applying the approximate Fokker-Planck equation we derived, we obtain the analytic expression of the stationary laser intensity distribution Pst(l) by studying the single-mode laser cubic model subject to colored cross-correlation additive and multiplicative noise, each of which is colored. Based on it, we discuss the effects on the stationary laser intensity distribution Pot(I) by cross-correlation between noises and "color" of noises (non-Markovian effect) when the laser system is above the threshold. In detail, we analyze two cases: One is that the three correlation-times (i.e.the self-correlation and cross-correlation times of the additive and multiplicative noise) are chosen to be the same value(Tl=T2=T3=T). For this case, the effect of noise cross-correlation is investigated emphatically, and we detect that only when λ≠ 0 can the noise-induced transition occur in the Pst (I) curve, and only when T≠ 0 and λ≠0, can the "reentrant noise-induced transition" occur. The other case is that the three correlation times are not the same value,T1≠T2≠T3. For this case, we find that the noise-induced transition occurring in the Pst(I) curve is entirely different when the values of T1,T2, and T3 are changed respectively. In particular, when T2 (serf-correlation time of additive noise) is cha~g~g, the ratio of the two maximums of the Pst( I) curve R exhibits an interesting phenomenon,"reentrant noise-induced transition", which demonstrates the effect of noise "color" (non-Markovian effect).

  13. Color pattern recognition based on the joint fractional Fourier transform correlator

    Weimin Jin; Yupei Zhang


    A new system of multi-channel single-output joint fractional Fourier transform correlator (JFRTC) for color pattern recognition is proposed based on the conventional system of multi-channel single-output joint transform correlator (JTC). The theoretical analysis and optical experiments are performed. With this method, one can obtain three correlation peaks at the output plane which show a pair of desired cross-correlation peaks and one auto-correlation peak. In comparison, the conventional system leads to more correlation peaks playing a noise role in color pattern recognition.

  14. Correlation Studies on a Prototype Color-Measurement System


    System. NATICK/TR-83/005, US Army Natick Research and Development Laboratories, Natick, MA 01760, September 1982, AD A124 505. 2 F.W. Billmeyer , Jr...color space. NATICK/TR-80/036, US Army Natick Research and Development Laboratories, Natick, MA 01760, September 1980, AD A094 163. Billmeyer , Jr., F.W

  15. Color Shade Instrumentation Correlation Study: Statistical Analysis. Revision


    Evaluation Procedure 9. Figure A-4 displays the observations for view environment. Illumination Brand Change Schedule Gretag MacBeth (1...3.90.00 (1) X Rite X Rite Colormaster 8.0.3 (1) Color iQC v.6.0 (1) Gretag MacBeth Gretag Quality Control System Version 329 (1) B-1 Appendix B

  16. Study of size effect using digital image correlation

    A. H. A. SANTOS

    Full Text Available Size effect is an important issue in concrete structures bearing in mind that it can influence many aspects of analysis such as strength, brittleness and structural ductility, fracture toughness and fracture energy, among others. Further this, ever more new methods are being developed to evaluate displacement fields in structures. In this paper an experimental evaluation of the size effect is performed applying Digital Image Correlation (DIC technique to measure displacements on the surface of beams. Three point bending tests were performed on three different size concrete beams with a notch at the midspan. The results allow a better understanding of the size effect and demonstrate the efficiency of Digital Image Correlation to obtain measures of displacements.

  17. Demosaicing images from colour cameras for digital image correlation

    Forsey, A.; Gungor, S.


    Digital image correlation is not the intended use for consumer colour cameras, but with care they can be successfully employed in such a role. The main obstacle is the sparsely sampled colour data caused by the use of a colour filter array (CFA) to separate the colour channels. It is shown that the method used to convert consumer camera raw files into a monochrome image suitable for digital image correlation (DIC) can have a significant effect on the DIC output. A number of widely available software packages and two in-house methods are evaluated in terms of their performance when used with DIC. Using an in-plane rotating disc to produce a highly constrained displacement field, it was found that the bicubic spline based in-house demosaicing method outperformed the other methods in terms of accuracy and aliasing suppression.


    MaShaopeng; JillGuanchang


    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.

  19. Color correlation for the recognition of Vibrio cholerae O1 in seawater

    Mourino-Perez, Rosa R.; Alvarez-Borrego, Josue


    Application of color correlation optical systems for the recognition of Vibrio cholerae 01 in seawater samples with matched filters and phase only filters recorded in holographic plates in three channels (RGB).

  20. Digitally synchronized LCD projector for multi-color fluorescence excitation in parallel capillary electrophoresis detection.

    Lin, Shi-Wei; Chang, Chih-Hang; Wu, Dai-Yang; Lin, Che-Hsin


    A simple method is proposed for modulating the excitation light used for multi-color fluorescence detection in a single capillary electrophoresis (CE) channel. In the proposed approach, a low-cost commercial liquid crystal device (LCD) projector with digitally-modulated LCD switches is used to provide the illumination light source and the fluorescence emitted from the CE chip is synchronously detected using an ultraviolet-visible-near infrared (UV-vis-NIR) spectrometer. The modulated light source enables the detection of multiple fluorescence signals within a single CE channel without the need of mechanically switching optical components. In order to enhance the sensing performance of the proposed system, two short-pass filters and one band-pass filter are inserted into the LCD projector to modify the wavelength spectra for fluorescence excitation. With this simple approach, the signal-to-noise (SN) ratio of the fluorescence detection signals is greatly improved by a factor of approximately 22 when detecting Atto647N fluorescent dye. The feasibility of the proposed multi-color CE detection approach is demonstrated by detecting two different samples including a mixed sample comprising FITC, Rhodamine B and Atto647N fluorescent dyes and a bio-sample composed of two ssDNAs labeled with FITC and Cy3, respectively. Results confirm that the digitally-modulated excitation system proposed in this study has significant potential for the parallel analysis of fluorescently-labeled bio-samples using a multi-color detection scheme.

  1. A Novel Effective Secure and Robust CDMA Digital Image Watermarking in YUV Color Space Using DWT2

    Mehdi Khalili


    Full Text Available This paper is allocated to CDMA digital images watermarking for ownership verification and image authentication applications, which for more security, watermark W is converted to a sequence and then a random binary sequence R of size n is adopted to encrypt the watermark; where n is the size of the watermark. This adopting process uses a pseudo-random number generator to determine the pixel to be used on a given key. After converting the host image to YUV color space and then wavelet decomposition of Y channel, this adopted watermark is embedded into the selected subbands coefficients of Y channel using the correlation properties of additive pseudo- random noise patterns. The experimental results show that the proposed approach provides extra imperceptibility, security and robustness against JPEG compression and different noises attacks compared to the similar proposed methods. Moreover, the proposed approach has no need of the original image to extract watermarks.

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

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


    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.

  3. Optical/digital color photography based on white-light information processing

    LUO; Gang; (


    [1]Porter, A. B., On the diffraction theory of microscope vision, Phil. Mag., 1906, 11(6): 154.[2]Zernike, F., Das Phasenkontrastverfahren bei der Mikroskopischen Beobachtung, Z. Tech. Phys., 1935, 16: 454.[3]Cutrona, L. J., On the application of coherent optical processing techniques to systhetic aperture radar, Proc. IEEE, 1965, 54: 1026.[4]Vander Lugt, A. B., Signal detection by complex spatial filtering, IEEE Trans. Inform. Theory, 1964, IT-10: 2.[5]Yu, F. T. S., White-light processing technique for archival storage of color films, Appl. Opt., 1980, 19: 2457.[6]Yu, F. T. S., Mu, G. G., Zhuang S. L., Color restoration of faded color films, Opitk, 1981, 58: 389.[7]Mu, G. G., Wang, J. Q., Fang, Z. L. et al., A white-light processing technique for color photography with a black-and-white film and a tricolor grating, Chin. J. Sci. Instrum., 1983, 4: 124.[8]Mu, G. G., Fang, Z. L., Wang, J. Q. et al., Color photography with black-and-white film, China Patent, CN1003811B, E28, 1989.[9]Mu, G. G., Fang, Z. L., Liu, F. L. et al., Color data image encoding method and apparatus with spectral zonal filter, U. S. Patent, 5452002, 9/1995.[10]Mu, G. G., Fang, Z. L., Liu, F. L. et al., A physical method for color photography, in Trends in Optics, International Commission for Optics, Vol. Ⅲ (ed. Consortini, A.), New York: Academic Press, 1996, 527-542.[11]Jiang, J., Lin, L., Fang, Z. L. et al., Color retrieval of encoded black-and-white film by local fourier transformation algorithm, J. Optoelectronics Laser, 1998, 9(3): 251.[12]Chavez, P. S., Sides, S. C., Anderson, J. A., Comparison of three deferent methods to merge multiresolution and multispectral data: Landsat TM and SPOT panchromatic, Photogrammetric Eng. Remote Sensing, 1991, 57(3): 295.[13]Yocky, A., Image merging and data fusion by means of the discrete two-dimensional wavelet transform, J. Opt. Soc. Am. A, 1995, 12(9): 1834.[14]Smith, A. R., Color gamut


    Dheerendra S Tomar


    Full Text Available This paper presents digital watermarking methods for authorization against copying or piracy of color images. Watermarking is a very important field for copyrights of various electronic documents and media. With images widely available on the Internet, it may sometimes be desirable to use watermarks. Digital watermarking is the processing of combined information into a digital signal. A watermark is a secondary image, which is overlaid on the host image, and provides a means of protecting the image. This paper presents the survey on digital watermark features, its classifications and applications. Various watermarking techniques have been studied in detail in mainly three domains: spatial, frequency and statistical domain. In spatial domain, Least-Significant Bit (LSB, SSM-Modulation-Based Technique has been developed. For DCT domain, block based approach and for wavelet domain, multi-level wavelet transformation technique and CDMA based approaches has been developed.The Discrete Wavelet Transform (DWT is currently used in a wide variety of signal processing applications. This paper also presents the various error matrices for analyses the robustness of watermarking method.

  5. Screening neonatal jaundice based on the sclera color of the eye using digital photography.

    Leung, Terence S; Kapur, Karan; Guilliam, Ashley; Okell, Jade; Lim, Bee; MacDonald, Lindsay W; Meek, Judith


    A new screening technique for neonatal jaundice is proposed exploiting the yellow discoloration in the sclera. It involves taking digital photographs of newborn infants' eyes (n = 110) and processing the pixel colour values of the sclera to predict the total serum bilirubin (TSB) levels. This technique has linear and rank correlation coefficients of 0.75 and 0.72 (both pdevice.

  6. Research of Direct Digital Correlative-Interferometric Radio Direction Finder with Double Correlation-convolutional Processing

    V. V. Tsyporenko


    Full Text Available Introduction. In this article the unsettled part of the general problem of the research of direct digital methods of correlative-interferometric direction-finding was solved. The purpose of the article is to optimize the direction-finding of the direct digital correlative-interferometric radio direction finder with double correlation-convolutional processing by its exactness. Fundamentals of researches. As a result of the conducted researches it was defined that the basic parameter of equalization of dispersion of error of estimation of direction on the source of radio radiation for the explored radio direction finder, which ought to be optimized, is the size of frequency converting change. Optimization. It was conducted the parametrical optimization of the direct digital correlative-interferometric radio direction finder with double correlation-convolutional processing by its exactness. As a result of the modelling the dependence of middle quadratic deflection of estimation of direction from the relation of signal/noise for the different possible values of circular frequency converting shift was obtained. Conclusions. The analytical calculations and the results of the modelling fully coincided, that confirmed the rightness of the researches and the authenticity of the results of optimization.

  7. Digital image correlation based on a fast convolution strategy

    Yuan, Yuan; Zhan, Qin; Xiong, Chunyang; Huang, Jianyong


    In recent years, the efficiency of digital image correlation (DIC) methods has attracted increasing attention because of its increasing importance for many engineering applications. Based on the classical affine optical flow (AOF) algorithm and the well-established inverse compositional Gauss-Newton algorithm, which is essentially a natural extension of the AOF algorithm under a nonlinear iterative framework, this paper develops a set of fast convolution-based DIC algorithms for high-efficiency subpixel image registration. Using a well-developed fast convolution technique, the set of algorithms establishes a series of global data tables (GDTs) over the digital images, which allows the reduction of the computational complexity of DIC significantly. Using the pre-calculated GDTs, the subpixel registration calculations can be implemented efficiently in a look-up-table fashion. Both numerical simulation and experimental verification indicate that the set of algorithms significantly enhances the computational efficiency of DIC, especially in the case of a dense data sampling for the digital images. Because the GDTs need to be computed only once, the algorithms are also suitable for efficiently coping with image sequences that record the time-varying dynamics of specimen deformations.

  8. Correlación entre diferentes métodos de evaluación de color en el clareamiento dental. Correlation between different methods for co

    Grez, Patrício Vildosóla; Casielles, Javier Martin; Godoy,Eduardo Fernandez; Aguirre,pablo Angel; Reyes, Ivonne Ovalle; Andrade, Marcelo Ferrarezi de [UNESP; Cortés,Gustavo Moncada; Oliveira Júnior, Osmir Batista de [UNESP


    The aim of this study was to evaluate the correlation of color change on bleaching tooth through delta E (ΔE) by the spectrophotometer Spectroshade (SS) and digital program Scanwhite (SW). Methods: 25 patient volunteers were recruited from Operative Dentistry at Universidad de Chile Dental School, between 18 to 30 years, with good oral hygiene. Exclusion criteria: Previous experienced tooth bleaching, anterior restorations, cervical lesions, pain dental, pregnant patient, stained teeth, malpo...

  9. Burst digital correlator as laser-Doppler velocimetry signal processor.

    Ikeda, Y; Nakajima, T


    A burst digital correlator (BDC) has been developed to obtain flow-velocity information at high data rates from wideband laser-Doppler signals of low signal-to-noise ratio (below 0 dB). Results with artificial signals show that, over a signal bandwidth of 5-120 MHz, the BDC has a measurement accuracy of less than 0.4% at a maximum data rate (number of measurements per second) of 208 kHz when 64 signal samples are correlated. The accuracy is better than 0.05% with a sample size of 512. The performance of the BDC was also evaluated in practical measurements of near-wall and strongly oscillatory recirculating flows.

  10. Full-field digital image correlation with Kriging regression

    Wang, Dezhi; DiazDelaO, F. A.; Wang, Weizhuo; Mottershead, John E.


    A full-field Digital Image Correlation (DIC) method with integrated Kriging regression is presented in this article. The displacement field is formulated as a best linear unbiased model that includes the correlations between all the locations in the Region of Interest (RoI). A global error factor is employed to extend conventional Kriging interpolation to quantify displacement errors of the control points. An updating strategy for the self-adaptive control grid is developed on the basis of the Mean Squared Error (MSE) determined from the Kriging model. Kriging DIC is shown to outperform several other full-field DIC methods when using open-access experimental data. Numerical examples are used to demonstrate the robustness of Kriging DIC to different choices of initial control points and to speckle pattern variability. Finally Kriging DIC is tested on an experimental example.

  11. Electron Correlation in Nonsequential Double Ionization of Helium by Two-Color Pulses

    ZHOU Yue-Ming; LIAO Qing; HUANG Cheng; TONG Ai-Hong; LU Pei-Xiang


    @@ We investigate the momentum and energy correlations between the two electrons from nonsequential double ionization(NSDI)of helium by strong two-color pulses with the classical three-dimensional ensemble model.The correlated momentum distribution in the direction parallel to the laser field exhibits an arc-like structure and the sum-energy spectrum shows a sharp peak for the NSDI of helium in the two-color fields.Back analysis reveals that the narrow time interval during which recollisions occur,the low returning energy and the short time delay between recollision and double ionization lead to the novel momentum and energy correlations.

  12. Bose-Einstein correlations and color reconnection in W-pair production.

    Chekanov, S. V.; De Wolf, E. A.; Kittel, W.; High Energy Physics; Univ. Instelling Antwerp; Univ. Nijmegen


    We propose a systematic study of Bose-Einstein correlations between identical hadrons coming from different W decays. Experimentally accessible signatures of these correlations as well as of possible color reconnection effects are discussed on the basis of two-particle inclusive densities.

  13. The Negative Correlation between Fiber Color and Quality Traits Revealed by QTL Analysis.

    Feng, Hongjie; Guo, Lixue; Wang, Gaskin; Sun, Junling; Pan, Zhaoe; He, Shoupu; Zhu, Heqin; Sun, Jie; Du, Xiongming


    Naturally existing colored cotton was far from perfection due to having genetic factors for lower yield, poor fiber quality and monotonous color. These factors posed a challenge to colored cotton breeding and innovation. To identify novel quantitative trait loci (QTL) for fiber color along with understanding of correlation between fiber color and quality in colored cotton, a RIL and two F2 populations were generated from crosses among Zong128 (Brown fiber cotton) and two white fiber cotton lines which were then analyzed in four environments. Two stable and major QTLs (qLC-7-1, qFC-7-1) for fiber lint and fuzz color were detected accounting for 16.01%-59.85% of the phenotypic variation across multiple generations and environments. Meanwhile, some minor QTLs were also identified on chromosomes 5, 14, 21 and 24 providing low phenotypic variation (color and quality has been detected between flanking markers NAU1043 and NAU3654 on chromosome 7 (A genome) over multiple environments. Of which, qLC-7-1, qFC-7-1 were responsible for positive effects and improved fiber color in offsprings. Meanwhile, the QTLs (qFL-7-1, qFU-7-1, qFF-7-1, qFE-7-1, and qFS-7-1) for fiber quality had negative effects and explained 2.19%-8.78% of the phenotypic variation. This multiple-effect locus for fiber color and quality may reveal the negative correlation between the two types of above traits, so paving the way towards cotton genetic improvement.

  14. Simulation study of beam extraction from a synchrotron using colored noise with digital filter

    Nakanishi, Tetsuya; Tsuruha, Kohei


    A simulation program is developed for a slow-extraction method using a fast Q magnet (FQ) and an RF-knockout. In this extraction method, after the separatrix is produced with excitation of sextupole magnets, a required quantity of circulating beam is extracted by shrinking the separatrix with excitation of the FQ. Then the emittance of circulating beam is diffused to an original size with the RF-knockout. This process is repeated with required timing until the entire circulating beam is completely extracted. An algorithm using a digital filter and white noise is proposed for a colored noise as a signal source for the RF-knockout. Spill structures with the present computing method were similar to the results obtained using a conventional algorithm with the sum of cosines of many frequency components. The results are also in agreement with the experimental results using the HIMAC synchrotron. The computing time of colored noise for simulation of 10 6 turns was 0.5 h for the filter method and 5.0 h for the conventional one. It is indicated that a colored noise with a wider frequency bandwidth gives a better spill structure that smoothly increases with time.

  15. Close Color Pair Signature ensemble Adaptive Threshold based Steganalsis for LSB Embedding in Digital Images

    S. Geetha


    Full Text Available We present a novel technique for effective steganalysis of high-color-depth digital images that have been subjected to embedding by LSB steganographic algorithms. The detection theory is based on the idea that under repeated embedding, the disruption of the signal characteristics is the highest for the first embedding and decreases subsequently. That is the marginal distortions due to repeated embeddings decrease monotonically. This decreasing distortion property exploited with Close Color Pair signature is used to construct the classifier that can distinguish between stego and cover images. For evaluation, a database composed of 1200 plain and stego images (at 10% and 20% payload and each one artificially adulterated with 20% additional data was established. Based on this database, extensive experiments were conducted to prove the feasibility of our proposed system. Our main results are (i a 90%+ positive-detection rate; (ii Close Color Pair ratio is not modified significantly when additional bit streams are embedded into a test image that is already tampered with a message.; (iii an image quality metric Czenakowski Measure, that is substantially sensitive to LSB embedding is utilized to derive the effective image adaptive threshold; (iv capable of detecting stego images with an embedding of even 10% payload while the earlier methods can achieve the same detection rate only with 20% payload.

  16. Color management of digital proofing based on color appearance model%基于色貌模型的数码打样色彩管理

    邓倩; 朱明; 楚高利


    为实现“所见即所得”和“所得即所见”,将色貌模型CIECAM02应用到数码打样,以IT8.7/3色标为标准试样,利用打印机,分别以高光相纸、喷墨打印纸、胶版纸为例,研究屏幕软打样与纸张数码打样的颜色匹配.通过一系列数学变换,实现颜色的三刺激值与观察条件下的颜色感知属性值之间的转换,使屏幕软打样与纸张数码打样结果更接近,也更符合人眼的视觉要求,进而实现跨媒体复制.%In order to realize‘what we see is what we get’and‘what we get is what we see’,color appearance models is intro-duced into paper digital proofing. In this paper,IT8. 7/3,Printer and three kinds of paper as the media for soft proofing and paper dig-ital proofing are chosen to design the color matching experiment based on the different presenting color principle. Using mathematical transforms to convert the tristimulus values X,Y,Z of test colors in a set of viewing condition to the perceptual attributes values. Through the introduction of color appearance model,the screen soft proofing and paper digital proofing result are closer,which meets the requirement of human vision. It can be used in cross-media color image reproduction.

  17. Correlated evolution of short wavelength sensitive photoreceptor sensitivity and color pattern in Lake Malawi cichlids

    Michael J. Pauers


    Full Text Available For evolutionary ecologists, the holy grail of visual ecology is to establish an unambiguous link between photoreceptor sensitivity, the spectral environment, and the perception of specific visual stimuli (e.g., mates, food, predators, etc.. Due to the bright nuptial colors of the males, and the role female mate choice plays in their evolution, the haplochromine cichlid fishes of the African great lakes are favorite research subjects for such investigations. Despite this attention, current evidence is equivocal; while distinct correlations among photoreceptor sensitivity, photic environment, and male coloration exist in Lake Victorian haplochromines, attempts to find such correlations in Lake Malawian cichlids have failed. Lake Malawi haplochromines have a wide variability in their short-wavelength-sensitive photoreceptors, especially compared to their mid- and long-wavelength-sensitive photoreceptors; these cichlids also vary in the degree to which they express one of three basic color patterns (vertical bars, horizontal stripes, and solid patches of colors, each of which is likely used in a different form of communication. Thus, we hypothesize that, in these fishes, spectral sensitivity and color pattern have evolved in a correlated fashion to maximize visual communication; specifically, ultraviolet sensitivity should be found in vertically-barred species to promote ‘private’ communication, while striped species should be less likely to have ultraviolet sensitivity, since their color pattern carries ‘public’ information. Using phylogenetic independent contrasts, we found that barred species had strong sensitivity to ultraviolet wavelengths, but that striped species typically lacked sensitivity to ultraviolet light. Further, the only variable, even when environmental variables were simultaneously considered, that could predict ultraviolet sensitivity was color pattern. We also found that, using models of correlated evolution, color

  18. Connecticut Coastal Airborne ADS40 Digital Imagery Acquisition and Natural Color and Color Infrared Orthophoto Production collected in September 2004

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Office for Coastal Management purchased digital ADS40 imagery and digital elevation models of the Connecticut coastline in 2004. The Coastal Connecticut...

  19. Study of the normalized intensity correlation function of a single-mode laser system with colored cross-correlated noises

    Bing Wang; Xiuqing Wu


    A single-mode laser system with colored cross-correlated additive and multiplicative noise terms is considered. By the means of projection operator method, we study the effects of the cross-correlation time τ and the cross-correlation intensity λ between noises on the normalized intensity correlation function C(s). It is found that if λ> 0 (λ< 0), the normalized intensity correlation function C(s) increases (decreases) with increasing the cross-correlation time τ, and at large value of τ, the variation of the normalized intensity correlation function C(s) becomes small. With the increase of the net gain a0, C(s) exhibits a maximum when λ is larger. However, a minimum and a maximum appear on C(s) curves with the increase of a0 when λ becomes smaller and smaller.

  20. Fully phase color image encryption based on joint fractional Fourier transform correlator and phase retrieval algorithm

    Ding Lu; Weimin Jin


    A novel fully phase color image encryption/decryption scheme based on joint fractional Fourier transform correlator (JFRTC) and phase retrieval algorithm (PRA) is proposed. The security of the system is enhanced by the fractional order as a new added key. This method takes full advantage of the parallel processing features of the optical system and could optically realize single-channel color image encryption.The system and operation procedures are simplified. The simulation results of a color image indicate that the new method provides efficient solutions with a strong sense of security.%@@ A novel fully phase color image encryption/decryption scheme based on joint fractional Fourier transform correlator (JFRTC) and phase retrieval algorithm (PRA) is proposed. The security of the system is enhanced by the fractional order as a new added key. This method takes full advantage of the parallel processing features of the optical system and could optically realize single-channel color image encryption. The system and operation procedures are simplified. The simulation results of a color image indicate that the new method provides efficient solutions with a strong sense of security.

  1. Identification of the plastic zone using digital image correlation

    M. Rossi


    Full Text Available In this paper Digital Image Correlation (DIC is used to study the evolution of the plastic zone close to a crack tip. A modified CT-specimen was used in order to fulfill the plane stress condition. The strain field around the crack tip was measured using two cameras and stereo DIC, so that out-of-plane movements are taken into account. Then, the Virtual Fields Method was used to identify the plastic zone, looking at the parts of the specimen which deviates from the linear elastic behavior. With such approach, it was possible to individuate the onset of plasticity close to the crack tip and follow its evolution. A comparison with FEM results is also provided.

  2. Correlated Color Temperature Tunable Multi-chip Light Emitting Diodes Light Source Design

    SHEN Hai-ping; PAN Jian-gen; FENG Hua-jun


    One of the methods to derive white light from light emitting diodes(LEDs) is the multi-chip white LED technology, which mixes the light from red, green and blue LEDs. Introduced is an optimal algorithm for the spectrum design of the multi-chip white LEDs in this paper. It optimizes the selection of single color LEDs and drive current controlling, so that the multi-chip white LED achieves the target correlated color temperature(CCT), as well as high luminous efficacy and good color rendering. A CCT tunable LED light source with four high-power LEDs is realized based on the above optimal design. Test results show that it maintains satisfactory color rendering and stable luminous efficacy across the whole CCT tuning range. Finally, discussed are the design improvement and the prospect of the future applications of the CCT tunable LED light source.

  3. Digital Image Correlation: Metrological Characterization in Mechanical Analysis

    Petrella, Orsola; Signore, Davide; Caramuta, Pietro; Toscano, Cinzia; Ferraiuolo, Michele


    The Digital Image Correlation (DIC) is a newly developed optical technique that is spreading in all engineering sectors because it allows the non-destructive estimation of the entire surface deformation without any contact with the component under analysis. These characteristics make the DIC very appealing in all the cases the global deformation state is to be known without using strain gages, which are the most used measuring device. The DIC is applicable to any material subjected to distortion caused by either thermal or mechanical load, allowing to obtain high-definition mapping of displacements and deformations. That is why in the civil and the transportation industry, DIC is very useful for studying the behavior of metallic materials as well as of composite materials. DIC is also used in the medical field for the characterization of the local strain field of the vascular tissues surface subjected to uniaxial tensile loading. DIC can be carried out in the two dimension mode (2D DIC) if a single camera is used or in a three dimension mode (3D DIC) if two cameras are involved. Each point of the test surface framed by the cameras can be associated with a specific pixel of the image and the coordinates of each point are calculated knowing the relative distance between the two cameras together with their orientation. In both arrangements, when a component is subjected to a load, several images related to different deformation states can be are acquired through the cameras. A specific software analyzes the images via the mutual correlation between the reference image (obtained without any applied load) and those acquired during the deformation giving the relative displacements. In this paper, a Metrological Characterization of the Digital Image Correlation is performed on aluminum and composite targets both in static and dynamic loading conditions by comparison between DIC and strain gauges measures. In the static test, interesting results have been obtained thanks

  4. Investigation of 3D surface acoustic waves in granular media with 3-color digital holography

    Leclercq, Mathieu; Picart, Pascal; Penelet, Guillaume; Tournat, Vincent


    This paper reports the implementation of digital color holography to investigate elastic waves propagating along a layer of a granular medium. The holographic set-up provides simultaneous recording and measurement of the 3D dynamic displacement at the surface. Full-field measurements of the acoustic amplitude and phase at different excitation frequencies are obtained. It is shown that the experimental data can be used to obtain the dispersion curve of the modes propagating in this granular medium layer. The experimental dispersion curve and that obtained from a finite element modeling of the problem are found to be in good agreement. In addition, full-field images of the interaction of an acoustic wave guided in the granular layer with a buried object are also shown.

  5. Correlation Between the Evaluation of Pigmented Lesions by a Multi-spectral Digital Skin Lesion Analysis Device and the Clinical and Histological Features of Melanoma

    Winkelmann, Richard R.; Rigel, Darrell S.; Ferris, Laura; Sober, Arthur; Tucker, Natalie; Cockerell, Clay J.


    Objective: To correlate Multi-spectral Digital Skin Lesion Analysis classifier scores with histopathological severity of pigmented lesions and clinical features of melanoma. Design: Classifier scores were computed for 1,632 skin lesions. Dermatologists evaluated the same lesions for Asymmetry, Border Irregularity, Color variegation, Diameter >6mm, Evolution, Patient’s Concern, Regression, and/or “Ugly Duckling” sign. Classifier scores were correlated to the number of clinical risk features an...

  6. A method for evaluating image quality of monochrome and color displays based on luminance by use of a commercially available color digital camera

    Tokurei, Shogo, E-mail:, E-mail: [Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan and Department of Radiology, Yamaguchi University Hospital, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505 (Japan); Morishita, Junji, E-mail:, E-mail: [Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582 (Japan)


    Purpose: The aim of this study is to propose a method for the quantitative evaluation of image quality of both monochrome and color liquid-crystal displays (LCDs) using a commercially available color digital camera. Methods: The intensities of the unprocessed red (R), green (G), and blue (B) signals of a camera vary depending on the spectral sensitivity of the image sensor used in the camera. For consistent evaluation of image quality for both monochrome and color LCDs, the unprocessed RGB signals of the camera were converted into gray scale signals that corresponded to the luminance of the LCD. Gray scale signals for the monochrome LCD were evaluated by using only the green channel signals of the camera. For the color LCD, the RGB signals of the camera were converted into gray scale signals by employing weighting factors (WFs) for each RGB channel. A line image displayed on the color LCD was simulated on the monochrome LCD by using a software application for subpixel driving in order to verify the WF-based conversion method. Furthermore, the results obtained by different types of commercially available color cameras and a photometric camera were compared to examine the consistency of the authors’ method. Finally, image quality for both the monochrome and color LCDs was assessed by measuring modulation transfer functions (MTFs) and Wiener spectra (WS). Results: The authors’ results demonstrated that the proposed method for calibrating the spectral sensitivity of the camera resulted in a consistent and reliable evaluation of the luminance of monochrome and color LCDs. The MTFs and WS showed different characteristics for the two LCD types owing to difference in the subpixel structure. The MTF in the vertical direction of the color LCD was superior to that of the monochrome LCD, although the WS in the vertical direction of the color LCD was inferior to that of the monochrome LCD as a result of luminance fluctuations in RGB subpixels. Conclusions: The authors

  7. An optimized color transformation for the analysis of digital images of hematoxylin & eosin stained slides.

    Zarella, Mark D; Breen, David E; Plagov, Andrei; Garcia, Fernando U


    Hematoxylin and eosin (H&E) staining is ubiquitous in pathology practice and research. As digital pathology has evolved, the reliance of quantitative methods that make use of H&E images has similarly expanded. For example, cell counting and nuclear morphometry rely on the accurate demarcation of nuclei from other structures and each other. One of the major obstacles to quantitative analysis of H&E images is the high degree of variability observed between different samples and different laboratories. In an effort to characterize this variability, as well as to provide a substrate that can potentially mitigate this factor in quantitative image analysis, we developed a technique to project H&E images into an optimized space more appropriate for many image analysis procedures. We used a decision tree-based support vector machine learning algorithm to classify 44 H&E stained whole slide images of resected breast tumors according to the histological structures that are present. This procedure takes an H&E image as an input and produces a classification map of the image that predicts the likelihood of a pixel belonging to any one of a set of user-defined structures (e.g., cytoplasm, stroma). By reducing these maps into their constituent pixels in color space, an optimal reference vector is obtained for each structure, which identifies the color attributes that maximally distinguish one structure from other elements in the image. We show that tissue structures can be identified using this semi-automated technique. By comparing structure centroids across different images, we obtained a quantitative depiction of H&E variability for each structure. This measurement can potentially be utilized in the laboratory to help calibrate daily staining or identify troublesome slides. Moreover, by aligning reference vectors derived from this technique, images can be transformed in a way that standardizes their color properties and makes them more amenable to image processing.

  8. Integrated global digital image correlation for interface delamination characterization

    Hoefnagels, Johan P.M.


    Interfacial delamination is a key reliability challenge in composites and micro-electronic systems due to (high-density) integration of dissimilar materials. Predictive finite element models are used to minimize delamination failures during design, but require accurate interface models to capture (irreversible) crack initiation and propagation behavior observed in experiments. Therefore, an Integrated Global Digital Image Correlation (I-GDIC) strategy is developed for accurate determination of mechanical interface behavior from in-situ delamination experiments. Recently, a novel miniature delamination setup was presented that enables in-situ microscopic characterization of interface delamination while sensitively measuring global load-displacement curves for all mode mixities. Nevertheless, extraction of detailed mechanical interface behavior from measured images is challenging, because deformations are tiny and measurement noise large. Therefore, an advanced I-GDIC methodology is developed which correlates the image patterns by only deforming the images using kinematically-admissible \\'eigenmodes\\' that correspond to the few parameters controlling the interface tractions in an analytic description of the crack tip deformation field, thereby greatly enhancing accuracy and robustness. This method is validated on virtual delamination experiments, simulated using a recently developed self-adaptive cohesive zone (CZ) finite element framework. © The Society for Experimental Mechanics, Inc. 2014.

  9. Precision Improvement of Photogrammetry by Digital Image Correlation

    Shih, Ming-Hsiang; Sung, Wen-Pei; Tung, Shih-Heng; Hsiao, Hanwei


    The combination of aerial triangulation technology and unmanned aerial vehicle greatly reduces the cost and application threshold of the digital surface model technique. Based on the report in the literatures, the measurement error in the x-y coordinate and in the elevation lies between 8cm~15cm and 10cm~20cm respectively. The measurement accuracy for the geological structure survey already has sufficient value, but for the slope and structures in terms of deformation monitoring is inadequate. The main factors affecting the accuracy of the aerial triangulation are image quality, measurement accuracy of control point and image matching accuracy. In terms of image matching, the commonly used techniques are Harris Corner Detection and Scale Invariant Feature Transform (SIFT). Their pairing error is in scale of pixels, usually lies between 1 to 2 pixels. This study suggests that the error on the pairing is the main factor causing the aerial triangulation errors. Therefore, this study proposes the application of Digital Image Correlation (DIC) method instead of the pairing method mentioned above. DIC method can provide a pairing accuracy of less than 0.01 pixel, indeed can greatly enhance the accuracy of the aerial triangulation, to have sub-centimeter level accuracy. In this study, the effects of image pairing error on the measurement error of the 3-dimensional coordinate of the ground points are explored by numerical simulation method. It was confirmed that when the image matching error is reduced to 0.01 pixels, the ground three-dimensional coordinate measurement error can be controlled in mm level. A combination of DIC technique and the traditional aerial triangulation provides the potential of application on the deformation monitoring of slope and structures, and achieve an early warning of natural disaster.

  10. Effects of spatiotemporal averaging processes on the estimation of spectral reflectance in color digital holography using speckle illuminations.

    Funamizu, Hideki; Shimoma, Shohei; Yuasa, Tomonori; Aizu, Yoshihisa


    We present the effects of spatiotemporal averaging processes on an estimation of spectral reflectance in color digital holography using speckle illuminations. In this technique, speckle fields emitted from a multimode fiber are used as both a reference wave and a wavefront illuminating an object. The interference patterns of two coherent waves for three wavelengths are recorded as digital holograms on a CCD camera. Speckle fields are changed by vibrating the multimode fiber using a vibrator, and a number of holograms are acquired to average reconstructed images. After performing an averaging process, which we refer to as a temporal averaging process in this study, using images reconstructed from multiple holograms, a spatial averaging process is applied using a smoothing window function. For the estimation of spectral reflectance in reconstructed images, we use the Wiener estimation method. The effects of the averaging processes on color reproducibility are evaluated by a chromaticity diagram, the root-mean-square error, and color differences.

  11. Evaluation of Ocean Color Scanner (OCS) photographic and digital data: Santa Barbara Channel test site, 29 October 1975 overflight

    Kraus, S. P.; Estes, J. E.; Kronenberg, M. R.; Hajic, E. J.


    A summary of Ocean Color Scanner data was examined to evaluate detection and discrimination capabilities of the system for marine resources, oil pollution and man-made sea surface targets of opportunity in the Santa Barbara Channel. Assessment of the utility of OCS for the determination of sediment transport patterns along the coastal zone was a secondary goal. Data products provided 1975 overflight were in digital and analog formats. In evaluating the OCS data, automated and manual procedures were employed. A total of four channels of data in digital format were analyzed, as well as three channels of color combined imagery, and four channels of black and white imagery. In addition, 1:120,000 scale color infrared imagery acquired simultaneously with the OCS data were provided for comparative analysis purposes.

  12. A web-based troubleshooting tool to help customers self-solve color issues with a digital printing workflow

    Santos-Villalobos, Hector J.; Loewen, Victor; Lehto, Mark; Allebach, Jan


    Current printing technologies enable customers to reproduce high quality, realistic, and colorful hard copies of their digital documents. Although the activity of printing is transparent to the customers, the progression of a customer's document through the color printing workflow (CPW) is a complex process that may alter the colors in the print job. Given the complexity of the CPW, it is a difficult problem to diagnose the source of the color issue. Novel tools and methods that address this challenge are beneficial for both the manufacturer and its customers. We propose a Web-based troubleshooting tool that helps customers to self-solve color issues with electrophotographic laser printers when printing solid colors in graphics and text. The tool helps the customer to reconfigure his/her CPW following printing best practices. If the issue is still unresolved, the tool guides the user to search the gamut of the printer for his/her color preference. The usability of the tool was carefully evaluated with human subject experiments. Also, the description and organization of the troubleshooting tasks were continuously reviewed and improved in regular meetings of the development team. In this paper, we describe the troubleshooting strategy, the color preference search algorithm, and the results of the usability experiments.

  13. Inter Channel Correlation based Demosaicking Algorithm for Enhanced Bayer Color Filter Array

    K. John Peter


    Full Text Available Demosaicking is a process of obtaining a full color image by interpolating the missing colors of an image captured from a digital still and video cameras that use a single-sensor array. In this study a new Color Filter Array (CFA is proposed. Which is based on the actual weight of the Human Visual System. It is developed based on the sensitivity level of the human eye to red as 29.9%, green as 58.7% and blue as 11.4%. This study also provides an effective iterative demosaicing algorithm applying a weighted-edge interpolation to handle green pixels followed by a series of color difference interpolation to update red, blue and green pixels. Before applying demosaicking algorithm Gaussian filter is applied to remove noise of the sensor applied image and also enhance the image quality. Experimental results show that the proposed method performs much better than other latest demosaicing techniques in terms of image quality and PSNR value.

  14. High-Frequency Color Doppler Sonography of Bullous Pemphigoid: Correlation With Histologic Findings.

    Porriño-Bustamante, María Librada; Alfageme, Fernando; Suárez, Lola; de Domingo, María Antonia González; Hospital, Mercedes; Roustán, Gastón


    Bullous pemphigoid is the most frequent autoimmune-mediated blistering skin disease, belonging to the group of subepidermal bullae. We performed high-frequency color Doppler sonography in 3 cases of bullous pemphigoid, in bullous and adjacent non-bullous skin, which showed homogeneous sonographic findings. Subepidermal cystic structures with dermal hypoechogenicity were observed in bullous skin. In nonbullous skin, the dermis showed hypoechogenicity compared to normal skin. Color Doppler signals were increased in both areas. These findings correlate histologically with subepidermal bullae and dermal inflammatory infiltrates.

  15. Does correlated color temperature affect the ability of humans to identify veins?

    Argyraki, Aikaterini; Clemmensen, Line Katrine Harder; Petersen, Paul Michael


    In the present study we provide empirical evidence and demonstrate statistically that white illumination settings can affect the human ability to identify veins in the inner hand vasculature. A special light-emitting diode lamp with high color rendering index (CRI 84–95) was developed...... and the effect of correlated color temperature was evaluated, in the range between 2600 and 5700 K at an illuminance of 40 9 lx on the ability of adult humans to identify veins. It is shown that the ability to identify veins can, on average, be increased up to 24% when white illumination settings that do...

  16. Evaluation of respiration-correlated digital tomosynthesis in lung1

    Santoro, Joseph; Kriminski, Sergey; Lovelock, D. Michael; Rosenzweig, Kenneth; Mostafavi, Hassan; Amols, Howard I.; Mageras, Gig S.


    Digital tomosynthesis (DTS) with a linear accelerator-mounted imaging system provides a means of reconstructing tomographic images from radiographic projections over a limited gantry arc, thus requiring only a few seconds to acquire. Its application in the thorax, however, often results in blurred images from respiration-induced motion. This work evaluates the feasibility of respiration-correlated (RC) DTS for soft-tissue visualization and patient positioning. Image data acquired with a gantry-mounted kilovoltage imaging system while recording respiration were retrospectively analyzed from patients receiving radiotherapy for non-small-cell lung carcinoma. Projection images spanning an approximately 30° gantry arc were sorted into four respiration phase bins prior to DTS reconstruction, which uses a backprojection, followed by a procedure to suppress structures above and below the reconstruction plane of interest. The DTS images were reconstructed in planes at different depths through the patient and normal to a user-selected angle close to the center of the arc. The localization accuracy of RC-DTS was assessed via a comparison with CBCT. Evaluation of RC-DTS in eight tumors shows visible reduction in image blur caused by the respiratory motion. It also allows the visualization of tumor motion extent. The best image quality is achieved at the end-exhalation phase of the respiratory motion. Comparison of RC-DTS with respiration-correlated cone-beam CT in determining tumor position, motion extent and displacement between treatment sessions shows agreement in most cases within 2–3 mm, comparable in magnitude to the intraobserver repeatability of the measurement. These results suggest the method’s applicability for soft-tissue image guidance in lung, but must be confirmed with further studies in larger numbers of patients. PMID:20384261

  17. Damage Assessment of Composite Structures Using Digital Image Correlation

    Caminero, M. A.; Lopez-Pedrosa, M.; Pinna, C.; Soutis, C.


    The steady increase of Carbon-Fiber Reinforced Polymer (CFRP) Structures in modern aircraft will reach a new dimension with the entry into service of the Boeing 787 and Airbus 350. Replacement of damaged parts will not be a preferable solution due to the high level of integration and the large size of the components involved. Consequently the need to develop repair techniques and processes for composite components is readily apparent. Bonded patch repair technologies provide an alternative to mechanically fastened repairs with significantly higher performance, especially for relatively thin skins. Carefully designed adhesively bonded patches can lead to cost effective and highly efficient repairs in comparison with conventional riveted patch repairs that cut fibers and introduce highly strained regions. In this work, the assessment of the damage process taking place in notched (open-hole) specimens under uniaxial tensile loading was studied. Two-dimensional (2D) and three-dimensional (3D) Digital Image Correlation (DIC) techniques were employed to obtain full-field surface strain measurements in carbon-fiber/epoxy T700/M21 composite plates with different stacking sequences in the presence of an open circular hole. Penetrant enhanced X-ray radiographs were taken to identify damage location and extent after loading around the hole. DIC strain fields were compared to finite element predictions. In addition, DIC techniques were used to characterise damage and performance of adhesively bonded patch repairs in composite panels under tensile loading. This part of work relates to strength/stiffness restoration of damaged composite aircraft that becomes more important as composites are used more extensively in the construction of modern jet airliners. The behaviour of bonded patches under loading was monitored using DIC full-field strain measurements. Location and extent of damage identified by X-ray radiography correlates well with DIC strain results giving confidence to

  18. An extension of digital volume correlation for multimodality image registration

    Tudisco, E.; Jailin, C.; Mendoza, A.; Tengattini, A.; Andò, E.; Hall, Stephen A.; Viggiani, Gioacchino; Hild, F.; Roux, S.


    The question of registering two images (or image volumes) acquired with different modalities, and thus exhibiting different contrast, at different positions is addressed based on an extension of global digital image (or volume) correlation. A specific comparison metric is introduced allowing the signature of the different phases to be related. A first solution consists of a Gaussian mixture to describe the joint distribution of gray levels, which not only provides a matching of both images, but also offers a natural segmentation indicator. A second ‘self-adapting’ solution does not include any postulated a priori model for the joint histogram and leads to a registration of the images based on their initial histograms. The algorithm is implemented with a pyramidal multiscale framework for the sake of robustness. The proposed multiscale technique is tested on two 3D images obtained from x-ray and neutron tomography respectively. The proposed approach brings the two images to coincidence with a sub-pixel accuracy and allows for a ‘natural’ segmentation of the different phases.

  19. A fast digital image correlation method for deformation measurement

    Pan, Bing; Li, Kai


    Fast and high-accuracy deformation analysis using digital image correlation (DIC) has been increasingly important and highly demanded in recent years. In literature, the DIC method using the Newton-Rapshon (NR) algorithm has been considered as a gold standard for accurate sub-pixel displacement tracking, as it is insensitive to the relative deformation and rotation of the target subset and thus provides highest sub-pixel registration accuracy and widest applicability. A significant drawback of conventional NR-algorithm-based DIC method, however, is its extremely huge computational expense. In this paper, a fast DIC method is proposed deformation measurement by effectively eliminating the repeating redundant calculations involved in the conventional NR-algorithm-based DIC method. Specifically, a reliability-guided displacement scanning strategy is employed to avoid time-consuming integer-pixel displacement searching for each calculation point, and a pre-computed global interpolation coefficient look-up table is utilized to entirely eliminate repetitive interpolation calculation at sub-pixel locations. With these two approaches, the proposed fast DIC method substantially increases the calculation efficiency of the traditional NR-algorithm-based DIC method. The performance of proposed fast DIC method is carefully tested on real experimental images using various calculation parameters. Results reveal that the computational speed of the present fast DIC is about 120-200 times faster than that of the traditional method, without any loss of its measurement accuracy

  20. Applications of Digital Correlation Method to Structure Inspection

    CHEN Junda; JIN Guanchang; MENG Libo


    In structure inspections, applications of optical techniques are rare, but the advantages of a noncontact, full field technique using a simple apparatus are attractive. The main requirements for structure inspection are the full-field strain measurement with the required precision and on-site measurement ability.The digital correlation method (DCM), a new optical deformation measurement tool, can satisfy all of the requirements for structure inspection. A smoothing algorithm which can greatly improve the strain measurement precision, and a 3-D DCM have been developed in this paper. For verifying this improvement, a comparison of strain measurements by computer-simulated speckle images has been carried out. Additionally,three structure inspection examples that cover typical materials and structure styles are presented: the interface shear stress distribution for reinforced concrete piles bedded on rock, the 3-D strain distribution of a composite vessel structure, and stresses in a hookup that connects two steel bridge structures. All the examples show that the new structural inspection tool is exemplary and illustrates the obvious advantages of this optical non-destructive technique.

  1. Deformation-phase measurement by digital speckle correlation method

    Zhao, Ran; Sun, Ping


    A novel algorithm which extracts the out-of-plane component of deformation phase from two continuous fringe patterns is proposed. The velocity field between two consecutive frames is estimated by digital speckle correlation method (DSCM). After that, according to the optical flow constrained equation, the whole-field deformation-phase map is obtained by the estimations of the velocity field and the local frequency of the original image. The operation of the proposed method is simple compared with other phase demodulation methods. Moreover, the new method works perfectly at the areas with dense fringes. In this paper, the proposed algorithm is introduced. Meanwhile, in order to verify the effectiveness, the new algorithm is applied to simulated interferogram and real fringe pattern with a centrally loaded and edge-clamped plate. The results of simulation and experiment show that the new method can demodulate the out-of-plane component of deformation phase from the visible in-plane velocity field without unwrapping process. Further, dynamic deformation-phase extraction will be realized when we know the time interval of two continuous images. The proposed algorithm provides a new approach for whole-field deformation-phase measurement and dynamic deformation measurement.

  2. Quark correlations in the Color Glass Condensate: Pauli blocking and the ridge

    Altinoluk, Tolga; Beuf, Guillaume; Kovner, Alex; Lublinsky, Michael


    We consider, for the first time, correlations between produced quarks in p-A collisions in the framework of the Color Glass Condensate. We find a quark-quark ridge that shows a dip at $\\Delta\\eta\\sim 2$ relative to the gluon-gluon ridge. The origin of this dip is the short range (in rapidity) Pauli blocking experienced by quarks in the wave function of the incoming projectile. We observe that these correlations, present in the initial state, survive the scattering process. We suggest that this effect may be observable in open charm-open charm correlations at the Large Hadron Collider.

  3. A 360-deg Digital Image Correlation system for materials testing

    Genovese, K.; Cortese, L.; Rossi, M.; Amodio, D.


    The increasing research interest toward natural and advanced engineered materials demands new experimental protocols capable of retrieving highly dense sets of experimental data on the full-surface of samples under multiple loading conditions. Such information, in fact, would allow to capture the possible heterogeneity and anisotropy of the material by using up-to-date inverse characterization methods. Although the development of object-specific test protocols could represent the optimal choice to address this need, it is unquestionable that universal testing machines (UTM) remain the most widespread and versatile option to test materials and components in both academic and industrial contexts. A major limitation of performing standard material tests with UTM, however, consists in the scarce information obtainable with the commonly associated sensors since they provide only global (LVDTs, extensometers, 2D-video analyzers) or local (strain gages) measures of displacement and strain. This paper presents a 3D Digital Image Correlation (DIC) system developed to perform highly accurate full-surface 360-deg measurements on either standard or custom-shaped samples under complex loading within universal testing machines. To this aim, a low cost and easy to setup video rig was specifically designed to overcome the practical limitations entailed with the integration of a multi-camera system within an already existing loading frame. In particular, the proposed system features a single SLR digital camera moved through multiple positions around the specimen by means of a large rotation stage. A proper calibration and data-processing procedure allows to automatically merge the experimental data obtained from the multiple views with an accuracy of 10-2 m m . The results of a full benchmarking of the metrological performances of the system are here reported and discussed together with illustrative examples of full-360-deg shape and deformation measurements on a Grade X65 steel


    Cristina Marinela Olarescu


    Full Text Available Heat treatment is renowned as the most environmentally friendly process of dimensional stabilization that can be applied to wood, in order to make it suitable for outdoor uses. It also darkens wood color and improves wood durability. The intensity of heat treatment can be appreciated by means of two parameters: the color change occured in wood due to the high temperature, and the mass loss, which is a measure of the degree of thermal degradation. In order to find a mathematical correlation between these two parameters, an experimental study was conducted with four European wood species, which were heat-treated at 180°C and 200ºC, for 1-3 hours, under atmosheric pressure.The paper presents the results concerning the color changes and mass losses recorded for the heat-treated wood samples compared to untreated wood.  For all four species, the dependency between the color change and the mass loss was found to be best described by a logarithmic regression equation with R2 of 0.93 to 0.99 for the soft species (spruce, pine and lime, and R2 of 0.77 for beech. The results of this study envisage to simplify the assessment procedure of the heat treatment efficiency, by only measuring the color – a feature that is both convenient and cost-effective. 

  5. Low-altitude aerial color digital photographic survey of the San Andreas Fault

    Lynch, David K.; Hudnut, Kenneth W.; Dearborn, David S.P.


    Ever since 1858, when Gaspard-Félix Tournachon (pen name Félix Nadar) took the first aerial photograph (Professional Aerial Photographers Association 2009), the scientific value and popular appeal of such pictures have been widely recognized. Indeed, Nadar patented the idea of using aerial photographs in mapmaking and surveying. Since then, aerial imagery has flourished, eventually making the leap to space and to wavelengths outside the visible range. Yet until recently, the availability of such surveys has been limited to technical organizations with significant resources. Geolocation required extensive time and equipment, and distribution was costly and slow. While these situations still plague older surveys, modern digital photography and lidar systems acquire well-calibrated and easily shared imagery, although expensive, platform-specific software is sometimes still needed to manage and analyze the data. With current consumer-level electronics (cameras and computers) and broadband internet access, acquisition and distribution of large imaging data sets are now possible for virtually anyone. In this paper we demonstrate a simple, low-cost means of obtaining useful aerial imagery by reporting two new, high-resolution, low-cost, color digital photographic surveys of selected portions of the San Andreas fault in California. All pictures are in standard jpeg format. The first set of imagery covers a 92-km-long section of the fault in Kern and San Luis Obispo counties and includes the entire Carrizo Plain. The second covers the region from Lake of the Woods to Cajon Pass in Kern, Los Angeles, and San Bernardino counties (151 km) and includes Lone Pine Canyon soon after the ground was largely denuded by the Sheep Fire of October 2009. The first survey produced a total of 1,454 oblique digital photographs (4,288 x 2,848 pixels, average 6 Mb each) and the second produced 3,762 nadir images from an elevation of approximately 150 m above ground level (AGL) on the

  6. Impact of neuronal heterogeneity on correlated colored noise-induced synchronization.

    Zhou, Pengcheng; Burton, Shawn D; Urban, Nathaniel N; Ermentrout, G Bard


    Synchronization plays an important role in neural signal processing and transmission. Many hypotheses have been proposed to explain the origin of neural synchronization. In recent years, correlated noise-induced synchronization has received support from many theoretical and experimental studies. However, many of these prior studies have assumed that neurons have identical biophysical properties and that their inputs are well modeled by white noise. In this context, we use colored noise to induce synchronization between oscillators with heterogeneity in both phase-response curves and frequencies. In the low noise limit, we derive novel analytical theory showing that the time constant of colored noise influences correlated noise-induced synchronization and that oscillator heterogeneity can limit synchronization. Surprisingly, however, heterogeneous oscillators may synchronize better than homogeneous oscillators given low input correlations. We also find resonance of oscillator synchronization to colored noise inputs when firing frequencies diverge. Collectively, these results prove robust for both relatively high noise regimes and when applied to biophysically realistic spiking neuron models, and further match experimental recordings from acute brain slices.

  7. Correlation of lycopene measured by HPLC with the L, a, b color readings of a hydroponic tomato and the relationship of maturity with color and lycopene content

    Arias, R.; Lee, T. C.; Logendra, L.; Janes, H.


    Tomatoes (Lycopersicon esculentum cv. Laura) were separated, according to the ripening stage, by a sensory panel into seven groups, and color was measured on the tomato surface with a Minolta Chroma meter. The L, a, b, hue, chroma, and lycopene content were plotted against the maturity stages of the tomatoes, and several good correlations were found. The a/b ratio and the lycopene content were the parameters that allowed six of seven maturity groups in the tomato to be statistically distinguished. The lycopene content, measured by HPLC, was also correlated with the color measurements, and the a, a/b, and (a/b)(2) color factors produced the best regressions. An estimation of the lycopene content in tomatoes can be achieved by using a portable chroma meter, with a possible field usage application. Equations to calculate the lycopene content of tomatoes based on the color readings are reported.

  8. Correlation of lycopene measured by HPLC with the L, a, b color readings of a hydroponic tomato and the relationship of maturity with color and lycopene content

    Arias, R.; Lee, T. C.; Logendra, L.; Janes, H.


    Tomatoes (Lycopersicon esculentum cv. Laura) were separated, according to the ripening stage, by a sensory panel into seven groups, and color was measured on the tomato surface with a Minolta Chroma meter. The L, a, b, hue, chroma, and lycopene content were plotted against the maturity stages of the tomatoes, and several good correlations were found. The a/b ratio and the lycopene content were the parameters that allowed six of seven maturity groups in the tomato to be statistically distinguished. The lycopene content, measured by HPLC, was also correlated with the color measurements, and the a, a/b, and (a/b)(2) color factors produced the best regressions. An estimation of the lycopene content in tomatoes can be achieved by using a portable chroma meter, with a possible field usage application. Equations to calculate the lycopene content of tomatoes based on the color readings are reported.

  9. Low Power Digital Correlator System for PATH Mission Project

    National Aeronautics and Space Administration — The NASA's PATH mission employs a synthetic aperture radiometer that produces 768 IF (10MHz - 500MHz) signals. Digitizing the signals results in 1.536Tb/s (1GS/s,...

  10. Spatial patterns of correlated scale size and scale color in relation to color pattern elements in butterfly wings.

    Iwata, Masaki; Otaki, Joji M


    Complex butterfly wing color patterns are coordinated throughout a wing by unknown mechanisms that provide undifferentiated immature scale cells with positional information for scale color. Because there is a reasonable level of correspondence between the color pattern element and scale size at least in Junonia orithya and Junonia oenone, a single morphogenic signal may contain positional information for both color and size. However, this color-size relationship has not been demonstrated in other species of the family Nymphalidae. Here, we investigated the distribution patterns of scale size in relation to color pattern elements on the hindwings of the peacock pansy butterfly Junonia almana, together with other nymphalid butterflies, Vanessa indica and Danaus chrysippus. In these species, we observed a general decrease in scale size from the basal to the distal areas, although the size gradient was small in D. chrysippus. Scales of dark color in color pattern elements, including eyespot black rings, parafocal elements, and submarginal bands, were larger than those of their surroundings. Within an eyespot, the largest scales were found at the focal white area, although there were exceptional cases. Similarly, ectopic eyespots that were induced by physical damage on the J. almana background area had larger scales than in the surrounding area. These results are consistent with the previous finding that scale color and size coordinate to form color pattern elements. We propose a ploidy hypothesis to explain the color-size relationship in which the putative morphogenic signal induces the polyploidization (genome amplification) of immature scale cells and that the degrees of ploidy (gene dosage) determine scale color and scale size simultaneously in butterfly wings.

  11. Family History Correlates of Digit Ratio Abnormalities in Schizophrenia

    Anjith Divakaran


    Full Text Available Background: The differences in digit ratio are proposed to arise due to differential effects of sex steroids on the growth of finger bones. In this study, we sought to examine the sex differences and the influence of family history of psychosis on digit ratio in patients with schizophrenia compared to matched healthy controls (HCs. Materials and Methods: Digit ratio (2D: 4D was examined for a large sample of schizophrenia patients (n=200 and HC (n=177 to evaluate the potential effects of family history. Results: The right hand 2D: 4D digit ratio was lesser in schizophrenia patients compared to HC (0.97±0.05 vs 0.98±0.04, t=2.2, P=0.02. There was a significant difference in the right hand 2D: 4D digit ratio of female patients with schizophrenia when compared to female HCs (0.96±0.05 vs 0.98±0.03, t=2.1, P=0.03 while males showed no such difference on either hands. On the contrary, family history‑positive males showed a significantly greater digit ratio for the left hand (FH present (0.99±0.04 vs HC (0.97±0.04, t=2.15, P=0.03, while there was no difference between family history‑positive females and HC. Conclusion: Overall, in patients, reversal of expected "directionality" in digit ratio was observed in our study with greater left 2D: 4D in male patients having a family history of schizophrenia being a novel finding. Reversal of sexual dimorphism has been linked to the pathogenesis of schizophrenia. It is possible that such reversal might have a putative genetic basis, perhaps only in men with schizophrenia.

  12. Automated measurement of the arteriolar-to-venular width ratio in digital color fundus photographs.

    Niemeijer, Meindert; Xu, Xiayu; Dumitrescu, Alina V; Gupta, Priya; van Ginneken, Bram; Folk, James C; Abramoff, Michael D


    A decreased ratio of the width of retinal arteries to veins [arteriolar-to-venular diameter ratio (AVR)], is well established as predictive of cerebral atrophy, stroke and other cardiovascular events in adults. Tortuous and dilated arteries and veins, as well as decreased AVR are also markers for plus disease in retinopathy of prematurity. This work presents an automated method to estimate the AVR in retinal color images by detecting the location of the optic disc, determining an appropriate region of interest (ROI), classifying vessels as arteries or veins, estimating vessel widths, and calculating the AVR. After vessel segmentation and vessel width determination, the optic disc is located and the system eliminates all vessels outside the AVR measurement ROI. A skeletonization operation is applied to the remaining vessels after which vessel crossings and bifurcation points are removed, leaving a set of vessel segments consisting of only vessel centerline pixels. Features are extracted from each centerline pixel in order to assign these a soft label indicating the likelihood that the pixel is part of a vein. As all centerline pixels in a connected vessel segment should be the same type, the median soft label is assigned to each centerline pixel in the segment. Next, artery vein pairs are matched using an iterative algorithm, and the widths of the vessels are used to calculate the AVR. We trained and tested the algorithm on a set of 65 high resolution digital color fundus photographs using a reference standard that indicates for each major vessel in the image whether it is an artery or vein. We compared the AVR values produced by our system with those determined by a semi-automated reference system. We obtained a mean unsigned error of 0.06 (SD 0.04) in 40 images with a mean AVR of 0.67. A second observer using the semi-automated system obtained the same mean unsigned error of 0.06 (SD 0.05) on the set of images with a mean AVR of 0.66. The testing data and

  13. Digital reconstructed radiography with multiple color image overlay for image-guided radiotherapy.

    Yoshino, Shinichi; Miki, Kentaro; Sakata, Kozo; Nakayama, Yuko; Shibayama, Kouichi; Mori, Shinichiro


    Registration of patient anatomical structures to the reference position is a basic part of the patient set-up procedure. Registration of anatomical structures between the site of beam entrance on the patient surface and the distal target position is particularly important. Here, to improve patient positional accuracy during set-up for particle beam treatment, we propose a new visualization methodology using digitally reconstructed radiographs (DRRs), overlaid DRRs, and evaluation of overlaid DRR images in clinical cases. The overlaid method overlays two DRR images in different colors by dividing the CT image into two CT sections at the distal edge of the target along the treatment beam direction. Since our hospital uses fixed beam ports, the treatment beam angles for this study were set at 0 and 90 degrees. The DRR calculation direction was from the X-ray tube to the imaging device, and set to 180/270 degrees and 135/225 degrees, based on the installation of our X-ray imaging system. Original and overlaid DRRs were calculated using CT data for two patients, one with a parotid gland tumor and the other with prostate cancer. The original and overlaid DRR images were compared. Since the overlaid DRR image was completely separated into two regions when the DRR calculation angle was the same as the treatment beam angle, the overlaid DRR visualization technique was able to provide rich information for aiding recognition of the relationship between anatomical structures and the target position. This method will also be useful in patient set-up procedures for fixed irradiation ports.

  14. Retinopathy online challenge: automatic detection of microaneurysms in digital color fundus photographs.

    Niemeijer, Meindert; van Ginneken, Bram; Cree, Michael J; Mizutani, Atsushi; Quellec, Gwénolé; Sanchez, Clara I; Zhang, Bob; Hornero, Roberto; Lamard, Mathieu; Muramatsu, Chisako; Wu, Xiangqian; Cazuguel, Guy; You, Jane; Mayo, Agustín; Li, Qin; Hatanaka, Yuji; Cochener, Béatrice; Roux, Christian; Karray, Fakhri; Garcia, María; Fujita, Hiroshi; Abramoff, Michael D


    The detection of microaneurysms in digital color fundus photographs is a critical first step in automated screening for diabetic retinopathy (DR), a common complication of diabetes. To accomplish this detection numerous methods have been published in the past but none of these was compared with each other on the same data. In this work we present the results of the first international microaneurysm detection competition, organized in the context of the Retinopathy Online Challenge (ROC), a multiyear online competition for various aspects of DR detection. For this competition, we compare the results of five different methods, produced by five different teams of researchers on the same set of data. The evaluation was performed in a uniform manner using an algorithm presented in this work. The set of data used for the competition consisted of 50 training images with available reference standard and 50 test images where the reference standard was withheld by the organizers (M. Niemeijer, B. van Ginneken, and M. D. Abràmoff). The results obtained on the test data was submitted through a website after which standardized evaluation software was used to determine the performance of each of the methods. A human expert detected microaneurysms in the test set to allow comparison with the performance of the automatic methods. The overall results show that microaneurysm detection is a challenging task for both the automatic methods as well as the human expert. There is room for improvement as the best performing system does not reach the performance of the human expert. The data associated with the ROC microaneurysm detection competition will remain publicly available and the website will continue accepting submissions.

  15. Utilization of Digital Image Processing In Process of Quality Control of The Primary Packaging of Drug Using Color Normalization Method

    Erwanto, Danang; Arttini Dwi Prasetyowati, Sri; Nuryanto Budi Susila, Eka


    In the process of quality control, accuracy is required so that the improper drug packaging is not included into the next production process. The automatic inspection system using digital image processing can be applied to replace the manual inspection system done by humans. The image captured from the vision sensor is RGB image which is then converted into grayscale. The process of converting RGB image into grayscale image is performed using the color normalization method to spread the data of RGB colors at each pixel. From the software of image processing using the color normalization method that have been created, it shows grayscale images on the drug object which have degrees of gray higher than the grayscale image section of the background when the degree of the R, G or B color of drug is higher than the degree of the R, G, B color on the background of packaging. The determination of threshold value indicates that the binary image of the drug is white and a binary image of the background of drug packaging is black.

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

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


    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...

  17. A 1 GHz sample rate, 256-channel, 1-bit quantization, CMOS, digital correlator chip

    Timoc, C.; Tran, T.; Wongso, J.


    This paper describes the development of a digital correlator chip with the following features: 1 Giga-sample/second; 256 channels; 1-bit quantization; 32-bit counters providing up to 4 seconds integration time at 1 GHz; and very low power dissipation per channel. The improvements in the performance-to-cost ratio of the digital correlator chip are achieved with a combination of systolic architecture, novel pipelined differential logic circuits, and standard 1.0 micron CMOS process.

  18. Neural Correlates of Subjective Awareness for Natural Scene Categorization of Color Photographs and Line-Drawings

    Fu, Qiufang; Liu, Yong-Jin; Dienes, Zoltan; Wu, Jianhui; Chen, Wenfeng; Fu, Xiaolan


    It remains controversial whether visual awareness is correlated with early activation indicated by VAN (visual awareness negativity), as the recurrent process hypothesis theory proposes, or with later activation indicated by P3 or LP (late positive), as suggested by global workspace theories. To address this issue, a backward masking task was adopted, in which participants were first asked to categorize natural scenes of color photographs and line-drawings and then to rate the clarity of their visual experience on a Perceptual Awareness Scale (PAS). The interstimulus interval between the scene and the mask was manipulated. The behavioral results showed that categorization accuracy increased with PAS ratings for both color photographs and line-drawings, with no difference in accuracy between the two types of images for each rating, indicating that the experience rating reflected visibility. Importantly, the event-related potential (ERP) results revealed that for correct trials, the early posterior N1 and anterior P2 components changed with the PAS ratings for color photographs, but did not vary with the PAS ratings for line-drawings, indicating that the N1 and P2 do not always correlate with subjective visual awareness. Moreover, for both types of images, the anterior N2 and posterior VAN changed with the PAS ratings in a linear way, while the LP changed with the PAS ratings in a non-linear way, suggesting that these components relate to different types of subjective awareness. The results reconcile the apparently contradictory predictions of different theories and help to resolve the current debate on neural correlates of visual awareness. PMID:28261141

  19. Does correlated color temperature affect the ability of humans to identify veins?

    Argyraki, Aikaterini; Clemmensen, Line Katrine Harder; Petersen, Paul Michael


    In the present study we provide empirical evidence and demonstrate statistically that white illumination settings can affect the human ability to identify veins in the inner hand vasculature. A special light-emitting diode lamp with high color rendering index (CRI 84–95) was developed and the eff......In the present study we provide empirical evidence and demonstrate statistically that white illumination settings can affect the human ability to identify veins in the inner hand vasculature. A special light-emitting diode lamp with high color rendering index (CRI 84–95) was developed...... and the effect of correlated color temperature was evaluated, in the range between 2600 and 5700 K at an illuminance of 40 9 lx on the ability of adult humans to identify veins. It is shown that the ability to identify veins can, on average, be increased up to 24% when white illumination settings that do...... not resemble incandescent light are applied. The illuminance reported together with the effect of white illumination settings on direct visual perception of biosamples are relevant for clinical investigations during the night. © 2015 Optical Society of America...

  20. Color calibration of an RGB digital camera for the microscopic observation of highly specular materials

    Martínez-García, Juan; Hébert, Mathieu; Trémeau, Alain


    Color calibration of imaging devices has been previously studied in a varied number of situations where the materials observed have diffuse or only slightly specular surfaces. Most of the calibration methods available in the literature consist in using standard diffuse color charts in order to determine the mathematical operations necessary to transform the colors measured by the imaging device into the reference colors obtained from the target chart. Unfortunately, there are many problems, such as sensor saturation, that arise when using these methods to calibrate devices intended for the observation of highly specular samples, especially in the 0°:0° illumination/observation geometry used in microscopic imaging systems. In this paper, we explore several color calibration methods adapted for the observation of highly specular materials, and propose one method in particular in which we use colored filters and a calibrated mirror in order to obtain a set of specular colored samples. By using 72 samples for learning, we tested the different methods on 50 other samples and obtained, with the best one, an average CIE-DeltaE94 color difference of 1.93 units, which is a fairly good performance for color measurements at the microscopic scale.

  1. Linear methods for input scenes restoration from signals of optical-digital pattern recognition correlator

    Starikov, Sergey N.; Konnik, Mikhail V.; Manykin, Edward A.; Rodin, Vladislav G.


    Linear methods of restoration of input scene's images in optical-digital correlators are described. Relatively low signal to noise ratio of a camera's photo sensor and extensional PSF's size are special features of considered optical-digital correlator. RAW-files of real correlation signals obtained by digital photo sensor were used for input scene's images restoration. It is shown that modified evolution method, which employs regularization by Tikhonov, is better among linear deconvolution methods. As a regularization term, an inverse signal to noise ratio as a function of spatial frequencies was used. For additional improvement of restoration's quality, noise analysis of boundary areas of the image to be reconstructed was performed. Experimental results on digital restoration of input scene's images are presented.

  2. Digital quantification of human eye color highlights genetic association of three new loci.

    F. Liu (Fan); A. Wollstein (Andreas); P.G. Hysi (Pirro); G.A. Ankra-Badu (Georgina); T.D. Spector (Timothy); D.J. Park (Daniel); G. Zhu; M. Larsson (Mats); D.L. Duffy (David); G.W. Montgomery (Grant); D.A. Mackey (David); S. Walsh (Susan); O. Lao Grueso (Oscar); A. Hofman (Albert); F. Rivadeneira Ramirez (Fernando); J.R. Vingerling (Hans); A.G. Uitterlinden (André); N.G. Martin (Nicholas); C.J. Hammond (Christopher); M.H. Kayser (Manfred)


    textabstractPrevious studies have successfully identified genetic variants in several genes associated with human iris (eye) color; however, they all used simplified categorical trait information. Here, we quantified continuous eye color variation into hue and saturation values using high-resolution

  3. Two Gluon Production and Longitudinal Correlations in the Color Glass Condensate

    Fukushima, Kenji


    We derive an analytical expression for the two-gluon multiplicity in the pA (light-heavy) collisions, and focus specifically on the rapidity dependent part. We approximate the gauge field from the heavy target as the Color Glass Condensate which interacts with the light projectile whose source density allows for a perturbative expansion. We discuss the longitudinal correlations of produced particles. Our calculation goes in part beyond the eikonal limit for the emitted gluons so that we can retain the exponential terms with respect to the rapidity difference. Our expression can thus describe the short-range correlations as well as the long-range ones for which our formula is reduced to the known expression. In a special case of two high-pt gluons in the back-to-back kinematics we find that dependence on the rapidity separation is only moderate even in the diagrammatically connected part.

  4. Hormonal correlates of breeding behavior and pouch color in the Magnificent Frigatebird, Fregata magnificens.

    Osorno, José Luis; Núñez-de la-Mora, Alejandra; D'Alba, Liliana; Wingfield, John C


    It is well known that testosterone (T) influences the expression of the behavior and many sexual traits during reproduction in vertebrates. However, patterns of circulating concentrations of T vary tremendously across free-living populations. Here the profiles of plasma T levels in the Magnificent Frigatebird, Fregata magnificens, are presented during the courtship, incubation and chick rearing stages of breeding. In addition, the predicted interrelationship of T and the expression of a sexually selected trait, the red gular pouch of males is investigated. Plasma levels of corticosterone (Cort) are reported in relation to the demands of breeding conditions in colonies. Blood samples were obtained from 26 males and 32 females in the 1993-1994 breeding season and 41 courting males in 1997. Pouch color and size were also estimated in these males. As expected, T levels changed across the breeding stages: birds showed high levels of T during courtship and much lower circulating levels during incubation and chick rearing. Consistent with the expected effect of T, individual pouch color and size correlated with circulating levels of this hormone. In this highly dimorphic species no correlation was found between T and body condition or tail asymmetry. Cort, in contrast, did not change across the three reproductive stages.

  5. Visual appearance effect on modified reconstruction color images of optical Fourier transform hologram by means of digital image processing

    Iizuka, Masayuki; Kariya, Makoto; Uehara, Shinobu; Nakashima, Yoshio; Takamatsu, Mamoru


    A blue white He-Cd laser composed of three R/G/B component beams in place of He-Ne laser is directly applied to fabricate the optical Fourier transform hologram (OFTH) using the red sensitive silver halide material (SO-253 film) for holography. As a result, the red beams play an important role as the coherent beams in the fabrication of OFTH. A green solid state laser is applied to fabricate the OFTH using the same film for holography. The visual appearance of reconstruted color images caused by He-Cd laser is discussed in contrast to that of an ordinary OFTH which can be made using the He-Ne laser and solid state laser. The visual color effect using the He-Cd laser is checked from the viewpoint of the relative real size and its place in the OFTH, and the visual depth sensation of overlapped ghost images called cross-talk in the Fresnel hologram. The purpose using a commercially available software such as HSL color model is to carry out the intuitive modification of overlapped and deteriorated color images in the digital reconstruction of OFTH and Fresnel hologram.

  6. Application of Digital Survey Mapping Technology in the Investigation of Colored Wood Statue in the Caoxi Temple

    Li, Y.; Zheng, Y.


    The colored wood statues in the CaoXi Temple represent the Sandashi(Manjushri, Samantabhadra , Avalokitesvar) in the Buddhism.These statues with great value were carved in Dali kingdom of the Song dynasty. Because of natural and man-made reasons, disease has become very seriously both in the painted layer on the surface and the structure inside. So it is very important to record the current situation, analyze the structure, craft and material, and detect the cause of disease. This paper takes the colored wood statues as the research object, and kinds of digital survey technology were applied in the process. The Research results will play an important role in the protection, explanation and display.

  7. Practical color calibration for dermoscopy, applied to a digital epiluminescence microscope.

    Grana, C; Pellacani, G; Seidenari, S


    The assessment of colors is essential for melanoma (MM) diagnosis, both for pattern analysis on dermoscopic images, and when using semiquantitative methods. Our aim was to provide a simple, precise characterization and reproducible calibration of the color response for dermoscopic instruments. Three processes were used to correct the non-uniform illumination pattern of the instrument, to easily estimate the camera gamma settings and to describe the color space conversion matrices required to produce standard images, in any color space. A specific color space was also developed to optimize the representation of dermatoscopic colors. The calibration technique was tested both on synthetic reference surfaces and on real images by comparing the difference between the images colors obtained with two different equipments. The differences between the images acquired by means of the two instruments, calculated on the reference patterns after calibration, were up to 10 times lower then before, while comparison of histograms referring to real images provided an improvement of about seven times on average. A complete workflow for dermatologic image calibration, which allows the user to continue using his own software and algorithms, but with a much higher informative content, is presented. The technique is simple and may improve cooperation between different research centers, in teleconsulting contexts or for result comparisons.

  8. Fatigue Crack Closure Analysis Using Digital Image Correlation

    Leser, William P.; Newman, John A.; Johnston, William M.


    Fatigue crack closure during crack growth testing is analyzed in order to evaluate the critieria of ASTM Standard E647 for measurement of fatigue crack growth rates. Of specific concern is remote closure, which occurs away from the crack tip and is a product of the load history during crack-driving-force-reduction fatigue crack growth testing. Crack closure behavior is characterized using relative displacements determined from a series of high-magnification digital images acquired as the crack is loaded. Changes in the relative displacements of features on opposite sides of the crack are used to generate crack closure data as a function of crack wake position. For the results presented in this paper, remote closure did not affect fatigue crack growth rate measurements when ASTM Standard E647 was strictly followed and only became a problem when testing parameters (e.g., load shed rate, initial crack driving force, etc.) greatly exceeded the guidelines of the accepted standard.

  9. Digit ratio, color polymorphism and egg testosterone in the Australian painted dragon.

    Michael Tobler

    Full Text Available Variation in exposure to sex hormones during early development contributes to phenotypic plasticity in vertebrate offspring. As a proposed marker for prenatal sex hormone exposure and because of their association with various physiological and behavioral characteristics, digit ratio and/or digit length have received notable interest within the field of evolutionary ecology. However, the validity of digit measures as a proxy of prenatal sex hormone exposure is controversial and only few studies have provided direct evidence for the link between digit development and prenatal sex hormones. Here, we report morph- and sex-specific variation in digit ratio in wild painted dragon lizards (Ctenophorus pictus. Lizards expressing a yellow bib have significantly larger third-to-fourth toe ratios (3D:4D than lizards without a bib. Males have significantly smaller 3D:4D than females. Furthermore, we show that experimental elevation of yolk testosterone significantly increases 3D:4D in hatchling painted dragon lizards, but has no influence on hatchling size. Our results provide direct and indirect evidence for the involvement of prenatal sex steroids in digit development and it is suggested that digit ratio may be used as a biomarker for prenatal steroid exposure in this reptilian species. As such, digit ratio may provide a useful tool to study temporal or spatial differences in the proximate hormonal mechanisms modulating physiological and behavioural phenotypes.

  10. CTA in the detection and quantification of vertebral artery pathologies: a correlation with color Doppler sonography

    Puchner, Stefan; Rand, Thomas; Reiter, Markus; Lammer, Johannes; Bucek, Robert A. [Medical University Vienna, Department of Cardiovascular and Interventional Radiology, Vienna (Austria); Haumer, Markus; Minar, Erich [Medical University Vienna, Department of Angiology, Vienna (Austria)


    We evaluated the feasibility of multidetector CT angiography (MDCTA) in the examination of vertebral artery (VA) pathologies and correlated the results with those of color Doppler sonography (CDS). In this retrospective cohort analysis, we identified 65 patients with suspected cerebrovascular disease, who underwent MDCTA and CDS of the supraaortic vessels within a maximum period of 1 month. We evaluated the feasibility and image quality of MDCTA in this indication, compared the value of reformatted images and axial source images in the grading of stenoses and correlated these results with those of CDS. The image quality of the MDCTA examination was classified as good in 64 patients (98.5%) and as moderate in 1 patient (1.5%). Axial source images and reformatted images agreed perfectly in terms of stenosis detection and grading as well as the detection of hypoplastic VAs ({kappa} = 1). The correlation between MDCTA and CDS was moderate ({kappa} = 0.56) in terms of stenosis detection and quantification and poor ({kappa} = 0.35) in terms of detection of hypoplasia of the VA. MDCTA is a feasible method for the evaluation of VA pathologies providing a good image quality. Image reformatting does not add any diagnostic value to the interpretation of axial source images. The correlation between MDCTA and CDS is only moderate, reflecting the clinically important limitations of CDS in this indication. (orig.)

  11. Magnetic resonance imaging in the evaluation of placental adhesive disorders: correlation with color Doppler ultrasound

    Masselli, Gabriele; Casciani, Emanuele; Polettini, Elisabetta; Gualdi, Gianfranco [Umberto I Hospital-La Sapienza University, Department of Radiology DEA, Rome (Italy); Brunelli, Roberto; Piccioni, Maria G.; Anceschi, Maurizio [Umberto I Hospital-La Sapienza University, Department of Gynecology and Obstetrics, Rome (Italy)


    The purpose of this study was to compare the value of pelvic ultrasound with color Doppler and magnetic resonance imaging (MRI) in: (1) the diagnosis of placental adhesive disorders (PADs), (2) the definition of the degree of placenta invasiveness, (3) determining the topographic correlation between the diagnostic images and the surgical results. Fifty patients in the third trimester of pregnancy with a diagnosis of placenta previa and at least one previous caesarean section underwent color Doppler ultrasound (US) and MRI. The sonographic and MRI diagnoses were compared with the final pathologic or operative findings. Outcomes at delivery were as follows: normal placenta (n = 38) and PAD (n = 12). MR and US Doppler showed no statistically difference in identiyfing patients with PAD (P = 0.74), while MRI was statistically better than US Doppler in evaluating the depth of placenta infiltration (P < 0.001). MRI accurately characterized the topography of invasion in 12/12 (100%) of the cases, while US accurately characterized the topography of invasion in 9/12 (75%) of the cases. In conclusion, we confirmed that pelvic US is highly reliable to diagnose or exclude the presence of PAD and found MRI to be an excellent tool for the staging and topographic evaluation of PAD. (orig.)

  12. Correlated color temperature preferred by observers for illumination of artistic paintings.

    Pinto, Paulo Daniel; Linhares, João Manuel Maciel; Nascimento, Sérgio Miguel Cardoso


    The visual effects of lighting on art paintings is an important aspect that should be considered by museum curators. The aim of this work was to determine the correlated color temperature (CCT) of daylight illumination preferred by observers when appreciating art paintings. Hyperspectral images of 11 oil paintings were collected at the museum, and the appearance of the paintings under daylight illuminants with CCT from 25,000 K to 3600 K was computed. In a psychophysical experiment using precise CRT reproductions of the paintings, observers had to adjust the CCT of the illuminant such that it produced the best visual impression. It was found that the distribution of observers' preferences had a maximum at a CCT of about 5100 K and that this value did not depend on whether the observers were undergraduate students or museum visitors or on the degree of adaptation to the color of the illumination. These results suggest that observers prefer a more bluish-white light than that normally used in museums.

  13. Color transparency and short-range correlations in exclusive pion photo- and electroproduction from nuclei

    Cosyn, W; Ryckebusch, J


    A relativistic and quantum mechanical framework to compute nuclear transparencies for pion photo- and electroproduction reactions is presented. Final-state interactions for the ejected pions and nucleons are implemented in a relativistic eikonal approach. At sufficiently large ejectile energies, a relativistic Glauber model can be adopted. At lower energies, the framework possesses the flexibility to use relativistic optical potentials. The proposed model can account for the color-transparency (CT) phenomenon and short-range correlations (SRC) in the nucleus. Results are presented for kinematics corresponding to completed and planned experiments at Jefferson Lab. The influence of CT and SRC on the nuclear transparency is studied. Both the SRC and CT mechanisms increase the nuclear transparency. The two mechanisms can be clearly separated, though, as they exhibit a completely different dependence on the hard scale parameter. The nucleon and pion transparencies as computed in the relativistic Glauber approach a...

  14. Selection of an Optimal Method for Calculation of Correlated Color Temperature

    Zheleznikova О. Ye.


    Full Text Available The article is dedicated to estimation of absolute errors in the methods of correlated color temperature (CCT calculation, namely the methods of Robertson (1968, McCamy (1992, Yoshi Ohno (2013, Javier Hernandez (1999 by means of the program developed by the authors. The work represents graphs of the absolute error distribution across the range of CCT definition. The authors outlined recommendations on use of the above methods in the colorimetric measurement practice based on the obtained results. The work also contains comparison of the “standard” variant of the Robertson’s method using 31 isotherms and the variants using more isotherms. It was demonstrated that with reduction of the period between isotherms the error tends to decrease. The calculation program was implemented with use of Python language and Numpy library, the tables were also computed by means of Python language and Scipy library, the graphs were plotted with the help of Matplotlib library.

  15. Optical Measurement Techniques for Rocket Engine Testing and Component Applications: Digital Image Correlation and Dynamic Photogrammetry

    Gradl, Paul


    NASA Marshall Space Flight Center (MSFC) has been advancing dynamic optical measurement systems, primarily Digital Image Correlation, for extreme environment rocket engine test applications. The Digital Image Correlation (DIC) technology is used to track local and full field deformations, displacement vectors and local and global strain measurements. This technology has been evaluated at MSFC through lab testing to full scale hotfire engine testing of the J-2X Upper Stage engine at Stennis Space Center. It has been shown to provide reliable measurement data and has replaced many traditional measurement techniques for NASA applications. NASA and AMRDEC have recently signed agreements for NASA to train and transition the technology to applications for missile and helicopter testing. This presentation will provide an overview and progression of the technology, various testing applications at NASA MSFC, overview of Army-NASA test collaborations and application lessons learned about Digital Image Correlation.

  16. Lack of Correlation of WAIS Digit Span with Clox 1 and the Dementia Rating Scale in MCI.

    Lortie, Jevin Jay; Remington, Ruth; Hoffmann, Heather; Shea, Thomas B


    Individuals with MCI declined in performance over 6 months in the Clock-drawing (Clox 1) and the WAIS Digit Span tests, but not in the Dementia Rating Scale (DRS). Individual performance on Clox 1 and Digit Span did not correlate after 6 months. Performance on the Digit Span Test also did not correlate with the DRS, but performance on Clox 1 correlated with the DRS. Performance in Clox 1 was, therefore, not a predictor of performance in the Digit Span Test. These findings support the use of a test battery containing the Digit Span test to detect and track cognitive decline in MCI.

  17. Lack of Correlation of WAIS Digit Span with Clox 1 and the Dementia Rating Scale in MCI

    Jevin Jay Lortie


    Full Text Available Individuals with MCI declined in performance over 6 months in the Clock-drawing (Clox 1 and the WAIS Digit Span tests, but not in the Dementia Rating Scale (DRS. Individual performance on Clox 1 and Digit Span did not correlate after 6 months. Performance on the Digit Span Test also did not correlate with the DRS, but performance on Clox 1 correlated with the DRS. Performance in Clox 1 was, therefore, not a predictor of performance in the Digit Span Test. These findings support the use of a test battery containing the Digit Span test to detect and track cognitive decline in MCI.

  18. Effect of salt stress in the regulation of anthocyanins and color of hibiscus flowers by digital image analysis.

    Trivellini, Alice; Gordillo, Belén; Rodríguez-Pulido, Francisco J; Borghesi, Eva; Ferrante, Antonio; Vernieri, Paolo; Quijada-Morín, Natalia; González-Miret, M Lourdes; Heredia, Francisco J


    The effect of salt stress (200 mM NaCl for 28 days) on physiological characteristics of Hibiscus rosa-sinensis, such as abscisic acid (ABA) content, electrolyte leakage, and photochemical efficiency in leaves, and its influence on biomass production, anthocyanin composition, and color expression of flowers were evaluated. Salinity significantly increased electrolyte leakage and ABA content in leaves and reduced the flower fresh weight. Chlorophyll fluorescence parameters were lower in salt stress condition, compared to control. Moreover, salt stress negatively affected the content of anthocyanins (mainly cyanidin-3-sophoroside), which resulted in a visually perceptible loss of color. The detailed anthocyanin composition monitored by HPLC-DAD-MS and the color variations by digital image analysis due to salt stress showed that the effect was more noticeable at the basal portion of petals. A forward stepwise multiple regression was performed for predicting the content of anthocyanins from appearance characteristics obtained by image analysis, reaching R-square values up to 0.90.


    翁文国; 范维澄; 廖光煊; 秦俊


    An improved method that brings enhancement in accuracy for the interrogation of (digital) PIV images is described in this paper. This method is based on cross-correlation with discrete window offset, which makes use of a translation of the second interrogation window and rebuilds it considering rotation and shear.The displacement extracted from PIV images is predicted and corrected by means of an iterative procedure. In addition, the displacement vectors are validated at each intermediate of the iteration process. The present improved cross-correlation method is compared with the conventional one in accuracy by interrogation of synthetic and real (digital) PIV images and the interrogation results are discussed.


    Samo Simončič


    Full Text Available The paper presents a newly developed fine search algorithm used in the application of digital correlation. In order to evaluate its performance a special purpose application was developed using C# programming language. The algorithm was then tested on a pre-prepared set of the computer generated speckled images. It turned out to be much faster than the conventional fine search algorithm. Consequently, it is a major step forward in a never ending quest for a fast digital correlation execution with sub pixel accuracy.

  1. Color Swapping to Enhance Breast Cancer Digital Images Qualities Using Stain Normalization

    Muhimmah, Izzati; Puspasari Wijaya, Dhina; Indrayanti


    Histopathology is the disease diagnosis by means of the visual examination of tissues under the microscope. The virtually transparent tissue sections were prepared using a number of colored histochemical stains bound selectively to the cellular components. A variation of colors comes to be a problem in histopathology based upon the microscope lighting for the range of factors. This research aimed to investigate an image enhancement by applying a nonlinear mapping approach to stain normalization and histogram equalization for contrast enhancement. Validation was carried out in 59 datasets with 96.6% accordance and expert justification.

  2. Superresolution imaging system by color-coded tilted-beam illumination in digital in-line holographic microscopy

    Granero, L.; Micó, V.; Ferreira, C.; Zalevsky, Z.; García, J.


    Digital in-line holographic microscopy (DIHM) relates with the capability to achieve microscopic imaging working without lensless in the regime of holography. In essence, DIHM proposes a simple layout where a point source of coherent light illuminates the sample and the diffracted wavefront is recorded by a digital sensor. However, DIHM lacks high numerical aperture (NA) due to both geometrical distortion and the mandatory compromise between the illumination pinhole diameter, the illumination wavelength, and the need to obtain a reasonable light efficiency. One way to improve the resolution in DIHM, is by allowing superresolution imaging by angular multiplexing using tilted beam illumination. This illumination allows the on-axis diffraction of different spatial frequency content of the sample's spectrum, different in comparison to the case when on-axis illumination is used. And after recover this additional spectral content, a synthetic numerical aperture (SNA) expanding up the cutoff frequency of the system in comparison with the on-axis illumination case can be assembled in a digital post-processing stage. In this contribution, we present a method to achieve one-dimensional (1-D) superresolved imaging in DIHM by a SINGLE SHOT illumination, using color-coded tilted beams. The method has been named as L-SESRIM (Lensless Single-Exposure Super-Resolved Interferometric Microscopy). Although the technique was previously presented showing very preliminary results [34], in this contribution we expand the experimental characterization (USAF resolution test target) as well as derive the theoretical frame for SNA generation using different illumination wavelengths.

  3. Characteristic of a Digital Correlation Radiometer Back End with Finite Wordlength

    Biswas, Sayak K.; Hyde, David W.; James, Mark W.; Cecil, Daniel J.


    The performance characteristic of a digital correlation radiometer signal processing back end (DBE) is analyzed using a simulator. The particular design studied here corresponds to the airborne Hurricane Imaging radiometer which was jointly developed by the NASA Marshall Space Flight Center, University of Michigan, University of Central Florida and NOAA. Laboratory and flight test data is found to be in accord with the simulation results. Overall design seems to be optimum for the typical input signal dynamic range. It was found that the performance of the digital kurtosis could be improved by lowering the DBE input power level. An unusual scaling between digital correlation channels observed in the instrument data is confirmed to be a DBE characteristic.

  4. The use of variable-step delta modulation in digital filtering and correlation analysis

    Pogribnoi, V. A.


    General expressions are obtained for convolutions and correlation functions using variable-quantization-step DM in conjunction with PCM, making it possible to realize low-cost processor circuits. Algorithms for the operation of processors for digital filtering and correlation analysis on the basis of this type of modulation are proposed. In addition, they are compared with algorithms for the operation of processors with linear PCM, DM, and delta-sigma modulation.

  5. Application of digital-image-correlation techniques in analysing cracked cylindrical pipes

    Shih-Heng Tung; Chung-Huan Sui


    Cracks induced by external excitation on a material that has defects may generate the stress concentration phenomenon. The stress concentration behaviour causes local buckling, which will induce the damage of the members made of this material. Thus, developing techniques to monitor the strain variation of a cracked member is an important study. The traditional technique (such as strain gauge) can only measure the average strain of a region. The strain variation within this region cannot be determined. Therefore, it cannot sufficiently reflect the mechanical behaviour surrounding the crack. The Digital image correlation technique recently developed is an image identification technique to be applied for measuring the object deformation. This technique is capable of correlating the digital images of an object before and after deformation and further determining the displacement and strain field of an object based on the corresponding position on the image. In this work, this technique is applied to analyse the mechanics of a cylindrical pipe experiencing crack destruction. The fixing device is used to avoid shaking the specimen during the pressurizing process. The image capture instruments are fixed on the stable frame to measure the deformation of specimen accurately. Through the cylindrical pipe cracking test, the capacity of the digital image correlation technique for surveying the strain variation in a tiny region is validated. Then, the experimental results obtained using the digital image correlation analysis is used to demonstrate the crack development tendency in defect materials and the stress concentration zone.

  6. Representative Elementary Area Determinations through Digital Photography, Image Analysis, and Soil Color

    Photography has been a welcome tool in assisting to document and convey qualitative soil information. Greater availability of digital cameras with increased information storage capabilities has promoted novel uses of this technology in investigations of water movement patterns, organic matter conte...

  7. Difference in electron- and gamma-irradiation effects on output characteristic of color CMOS digital image sensors

    MENG Xiangti; KANG Aiguo; ZHANG Ximin; LI Jihong; HUANG Qiang; LI Fengmei; LIU Xiaoguang; ZHOU Hongyu


    Changes of the average brightness and non-uniformity of dark output images, and quality of pictures captured under natural lighting for the color CMOS digital image sensors irradiated at different electron doses have been studied in comparison to those from the γ-irradiated sensors. For the electron-irradiated sensors, the non-uniformity increases obviously and a small bright region on the dark image appears at the dose of 0.4 kGy. The average brightness increases at 0.4 kGy, increases sharply at 0.5 kGy. The picture is very blurry only at 0.6 kGy, showing the sensor undergoes severe performance degradation. Electron radiation damage is much more severe than γ radiation damage for the CMOS image sensors. A possible explanation is presented in this paper.

  8. Detection of retinal lesions in diabetic retinopathy: comparative evaluation of 7-field digital color photography versus red-free photography.

    Venkatesh, Pradeep; Sharma, Reetika; Vashist, Nagender; Vohra, Rajpal; Garg, Satpal


    Red-free light allows better detection of vascular lesions as this wavelength is absorbed by hemoglobin; however, the current gold standard for the detection and grading of diabetic retinopathy remains 7-field color fundus photography. The goal of this study was to compare the ability of 7-field fundus photography using red-free light to detect retinopathy lesions with corresponding images captured using standard 7-field color photography. Non-stereoscopic standard 7-field 30° digital color fundus photography and 7-field 30° digital red-free fundus photography were performed in 200 eyes of 103 patients with various grades of diabetic retinopathy ranging from mild to moderate non-proliferative diabetic retinopathy to proliferative diabetic retinopathy. The color images (n = 1,400) were studied with corresponding red-free images (n = 1,400) by one retina consultant (PV) and two senior residents training in retina. The various retinal lesions [microaneurysms, hemorrhages, hard exudates, soft exudates, intra-retinal microvascular anomalies (IRMA), neovascularization of the retina elsewhere (NVE), and neovascularization of the disc (NVD)] detected by all three observers in each of the photographs were noted followed by determination of agreement scores using κ values (range 0-1). Kappa coefficient was categorized as poor (≤0), slight (0.01-0.20), fair (0.2 -0.40), moderate (0.41-0.60), substantial (0.61-0.80), and almost perfect (0.81-1). The number of lesions detected by red-free images alone was higher for all observers and all abnormalities except hard exudates. Detection of IRMA was especially higher for all observers with red-free images. Between image pairs, there was substantial agreement for detection of hard exudates (average κ = 0.62, range 0.60-0.65) and moderate agreement for detection of hemorrhages (average κ = 0.52, range 0.45-0.58), soft exudates (average κ = 0.51, range 0.42-0.61), NVE (average κ = 0.47, range 0.39-0.53), and NVD

  9. Computational color technology

    Kang, Henry R


    Henry Kang provides the fundamental color principles and mathematical tools to prepare the reader for a new era of color reproduction, and for subsequent applications in multispectral imaging, medical imaging, remote sensing, and machine vision. This book is intended to bridge the gap between color science and computational color technology, putting color adaptation, color constancy, color transforms, color display, and color rendition in the domain of vector-matrix representations and theories. Computational Color Technology deals with color digital images on the spectral level using vector-m

  10. Lack of Correlation of WAIS Digit Span with Clox 1 and the Dementia Rating Scale in MCI

    Jevin Jay Lortie; Ruth Remington; Heather Hoffmann; Shea, Thomas B


    Individuals with MCI declined in performance over 6 months in the Clock-drawing (Clox 1) and the WAIS Digit Span tests, but not in the Dementia Rating Scale (DRS). Individual performance on Clox 1 and Digit Span did not correlate after 6 months. Performance on the Digit Span Test also did not correlate with the DRS, but performance on Clox 1 correlated with the DRS. Performance in Clox 1 was, therefore, not a predictor of performance in the Digit Span Test. These findings support the use of ...

  11. Correlations between Color Gradients and Structural Parameters of the Disks in Late-type Spiral Galaxies%晚型旋涡星系盘的颜色梯度与结构参数的相关关系

    李化南; 郑晓光


    From Data Release Two of Sloan Digital Sky Survey (SDSS DR2), 395 latetype spiral galaxies brighter than 15m in r band are selected. The correlations between the color gradients and other structural parameters of disks are investigated. It is shown that there is no correlation between the color gradients and absolute magnitude (mass); there are strong correlations between the color gradients and sizes of the disks, i.e., the larger the disks, the steeper the color gradients. There are also strong correlations between the color gradients and colors. The bluer the disks, the steeper the color gradients. It is also shown that the color gradients are strongly dependent on the surface brightness of disk. The disk with brighter surface exhibits steeper color gradients. In the end, the constraint of the correlations between the color gradients and other structural parameters of the disks in the late-type spiral galaxies on the star formation history is also discussed.%从Sloan数字巡天第2批释放的数据(SDSS DR2)中选择了395个在r波段亮于15等的面向晚型旋涡星系作为样本,研究了盘的颜色梯度与结构参数的关系.结果表明:盘的颜色梯度与盘的绝对星等(质量)无关;盘的颜色梯度与盘的尺度有关,越大的盘颜色梯度越陡;盘的颜色梯度与盘的颜色有关,越蓝的盘颜色梯度越陡;盘的颜色梯度与盘的表面亮度有关,越亮的盘颜色梯度越陡,并简单讨论了盘的颜色梯度与各结构参数的相关关系对晚型旋涡星系盘恒星形成历史的约束.

  12. NanoString, a novel digital color-coded barcode technology: current and future applications in molecular diagnostics.

    Tsang, Hin-Fung; Xue, Vivian Weiwen; Koh, Su-Pin; Chiu, Ya-Ming; Ng, Lawrence Po-Wah; Wong, Sze-Chuen Cesar


    Formalin-fixed, paraffin-embedded (FFPE) tissue sample is a gold mine of resources for molecular diagnosis and retrospective clinical studies. Although molecular technologies have expanded the range of mutations identified in FFPE samples, the applications of existing technologies are limited by the low nucleic acids yield and poor extraction quality. As a result, the routine clinical applications of molecular diagnosis using FFPE samples has been associated with many practical challenges. NanoString technologies utilize a novel digital color-coded barcode technology based on direct multiplexed measurement of gene expression and offer high levels of precision and sensitivity. Each color-coded barcode is attached to a single target-specific probe corresponding to a single gene which can be individually counted without amplification. Therefore, NanoString is especially useful for measuring gene expression in degraded clinical specimens. Areas covered: This article describes the applications of NanoString technologies in molecular diagnostics and challenges associated with its applications and the future development. Expert commentary: Although NanoString technology is still in the early stages of clinical use, it is expected that NanoString-based cancer expression panels would play more important roles in the future in classifying cancer patients and in predicting the response to therapy for better personal therapeutic care.

  13. Optoelectronic Recoded and Nonrecoded Trinary Signed-Digit Adder that uses Optical Correlation.

    Cherri, A K; Habib, M K; Alam, M S


    A symbolic-substitution-based optical numeric processor that uses recoded and nonrecoded trinary signed-digit (TSD) number representations is proposed. Also, we propose new joint spatial encodings for the TSD numbers that reduce the symbolic-substitution computation rules involved in the processor. Optoelectronic implementation of the proposed recoded adder is feasible. Also, the nonrecoded TSD addition can be performed optically in two steps. Both the proposed recoded and nonrecoded adders are more compact than a recently reported modified signed-digit counterpart and use fewer correlators and spatial light modulators.

  14. Interaction of Shock Waves in Cement Mortar Plate Investigated by the Digital Speckle Correlation Method

    LI Xu-Dong; LIU Kai-Xin; ZHANG Guang-Sheng; WEN Shang-Gang; TAN Fu-Li


    @@ Interaction of shock waves in cement mortar plate is studied by digital speckle correlation method and digital high-speed photography technique. When the plates were destroyed by two detonators exploding at the same time, variation of shock wave field is obtained. Experimental results show that the interaction of shock waves will result in a nonlinear huge increase of local normal strain, leading to large deformation and serious destruction. However, the occurrence of this strongly nonlinear phenomenon sensitively depends on the interval between detonators, and it will only appear when the interval is smaller than the diameter of the region where shock waves exist.

  15. 口内数码摄影辅助构建三维彩色数字牙列模型%Constructing 3-dimensional colorized digital dental model assisted by digital photogra-phy

    叶红强; 柳玉树; 刘云松; 宁静; 赵一姣; 周永胜


    目的:探索一种构建通用三维彩色数字牙列模型的方法,获得可在常见三维软件中显示和编辑处理的三维彩色数字牙列模型,提高牙列模型在通用三维软件中的仿真效果。方法:使用口内扫描仪扫描牙列获得数字化三维牙列模型,并以STL格式导出,同时用单镜头反光数码相机按照美国牙科美容协会病例摄影要求拍摄口内照片,选择其中5张照片。在Geomagic Studio 2013软件中导入三维牙列数据,并将5张口内照片分别投影至数字化三维牙列模型表面,精细调整不同照片的交界区域使其过渡自然,获得带有颜色信息的三维牙列模型,以OBJ格式或WRP格式(Geomagic软件专用格式)保存和导出。以患者评价为标准对三维数字模型的颜色仿真效果进行评价。结果:基于口内扫描和口内数码照片,构建了可在常见三维软件中显示和编辑的通用三维彩色数字牙列模型,获得较好的牙列颜色仿真效果。在临床上,将此三维彩色牙列模型与面部三维扫描图像配准和复合后用于前牙美学修复的数字化术前设计和修复效果虚拟预测中,提高了医患交流的效率及患者对修复效果的认知程度。结论:结合口内扫描和口内数码摄影可构建出颜色仿真效果良好的通用三维彩色数字牙列模型,在临床应用中可提高三维数字牙列模型的仿真效果,加强医患沟通效率和效果。%Objective:To explore a method of constructing universal 3-dimensional (3D)colorized digital dental model which can be displayed and edited in common 3 D software (such as Geomagic se-ries),in order to improve the visual effect of digital dental model in 3D software.Methods:The mor-phological data of teeth and gingivae were obtained by intra-oral scanning system (3Shape TRIOS),con-structing 3D digital dental models.The 3D digital dental models were exported as STL files

  16. Automated Detection and Differentiation of Drusen, Exudates, and Cotton-Wool Spots in Digital Color Fundus Photographs for Diabetic Retinopathy Diagnosis

    Niemeijer, M.; van Ginneken, B.; Russel, S.R.; Suttorp-Schulten, M.S.A.; Abràmoff, M.D.


    purpose. To describe and evaluate a machine learning-based, automated system to detect exudates and cotton-wool spots in digital color fundus photographs and differentiate them from drusen, for early diagnosis of diabetic retinopathy. methods. Three hundred retinal images from one eye of 300

  17. Portable digital lock-in instrument to determine chemical constituents with single-color absorption measurements for Global Health Initiatives

    Vacas-Jacques, Paulino [Little Devices Group, SUTD-MIT International Design Center, Cambridge, Massachusetts 02139 (United States); Wellman Center for Photomedicine and Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Linnes, Jacqueline [Little Devices Group, SUTD-MIT International Design Center, Cambridge, Massachusetts 02139 (United States); Biomedical Engineering Department, Boston University, Boston, Massachusetts 02215 (United States); Young, Anna; Gomez-Marquez, Jose [Little Devices Group, SUTD-MIT International Design Center, Cambridge, Massachusetts 02139 (United States); Gerrard, Victoria [Little Devices Group, SUTD-MIT International Design Center, Cambridge, Massachusetts 02139 (United States); Opportunity Lab, Singapore University for Technology and Design, Singapore 138682 (Singapore)


    Innovations in international health require the use of state-of-the-art technology to enable clinical chemistry for diagnostics of bodily fluids. We propose the implementation of a portable and affordable lock-in amplifier-based instrument that employs digital technology to perform biochemical diagnostics on blood, urine, and other fluids. The digital instrument is composed of light source and optoelectronic sensor, lock-in detection electronics, microcontroller unit, and user interface components working with either power supply or batteries. The instrument performs lock-in detection provided that three conditions are met. First, the optoelectronic signal of interest needs be encoded in the envelope of an amplitude-modulated waveform. Second, the reference signal required in the demodulation channel has to be frequency and phase locked with respect to the optoelectronic carrier signal. Third, the reference signal should be conditioned appropriately. We present three approaches to condition the signal appropriately: high-pass filtering the reference signal, precise offset tuning the reference level by low-pass filtering, and by using a voltage divider network. We assess the performance of the lock-in instrument by comparing it to a benchmark device and by determining protein concentration with single-color absorption measurements. We validate the concentration values obtained with the proposed instrument using chemical concentration measurements. Finally, we demonstrate that accurate retrieval of phase information can be achieved by using the same instrument.


    Dominique Lafon


    Full Text Available The goal of this article is to present specific capabilities and limitations of the use of color digital images in a characterization process. The whole process is investigated, from the acquisition of digital color images to the analysis of the information relevant to various applications in the field of material characterization. A digital color image can be considered as a matrix of pixels with values expressed in a vector-space (commonly 3 dimensional space whose specificity, compared to grey-scale images, is to ensure a coding and a representation of the output image (visualisation printing that fits the human visual reality. In a characterization process, it is interesting to regard color image attnbutes as a set of visual aspect measurements on a material surface. Color measurement systems (spectrocolorimeters, colorimeters and radiometers and cameras use the same type of light detectors: most of them use Charge Coupled Devices sensors. The difference between the two types of color data acquisition systems is that color measurement systems provide a global information of the observed surface (average aspect of the surface: the color texture is not taken into account. Thus, it seems interesting to use imaging systems as measuring instruments for the quantitative characterization of the color texture.

  19. Terminology of Color Management for Digital Television%数字电视颜色管理术语

    李桂苓; 徐岩; 李彦


    In recent years, the importance of expanding the color gamut of capturing and reproduction color pictures and, improving visual effects have been emphasized internationally. ISO and IEC have established related serial of standards, but it has not been paid enough attention inside China. This article summarized and selected some terminologies of color management for digital television based on our science and research projects, it contains more than 100 terminologies. We especially selected new terminologies appeared within recent years, as well as rare, unclearly defined and confusing items. We also proposed Chinese names for non-standard names. Every terminology is given its corresponding English name, then underneath each terminology, the first paragraph contains the definition and its associated standard if applicable, the other paragraphs are brief description, related data etc. We strive to use standardized description, accurate data, and hope it can provide references to standardize, manage and improve digital television picture's chroma performance.%近年来,国际上对扩大摄取和重现彩色图像颜色范围和改善视觉效果很重视,ISO和IEC已制订相关标准,而中国国内对此尚未引起足够关注.汇总和筛选了科研工作中积累的数字电视颜色管理术语,共100余条.着重选取了近年出现或不够常见、含义不清、容易混淆的词条.对某些不够规范的称呼建议了中文名称.各词条给出了对应的英文表述.词条名称以下,第一段为定义或对应的标准,其他段为简要解释,相关数据等.文字力求规范,数据力求准确,希对规范、管理和改善数字电视图像色度性能有一定参考价值.

  20. High-speed four-color infrared digital imaging for studying in-cylinder processes in a DI diesel engine

    Rhee, K. T.


    The study was to investigate in-cylinder events of a direct injection-type diesel engine by using a new high-speed infrared (IR) digital imaging systems for obtaining information that was difficult to achieve by the conventional devices. For this, a new high-speed dual-spectra infrared digital imaging system was developed to simultaneously capture two geometrically identical (in respective spectral) sets of IR images having discrete digital information in a (64x64) matrix at rates as high as over 1,800 frames/sec each with exposure period as short as 20 micron sec. At the same time, a new advanced four-color W imaging system was constructed. The first two sets of spectral data were the radiation from water vapor emission bands to compute the distributions of temperature and specie in the gaseous mixture and the remaining two sets of data were to find the instantaneous temperature distribution over the cylinder surface. More than eight reviewed publications have been produced to report many new findings including: Distributions of Water Vapor and Temperature in a Flame; End Gas Images Prior to Onset of Knock; Effect of MTBE on Diesel Combustion; Impact of Oxygen Enrichment on In-cylinder Reactions; Spectral IR Images of Spray Plume; Residual Gas Distribution; Preflame Reactions in Diesel Combustion; Preflame Reactions in the End Gas of an SI Engine; Postflame Oxidation; and Liquid Fuel Layers during Combustion in an SI Engine. In addition, some computational analysis of diesel combustion was performed using KIVA-II program in order to compare results from the prediction and the measurements made using the new IR imaging diagnostic tool.

  1. Correlates of red throat coloration in female stickleback and their potential evolutionary significance

    Yong, Lengxob; Guo, Ruqing; Wright, Daniel S.; Mears, Samantha A.; Pierotti, Michele; McKinnon, Jeffrey S.


    Background: In two stream-resident populations of threespine stickleback (Gasterosteus aculeatus), females often exhibit male-typical red throat coloration. These fish inhabit the Little Campbell River (British Columbia) and Matadero Creek (California). An anadromous population that lacks such color

  2. Correlates of red throat coloration in female stickleback and their potential evolutionary significance

    Yong, Lengxob; Guo, Ruqing; Wright, Daniel S.; Mears, Samantha A.; Pierotti, Michele; McKinnon, Jeffrey S.


    Background: In two stream-resident populations of threespine stickleback (Gasterosteus aculeatus), females often exhibit male-typical red throat coloration. These fish inhabit the Little Campbell River (British Columbia) and Matadero Creek (California). An anadromous population that lacks such color

  3. Correlation Between the Evaluation of Pigmented Lesions by a Multi-spectral Digital Skin Lesion Analysis Device and the Clinical and Histological Features of Melanoma.

    Winkelmann, Richard R; Rigel, Darrell S; Ferris, Laura; Sober, Arthur; Tucker, Natalie; Cockerell, Clay J


    To correlate Multi-spectral Digital Skin Lesion Analysis classifier scores with histopathological severity of pigmented lesions and clinical features of melanoma. Classifier scores were computed for 1,632 skin lesions. Dermatologists evaluated the same lesions for Asymmetry, Border Irregularity, Color variegation, Diameter >6mm, Evolution, Patient's Concern, Regression, and/or "Ugly Duckling" sign. Classifier scores were correlated to the number of clinical risk features and for six histopathological severity levels of pigmented lesions. Average classifier score, Welch's t-test, and chi-square analysis. Melanomas had higher mean classifier scores (3.5) than high-grade dysplastic nevi (2.7, p=0.002), low-grade dysplastic nevi (1.7, pClassifier score and the number of clinical risk characteristics directly correlated (Pearson coefficient 0.32, pclassifier scores to clinical and histological melanoma features supports the effectiveness of Multi-spectral Digital Skin Lesion Analysis in assessing the risk of pigmented lesions requiring biopsy. Optimizing outcomes of dermatologist decisions to biopsy suspicious pigmented lesions may be enhanced utilizing Multi-spectral Digital Skin Lesion Analysis.

  4. A high performance cost-effective digital complex correlator for an X-band polarimetry survey.

    Bergano, Miguel; Rocha, Armando; Cupido, Luís; Barbosa, Domingos; Villela, Thyrso; Boas, José Vilas; Rocha, Graça; Smoot, George F


    The detailed knowledge of the Milky Way radio emission is important to characterize galactic foregrounds masking extragalactic and cosmological signals. The update of the global sky models describing radio emissions over a very large spectral band requires high sensitivity experiments capable of observing large sky areas with long integration times. Here, we present the design of a new 10 GHz (X-band) polarimeter digital back-end to map the polarization components of the galactic synchrotron radiation field of the Northern Hemisphere sky. The design follows the digital processing trends in radio astronomy and implements a large bandwidth (1 GHz) digital complex cross-correlator to extract the Stokes parameters of the incoming synchrotron radiation field. The hardware constraints cover the implemented VLSI hardware description language code and the preliminary results. The implementation is based on the simultaneous digitized acquisition of the Cartesian components of the two linear receiver polarization channels. The design strategy involves a double data rate acquisition of the ADC interleaved parallel bus, and field programmable gate array device programming at the register transfer mode. The digital core of the back-end is capable of processing 32 Gbps and is built around an Altera field programmable gate array clocked at 250 MHz, 1 GSps analog to digital converters and a clock generator. The control of the field programmable gate array internal signal delays and a convenient use of its phase locked loops provide the timing requirements to achieve the target bandwidths and sensitivity. This solution is convenient for radio astronomy experiments requiring large bandwidth, high functionality, high volume availability and low cost. Of particular interest, this correlator was developed for the Galactic Emission Mapping project and is suitable for large sky area polarization continuum surveys. The solutions may also be adapted to be used at signal processing

  5. Determination of Vertical Interproximal Bone Loss Topography: Correlation Between Indirect Digital Radiographic Measurement and Clinical Measurement

    Esmaeli, Farzad; Shirmohammadi, Adileh; Faramarzie, Masoumeh; Abolfazli, Nader; Rasouli, Hossein; Fallahi, Saied


    Background Diagnosis and accuracy in determining the exact location, extent and configuration of bony defects of the jaw are of utmost importance to determine prognosis, treatment planning and long-term preservation of teeth. If relatively accurate diagnosis can be established by radiography, proper treatment planning prior to treatment procedures will be possible. Objectives The aim of the present study was to assess the correlation between indirect digital radiographic measurements and clinical measurements in determining the topography of interproximal bony defects. Patients and Methods Twenty interproximal bony defects, preferably in the mandibular and maxillary 5↔5 area were selected and radiographed using the parallel periapical technique. The radiographs were corrected and digitized on a computer using “Linear Measurement” software; then the three parameters of the base of defect (BD), alveolar crest (AC) and cementoenamel junction (CEJ) were determined using a software. Subsequent to radiographic measurements, clinical measurements were carried out meticulously during flap procedures. Then linear measurements were carried out using a periodontal probe to determine the defect depth and its mesiodistal width. Then the amount of correlation between these two measurements was assessed by Pearson's correlation coefficient. Results The correlation between clinical and radiographic measurements in defect depth determination, in the evaluation of defect angle and in determination of defect width were 88%, 98% and 90%, respectively. Conclusions Indirect digital radiographic technique can be used to diagnose intra-osseous defects, providing a better opportunity to treat bony defects. PMID:23329969

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

    Germaneau A.


    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%.

  7. A low-resolution, GSa/s streaming digitizer for a correlation-based trigger system

    Nishimura, Kurtis; Cao, Zhe; Cooney, Michael; Gorham, Peter; Macchiarulo, Luca; Ritter, Lisa; Romero-Wolf, Andres; Varner, Gary


    Searches for radio signatures of ultra-high energy neutrinos and cosmic rays could benefit from improved efficiency by using real-time beamforming or correlation triggering. For missions with power limitations, such as the ANITA-3 Antarctic balloon experiment, full speed high resolution digitization of incoming signals is not practical. To this end, the University of Hawaii has developed the Realtime Independent Three-bit Converter (RITC), a 3-channel, 3-bit, streaming analog-to-digital converter implemented in the IBM-8RF 0.13 um process. RITC is primarily designed to digitize broadband radio signals produced by the Askaryan effect, and thus targets an analog bandwidth of >1 GHz, with a sample-and-hold architecture capable of storing up to 2.6 gigasamples-per-second. An array of flash analog-to-digital converters perform 3-bit conversion of sets of stored samples while acquisition continues elsewhere in the sampling array. A serial interface is provided to access an array of on chip digital-to-analog convert...

  8. A Review of Various Transform Domain Digital Image Fusion for Multifocus Colored Images

    Arun Begill


    Full Text Available Image fusion is the idea to enhance the image content by fusing two or more images obtained from visual sensor network. The main goal of image fusion is to eliminate redundant information and merging more useful information from source images. Various transform domain image fusion methods like DWT, SIDWT and DCT, ACMax DCT etc. are developed in recent years. Every method has its own advantages and disadvantages. ACMax Discrete cosine transform (DCT is very efficient approach for image fusion because of its energy compaction property as well as improve quality of image. Furthermore, this technique has also some disadvantages like color artifacts, noise and degrade the sharpness of edges. In this paper ACMax DCT method is integrated with saturation weighting and Joint Trilateral filter to get the high quality image and compare with traditional methods. The results have shown that ACMax DCT with Saturation weighting and Joint Trilateral filter method has outperformed the state of art techniques.

  9. Optical Measurement of In-plane Elastic Waves in Mechanical Metamaterials Through Digital Image Correlation

    Schaeffer, Marshall; Ruzzene, Massimo


    We report on a Digital Image Correlation-based technique for the detection of in-plane elastic waves propagating in structural lattices. The experimental characterization of wave motion in lattice structures is currently of great interest due its relevance to the design of novel mechanical metamaterials with unique/unusual properties such as strongly directional behavior, negative refractive indexes and topologically protected wave motion. Assessment of these functionalities often requires the detection of highly spatially resolved in-plane wavefields, which for reticulated or porous structural assemblies is an open challenge. A Digital Image Correlation approach is implemented that tracks small displacements of the lattice nodes by centering image subsets about the lattice intersections. A high speed camera records the motion of the points by properly interleaving subsequent frames thus artificially enhancing the available sampling rate. This, along with an imaging stitching procedure, enables the capturing ...

  10. Study on digital correlation demodulation technology of micro quartz tuning fork gyroscope

    Zhang, Zhixiong; Feng, Lihui; Sun, Yu-Nan


    A signal demodulation scheme for micro quartz tuning fork gyroscope based on digital correlation demodulation technology is proposed. In the operation of quartz gyroscope the reference signal should be in the resonance state with steady amplitude and the reference signal should be in-phase and has the same frequency with the driving signal. The quartz gyroscope signal processing platform is designed on the foundation of DEC6713 DSP development board successfully. The adaptive algorithm including the reference signal frequency tacking, the amplitude automatic gain controlling, the reference signal phase locking, and complex correlation demodulation are devised, and the algorithm is programmed. It is proved that the digital signal process scheme is feasible by means of experimentation.

  11. Experimental investigation of interface curing stresses between PMMA and composite using digital speckle correlation method


    This paper studies the interface curing stresses between polymethyl methacrylate (PMMA) and composite by means of digital speckle correlation method (DSCM).A new method by combining DSCM with the marker points is developed to measure the interface curing stresses,and the measurement principle is introduced.The interface curing stresses between PMMA and composite with different curing bonding conditions are measured and analyzed,this indicates that the residual stress for furnace heating and furnace cooling ...

  12. A General Analysis of the Impact of Digitization in Microwave Correlation Radiometers

    Hyuk Park


    Full Text Available This study provides a general framework to analyze the effects on correlation radiometers of a generic quantization scheme and sampling process. It reviews, unifies and expands several previous works that focused on these effects separately. In addition, it provides a general theoretical background that allows analyzing any digitization scheme including any number of quantization levels, irregular quantization steps, gain compression, clipping, jitter and skew effects of the sampling period.

  13. Displacement and strain field assessment of PDMS using digital image correlation

    Mendonça, B; Ribeiro, J. E.; Lopes, H.; martins, p; M. A. P. Vaz


    The main goal of this work is the characterization of the hyper-elastic mechanical behaviour of PDMS. The special specimens of PDMS (Sylgard® 184) were tested in a bi-axial tensile machine. The displacement and strain fields were measured using a commercial digital image correlation system (ARAMIS of GOM) during the tensile test. The experimental measurements are compared with numerical simulations, which use the most popular algorithms of constitutive models to characterize the hyper-elastic...

  14. Displacement and strain field assessment of PDMS using digital image correlation

    Mendonça, B; Ribeiro, J. E.; Lopes, H.; martins, p; M. A. P. Vaz; Gomes, S.


    The main goal of this work is to characterize the hyper-elastic mechanical behaviour of PDMS. For that, were made-up special specimens of PDMS (Sylgard® 184) for test them in bi-axial tensile machine. During the tensile test was used a commercial digital image correlation system (ARAMIS of GOM) to obtain de displacement and strain fields. These measurements are compared with numerical simulations which uses the more popular algorithms of constitutive models.

  15. A 'user friendly' geographic information system in a color interactive digital image processing system environment

    Campbell, W. J.; Goldberg, M.


    NASA's Eastern Regional Remote Sensing Applications Center (ERRSAC) has recognized the need to accommodate spatial analysis techniques in its remote sensing technology transfer program. A computerized Geographic Information System to incorporate remotely sensed data, specifically Landsat, with other relevant data was considered a realistic approach to address a given resource problem. Questions arose concerning the selection of a suitable available software system to demonstrate, train, and undertake demonstration projects with ERRSAC's user community. The very specific requirements for such a system are discussed. The solution found involved the addition of geographic information processing functions to the Interactive Digital Image Manipulation System (IDIMS). Details regarding the functions of the new integrated system are examined along with the characteristics of the software.

  16. Correlates of red throat coloration in female stickleback and their potential evolutionary significance

    Yong, Lengxob; Guo, Ruqing; Wright, Daniel S.; Mears, Samantha A.; Pierotti, Michele; McKinnon, Jeffrey S.

    Background: In two stream-resident populations of threespine stickleback (Gasterosteus aculeatus), females often exhibit male-typical red throat coloration. These fish inhabit the Little Campbell River (British Columbia) and Matadero Creek (California). An anadromous population that lacks such

  17. Relighting multiple color textures

    DIAO Chang-yu; LU Dong-ming; LIU Gang


    With the development of digital library technology, library books made of paper can be digital released and read, and Endangered Cultural Heritages can be preserved. Traditional library's contents and functions can be greatly enhanced by digital technologies. For these new library objects, the primary key problem is precisely reconstructing their 3D models. When constructing complete 3D models, multiple color texture maps are often necessary. A commonly encountered problem uncounted during fusing of textures from multiple color images is color distortion. Each texture of a single 3D model may be obtained under possibly different lighting conditions and color response of the camera. To remove any visible seam and improve color consistency between the textures while avoiding color distortion, we propose a new efficient algorithm to relight all the texture images globally,spread residual light difference, and recolor each image by homogeneous transformation. A relative illumination model was adopted to obtain the relighting function. We choose lαβ color space with minimal correlation between channels for many natural scenes, for calculating the relighting result. Looking into two overlapped images A and B, we can pairwise relight B into A's luminosity condition in two steps. We first scale B's l channel by the lA/lB ratio of the overlapped region. We can assume A and B are in a same color plane now. Then a homogeneous transformation is applied to B's α and β channels which moves B into A's hue and saturation condition. For multiple overlapped color textures, a patch based weighted global relighting method was proposed to minimize the total color difference. The pairwise relighting method was used between each two overlapped images, and the difference in every overlapped region after relighting was weighted and summed up to construct an energy value. We used Nelder-Mead method to find a minimal energy value and the relighting parameters for every image. After

  18. Color-magnitude distribution of face-on nearby galaxies in Sloan digital sky survey DR7

    Jin, Shuo-Wen; Feng, Long-Long [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Gu, Qiusheng; Huang, Song; Shi, Yong, E-mail: [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)


    We have analyzed the distributions in the color-magnitude diagram (CMD) of a large sample of face-on galaxies to minimize the effect of dust extinctions on galaxy color. About 300,000 galaxies with log (a/b) < 0.2 and redshift z < 0.2 are selected from the Sloan Digital Sky Survey DR7 catalog. Two methods are employed to investigate the distributions of galaxies in the CMD, including one-dimensional (1D) Gaussian fitting to the distributions in individual magnitude bins and two-dimensional (2D) Gaussian mixture model (GMM) fitting to galaxies as a whole. We find that in the 1D fitting, two Gaussians are not enough to fit galaxies with the excess present between the blue cloud and the red sequence. The fitting to this excess defines the center of the green valley in the local universe to be (u – r){sub 0.1} = –0.121M {sub r,} 0{sub .1} – 0.061. The fraction of blue cloud and red sequence galaxies turns over around M {sub r,} {sub 0.1} ∼ –20.1 mag, corresponding to stellar mass of 3 × 10{sup 10} M {sub ☉}. For the 2D GMM fitting, a total of four Gaussians are required, one for the blue cloud, one for the red sequence, and the additional two for the green valley. The fact that two Gaussians are needed to describe the distributions of galaxies in the green valley is consistent with some models that argue for two different evolutionary paths from the blue cloud to the red sequence.

  19. Ultraviolet Continuum Color Variability of Luminous Sloan Digital Sky Survey QSOs

    Sakata, Yu; Minezaki, Takeo; Yoshii, Yuzuru; Kobayashi, Yukiyasu; Koshida, Shintaro; Sameshima, Hiroaki


    We examine whether the spectral energy distribution of UV continuum emission of active galactic nuclei changes during flux variation. We used multi-epoch photometric data of QSOs in the Stripe 82 observed by the SDSS Legacy Survey and selected 10 bright QSOs observed with high photometric accuracies, in the redshift range of z = 1.0-2.4 where strong broad emission lines such as Ly\\alpha and CIV do not contaminate SDSS filters, to examine spectral variation of the UV continuum emission with broadband photometries. All target QSOs showed clear flux variations during the monitoring period 1998-2007, and the multi-epoch flux data in two different bands obtained on the same night showed a linear flux-to-flux relationship for all target QSOs. Assigning the flux in the longer wavelength to the x-axis in the flux-to-flux diagram, the x-intercept of the best-fit linear regression line was positive for most targets, which means that their colors in the observing bands become bluer as they become brighter. Then, the hos...

  20. Combining digital watermarking and fingerprinting techniques to identify copyrights for color images.

    Hsieh, Shang-Lin; Chen, Chun-Che; Shen, Wen-Shan


    This paper presents a copyright identification scheme for color images that takes advantage of the complementary nature of watermarking and fingerprinting. It utilizes an authentication logo and the extracted features of the host image to generate a fingerprint, which is then stored in a database and also embedded in the host image to produce a watermarked image. When a dispute over the copyright of a suspect image occurs, the image is first processed by watermarking. If the watermark can be retrieved from the suspect image, the copyright can then be confirmed; otherwise, the watermark then serves as the fingerprint and is processed by fingerprinting. If a match in the fingerprint database is found, then the suspect image will be considered a duplicated one. Because the proposed scheme utilizes both watermarking and fingerprinting, it is more robust than those that only adopt watermarking, and it can also obtain the preliminary result more quickly than those that only utilize fingerprinting. The experimental results show that when the watermarked image suffers slight attacks, watermarking alone is enough to identify the copyright. The results also show that when the watermarked image suffers heavy attacks that render watermarking incompetent, fingerprinting can successfully identify the copyright, hence demonstrating the effectiveness of the proposed scheme.

  1. Combining Digital Watermarking and Fingerprinting Techniques to Identify Copyrights for Color Images

    Shang-Lin Hsieh


    Full Text Available This paper presents a copyright identification scheme for color images that takes advantage of the complementary nature of watermarking and fingerprinting. It utilizes an authentication logo and the extracted features of the host image to generate a fingerprint, which is then stored in a database and also embedded in the host image to produce a watermarked image. When a dispute over the copyright of a suspect image occurs, the image is first processed by watermarking. If the watermark can be retrieved from the suspect image, the copyright can then be confirmed; otherwise, the watermark then serves as the fingerprint and is processed by fingerprinting. If a match in the fingerprint database is found, then the suspect image will be considered a duplicated one. Because the proposed scheme utilizes both watermarking and fingerprinting, it is more robust than those that only adopt watermarking, and it can also obtain the preliminary result more quickly than those that only utilize fingerprinting. The experimental results show that when the watermarked image suffers slight attacks, watermarking alone is enough to identify the copyright. The results also show that when the watermarked image suffers heavy attacks that render watermarking incompetent, fingerprinting can successfully identify the copyright, hence demonstrating the effectiveness of the proposed scheme.

  2. Variable Correlation Digital Noise Source on FPGA — A Versatile Tool for Debugging Radio Telescope Backends

    Buch, Kaushal D.; Gupta, Yashwant; Ajith Kumar, B.

    Contemporary wideband radio telescope backends are generally developed on Field Programmable Gate Arrays (FPGA) or hybrid (FPGA+GPU) platforms. One of the challenges faced while developing such instruments is the functional verification of the signal processing backend at various stages of development. In the case of an interferometer or pulsar backend, the typical requirement is for one independent noise source per input, with provision for a common, correlated signal component across all the inputs, with controllable level of correlation. This paper describes the design of a FPGA-based variable correlation Digital Noise Source (DNS), and its applications to built-in testing and debugging of correlators and beamformers. This DNS uses the Central Limit Theorem-based approach for generation of Gaussian noise, and the architecture is optimized for resource requirements and ease of integration with existing signal processing blocks on FPGA.

  3. Museum lighting for golden artifacts, with low correlated color temperature, high color uniformity and high color rendering index, using diffusing color mixing of red, cyan, and white-light-emitting diodes

    Thorseth, Anders; Corell, Dennis Dan; Poulsen, Peter Behrensdorff


    at the Royal Danish Collection at Rosenborg Castle. Color mixing of red, cyan, and white LEDs was employed to achieve the spectral power distribution needed for the required CCT and a CRI above 90. Color uniformity is achieved by the use of a highly diffusing reflector. The system has shown energy saving above......Museum lighting presents challenges mainly due to the demand for precise color rendering and the damaging effects of radiation. Golden objects must normally be illuminated by the non-standard CCT of 2200 K. An LED system that conforms to these requirements has been developed and implemented...

  4. Correlation of a quantitative videocapillaroscopic score with the development of digital skin ulcers in scleroderma patients

    A. Antonelli


    Full Text Available Background: Systemic sclerosis (SSc is an autoimmune disease characterized by fibrosis of the skin and visceral organs. The microangiopathy is early detectable in the course of the disease by nailfold videocapillaroscopy (NVC, a non-invasive technique with a high diagnostic value. Objective: Aim of our study was to evaluate the feasibility of a quantitative score and its correlation with the digital skin ulcers, which frequently complicate SSc microangiopathy. Methods: We retrospectively analysed the NVC of 65 SSc patients, performed by 200x videocapillaroscopy connected to image analyse software (Videocap; DS MediGroup, Milan, Italy. The analysis of NVC images included: total number of capillaries in the distal row (N, maximum diameter (D and number of giant capillaries (M, M/N ratio and percentage of M, presence/absence of micro-haemorrhages and tortuosity. Results: 21/65 SSc patients experienced digital ulcers within three months after the NVC examination. The N, D, M/N, and percentage of M significantly correlated with the appearance of ischemic ulcers. A multiple regression analysis showed a statistically significant correlation for N, M/N and D, while sensitivity and specificity of these parameters were unsatisfactory. A capillaroscopic score, according to the formula D·M/N2, showed a high specificity and sensibility (93.2% and 85.7% respectively; area under ROC curve: 0.918 to predict the appearance of digital ulcers. Conclusions: This capillaroscopic score may represent a feasible and simple tool in SSc patients’ assessment. The routinely use of this parameter might permit to recognize and to preventively treat SSc patients at high risk to develop digital ulcers.

  5. Color Reproduction with a Smartphone

    Thoms, Lars-Jochen; Colicchia, Giuseppe; Girwidz, Raimund


    The world is full of colors. Most of the colors we see around us can be created on common digital displays simply by superposing light with three different wavelengths. However, no mixture of colors can produce a fully pure color identical to a spectral color. Using a smartphone, students can investigate the main features of primary color addition…

  6. Color Reproduction with a Smartphone

    Thoms, Lars-Jochen; Colicchia, Giuseppe; Girwidz, Raimund


    The world is full of colors. Most of the colors we see around us can be created on common digital displays simply by superposing light with three different wavelengths. However, no mixture of colors can produce a fully pure color identical to a spectral color. Using a smartphone, students can investigate the main features of primary color addition…

  7. Experimental study on strain distribution of ionic polymer-metal composite actuator using digital image correlation

    Liu, Hongguang; Xiong, Ke; Wang, Man; Bian, Kan; Zhu, Kongjun


    Ionic polymer-metal composite (IPMC) cantilever actuators demonstrate significant bending deformation upon application of excitation voltage across the electrodes. In this paper a cantilever beam shaped IPMC actuator with platinum (Pt) electrodes is fabricated to investigate the micro-scale lateral deformation behavior under DC voltages using a digital microscope to measure the deformation. The digital image correlation (DIC) method is utilized to analyze the displacement and strain fields of the sample. The experimental results indicate that the longitudinal normal strain is linearly distributed along the thickness direction and the strain gradient is approximately exponential with excitation voltage. The amplitude of the transverse strain is bigger than the longitudinal strain, and the strains are also found to decrease along the length direction of the IPMC cantilever actuator. The longitudinal and transverse normal strains of the IPMC actuator under DC voltages are compressive strains due to water loss effect in the air.

  8. Digital image correlation involves an inverse problem: A regularization scheme based on subset size constraint

    Zhan, Qin; Yuan, Yuan; Fan, Xiangtao; Huang, Jianyong; Xiong, Chunyang; Yuan, Fan


    Digital image correlation (DIC) is essentially implicated in a class of inverse problem. Here, a regularization scheme is developed for the subset-based DIC technique to effectively inhibit potential ill-posedness that likely arises in actual deformation calculations and hence enhance numerical stability, accuracy and precision of correlation measurement. With the aid of a parameterized two-dimensional Butterworth window, a regularized subpixel registration strategy is established, in which the amount of speckle information introduced to correlation calculations may be weighted through equivalent subset size constraint. The optimal regularization parameter associated with each individual sampling point is determined in a self-adaptive way by numerically investigating the curve of 2-norm condition number of coefficient matrix versus the corresponding equivalent subset size, based on which the regularized solution can eventually be obtained. Numerical results deriving from both synthetic speckle images and actual experimental images demonstrate the feasibility and effectiveness of the set of newly-proposed regularized DIC algorithms.

  9. The feasibility and application of gray scale adjustment method in high temperature digital image correlation

    Wang, Shen; Yao, Xue Feng; Su, Yun Quan; Liu, Wei


    In this paper, the basic principle and application of linear gray scale adjustment method are investigated in high temperature digital image correlation (DIC) technology. First, the simple linear gray scale adjustment method is proposed, which can adjust the gray scale value of the saturated pixels and diminish the correlation error caused by the saturated pixels. Then, both the simulated high temperature images and DIC correlation results before and after the gray scale adjustment are provided and analyzed to verify its effectiveness, in which the displacement error decreased from 0.1 pixels to 0.04 pixels after the linear gray scale adjustment for high temperature images. Finally, the linear gray scale adjustment method is used to extract the displacement with high accuracy in high temperature experiment of SiC specimen, and the displacement error decreased from 0.5 pixels to 0.1 pixels after the linear gray scale adjustment.

  10. Estimating the purebred-crossbred genetic correlation for uniformity of eggshell color in laying hens

    Mulder, Herman; Visscher, Jeroen; Fablet, Julien


    Background: Uniformity of eggs is an important aspect for retailers because consumers prefer homogeneous products. One of these characteristics is the color of the eggshell, especially for brown eggs. Existence of a genetic component in environmental variance would enable selection for uniformity

  11. High-Resolution Digital Two-Color PIV for Turbomachinery Flows

    Copenhaver, W.; Gogineni, S.; Goss, L.


    Turbomachinery flows are inherently unsteady. However, steady design methods are currently used to develop turbomachinery, with the lack of basic understanding of unsteady effects being compensated by use of extensive empirical correlations. Conventional laser anemometry provides quantitative evidence of unsteady effects in turbomachinery but is limited in fully exploring this phenomenon. The PIV technique holds great promise for elucidating unsteady flow mechanisms in turbomachinery if obstacles to its application in a transonic turbomachine can be overcome. Implementation involves critical issues such as tracer seeding and optical access for transmitter and receiver. Initially, an 18-in.-dia. axial fan is used to explore these issues. One optical configuration considered is the fiber-optic fanning light sheet in conjunction with high-power pulsed lasers. Instantaneous velocity measurements are made between blades at different spanwise locations.


    ZHANG Jue; XIONG Chunyang; LI Hongju; LI Ming; WANG Jianxiang; FANG Jing


    This paper presents the applications of digital image correlation technique to the mesoscopic damage and fracture study of some granular based composite materials including steelfiber reinforced concrete, sandstone and crystal-polymer composite. The deformation fields of the composite materials resulted from stress localization were obtained by the correlation computation of the surface images with loading steps and thus the related damage prediction and fracture parameters were evaluated. The correlation searching could be performed either directly based on the gray levels of the digital images or from the wavelet transform (WT) coefficients of the transform spectrum. The latter was developed by the authors and showed higher resolution and sensitivity to the singularity detection.Because the displacement components came from the rough surfaces of the composite materials without any coats of gratings or fringes of optical interferometry, both surface profiles and the deformation fields of the composites were visualized which was helpful to compare each other to analyze the damage of those heterogeneous materials.

  13. Determination of Vertical Interproximal Bone Loss Topography: Correlation Between Indirect Digital Radiographic Measurement and Clinical Measurement

    Farzad Esmaeli


    Full Text Available Background: Diagnosis and accuracy in determining the exact location, extent and configurationof bony defects of the jaw are of utmost importance to determine prognosis,treatment planning and long-term preservation of teeth. If relatively accurate diagnosiscan be established by radiography, proper treatment planning prior to treatment procedureswill be possible.Objectives: The aim of the present study was to assess the correlation between indirectdigital radiographic measurements and clinical measurements in determining the topographyof interproximal bony defects.Patients and Methods: Twenty interproximal bony defects, preferably in the mandibularand maxillary 5↔5 area were selected and radiographed using the parallel periapical technique.The radiographs were corrected and digitized on a computer using “Linear Measurement”software; then the three parameters of the base of defect (BD, alveolar crest(AC and cementoenamel junction (CEJ were determined using a software. Subsequentto radiographic measurements, clinical measurements were carried out meticulouslyduring flap procedures. Then linear measurements were carried out using a periodontalprobe to determine the defect depth and its mesiodistal width. Then the amount of correlationbetween these two measurements was assessed by Pearson's correlation coefficient.Results: The correlation between clinical and radiographic measurements in defect depthdetermination, in the evaluation of defect angle and in determination of defect widthwere 88%, 98% and 90%, respectively.Conclusions: Indirect digital radiographic technique can be used to diagnose intra-osseousdefects, providing a better opportunity to treat bony defects.

  14. Fast correlation technique for glacier flow monitoring by digital camera and space-borne SAR images

    Moreau Luc


    Full Text Available Abstract Most of the image processing techniques have been first proposed and developed on small size images and progressively applied to larger and larger data sets resulting from new sensors and application requirements. In geosciences, digital cameras and remote sensing images can be used to monitor glaciers and to measure their surface velocity by different techniques. However, the image size and the number of acquisitions to be processed to analyze time series become a critical issue to derive displacement fields by the conventional correlation technique. In this paper, a mathematical optimization of the classical normalized cross-correlation and its implementation are described to overcome the computation time and window size limitations. The proposed implementation is performed with a specific memory management to avoid most of the temporary result re-computations. The performances of the software resulting from this optimization are assessed by computing the correlation between optical images of a serac fall, and between Synthetic Aperture Radar (SAR images of Alpine glaciers. The optical images are acquired by a digital camera installed near the Argentière glacier (Chamonix, France and the SAR images are acquired by the high resolution TerraSAR-X satellite over the Mont-Blanc area. The results illustrate the potential of this implementation to derive dense displacement fields with a computational time compatible with the camera images acquired every 2 h and with the size of the TerraSAR-X scenes covering 30 × 50 km2.

  15. Use of a Digital Image Correlation Technique for Measuring the Material Properties of Beetle Wing

    Tailie Jin; Nam Seo Goo; Sung-Choong Woo; Hoon Cheol Park


    Beetle wings are very specialized flight organs consisting of the veins and membranes. Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally. In the present study, we have used a Digital lmage Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane. Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm). We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane. The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator. We used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a specimen. The thickness of the beetle wing varied at different points of the membrane. The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy; the elastic modulus in the chordwise direction is approximately 2.65 GPa, which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa. As a result, the digital image correlation-based ARAMIS system was suc-cessfully used to measure the elastic modulus of a beetle wing. In addition to membrane's elastic modulus, we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine. The result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.

  16. Digitization

    Finnemann, Niels Ole


    Processes of digitization have for years represented a major trend in the developments of modern society but have only recently been related to processes of mediatization. The purpose of this article is to look into the relation between the concepts of mediatization and digitization and to clarify...... what a concept of digital media might add to the understanding of processes of mediatization and what the concept of mediatization might add to the understanding of digital media. It is argued that digital media open an array of new trajectories in human communication, trajectories which were...... not anticipated in previous conceptualizations of media and mediatization. If digital media are to be included, the concept of mediatization has to be revised and new parameters are to be built into the concept of media. At the same time it is argued that the concept of mediatization still provides a variety...

  17. Research of aluminium alloy aerospace structure aperture measurement based on 3D digital speckle correlation method

    Bai, Lu; Wang, Hongbo; Zhou, Jiangfan; Yang, Rong; Zhang, Hui


    In this paper, the aperture change of the aluminium alloy aerospace structure under real load is researched. Static experiments are carried on which is simulated the load environment of flight course. Compared with the traditional methods, through experiments results, it's proved that 3D digital speckle correlation method has good adaptability and precision on testing aperture change, and it can satisfy measurement on non-contact,real-time 3D deformation or stress concentration. The test results of new method is compared with the traditional method.

  18. Pollution detection by digital correlation of multispectral, stero-image pairs.

    Krause, F. R.; Betz, H. T.; Lysobey, D. H.


    Remote detection of air pollution circulation patterns is proposed to eventually predict the accumulation of hazardous surface concentrations in time for preventive emission control operations. Earth observations from space platforms will contain information on the height, mean velocity and lateral mixing scales of inversion layers and pollution plumes. Although this information is often not visible on photographs, it could conceivably be retrieved through a digital cross-correlation of multispectral stereo image pairs. Laboratory and field test results are used to illustrate the detection of non-visual inversion layers, the reduction of dominant signal interference, and the spectroscopic identification of combustion products.

  19. Channel capacity and digital modulation schemes in correlated Weibull fading channels with nonidentical statistics

    Xiao Hailin; Nie Zaiping; Yang Shiwen


    The novel closed-form expressions for the average channel capacity of dual selection diversity is presented, as well as, the bit-error rate (BER) of several coherent and noncoherent digital modulation schemes in the correlated Weibull fading channels with nonidentical statistics.The results are expressed in terms of Meijer's Gfunction, which can be easily evaluated numerically.The simulation results are presented to validate the proposed theoretical analysis and to examine the effects of the fading severity on the concerned quantities.

  20. Strain and displacement controls by fibre bragg grating and digital image correlation

    Waldbjørn, Jacob Paamand; Høgh, Jacob Herold; Schmidt, Jacob Wittrup


    the test based on measurements performed directly on the test specimen. In this paper, fibre Bragg grating (FBG) and Digital Image Correlation (DIC) are used to control a test. The FBG sensors offer the possibility of measuring strains inside the specimen, while the DIC system measures strains...... and displacement on the surface of the specimen. In this paper, a three-point bending test is used to demonstrate the functionality of a control loop, where the FBG and DIC signals are used as control channels. The FBG strain control was capable of controlling the test within an error tolerance of 20 μm m-1...

  1. Measurement of Local Deformations in Steel Monostrands Using Digital Image Correlation

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.


    , difficulties with the placement of strain gauges in the vicinity of the anchorage, and, most importantly, the relatively small magnitude of deformation occurring in the monostrand. This paper focuses on the measurement of localized deformations in high-strength steel monostrands using the digital image...... correlation (DIC) technique. The presented technique enables the measurement of individual wire strains along the length of the monostrand and also provides quantitative information on the relative movement between individual wires, leading to a more in-depth understanding of the underlying fatigue mechanisms...

  2. High-speed 3D digital image correlation vibration measurement: Recent advancements and noted limitations

    Beberniss, Timothy J.; Ehrhardt, David A.


    A review of the extensive studies on the feasibility and practicality of utilizing high-speed 3 dimensional digital image correlation (3D-DIC) for various random vibration measurement applications is presented. Demonstrated capabilities include finite element model updating utilizing full-field 3D-DIC static displacements, modal survey natural frequencies, damping, and mode shape results from 3D-DIC are baselined against laser Doppler vibrometry (LDV), a comparison between foil strain gage and 3D-DIC strain, and finally the unique application to a high-speed wind tunnel fluid-structure interaction study. Results show good agreement between 3D-DIC and more traditional vibration measurement techniques. Unfortunately, 3D-DIC vibration measurement is not without its limitations, which are also identified and explored in this study. The out-of-plane sensitivity required for vibration measurement for 3D-DIC is orders of magnitude less than LDV making higher frequency displacements difficult to sense. Furthermore, the digital cameras used to capture the DIC images have no filter to eliminate temporal aliasing of the digitized signal. Ultimately DIC is demonstrated as a valid alternative means to measure structural vibrations while one unique application achieves success where more traditional methods would fail.

  3. a New Digital Image Correlation Software for Displacements Field Measurement in Structural Applications

    Ravanelli, R.; Nascetti, A.; Di Rita, M.; Belloni, V.; Mattei, D.; Nisticó, N.; Crespi, M.


    Recently, there has been a growing interest in studying non-contact techniques for strain and displacement measurement. Within photogrammetry, Digital Image Correlation (DIC) has received particular attention thanks to the recent advances in the field of lowcost, high resolution digital cameras, computer power and memory storage. DIC is indeed an optical technique able to measure full field displacements and strain by comparing digital images of the surface of a material sample at different stages of deformation and thus can play a major role in structural monitoring applications. For all these reasons, a free and open source 2D DIC software, named py2DIC, was developed at the Geodesy and Geomatics Division of DICEA, University of Rome La Sapienza. Completely written in python, the software is based on the template matching method and computes the displacement and strain fields. The potentialities of Py2DIC were evaluated by processing the images captured during a tensile test performed in the Lab of Structural Engineering, where three different Glass Fiber Reinforced Polymer samples were subjected to a controlled tension by means of a universal testing machine. The results, compared with the values independently measured by several strain gauges fixed on the samples, demonstrate the possibility to successfully characterize the deformation mechanism of the investigated material. Py2DIC is indeed able to highlight displacements at few microns level, in reasonable agreement with the reference, both in terms of displacements (again, at few microns in the average) and Poisson's module.

  4. Dithering Digital Ripple Correlation Control for Photovoltaic Maximum Power Point Tracking

    Barth, C; Pilawa-Podgurski, RCN


    This study demonstrates a new method for rapid and precise maximum power point tracking in photovoltaic (PV) applications using dithered PWM control. Constraints imposed by efficiency, cost, and component size limit the available PWM resolution of a power converter, and may in turn limit the MPP tracking efficiency of the PV system. In these scenarios, PWM dithering can be used to improve average PWM resolution. In this study, we present a control technique that uses ripple correlation control (RCC) on the dithering ripple, thereby achieving simultaneous fast tracking speed and high tracking accuracy. Moreover, the proposed method solves some of the practical challenges that have to date limited the effectiveness of RCC in solar PV applications. We present a theoretical derivation of the principles behind dithering digital ripple correlation control, as well as experimental results that show excellent tracking speed and accuracy with basic hardware requirements.

  5. Optical Measurement of In-plane Waves in Mechanical Metamaterials Through Digital Image Correlation

    Schaeffer, Marshall; Trainiti, Giuseppe; Ruzzene, Massimo


    We report on a Digital Image Correlation-based technique for the detection of in-plane elastic waves propagating in structural lattices. The experimental characterization of wave motion in lattice structures is currently of great interest due its relevance to the design of novel mechanical metamaterials with unique/unusual properties such as strongly directional behaviour, negative refractive indexes and topologically protected wave motion. Assessment of these functionalities often requires the detection of highly spatially resolved in-plane wavefields, which for reticulated or porous structural assemblies is an open challenge. A Digital Image Correlation approach is implemented that tracks small displacements of the lattice nodes by centring image subsets about the lattice intersections. A high speed camera records the motion of the points by properly interleaving subse- quent frames thus artificially enhancing the available sampling rate. This, along with an imaging stitching procedure, enables the capturing of a field of view that is sufficiently large for subsequent processing. The transient response is recorded in the form of the full wavefields, which are processed to unveil features of wave motion in a hexagonal lattice. Time snapshots and frequency contours in the spatial Fourier domain are compared with numerical predictions to illustrate the accuracy of the recorded wavefields.

  6. A methodology for use of digital image correlation for hot mix asphalt testing

    Ramos, Estefany

    Digital Image Correlation (DIC) is a relatively new technology which aids in the measurement of material properties without the need for installation of sensors. DIC is a noncontact measuring technique that requires the specimen to be marked with a random speckled pattern and to be photographed during the test. The photographs are then post-processed based on the location of the pattern throughout the test. DIC can aid in calculating properties that would otherwise be too difficult even with other measuring instruments. The objective of this thesis is to discuss the methodology and validate the use of DIC in different hot mix asphalt (HMA) tests, such as, the Overlay Tester (OT) Test, Indirect Tensile (IDT) Test, and the Semicircular Bending (SCB) Test. The DIC system provides displacements and strains in any visible surface. The properly calibrated 2-D or 3-D DIC data can be used to understand the complex stress and strain distributions and the modes of the initiation and propagation of cracks. The use of this observational method will lead to further understanding of the complex boundary conditions of the different test, and therefore, allowing it to be implemented in the analysis of other materials. The use of digital image correlation will bring insight and knowledge onto what is happening during a test.

  7. A Review of Surface Deformation and Strain Measurement Using Two-Dimensional Digital Image Correlation

    Khoo Sze-Wei


    Full Text Available Among the full-field optical measurement methods, the Digital Image Correlation (DIC is one of the techniques which has been given particular attention. Technically, the DIC technique refers to a non-contact strain measurement method that mathematically compares the grey intensity changes of the images captured at two different states: before and after deformation. The measurement can be performed by numerically calculating the displacement of speckles which are deposited on the top of object’s surface. In this paper, the Two-Dimensional Digital Image Correlation (2D-DIC is presented and its fundamental concepts are discussed. Next, the development of the 2D-DIC algorithms in the past 33 years is reviewed systematically. The improvement of 2DDIC algorithms is presented with respect to two distinct aspects: their computation efficiency and measurement accuracy. Furthermore, analysis of the 2D-DIC accuracy is included, followed by a review of the DIC applications for two-dimensional measurements.

  8. Trace gas detection and monitoring with the Digital Array Gas-correlation Radiometer (DAGR)

    Gordley, Larry L.; Hervig, Mark E.; Fish, Chad; McHugh, Martin J.


    We present the first results from a Digital Array Gas-correlation Radiometer (DAGR) prototype sensor, and discuss applications in remote sensing of trace gases. The sensor concept is based on traditional and reliable Gas Filter Correlation Radiometry (GFCR), but overcomes the limitations in solar backscatter applications. The DAGR sensor design can be scaled to the size of a digital camera and is ideal for downlooking detection of gases in the boundary layer, where solar backscatter measurements are needed to overcome the lack of thermal contrast in the IR. Ground-based portable DAGR sensors can monitor carbon sequestration sites or industrial facilities. Aircraft or UAV deployment can quickly survey large areas and are particularly well suited for gas leak detection or carbon monitoring. From space-based platforms, Doppler modulation can be exploited to produce an extremely fine spectral resolution with effective resolving power exceeding 100,000. Such space-based DAGR observations could provide near-global sensing of climatically important species such as such as CO2, CO, CH4, O3 and N2O. Planetary science applications include detection and mapping of biomarkers in the Martian atmosphere.

  9. Digital Image Correlation Techniques Applied to Large Scale Rocket Engine Testing

    Gradl, Paul R.


    Rocket engine hot-fire ground testing is necessary to understand component performance, reliability and engine system interactions during development. The J-2X upper stage engine completed a series of developmental hot-fire tests that derived performance of the engine and components, validated analytical models and provided the necessary data to identify where design changes, process improvements and technology development were needed. The J-2X development engines were heavily instrumented to provide the data necessary to support these activities which enabled the team to investigate any anomalies experienced during the test program. This paper describes the development of an optical digital image correlation technique to augment the data provided by traditional strain gauges which are prone to debonding at elevated temperatures and limited to localized measurements. The feasibility of this optical measurement system was demonstrated during full scale hot-fire testing of J-2X, during which a digital image correlation system, incorporating a pair of high speed cameras to measure three-dimensional, real-time displacements and strains was installed and operated under the extreme environments present on the test stand. The camera and facility setup, pre-test calibrations, data collection, hot-fire test data collection and post-test analysis and results are presented in this paper.

  10. An autonomous surface discontinuity detection and quantification method by digital image correlation and phase congruency

    Cinar, A. F.; Barhli, S. M.; Hollis, D.; Flansbjer, M.; Tomlinson, R. A.; Marrow, T. J.; Mostafavi, M.


    Digital image correlation has been routinely used to measure full-field displacements in many areas of solid mechanics, including fracture mechanics. Accurate segmentation of the crack path is needed to study its interaction with the microstructure and stress fields, and studies of crack behaviour, such as the effect of closure or residual stress in fatigue, require data on its opening displacement. Such information can be obtained from any digital image correlation analysis of cracked components, but it collection by manual methods is quite onerous, particularly for massive amounts of data. We introduce the novel application of Phase Congruency to detect and quantify cracks and their opening. Unlike other crack detection techniques, Phase Congruency does not rely on adjustable threshold values that require user interaction, and so allows large datasets to be treated autonomously. The accuracy of the Phase Congruency based algorithm in detecting cracks is evaluated and compared with conventional methods such as Heaviside function fitting. As Phase Congruency is a displacement-based method, it does not suffer from the noise intensification to which gradient-based methods (e.g. strain thresholding) are susceptible. Its application is demonstrated to experimental data for cracks in quasi-brittle (Granitic rock) and ductile (Aluminium alloy) materials.

  11. Optical Measurement of In-plane Waves in Mechanical Metamaterials Through Digital Image Correlation

    Schaeffer, Marshall; Trainiti, Giuseppe; Ruzzene, Massimo


    We report on a Digital Image Correlation-based technique for the detection of in-plane elastic waves propagating in structural lattices. The experimental characterization of wave motion in lattice structures is currently of great interest due its relevance to the design of novel mechanical metamaterials with unique/unusual properties such as strongly directional behaviour, negative refractive indexes and topologically protected wave motion. Assessment of these functionalities often requires the detection of highly spatially resolved in-plane wavefields, which for reticulated or porous structural assemblies is an open challenge. A Digital Image Correlation approach is implemented that tracks small displacements of the lattice nodes by centring image subsets about the lattice intersections. A high speed camera records the motion of the points by properly interleaving subse- quent frames thus artificially enhancing the available sampling rate. This, along with an imaging stitching procedure, enables the capturing of a field of view that is sufficiently large for subsequent processing. The transient response is recorded in the form of the full wavefields, which are processed to unveil features of wave motion in a hexagonal lattice. Time snapshots and frequency contours in the spatial Fourier domain are compared with numerical predictions to illustrate the accuracy of the recorded wavefields. PMID:28205589

  12. Development of digital image correlation method to analyse crack variations of masonry wall

    Shih-Heng Tung; Ming-Hsiang Shih; Wen-Pei Sung


    The detection of crack development in a masonry wall forms an important study for investigating the earthquake resistance capability of the masonry structures. Traditionally, inspecting the structure and documenting the findings were done manually. The procedures are time-consuming, and the results are sometimes inaccurate. Therefore, the digital image correlation (DIC) technique is developed to identify the strain and crack variations. This technique is non-destructive for inspecting the whole displacement and strain field. Tests on two masonry wall samples were performed to verify the performance of the digital image correlation method. The phenomena of micro cracks, strain concentration situation and nonuniform deformation distribution which could not have been observed preciously by manual inspection are successfully identified using DIC. The crack formation tendencies on masonry wall can be observed at an earlier stage by this proposed method. These results show a great application potential of the DIC technique for various situations such as inspecting shrinkage-induced cracks in fresh concrete, masonry and reinforced concrete structures, and safety of bridges.

  13. Full-field Measurement of Deformation and Vibration using Digital Image Correlation

    Liang-Chih Chen


    Full Text Available The main intention of this study was to investigate the full-field measurement of de-formation and vibration using a program we developed for digital image correlation. Digital image correlation is a measuring method that can calculate the displacement of each point on an object by using recorded images. By capturing continuous images of the object in deformation or in motion, the displacements of feature points on the object can be tracked and used in calculations to determine the full-field deformation, strain and vibration of the object. We used the fast and simple algorithm in our program as the core, and conducted non-contact full-field displacement measurement by tracking feature points from images taken after motion. The measuring accuracy can be up to 0.1 pixel. Our experimental results show the technique to be very accurate and useful. We also applied this technique under conditions where an ordinary sensor could not be used.

  14. HI Selected Galaxies in the Sloan Digital Sky Survey II: The Colors of Gas-Rich Galaxies

    West, Andrew A; Dalcanton, Julianne J; Disney, Mike J; Rockosi, Constance R; Ivezic, Zeljko


    We utilize color information for an HI-selected sample of 195 galaxies to explore the star formation histories and physical conditions that produce the observed colors. We show that the HI selection creates a significant offset towards bluer colors that can be explained by enhanced recent bursts of star formation. There is also no obvious color bimodality, because the HI selection restricts the sample to bluer, actively star forming systems, diminishing the importance of the red sequence. Rising star formation rates are still required to explain the colors of galaxies bluer than g-r < 0.3. We also demonstrate that the colors of the bluest galaxies in our sample are dominated by emission lines and that stellar population synthesis models alone (without emission lines) are not adequate for reproducing many of the galaxy colors. These emission lines produce large changes in the r-i colors but leave the g-r color largely unchanged. In addition, we find an increase in the dispersion of galaxy colors at low mass...

  15. Color-dye injection of monochorionic placentas and correlation with pregnancy complications.

    Lanna, Mariano Matteo; Consonni, Dario; Faiola, Stefano; Schena, Vito; Ratti, Martina; Ferrazzi, Enrico; Rustico, Maria Angela


    Vascular anastomoses in monochorionic (MC) twin placenta can be easily identified with color-dye injection. The aim of this study is to analyze the relationship between different type of anastomoses and twin pregnancy complications. From January 2011 to October 2014, MC placentas were analyzed with color-dye injection and five group of pregnancies were identified: those that were not complicated (NC), those complicated with selective intrauterine growth restriction (sIUGR), twin-twin transfusion syndrome (TTTS), or twin anemia-polycitemia sequence (TAPS) and those with amniotic fluid discordance (AFD) between twins. Cases of TTTS treated with endoscopic laser coagulation of placenta anastomoses or cases with in utero death of one twin were excluded. A total of 118 MC placentas were observed, 58 (49%) NC, 35 (30%) sIUGR, 10 (8%) TTTS, 13 (11%) AFD and 2 (2%) TAPS. The median number of anastomoses was 7 (range 1-15), 8 (2-18), 4 (2-11), 7 (2-13) and 1 (1-1), respectively. At least one artero-venous anastomoses was found in the placenta observed, while the prevalence of artero-arterial anastomoses was 95% for NC, 91% for sIUGR, 60% for TTTS, and 77% for AFD; no TAPS placenta had this type of anastomoses. The diameter of arteroarterial anastomoses was greater in the AFD group (3.3 mm), compared to the NC, sIUGR and TTTS groups (2.3, 2.5 and 1.4 respectively, p 0.04). In this large serie of MC placenta analyzed with color-dye injection, a specific distribution of anastomoses emerged for twins with amniotic fluid discordance, which points to a need for intensive surveillance. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Color Doppler ultrasound evaluation of asphyxial neonatal left ventricular function and its correlation with target organ damage

    Cheng-Cai Chen; Li-Zhen Li; Qi-Sheng Lu; Yan-Ling Lang


    Objective:To study the color Doppler ultrasound parameters of asphyxial neonatal left ventricular function and the correlation with target organ damage.Methods: Normal neonates, mildly asphyxial neonates and severely asphyxial neonates born in our hospital between January 2014 and December 2015 were selected as the control group (n = 46), mild asphyxia group (n= 37) and severe asphyxia group (n = 23) respectively. On the 1st day after birth, color Doppler ultrasound was used to evaluate left ventricular function, and serum was collected to determine myocardial tissue injury, brain tissue injury and brain tissue metabolism indexes. Results: Color Doppler ultrasound parameters cardiac output (CO), ejection fraction (EF) and left ventricular fraction shortening (FS) as well as serum folate and vitamin B12 content of mild asphyxia group and severe asphyxia group were significantly lower than those of control group (P<0.05) while serum creatine kinase isoenzyme (CK-MB), troponin I (cTnI), troponin T (cTnT), S100B, neuron-specific enolase (NSE), creatine kinase BB (CK-BB), glycogen phosphorylase BB (GPBB), and homocysteine (Hcy) content were significantly higher than those of control group (P<0.05); CO, FS and EF as well as serum folate and vitamin B12 content of severe asphyxia group were significantly lower than those of mild asphyxia group (P<0.05) while serum CK-MB, cTnT, cTnI, S100B, NSE, CK-BB, GPBB and Hcy content were significantly higher than those of mild asphyxia group (P<0.05).Conclusions:Color Doppler ultrasound can accurately assess asphyxial neonatal left ventricular function damage degree and is closely related to myocardial tissue injury and brain tissue injury degree.

  17. Method and apparatus for a single channel digital communications system. [synchronization of received PCM signal by digital correlation with reference signal

    Couvillon, L. A., Jr.; Carl, C.; Goldstein, R. M.; Posner, E. C.; Green, R. R. (Inventor)


    A method and apparatus are described for synchronizing a received PCM communications signal without requiring a separate synchronizing channel. The technique provides digital correlation of the received signal with a reference signal, first with its unmodulated subcarrier and then with a bit sync code modulated subcarrier, where the code sequence length is equal in duration to each data bit.

  18. Effects of detector blur and correlated noise on digital breast tomosynthesis reconstruction

    Zheng, Jiabei; Fessler, Jeffrey A.; Chan, Heang-Ping


    To improve digital breast tomosynthesis (DBT) image quality, we are developing model-based iterative reconstruction methods. We developed the SQS-DBCN algorithm, which incorporated detector blur into the system model and correlation into the noise model under some simplifying assumptions. In this paper, we further improved the regularization in the SQS-DBCN method by incorporating neighbors along the diagonal directions. To further understand the role of the different components in the system model of the SQS-DBCN method, we reconstructed DBT images without modeling either the detector blur or noise correlation for comparison. Visual comparison of the reconstructed images showed that regularizing with diagonal directions reduced artifacts and the noise level. The SQS-DBCN reconstructed images had better image quality than reconstructions without models for detector blur or correlated noise, as indicated by the contrast-to-noise ratios (CNR) of MCs and textural artifacts. These results indicated that regularized DBT reconstruction with detector blur and correlated noise modeling, even with simplifying assumptions, can improve DBT image quality compared to that without system modeling.

  19. Correlating Formal Semantic Models of Reo Connectors: Connector Coloring and Constraint Automata

    Sung-Shik T.Q. Jongmans


    Full Text Available Over the past decades, coordination languages have emerged for the specification and implementation of interaction protocols for communicating software components. This class of languages includes Reo, a platform for compositional construction of connectors. In recent years, various formalisms for describing the behavior of Reo connectors have come to existence, each of them serving its own purpose. Naturally, questions about how these models relate to each other arise. From a theoretical point of view, answers to these questions provide us with better insight into the fundamentals of Reo, while from a more practical perspective, these answers broaden the applicability of Reo's development tools. In this paper, we address one of these questions: we investigate the equivalence between coloring models and constraint automata, the two most dominant and practically relevant semantic models of Reo. More specifically, we define operators that transform one model to the other (and vice versa, prove their correctness, and show that they distribute over composition. To ensure that the transformation operators map one-to-one (instead of many-to-one, we extend coloring models with data constraints. Though primarily a theoretical contribution, we sketch some potential applications of our results: the broadening of the applicability of existing tools for connector verification and animation.

  20. Color Doppler Ultrasound Study of Glomuvenous Malformations with its Clinical and Histologic Correlations.

    Wortsman, X; Millard, F; Aranibar, L


    Glomuvenous malformations are hamartomatous lesions characterized by the presence of glomus cells in the vascular smooth muscle. We present the clinical and color Doppler ultrasound features of a series of 13 cases of histologically confirmed glomuvenous malformations. In all cases, the ultrasound study revealed moderately delimited superficial dermal and hypodermal pseudonodular structures of mixed echogenicity, with hypoechoic and heterogeneous areas and anechoic, pseudocystic tubular and lacunar zones. Arterial and venous vessels, mainly with a low flow (≤ 15cm/s) were observed in 85% of patients, but no arteriovenous shunts were present. Deeper structures were not affected and no phleboliths were detected. The clinical and ultrasound findings could facilitate diagnosis, surgical planning, and noninvasive follow-up in these tumors. Copyright © 2017 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.

  1. Calibration of stereo-digital image correlation for deformation measurement of large engineering components

    Shao, Xinxing; Dai, Xiangjun; Chen, Zhenning; Dai, Yuntong; Dong, Shuai; He, Xiaoyuan


    The development of stereo-digital image correlation (stereo-DIC) enables the application of vision-based technique that uses digital cameras to the deformation measurement of materials and structures. Compared with traditional contact measurements, the stereo-DIC technique allows for non-contact measurement, has a non-intrusive characteristic, and can obtain full-field deformation information. In this paper, a speckle-based calibration method is developed to calibrate the stereo-DIC system when the system is applied for deformation measurement of large engineering components. By combining speckle analysis with the classical relative orientation algorithm, relative rotation and translation between cameras can be calibrated based on analysis of experimental speckle images. For validation, the strain fields of a four-point bending beam and an axially loaded concrete column were determined by the proposed calibration method and stereovision measurement. As a practical application, the proposed calibration method was applied for strain measurement of a ductile iron cylindrical vessel in the drop test. The measured results verify that the proposed calibration method is effective for deformation measurement of large engineering components.

  2. Investigation of Correlation of Test Sequences for Reliability Testing of Digital Physical System Components

    Kushik, N. G.; López, J. E.; Yevtushenko, N. V.


    The topical problem of effective verification of digital circuits of different physical systems remains a hot topic. Devices ranging from embedded components to perform specific tasks or experiments to modern communication clusters used for data transmission are concerned. The method of synthesis of the test sequences is based on injection of faults into a reference circuit and deriving a corresponding distinguishing sequence which detects this fault. The method is known as mutation testing and is widely used for the synthesis of high-quality verification tests for digital circuits. Naturally, test suits that detect faults of various classes, and larger amount of faults, are of greater interest. The paper studies the correlation between different test suits derived for different mutant types. The considered fault types include 1) single stuck-at faults, 2) bridges, and 3) hardly detectable faults, i.e., slightly modifying the behavior of a single circuit gate. Tests for detecting faults of each type are derived for the B01-B10 benchmark package (ITC'99 benchmarks (Second Release)), which are components of physical systems intended for various applications including processing of data obtained, load balancing systems, etc. Experiments aim to access the fault coverage of the test derived for one mutant type against faults of other types. It is shown experimentally that the synthesis of tests of one type, including a single stuck-at fault test, is insufficient, because its fault coverage for faults of other types cannot exceed 60%.

  3. In-plane displacement and strain measurements using a camera phone and digital image correlation

    Yu, Liping; Pan, Bing


    In-plane displacement and strain measurements of planar objects by processing the digital images captured by a camera phone using digital image correlation (DIC) are performed in this paper. As a convenient communication tool for everyday use, the principal advantages of a camera phone are its low cost, easy accessibility, and compactness. However, when used as a two-dimensional DIC system for mechanical metrology, the assumed imaging model of a camera phone may be slightly altered during the measurement process due to camera misalignment, imperfect loading, sample deformation, and temperature variations of the camera phone, which can produce appreciable errors in the measured displacements. In order to obtain accurate DIC measurements using a camera phone, the virtual displacements caused by these issues are first identified using an unstrained compensating specimen and then corrected by means of a parametric model. The proposed technique is first verified using in-plane translation and out-of-plane translation tests. Then, it is validated through a determination of the tensile strains and elastic properties of an aluminum specimen. Results of the present study show that accurate DIC measurements can be conducted using a common camera phone provided that an adequate correction is employed.

  4. Digital Image Correlation of Concrete Slab at University of Tennessee, Knoxville

    Mahadevan, Sankaran [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pham, Binh T. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kyle, Neal [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Some degradation mechanisms of concrete manifest themselves via swelling or by other shape deformation of the concrete. Specifically, degradation of concrete structure damaged by ASR is viewed as one of the dominant factors impacting the structural integrity of aging nuclear power plants. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. Number of nondestructive examination techniques (i.e., thermography, digital image correlation, mechanical deformation measurements, nonlinear impact resonance (DIC) acoustic spectroscopy, and vibro-acoustic modulation) is used to detect the damage caused by ASR. DIC techniques have been increasing in popularity, especially in micro- and nano-scale mechanical testing applications due to its relative ease of implementation and use. Advances in computer technology and digital cameras help this method moving forward. To ensure the best outcome of the DIC system, important factors in the experiment are identified. They include standoff distance, speckle size, speckle pattern, and durable paint. These optimal experimental options are selected basing on a thorough investigation. The resulting DIC deformation map indicates that this technique can be used to generate data related to degradation assessment of concrete structure damaged by the impact of ASR.

  5. Application of digital image correlation method for analysing crack variation of reinforced concrete beams

    Ming-Hsiang Shih; Wen-Pei Sung


    The Digital Image Correlation (DIC) method is a fast-growing emerging technology that provides a low-cost method for measuring the strain of an object. In this study, the feasibility of using this method to observe cracks developed in reinforced concrete beams will be explored so that a practical application can be proposed. The DIC method has been applied for analysing the field of surface displacement and strain; it is not applicable for measuring non-continuous field of displacement. However, if a singular point (i.e., crack points) can be considered as the area of concentrated strain by imitating the treatment of micro-cracks using the finite element method, the region of concentrated strain field based on analyses of digital images can be applied for determining the locations of cracks. Laboratory results show that cracks developed in reinforced cement beams can be observed with a good precision using the von Mises strain field, and that smaller grids lead to clearer crack images. In addition to identifying visible cracks, the DIC image analysis will enable researchers to identify minute cracks that are not visible to naked eyes. Additionally, the DIC method has more accuracy and precision than visual observation for analysing crack loadings so that earlier warnings can be realized before cracks develop in the specimen.

  6. Categorical and continuous - disentangling the neural correlates of the carry effect in multi-digit addition

    Dressel Katharina


    Full Text Available Abstract Background Recently it was suggested that the carry effect observed in addition involves both categorical and continuous processing characteristics. Methods In the present study, we aimed at identifying the specific neural correlates associated with processing either categorical or continuous aspects of the carry effect in an fMRI study on multi-digit addition. Results In line with our expectations, we observed two distinct parts of the fronto-parietal network subserving numerical cognition to be associated with either one of these two characteristics. On the one hand, the categorical aspect of the carry effect was associated with left-hemispheric language areas and the basal ganglia probably reflecting increased demands on procedural and problem solving processes. Complementarily, the continuous aspect of the carry effect was associated with increased intraparietal activation indicating increasing demands on magnitude processing as well as place-value integration with increasing unit sum. Conclusions In summary, the findings suggest representations and processes underlying the carry effect in multi-digit addition to be more complex and interactive than assumed previously.

  7. Infrared thermography coupled with digital image correlation in studying plastic deformation on the mesoscale level

    Wang, Xiaogang; Witz, Jean-François; El Bartali, Ahmed; Jiang, Chao


    This paper focuses on a study of plastic deformation on the mesoscale level by infrared thermography coupled with digital image correlation. First, a novel technique for fully-coupled thermal and kinematic measurements was developed, and the common problem of spatial coupling in the multifield measurement was solved successfully using an image registration method. Then the developed technique was applied to investigate the plastic deformation of a pure aluminium oligocrystal specimen in a tensile test. The deformed specimen manifested high strains of type out-of-plane, which were found closely associated with the crystallographic structure. From a metrological point of view, the out-of-plane effect on the thermographic measurement was analyzed, and the pertinent radiometric artifacts were estimated. The source of errors was verified through a correlation analysis between the estimated artifacts and specimen surface profile. Moreover, the out-of-plane effect on the kinematic measurement was investigated, and the relevant errors were analyzed via the correlation residual. The analysis highlighted the role of the microstructure that played in the plastic deformation and showed that grain boundary was crucial in shaping the heterogeneous deformation patterns for aluminium oligocrystals.

  8. Automated initial guess in digital image correlation aided by Fourier-Mellin transform

    Pan, Bing; Wang, Yuejiao; Tian, Long


    The state-of-the-art digital image correlation (DIC) method using iterative spatial-domain cross correlation, e.g., the inverse-compositional Gauss-Newton algorithm, for full-field displacement mapping requires an initial guess of deformation, which should be sufficiently close to the true value to ensure a rapid and accurate convergence. Although various initial guess approaches have been proposed, automated, robust, and fast initial guess remains to be a challenging task, especially when large rotation occurs to the deformed images. An integrated scheme, which combines the Fourier-Mellin transform-based cross correlation (FMT-CC) for seed point initiation with a reliability-guided displacement tracking (RGDT) strategy for the remaining points, is proposed to provide accurate initial guess for DIC calculation, even in the presence of large rotations. By using FMT-CC algorithm, the initial guess of the seed point can be automatically and accurately determined between pairs of interrogation subsets with up to ±180 deg of rotation even in the presence of large translation. Then the initial guess of the rest of the calculation points can be accurately predicted by the robust RGDT scheme. The robustness and effectiveness of the present initial guess approach are verified by numerical simulation tests and real experiment.

  9. Digital Signal Processing using Stream High Performance Computing: A 512-input Broadband Correlator for Radio Astronomy

    Kocz, J; Barsdell, B R; Price, D; Bernardi, G; Bourke, S; Clark, M A; Craig, J; Dexter, M; Dowell, J; Eftekhari, T; Ellingson, S; Hallinan, G; Hartman, J; Jameson, A; MacMahon, D; Taylor, G; Schinzel, F; Werthimer, D


    A "large-N" correlator that makes use of Field Programmable Gate Arrays and Graphics Processing Units has been deployed as the digital signal processing system for the Long Wavelength Array station at Owens Valley Radio Observatory (LWA-OV), to enable the Large Aperture Experiment to Detect the Dark Ages (LEDA). The system samples a ~100MHz baseband and processes signals from 512 antennas (256 dual polarization) over a ~58MHz instantaneous sub-band, achieving 16.8Tops/s and 0.236 Tbit/s throughput in a 9kW envelope and single rack footprint. The output data rate is 260MB/s for 9 second time averaging of cross-power and 1 second averaging of total-power data. At deployment, the LWA-OV correlator was the largest in production in terms of N and is the third largest in terms of complex multiply accumulations, after the Very Large Array and Atacama Large Millimeter Array. The correlator's comparatively fast development time and low cost establish a practical foundation for the scalability of a modular, heterogeneo...

  10. Correlation and registration of ERTS multispectral imagery. [by a digital processing technique

    Bonrud, L. O.; Henrikson, P. J.


    Examples of automatic digital processing demonstrate the feasibility of registering one ERTS multispectral scanner (MSS) image with another obtained on a subsequent orbit, and automatic matching, correlation, and registration of MSS imagery with aerial photography (multisensor correlation) is demonstrated. Excellent correlation was obtained with patch sizes exceeding 16 pixels square. Qualities which lead to effective control point selection are distinctive features, good contrast, and constant feature characteristics. Results of the study indicate that more than 300 degrees of freedom are required to register two standard ERTS-1 MSS frames covering 100 by 100 nautical miles to an accuracy of 0.6 pixel mean radial displacement error. An automatic strip processing technique demonstrates 600 to 1200 degrees of freedom over a quater frame of ERTS imagery. Registration accuracies in the range of 0.3 pixel to 0.5 pixel mean radial error were confirmed by independent error analysis. Accuracies in the range of 0.5 pixel to 1.4 pixel mean radial error were demonstrated by semi-automatic registration over small geographic areas.

  11. Increasing accuracy and precision of digital image correlation through pattern optimization

    Bomarito, G. F.; Hochhalter, J. D.; Ruggles, T. J.; Cannon, A. H.


    The accuracy and precision of digital image correlation (DIC) is based on three primary components: image acquisition, image analysis, and the subject of the image. Focus on the third component, the image subject, has been relatively limited and primarily concerned with comparing pseudo-random surface patterns. In the current work, a strategy is proposed for the creation of optimal DIC patterns. In this strategy, a pattern quality metric is developed as a combination of quality metrics from the literature rather than optimization based on any single one of them. In this way, optimization produces a pattern which balances the benefits of multiple quality metrics. Specifically, sum of square of subset intensity gradients (SSSIG) was found to be the metric most strongly correlated to DIC accuracy and thus is the main component of the newly proposed pattern quality metric. A term related to the secondary auto-correlation peak height is also part of the proposed quality metric which effectively acts as a constraint upon SSSIG ensuring that a regular (e.g., checkerboard-type) pattern is not achieved. The combined pattern quality metric is used to generate a pattern that was on average 11.6% more accurate than a randomly generated pattern in a suite of numerical experiments. Furthermore, physical experiments were performed which confirm that there is indeed improvement of a similar magnitude in DIC measurements for the optimized pattern compared to a random pattern.

  12. Note: Dynamic strain field mapping with synchrotron X-ray digital image correlation

    Lu, L. [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China); The Peac Institute of Multiscale Sciences, Chengdu, Sichuan 610207 (China); Fan, D.; Luo, S. N., E-mail: [The Peac Institute of Multiscale Sciences, Chengdu, Sichuan 610207 (China); Bie, B. X. [The Peac Institute of Multiscale Sciences, Chengdu, Sichuan 610207 (China); School of Science, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Ran, X. X.; Qi, M. L., E-mail: [School of Science, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Parab, N.; Sun, J. Z.; Liao, H. J.; Hudspeth, M. C.; Claus, B. [School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907 (United States); Fezzaa, K.; Sun, T. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Chen, W. [School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907 (United States); School of Material Science Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Gong, X. L., E-mail: [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China)


    We present a dynamic strain field mapping method based on synchrotron X-ray digital image correlation (XDIC). Synchrotron X-ray sources are advantageous for imaging with exceptional spatial and temporal resolutions, and X-ray speckles can be produced either from surface roughness or internal inhomogeneities. Combining speckled X-ray imaging with DIC allows one to map strain fields with high resolutions. Based on experiments on void growth in Al and deformation of a granular material during Kolsky bar/gas gun loading at the Advanced Photon Source beamline 32ID, we demonstrate the feasibility of dynamic XDIC. XDIC is particularly useful for dynamic, in-volume, measurements on opaque materials under high strain-rate, large, deformation.

  13. Path (un)predictability of two interacting cracks in polycarbonate sheets using Digital Image Correlation

    Koivisto, J.; Dalbe, M.-J.; Alava, M. J.; Santucci, S.


    Crack propagation is tracked here with Digital Image Correlation analysis in the test case of two cracks propagating in opposite directions in polycarbonate, a material with high ductility and a large Fracture Process Zone (FPZ). Depending on the initial distances between the two crack tips, one may observe different complex crack paths with in particular a regime where the two cracks repel each other prior to being attracted. We show by strain field analysis how this can be understood according to the principle of local symmetry: the propagation is to the direction where the local shear - mode KII in fracture mechanics language - is zero. Thus the interactions exhibited by the cracks arise from symmetry, from the initial geometry, and from the material properties which induce the FPZ. This complexity makes any long-range prediction of the path(s) impossible.

  14. Digital image correlation used to analyze a brick under compression test

    Saldaña Heredia, Alonso; Márquez Aguilar, Pedro A.; Molina Ocampo, Arturo; Zamudio Lara, Álvaro


    In mechanics of materials it is important to know the stress-strain relation of each material in order to understand their behaviour under different loads. The brick is one of the most used materials in structural mechanics and they are always under loads. This work is implemented using one beam and the speckles created by its reflection. Strain field measurement with noninvasive techniques is needed in order to sense rubber-like materials. We present an experimental approach that describes the mechanical behavior of structural materials under compression tests, which are done in a universal testing machine. In this work we show an evaluation of the displacement field obtained by digital image correlation allowing us to evaluate the heterogeneous strain field evolution observed during these test.

  15. Application of Digital Image Correlation to Measurement of Packaging Material Mechanical Properties

    Jian-Wei Zhou


    Full Text Available Among various packaging materials, papers and polymer plastics are the most common due to their light weights, low costs, and other advantages. However, their mechanical properties are difficult to measure precisely because of their softness. To overcome the difficulty, a new measure instrument prototype is proposed based on an optical method known as the digital image correlation (DIC. Experiments are designed to apply the DIC to measure mechanical properties of flexible packaging materials, including the stress-strain relationship, the Poisson ratio, the coefficient of heat expansion, the creep deformation, and the top-pressure deformation of corrugated box. In addition, the low frequency vibration of package is simulated, and the vibration frequencies are measured by DIC. Results obtained in the experiments illustrate the advantages of the DIC over traditional methods: noncontact, no reinforced effect, high precision over entire area, wide measurement range, and good measurement stability.

  16. A posteriori compensation of the systematic error due to polynomial interpolation in digital image correlation

    Baldi, Antonio; Bertolino, Filippo


    It is well known that displacement components estimated using digital image correlation are affected by a systematic error due to the polynomial interpolation required by the numerical algorithm. The magnitude of bias depends on the characteristics of the speckle pattern (i.e., the frequency content of the image), on the fractional part of displacements and on the type of polynomial used for intensity interpolation. In literature, B-Spline polynomials are pointed out as being able to introduce the smaller errors, whereas bilinear and cubic interpolants generally give the worst results. However, the small bias of B-Spline polynomials is partially counterbalanced by a somewhat larger execution time. We will try to improve the accuracy of lower order polynomials by a posteriori correcting their results so as to obtain a faster and more accurate analysis.

  17. Deformation analysis of ferrite/pearlite banded structure under uniaxial tension using digital image correlation

    Zhang, Xiaochuan; Wang, Yong; Yang, Jia; Qiao, Zhixia; Ren, Chunhua; Chen, Cheng


    The ferrite/pearlite banded structure causes the anisotropic behavior of steel. In this paper, digital image correlation (DIC) was used to analyze the micro deformation of this microstructure under uniaxial tension. The reliability of DIC for this application was verified by a zero-deformation experiment. The results show that the performance of DIC can satisfy the requirements of the tensile deformation measurement. Then, two uniaxial tensile tests in different directions (longitudinal direction and transverse direction) were carried out and DIC was used to measure the micro deformation of the ferrite/pearlite banded structure. The measured results show that the ferrite bands undergo the main deformation in the transverse tension, which results in the relatively weaker tensile properties in the transverse direction than in the longitudinal direction. This work is useful to guide the modification of the bands morphology and extend the application scope of DIC.

  18. Path (un)predictability of two interacting cracks in polycarbonate sheets using Digital Image Correlation.

    Koivisto, J; Dalbe, M-J; Alava, M J; Santucci, S


    Crack propagation is tracked here with Digital Image Correlation analysis in the test case of two cracks propagating in opposite directions in polycarbonate, a material with high ductility and a large Fracture Process Zone (FPZ). Depending on the initial distances between the two crack tips, one may observe different complex crack paths with in particular a regime where the two cracks repel each other prior to being attracted. We show by strain field analysis how this can be understood according to the principle of local symmetry: the propagation is to the direction where the local shear - mode KII in fracture mechanics language - is zero. Thus the interactions exhibited by the cracks arise from symmetry, from the initial geometry, and from the material properties which induce the FPZ. This complexity makes any long-range prediction of the path(s) impossible.

  19. Experimental multiscale measurements for the mechanical identification of a cortical bone by digital image correlation.

    Nguyen, Manh-Tu; Allain, Jean-Marc; Gharbi, Hakim; Desceliers, Christophe; Soize, Christian


    The implementation of the experimental methodology by optical measurements of mechanical fields, the development of a test bench, the specimen preparation, the experimental measurements, and the digital image correlation (DIC) method, have already been the object of research in the context of biological materials. Nevertheless, in the framework of the experimental identification of a mesoscopic stochastic model of the random apparent elasticity field, measurements of one specimen is required at both the macroscopic scale and the mesoscopic scale under one single loading. The nature of the cortical bone induces some difficulties, as no single speckled pattern technique is available for simultaneously obtaining the displacement at the macroscopic scale and at the mesoscopic scale. In this paper, we present a multiscale experimental methodology based on (i) an experimental protocol for one specimen of a cortical bone, (ii) its measuring bench, (iii) optical field measurements by DIC method, (iv) the experimental results, and (v) the multiscale experimental identification by solving a statistical inverse problem.

  20. Automatic detection and classification of damage zone(s) for incorporating in digital image correlation technique

    Bhattacharjee, Sudipta; Deb, Debasis


    Digital image correlation (DIC) is a technique developed for monitoring surface deformation/displacement of an object under loading conditions. This method is further refined to make it capable of handling discontinuities on the surface of the sample. A damage zone is referred to a surface area fractured and opened in due course of loading. In this study, an algorithm is presented to automatically detect multiple damage zones in deformed image. The algorithm identifies the pixels located inside these zones and eliminate them from FEM-DIC processes. The proposed algorithm is successfully implemented on several damaged samples to estimate displacement fields of an object under loading conditions. This study shows that displacement fields represent the damage conditions reasonably well as compared to regular FEM-DIC technique without considering the damage zones.

  1. Pitch evaluation of gratings based on a digital image correlation technique

    Lu, Yancong; Jia, Wei; Wei, Chunlong; Yu, Junjie; Li, Shubin; Li, Yanyang; Li, Minkang; Qiu, Jucheng; Wang, Shaoqing; Zhou, Changhe


    The digital image correlation (DIC) technique used for metrological grating evaluation is presented in this paper. A CCD camera is used to acquire the grating image, and the DIC technique together with the peak-position detection method is used to evaluate the grating pitches. The theoretical analysis and simulations are performed to confirm that the performance of our technique is as accurate as the Fourier transform (FT) technique, and is capable of noise resistance. As an example, the uniformity of the grating fabricated in our laboratory is measured using this method. The experimental results show that this grating has a peak-to-valley uniformity of 48 nm during a long range of 35 mm, and our technique has a higher repeatability than the FT technique in our measurement strategy. This work should be of great significance for the evaluation of metrological grating for optical encoders.

  2. Impact of lens distortions on strain measurements obtained with 2D digital image correlation

    Lava, P.; Van Paepegem, W.; Coppieters, S.; De Baere, I.; Wang, Y.; Debruyne, D.


    The determination of strain fields based on displacements obtained via digital image correlation (DIC) at the micro-strain level (≤1000 μm/m) is still a cumbersome task. In particular when high-strain gradients are involved, e.g. in composite materials with multidirectional fibre reinforcement, uncertainties in the experimental setup and errors in the derivation of the displacement fields can substantially hamper the strain identification process. In this contribution, the aim is to investigate the impact of lens distortions on strain measurements. To this purpose, we first perform pure rigid body motion experiments, revealing the importance of precise correction of lens distortions. Next, a uni-axial tensile test on a textile composite with spatially varying high strain gradients is performed, resulting in very accurately determined strains along the fibers of the material.

  3. Shear strain determination of the polymer polydimethysiloxane (PMDS) using digital image correlation in different temperatures

    De Oliveira, G N [Pos-graduacao em Engenharia Mecanica, TEM/PGMEC, Universidade Federal Fluminense, Rua Passo da Patria, 156, Niteroi, R.J., Brazil, Cep.: 24.210-240 (Brazil); Nunes, L C S [Laboratorio de Mecanica Teorica e Aplicada, Departamento de Engenharia Mecanica, Universidade Federal Fluminense, Rua Passo da Patria, 156, Niteroi, R.J., Brazil, Cep.: 24.210-240 (Brazil); Dos Santos, P A M, E-mail: [Instituto de Fisica, Laboratorio de Optica Nao-linear e Aplicada, Universidade Federal Fluminense, Av. Gal. Nilton Tavares de Souza, s/n, Gragoata, Niteroi, R.J., Brazil, Cep.:24.210-346 (Brazil)


    In the present work a digital image correlation (DIC) method is used in order to analyze the adhesive shear modulus of poly-dimethylsiloxane (PDMS) submitted to different loads and temperatures. This is an optical-numerical full-field surface displacement measurement method. It is based on a comparison between two images of a specimen coated by a random speckled pattern in the undeformed and in the deformed states. A single lap joint testing is performed. This is a standard test specimen for characterizing adhesive properties and it is considered the simplest form of adhesive joints. For the single lap joint specimen, steel adherends are bonded using a flexible rubber elastic polymer (PDMS), which is a commercially available silicone elastic rubber.

  4. Multiscale displacement field measurements of compressed mineral-wool samples by digital image correlation

    Hild, Francois; Raka, Bumedijen; Baudequin, Maud; Roux, Stephane; Cantelaube, Florence


    We propose a multiscale approach to determine the displacement field by digital image correlation. The displacement field is first estimated on a coarse resolution image and progressively finer details are introduced in the analysis as the displacement is more and more securely and accurately determined. Such a scheme has been developed to increase the robustness, accuracy, and reliability of the image-matching algorithm. The procedure is used on two different types of examples. The first one deals with a representative image that is deformed precisely and purposefully to assess the intrinsic performances. In particular, the maximum measurable strain is determined. The second case deals with a series of pictures taken during compression experiments on mineral-wool samples. The different steps of the procedure are analyzed and their respective role is assessed. Both reflection and transmission images are tested.

  5. Stress and structural damage sensing piezospectroscopic coatings validated with digital image correlation

    Gregory Freihofer


    Full Text Available The piezospectroscopic effect, relating a material’s stress state and spectral signature, has recently demonstrated tailorable sensitivity when the photo-luminescent alpha alumina is distributed in nanoparticulate form within a matrix. Here, the stress-sensing behavior of an alumina-epoxy nanoparticle coating, applied to a composite substrate in an open hole tension configuration, is validated with the biaxial strain field concurrently determined through digital image correlation. The coating achieved early detection of composite failure initiation at 77% failure load, and subsequently tracked stress distribution in the immediate vicinity of the crack as it progressed, demonstrating non-invasive stress and damage detection with multi-scale spatial resolution.

  6. Multi-scale crack closure measurements with digital image correlation on Haynes 230

    Stefano Beretta


    Full Text Available An experimental campaign was developed to study fatigue crack growth in Haynes 230, a Ni-based superalloy. The effects of crack closure were investigated with digital image correlation, by applying two different approaches. Initially, full field regression algorithms were applied to extract the effective stress intensity factor ranges from the singular displacement field measured at crack tips. Local closure measurements were then performed by considering crack flanks relative displacements. Two points virtual extensometers were applied in this phase. Experimental results were then compared to the reference da/dN –ΔKeff curve: it was found that the correct estimation of crack opening levels shifts all the experimental points on the reference curve, showing that DIC can be successfully applied to measure crack closure effects.

  7. Identification of the elastic stiffness of composites using the virtual fields method and digital image correlation

    Jiang, Lebin; Guo, Baoqiao; Xie, Huimin


    This paper presents an effective methodology for characterizing the mechanical parameters of composites using digital image correlation combined with the virtual fields method. By using a three-point bending test configuration, this method can identify all mechanical parameters of the material with merely a single test. Successful results verified that this method is especially effective for characterizing composite materials. In this study, the method is applied to measure the orthotropic elastic parameters of fiber-reinforced polymer-matrix composites before and after the hygrothermal aging process. The results indicate that the hygrothermal aging environment significantly influences the mechanical property of a composite. The components of the parameters in the direction of the fiber bundle decreased significantly. From the accuracy analysis, we found that the actual measurement accuracy is sensitive to a shift of the horizontal edges and rotation of the vertical edges.

  8. Phase noise characterization of sub-hertz linewidth lasers via digital cross correlation

    Xie, Xiaopeng; Bouchand, Romain; Nicolodi, Daniele; Lours, Michel; Alexandre, Christophe; Le Coq, Yann


    Phase noise or frequency noise is a key metrics to evaluate the short term stability of a laser. This property is of a great interest for the applications but delicate to characterize, especially for narrow line-width lasers. In this letter, we demonstrate a digital cross correlation scheme to characterize the absolute phase noise of sub-hertz line-width lasers. Three 1,542 nm ultra-stable lasers are used in this approach. For each measurement two lasers act as references to characterize a third one. Phase noise power spectral density from 0.5 Hz to 0.8 MHz Fourier frequencies can be derived for each laser by a mere change in the configuration of the lasers. This is the first time showing the phase noise of sub-hertz line-width lasers with no reference limitation. We also present an analysis of the laser phase noise performance.

  9. A new look at the visible color correlations of Centaurs and KBOs: what’s there and what we may be missing.

    Peixinho, Nuno; Delsanti, Audrey; Doressoundiram, Alain


    Broadband surface colors of Centaurs and KBOs are usually seen as a mere rough approximation of their reflectivity spectra. Whereas JHK colors are not the best proxy for the near-IR spectra with possible presence of absorption features of several ices, BVRI colors have shown to be so when it comes to visible spectra. We have compiled a data-set of visible colors available in the literature for 369 objects and analyzed their color vs. color correlations and their color vs. orbital parameters correlations, both globally and by dynamical family. In this work we present the first study on: i) the “degradation” of the detectable strength of a correlation as a function of data error-bars, ii) the “risk” of missing-out existing correlations due to low sampling, iii) the sample-sizes required to “warrant” detection at a given significance level, iv) the use of partial correlations to disentangle complex mutual correlations, and v) the high sensitivity of the so-called “reddening line” to the central wavelength of similar filters at different telescopes. We will discuss, in particular: a) how data error-bars impose a limit on the detectable correlations regardless of sample size and, therefore, once that limit is achieved it is important to diminish the error-bars but pointless to enlarge the sampling with the same or larger errors; b) how almost all families still require larger samplings to “ensure” the detection of correlations stronger than +/-0.5, i.e. correlations that may “explain” ~25% or more of the color variability; and c) how it is statistically equivalent to use any of the different “flavors” of orbital excitation or collisional velocity parameters regarding the famous color-inclination correlation among Classical KBOs, whereas the inclination and Tisserand parameter relative no Neptune cannot be separated from one another.Acknowledgements: NP acknowledges funding by the Gemini-Conicyt Fund, allocated to the project #32120036.

  10. Dynamical properties of a tumor growth system in the presence of immunization and colored cross-correlated noises

    Jia Zhenglin; Mei Dongcheng, E-mail: [Department of Physics, Yunnan University, Kunming 650091, Yunnan (China)


    We investigate the effects of the noise parameters and immunization strength {beta} on the dynamical properties of a tumor growth system with both immunization and colored cross-correlated noises. The analytical expressions for the associated relaxation time T{sub C} and the normalized correlation function C(s) are derived by means of the projection operator method. The results indicate that: (i) T{sub C} as a function of the multiplicative noise intensity {alpha} shows resonance-like behavior, i.e. the curves of T{sub C} versus {alpha} exhibit a single-peak structure and its peak position changes with increasing correlation strength between noises {lambda}, the autocorrelation time of multiplicative noise {tau}{sub 1}, the autocorrelation time of additive noise {tau}{sub 2} and the cross-correlation time {tau}{sub 3}. This behavior can be understood in terms of the noise-enhanced stability effect and the influence of the memory effects on it. (ii) The increasing {lambda}, {tau}{sub 1}, {tau}{sub 2} and the additive noise intensity D slow down the fluctuation decay of the tumor population, whereas the increasing {tau}{sub 3} and {beta} speed it up. (iii) C(s) increases as {lambda}, {tau}{sub 1}, {tau}{sub 2} and {beta} increase, while it decreases with {tau}{sub 3} increasing. Our study shows that the effects of some noise parameters on tumor growth can be modified due to the presence of the immunization effect.

  11. Evaluación del nivel de repetibilidad para medidas de color obtenidas mediante dos sistemas de captura digital de imagen

    Chorro Calderón, Elísabet; Vilaseca Ricart, Meritxell; Herrera Ramírez, Jorge Alexis; Perales Romero, Esther; Martínez Verdú, Francisco Miguel; Pujol Ramo, Jaume


    Póster presentado en el IX Congreso Nacional del Color, Alicante, 29-30 junio, 1-2 julio 2010. En muchas ocasiones tanto sistemas convencionales como multiespectrales de captura digital de imágenes, son usados para realizar medidas colorimétricas. Sin embargo, antes de empezar a utilizar un dispositivo de captura de imagen como espectroradiómetro es altamente recomendable realizar un estudio de repetibilidad y reproducibilidad del sistema para asegurar cierta fiabilidad en las medidas. En ...

  12. Effect of gold wire bonding process on angular correlated color temperature uniformity of white light-emitting diode.

    Wu, Bulong; Luo, Xiaobing; Zheng, Huai; Liu, Sheng


    Gold wire bonding is an important packaging process of lighting emitting diode (LED). In this work, we studied the effect of gold wire bonding on the angular uniformity of correlated color temperature (CCT) in white LEDs whose phosphor layers were coated by freely dispersed coating process. Experimental study indicated that different gold wire bonding impacts the geometry of phosphor layer, and it results in different fluctuation trends of angular CCT at different spatial planes in one LED sample. It also results in various fluctuating amplitudes of angular CCT distributions at the same spatial plane for samples with different wire bonding angles. The gold wire bonding process has important impact on angular uniformity of CCT in LED package.

  13. Digital image correlation method for calculating coefficients of Williams expansion in compact tension specimen

    Ayatollahi, Majid R.; Moazzami, Mostafa


    The digital image correlation (DIC) method is used to obtain the coefficients of higher-order terms in the Williams expansion in a compact tension (CT) specimens made of polymethyl methacrylate (PMMA). The displacement field is determined by the correlation between reference image (i.e., before deformation) and deformed image. The part of displacements resulting from rigid body motion and rotation is eliminated from the displacement field. For a large number of points in the vicinity of the crack tip, an over-determined set of simultaneous linear equations is collected, and by using the fundamental concepts of the least-squares method, the coefficients of the Williams expansion are calculated for pure mode I conditions. The experimental results are then compared with the numerical results calculated by finite element method (FEM). Very good agreement is shown to exist between the DIC and FE results confirming the effectiveness of the DIC technique in obtaining the coefficients of higher order terms of Williams series expansion from the displacement field around the crack tip.

  14. Effect of camera temperature variations on stereo-digital image correlation measurements

    Pan, Bing


    In laboratory and especially non-laboratory stereo-digital image correlation (stereo-DIC) applications, the extrinsic and intrinsic parameters of the cameras used in the system may change slightly due to the camera warm-up effect and possible variations in ambient temperature. Because these camera parameters are generally calibrated once prior to measurements and considered to be unaltered during the whole measurement period, the changes in these parameters unavoidably induce displacement/strain errors. In this study, the effect of temperature variations on stereo-DIC measurements is investigated experimentally. To quantify the errors associated with camera or ambient temperature changes, surface displacements and strains of a stationary optical quartz glass plate with near-zero thermal expansion were continuously measured using a regular stereo-DIC system. The results confirm that (1) temperature variations in the cameras and ambient environment have a considerable influence on the displacements and strains measured by stereo-DIC due to the slightly altered extrinsic and intrinsic camera parameters; and (2) the corresponding displacement and strain errors correlate with temperature changes. For the specific stereo-DIC configuration used in this work, the temperature-induced strain errors were estimated to be approximately 30–50 με/°C. To minimize the adverse effect of camera temperature variations on stereo-DIC measurements, two simple but effective solutions are suggested.

  15. The Three-Point Correlation Function of Luminous Red Galaxies in the Sloan Digital Sky Survey

    Kulkarni, G V; Sheth, R K; Seo, H J; Eisenstein, D J; Gray, A; Kulkarni, Gauri V.; Nichol, Robert C.; Sheth, Ravi K.; Seo, Hee-Jong; Eisenstein, Daniel J.; Gray, Alexander


    We present measurements of the redshift-space three-point correlation function of 50,967 Luminous Red Galaxies (LRGs) from Data Release 3 (DR3) of the Sloan Digital Sky Survey (SDSS). We have studied the shape dependence of the reduced three-point correlation function (Qz(s,q,theta)) on three different scales, s=4, 7 and 10 h-1 Mpc, and over the range of 1 < q < 3 and 0 < theta < 180. On small scales (s=4 h-1 Mpc), Qz is nearly constant, with little change as a function of q and theta. However, there is evidence for a shallow U-shaped behaviour (with theta) which is expected from theoretical modeling of Qz . On larger scales (s=7 and 10 h-1 Mpc), the U-shaped anisotropy in Qz (with theta) is more clearly detected. We compare this shape-dependence in Qz(s,q,theta) with that seen in mock galaxy catalogues which were generated by populating the dark matter halos in large N-body simulations with mock galaxies using various Halo Occupation Distributions (HOD). We find that the combination of the observ...

  16. The use of digital image correlation for non-destructive and multi-scale damage quantification

    Schwartz, Eric; Saralaya, Raghavendra; Cuadra, Jefferson; Hazeli, Kavan; Vanniamparambil, Prashanth A.; Carmi, Rami; Bartoli, Ivan; Kontsos, Antonios


    This research demonstrates the use of Digital Image Correlation (DIC) as a non-contact, non-destructive testing and evaluation (NDT and E) technique by presenting experimental results pertinent to damage monitoring and quantification in several material systems at different length scales of interest. At the microstructural level compact tension aluminum alloy specimens were tested under Mode I loading conditions using an appropriate field of view to track grain scale crack initiation and growth. The results permitted the quantification of the strain accumulation near the tip of the fatigue pre-crack, as well as the computation of the relevant crack opening displacement as a function of crack length. At the mesoscale level, damage quantification in fiber reinforced composites subject to both tensile and fatigue loading conditions was achieved by using the DIC as part of a novel integrated NDT approach combining both acoustic and thermal methods. DIC in these experiments provided spatially resolved and high accuracy strain measurements capable to track the formation of damage "hot spots" that corresponded to the sites of the ultimately visible fracture pattern, while it further allowed the correlation of mechanical parameters to thermal and acoustic features. Finally, at the macrostructural level DIC measurements were also performed and compared to traditional displacement gauges mounted on a steel deck model subject to both static and dynamic loads, as well as on masonry structures including hollow and grouted concrete walls.

  17. Increasing the computational efficient of digital cross correlation by a vectorization method

    Chang, Ching-Yuan; Ma, Chien-Ching


    This study presents a vectorization method for use in MATLAB programming aimed at increasing the computational efficiency of digital cross correlation in sound and images, resulting in a speedup of 6.387 and 36.044 times compared with performance values obtained from looped expression. This work bridges the gap between matrix operations and loop iteration, preserving flexibility and efficiency in program testing. This paper uses numerical simulation to verify the speedup of the proposed vectorization method as well as experiments to measure the quantitative transient displacement response subjected to dynamic impact loading. The experiment involved the use of a high speed camera as well as a fiber optic system to measure the transient displacement in a cantilever beam under impact from a steel ball. Experimental measurement data obtained from the two methods are in excellent agreement in both the time and frequency domain, with discrepancies of only 0.68%. Numerical and experiment results demonstrate the efficacy of the proposed vectorization method with regard to computational speed in signal processing and high precision in the correlation algorithm. We also present the source code with which to build MATLAB-executable functions on Windows as well as Linux platforms, and provide a series of examples to demonstrate the application of the proposed vectorization method.

  18. Effect of camera temperature variations on stereo-digital image correlation measurements.

    Pan, Bing; Shi, Wentao; Lubineau, Gilles


    In laboratory and especially non-laboratory stereo-digital image correlation (stereo-DIC) applications, the extrinsic and intrinsic parameters of the cameras used in the system may change slightly due to the camera warm-up effect and possible variations in ambient temperature. Because these camera parameters are generally calibrated once prior to measurements and considered to be unaltered during the whole measurement period, the changes in these parameters unavoidably induce displacement/strain errors. In this study, the effect of temperature variations on stereo-DIC measurements is investigated experimentally. To quantify the errors associated with camera or ambient temperature changes, surface displacements and strains of a stationary optical quartz glass plate with near-zero thermal expansion were continuously measured using a regular stereo-DIC system. The results confirm that (1) temperature variations in the cameras and ambient environment have a considerable influence on the displacements and strains measured by stereo-DIC due to the slightly altered extrinsic and intrinsic camera parameters; and (2) the corresponding displacement and strain errors correlate with temperature changes. For the specific stereo-DIC configuration used in this work, the temperature-induced strain errors were estimated to be approximately 30-50 με/°C. To minimize the adverse effect of camera temperature variations on stereo-DIC measurements, two simple but effective solutions are suggested.

  19. A new procedure of modal parameter estimation for high-speed digital image correlation

    Huňady, Róbert; Hagara, Martin


    The paper deals with the use of 3D digital image correlation in determining modal parameters of mechanical systems. It is a non-contact optical method, which for the measurement of full-field spatial displacements and strains of bodies uses precise digital cameras with high image resolution. Most often this method is utilized for testing of components or determination of material properties of various specimens. In the case of using high-speed cameras for measurement, the correlation system is capable of capturing various dynamic behaviors, including vibration. This enables the potential use of the mentioned method in experimental modal analysis. For that purpose, the authors proposed a measuring chain for the correlation system Q-450 and developed a software application called DICMAN 3D, which allows the direct use of this system in the area of modal testing. The created application provides the post-processing of measured data and the estimation of modal parameters. It has its own graphical user interface, in which several algorithms for the determination of natural frequencies, mode shapes and damping of particular modes of vibration are implemented. The paper describes the basic principle of the new estimation procedure which is crucial in the light of post-processing. Since the FRF matrix resulting from the measurement is usually relatively large, the estimation of modal parameters directly from the FRF matrix may be time-consuming and may occupy a large part of computer memory. The procedure implemented in DICMAN 3D provides a significant reduction in memory requirements and computational time while achieving a high accuracy of modal parameters. Its computational efficiency is particularly evident when the FRF matrix consists of thousands of measurement DOFs. The functionality of the created software application is presented on a practical example in which the modal parameters of a composite plate excited by an impact hammer were determined. For the

  20. Full-color holographic 3D printer

    Takano, Masami; Shigeta, Hiroaki; Nishihara, Takashi; Yamaguchi, Masahiro; Takahashi, Susumu; Ohyama, Nagaaki; Kobayashi, Akihiko; Iwata, Fujio


    A holographic 3D printer is a system that produces a direct hologram with full-parallax information using the 3-dimensional data of a subject from a computer. In this paper, we present a proposal for the reproduction of full-color images with the holographic 3D printer. In order to realize the 3-dimensional color image, we selected the 3 laser wavelength colors of red (λ=633nm), green (λ=533nm), and blue (λ=442nm), and we built a one-step optical system using a projection system and a liquid crystal display. The 3-dimensional color image is obtained by synthesizing in a 2D array the multiple exposure with these 3 wavelengths made on each 250mm elementary hologram, and moving recording medium on a x-y stage. For the natural color reproduction in the holographic 3D printer, we take the approach of the digital processing technique based on the color management technology. The matching between the input and output colors is performed by investigating first, the relation between the gray level transmittance of the LCD and the diffraction efficiency of the hologram and second, by measuring the color displayed by the hologram to establish a correlation. In our first experimental results a non-linear functional relation for single and multiple exposure of the three components were found. These results are the first step in the realization of a natural color 3D image produced by the holographic color 3D printer.

  1. Doppler ultrasound study of penis in men with systemic sclerosis: a correlation with Doppler indices of renal and digital arteries.

    Rosato, E; Barbano, B; Gigante, A; Cianci, R; Molinaro, I; Quarta, S; Digiulio, M A; Messineo, D; Pisarri, S; Salsano, F


    Erectile dysfunction (ED) prevalence in male systemic sclerosis (SSc) is high and its pathogenesis is unclear. The aim of the study is to assess correlation between Doppler ultrasound indices of penis and kidneys or digital arteries in male systemic sclerosis. Fourteen men with systemic sclerosis were enrolled in this study. Erectile function was investigated by the International Index of Erectile Function-5. Peak systolic velocity, end diastolic velocity, resistive index, pulsative index, and systolic/diastolic ratio were measured on the cavernous arteries at the peno-scrotal junction in the flaccid state, on the interlobar artery of both kidneys and all ten proper palmar digital arteries. Ten (71 percent) patients have an International Index of Erectile Function-5 less than 21. Reduction of penis peak systolic velocity was observed in all SSc subjects. Doppler indices of cavernous arteries correlate with the International Index of Erectile Function-5. The renal and digital arteries resistive index demonstrated a good correlation (p less than 0.0001) with International Index of Erectile Function-5. A positive correlation exists between penis and kidney arteries Doppler indices: end diastolic velocity (p less than 0.05, r=0.54), resistive index (p less than 0.0001, r=0.90), systolic/diastolic ratio (p less than 0.01, r=0.69). A positive correlation was observed between penis and digital arteries Doppler indices: peak systolic velocity (p less than 0.01, r=0.68), end diastolic velocity (p less than 0.01, r=0.75), resistive index (p less than 0.001, r=0.79), systolic/diastolic ratio (p less than 0.05, r=0.59). A correlation exists between arterial impairment of penis and renal or digital arteries.

  2. 园林彩画信息数字化保护与应用%Digitalized Protection and Application on Information of Garden Colored Drawing

    党睿; 刘刚


    The article analyzed color matching is lack of a unified scientific guidance,damaged of sunlight and artificial lighting in field of colored drawing of ancient buildings and garden.The article put the Summer Palace as sample,established "protective and practical system of digitization on the summer palace's colored drawing" by adopted the method of combining field research and data searching,combining traditional craft and modem graphics,combining instrument check and software analysis,combining irradiating entity model experiment and quantitative measuring data.The research achieved Munsell color coordinate and light decay value,then made standard color card and light decay curve.At last integrated all research productions and completely resolved above-mentioned two issues.At the same time,the system can provide a complete information copy for the protecting colored drawing of ancient garden,and make a contribution to Inheritance,promotion and development of colored drawing.%针对目前古建园林彩画所面临的“色彩配比缺乏统一科学指导,天然光照及人工照明对其造成损害”两大问题,以颐和园彩画为样本,采用资料查询整理与现场调研统计相结合、传统工艺与现代科技相结合、仪器检测与软件分析相结合、实验室模型照射与定量化数据测量相结合的方法进行研究,得到彩画色彩的孟塞尔参数和光照衰变指标,进而制作色彩标准色卡并绘制光照衰变规律曲线,最终集成研究成果建立“颐和园彩画信息数字化保护与应用系统”,解决目的彩画所面临的上述两大问题.研究结果可为古建园林彩画的修缮保护工作提供完整的信息副本,并能为彩画的传承、推广与发展做出贡献.

  3. Digital Particle Image Velocimetry (DPIV) Used for Space-Time Correlations in Nozzle Flow

    Wernet, Mark P.; Bridges, James E.


    An optical measurement technique known as Digital Particle Image Velocimetry (DPIV) was used previously to characterize the first- and second-order statistical properties of both cold and hot jet flows from externally mixed nozzles in NASA Glenn Research Center's Nozzle Acoustic Test Rig. In this technique, an electronic camera records particles entrained in a flow as a laser light sheet is pulsed at two instances in time. Correlation processing of the recorded particle image pairs yields the two-component velocity field across the imaged plane of the flow. The information acquired using DPIV is being used to improve our understanding of the decay of turbulence in jet flows-a critical element for understanding the acoustic properties of the flow. Recently, two independent DPIV systems were installed in Glenn's Small Hot Jet Acoustic Rig, enabling multiplane correlations in time and space. The data were collected over a range of different Mach numbers and temperature ratios. DPIV system 1 was fixed to a large traverse rig, and DPIV system 2 was mounted on a small traverse system mounted on the large traverse frame. The light sheets from the two DPIV systems were aligned to lie in the same axial plane, with DPIV system 2 being independently traversed downstream along the flow direction. For each measurement condition, the DPIV systems were started at a fully overlapping orientation. A polarization separation technique was used to avoid cross-talk between the two systems. Then, the DPIV systems fields were shifted axially apart, in successively increasing steps. The downstream DPIV system 2 was triggered at a short time delay after the upstream DPIV system 1, where the time delay was proportional to the convective flow velocity in the shear layer of the jet flow and the axial separation of the two DPIV systems. The acquired data were processed to obtain the instantaneous velocity vector maps over a range of time delays and spatial separations. The velocity fields from

  4. A method for stereoscopic strain analysis of the right ventricle by digital image correlation during coronary bypass surgery: short communication.

    Mirow, Nikolas; Hokka, Mikko; Nagel, Horst; Irqsusi, Marc; Moosdorf, Rainer G; Kuokkala, Veli-Tapani; Vogt, Sebastian


    Perioperative cardiosurgical management of volume therapy remains one of the challenging tasks in cases of patients with severe heart disease. Early detection of congestive cardiac failure prevents subsequent low output and worse outcome. An effective method for controlling extracorporeal circulation is created by developing a non-invasive intraoperative method for right ventricular strain analysis through digital image contrast correlation.

  5. Column-Parallel Single Slope ADC with Digital Correlated Multiple Sampling for Low Noise CMOS Image Sensors

    Chen, Y.; Theuwissen, A.J.P.; Chae, Y.


    This paper presents a low noise CMOS image sensor (CIS) using 10/12 bit configurable column-parallel single slope ADCs (SS-ADCs) and digital correlated multiple sampling (CMS). The sensor used is a conventional 4T active pixel with a pinned-photodiode as photon detector. The test sensor was fabricat

  6. High-throughput profiling of tissue and tissue model microarrays: Combined transmitted light and 3-color fluorescence digital pathology

    Michel Nederlof


    Full Text Available For many years pathologists have used Hematoxylin and Eosin (H&E, single marker immunohistochemistry (IHC and in situ hybridization with manual analysis by microscopy or at best simple digital imaging. There is a growing trend to update pathology to a digital workflow to improve objectivity and productivity, as has been done in radiology. There is also a need for tissue-based multivariate biomarker assays to improve the accuracy of diagnostic, prognostic, and predictive testing. Multivariate tests are not compatible with the traditional single marker, manual analysis pathology methods but instead require a digital platform with brightfield and fluorescence imaging, quantitative image analysis, and informatics. Here we describe the use of the Hamamatsu NanoZoomer Digital Pathology slide scanner with HCImage software for combined brightfield and multiplexed fluorescence biomarker analysis and highlight its applications in biomarker research and pathology testing. This combined approach will be an important aid to pathologists in making critical diagnoses.

  7. Feasibility of color measurement for iris using digital camera%数码技术测定虹膜色彩的可行性

    郑国伟; 宋岩; 陆兰


    背景:天然虹膜颜色个体差异大、种类多,常规肉眼比色由于比色方法、比色环境及操作者的个体差异的局限性,选色结果往往不能令患者满意.目的:评价数码技术应用于虹膜配色的可行性与合理性.方法:使用数码相机,在稳定光源环境(D65标准光源)、固定拍摄参数(光圈f/2.8,快门1/45 s,感光度ISO 100,图像格式RAW)条件下,拍摄148例单眼球缺失病例的虹膜,患者年龄24~49岁;图像经Camera RAW for Adobe Photoshop 7.0专业软件处理后,观察虹膜的色彩特征,采集虹膜色彩数据,运用"HSB模型"滑杆显示不同患者天然虹膜的色相(H)、饱和度(S)、亮度(B)数值.使用SPSS 13.0统计软件作进一步描述性分析及χ2检验.结果与结论:148例单眼球缺失患者运用"HSB模型"比色,141例义眼虹膜色质良好,与健眼协调;4例色质稍偏差,细看能区别出修复体;3例与健眼虹膜有较大差别.提示依据孟赛尔HVC颜色系统,运用"HSB模型",借助数码相机、计算机并结合相关软件,对不同颜色进行测定、分析,方法科学、具有量化性,比色快速、方便、准确.所取设备易取,具有一定的临床应用价值.%BACKGROUND: Because of individual differences in the natural iris color and colorimetric method, colorimetric environment and the operator, color Selection results often do not make a patient satisfaction.OBJECTIVE: To evaluate the reliability and reasonability of iris color matching by using the digital camera.METHODS: The irises from 148 volunteers aged between 24 to 49 years were recorded by a digital camera in studio environment (D65 standard illuminant). Photographs were taken under a set exposure parameters (AE f/2.8, I/45 s, ISO 100) and saved in RAW image file format. The characteristics of color of the tested iris were visually observed, and the color values were obtained from the digital images using Camera RAW for Adobe Photoshop 7.0. Through partial color

  8. Embedding Color Watermarks in Color Images

    Wu Tung-Lin


    Full Text Available Robust watermarking with oblivious detection is essential to practical copyright protection of digital images. Effective exploitation of the characteristics of human visual perception to color stimuli helps to develop the watermarking scheme that fills the requirement. In this paper, an oblivious watermarking scheme that embeds color watermarks in color images is proposed. Through color gamut analysis and quantizer design, color watermarks are embedded by modifying quantization indices of color pixels without resulting in perceivable distortion. Only a small amount of information including the specification of color gamut, quantizer stepsize, and color tables is required to extract the watermark. Experimental results show that the proposed watermarking scheme is computationally simple and quite robust in face of various attacks such as cropping, low-pass filtering, white-noise addition, scaling, and JPEG compression with high compression ratios.

  9. Experimental analysis of image noise and interpolation bias in digital image correlation

    Gao, Zeren; Xu, Xiaohai; Su, Yong; Zhang, Qingchuan


    The popularization of the digital image correlation (DIC) method has raised urgent needs to evaluate the accuracy of this method. However, there are still some problems to be solved. Among the problems, the effects of various factors, such as the image noise caused by the camera sensors, the employed interpolation algorithm, and the structure of the speckle patterns, have become a major concern. To experimentally measure the position-dependent systematic error (i.e. interpolation bias) caused by non-ideal interpolation algorithm is an important way to evaluate the quality of the speckle patterns in the correlation method, and remains unsolved. In this work, a novel, simple and convenient method is proposed to measure the interpolation bias. In the new method which can avoid the out-of-plane displacements and the mechanical errors of translation stages, integral-pixel shifts are applied to the image shown on the screen so that sub-pixel displacements can be realized in the images captured by the camera via proper experimental settings. Besides, the fluctuations of the image noise and the sub-pixel displacement errors caused by the image noise are experimentally analyzed by employing three types of cameras commonly used in the DIC measurements. Experimental results indicate that the fluctuations of the image noise are not only proportional to the image gray value, but also dependent on the type of the employed camera. On the basis of eliminating the image noise via the image averaging technique, high-precision interpolation bias curves more than one period are experimentally obtained by the proposed method.

  10. Comparison of Subset-Based Local and Finite Element-Based Global Digital Image Correlation

    Pan, Bing


    Digital image correlation (DIC) techniques require an image matching algorithm to register the same physical points represented in different images. Subset-based local DIC and finite element-based (FE-based) global DIC are the two primary image matching methods that have been extensively investigated and regularly used in the field of experimental mechanics. Due to its straightforward implementation and high efficiency, subset-based local DIC has been used in almost all commercial DIC packages. However, it is argued by some researchers that FE-based global DIC offers better accuracy because of the enforced continuity between element nodes. We propose a detailed performance comparison between these different DIC algorithms both in terms of measurement accuracy and computational efficiency. Then, by measuring displacements of the same calculation points using the same calculation algorithms (e.g., correlation criterion, initial guess estimation, subpixel interpolation, optimization algorithm and convergence conditions) and identical calculation parameters (e.g., subset or element size), the performances of subset-based local DIC and two FE-based global DIC approaches are carefully compared in terms of measurement error and computational efficiency using both numerical tests and real experiments. A detailed examination of the experimental results reveals that, when subset (element) size is not very small and the local deformation within a subset (element) can be well approximated by the shape function used, standard subset-based local DIC approach not only provides better results in measured displacements, but also demonstrates much higher computation efficiency. However, several special merits of FE-based global DIC approaches are indicated.

  11. A kinematic measurement for ductile and brittle failure of materials using digital image correlation

    M.M. Reza Mousavi


    Full Text Available This paper addresses some material level test which is done on quasi-brittle and ductile materials in the laboratory. The displacement control experimental program is composed of mortar cylinders under uniaxial compression shows quasi-brittle behavior and seemingly round-section aluminum specimens under uniaxial tension represents ductile behavior. Digital Image Correlation gives full field measurement of deformation in both aluminum and mortar specimens. Likewise, calculating the relative displacement of two points located on top and bottom of virtual LVDT, which is virtually placed on the surface of the specimen, gives us the classical measure of strain. However, the deformation distribution is not uniform all over the domain of specimens mainly due to imperfect nature of experiments and measurement devices. Displacement jumps in the fracture zone of mortar specimens and strain localization in the necking area for the aluminum specimen, which are reflecting different deformation values and deformation gradients, is compared to the other regions. Since the results are inherently scattered, it is usually non-trivial to smear out the stress of material as a function of a single strain value. To overcome this uncertainty, statistical analysis could bring a meaningful way to closely look at scattered results. A large number of virtual LVDTs are placed on the surface of specimens in order to collect statistical parameters of deformation and strain. Values of mean strain, standard deviation and coeffcient of variations for each material are calculated and correlated with the failure type of the corresponding material (either brittle or ductile. The main limiters for standard deviation and coeffcient of variations for brittle and ductile failure, in pre-peak and post-peak behavior are established and presented in this paper. These limiters help us determine whether failure is brittle or ductile without determining of stress level in the material.

  12. Some practical considerations in finite element-based digital image correlation

    Wang, Bo


    As an alternative to subset-based digital image correlation (DIC), finite element-based (FE-based) DIC method has gained increasing attention in the experimental mechanics community. However, the literature survey reveals that some important issues have not been well addressed in the published literatures. This work therefore aims to point out a few important considerations in the practical algorithm implementation of the FE-based DIC method, along with simple but effective solutions that can effectively tackle these issues. First, to better accommodate the possible intensity variations of the deformed images practically occurred in real experiments, a robust zero-mean normalized sum of squared difference criterion, instead of the commonly used sum of squared difference criterion, is introduced to quantify the similarity between reference and deformed elements in FE-based DIC. Second, to reduce the bias error induced by image noise and imperfect intensity interpolation, low-pass filtering of the speckle images with a 5×5 pixels Gaussian filter prior to correlation analysis, is presented. Third, to ensure the iterative calculation of FE-based DIC converges correctly and rapidly, an efficient subset-based DIC method, instead of simple integer-pixel displacement searching, is used to provide accurate initial guess of deformation for each calculation point. Also, the effects of various convergence criteria on the efficiency and accuracy of FE-based DIC are carefully examined, and a proper convergence criterion is recommended. The efficacy of these solutions is verified by numerical and real experiments. The results reveal that the improved FE-based DIC offers evident advantages over existing FE-based DIC method in terms of accuracy and efficiency. © 2015 Elsevier Ltd. All rights reserved.

  13. Shrinkage of dental composite in simulated cavity measured with digital image correlation.

    Li, Jianying; Thakur, Preetanjali; Fok, Alex S L


    Polymerization shrinkage of dental resin composites can lead to restoration debonding or cracked tooth tissues in composite-restored teeth. In order to understand where and how shrinkage strain and stress develop in such restored teeth, Digital Image Correlation (DIC) was used to provide a comprehensive view of the displacement and strain distributions within model restorations that had undergone polymerization shrinkage. Specimens with model cavities were made of cylindrical glass rods with both diameter and length being 10 mm. The dimensions of the mesial-occlusal-distal (MOD) cavity prepared in each specimen measured 3 mm and 2 mm in width and depth, respectively. After filling the cavity with resin composite, the surface under observation was sprayed with first a thin layer of white paint and then fine black charcoal powder to create high-contrast speckles. Pictures of that surface were then taken before curing and 5 min after. Finally, the two pictures were correlated using DIC software to calculate the displacement and strain distributions. The resin composite shrunk vertically towards the bottom of the cavity, with the top center portion of the restoration having the largest downward displacement. At the same time, it shrunk horizontally towards its vertical midline. Shrinkage of the composite stretched the material in the vicinity of the "tooth-restoration" interface, resulting in cuspal deflections and high tensile strains around the restoration. Material close to the cavity walls or floor had direct strains mostly in the directions perpendicular to the interfaces. Summation of the two direct strain components showed a relatively uniform distribution around the restoration and its magnitude equaled approximately to the volumetric shrinkage strain of the material.

  14. Discrete volumetric digital image correlation for the investigation of granular type media at microscale: accuracy assessment

    Bornert M.


    Full Text Available The recent development of efficient 3D imaging tools such as X-Rays computed microtomography combined with the extension to volumetric images of Digital Image Correlation (DIC techniques provide new insights on the analysis of materials and structures. Among many other possible fields of application, geomaterials are good candidates for such investigations, owing to their relative transparency to X-rays and the presence in many samples of a natural contrast suitable for deformation mapping. However, these materials often deform discontinuously at microscale, for instance in the form of the development of a networks of microcracks. Discontinuity is even the dominant rule in granular-type materials such as sand in which the contribution to overall deformation of the microcontinuous phenomena -elastic strains inside grains- are negligible. To investigate deformation at the scale of these discontinuous mechanisms, specific DIC algorithms are required, which override the assumption of continuity of the transformation at the scale of the correlation windows. The recent so-called Discrete-DIC procedure (Hall et al, 2010 is a possible answer. We recall here its general principles and focus on its potential accuracy, from both theoretical and practical points of view. We show that the position and the rotation of individual grains with an average diameter of 500µm can be determined from images recorded with a laboratory microCT scanner, with a 15µm voxel size, with an accuracy of the order of 1µm and 0,1 degree, respectively.

  15. Spatial-temporal subset based digital image correlation considering the temporal continuity of deformation

    Wang, Xian; Liu, Xuejin; Zhu, Haibin; Ma, Shaopeng


    An improved digital image correlation (DIC) scheme termed spatial-temporal subset-based DIC (STS-DIC) that incorporates the temporal continuity of deformation is proposed. Provided that displacement at a certain physical point on a specimen in several successive frames is temporally continuous and can be expressed as a linear relationship over time, the STS-DIC scheme is constructed between the reference subset and spatial-temporal deformed subset consisting of several subsets from a period of successive frames. The proposed method is verified by simulated speckle images and experimental tests featuring different types of deformation. Compared to the traditional subset-based DIC, the STS-DIC proposed in this paper takes advantage of noise suppression so as to improve the accuracy, especially for speckle images with larger noise. More importantly, it is found that the computational demand of STS-DIC is much lower than that of mesh-based (global) DIC incorporating the temporal continuity, despite achieving comparable accuracy. Therefore, STS-DIC is expected to be useful as a practical and flexible tool in complex-environment measurements with low signal-to-noise-ratio speckle images.

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

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


    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.

  17. Stress distribution retrieval in granular materials: A multi-scale model and digital image correlation measurements

    Bruno, Luigi; Decuzzi, Paolo; Gentile, Francesco


    The promise of nanotechnology lies in the possibility of engineering matter on the nanoscale and creating technological interfaces that, because of their small scales, may directly interact with biological objects, creating new strategies for the treatment of pathologies that are otherwise beyond the reach of conventional medicine. Nanotechnology is inherently a multiscale, multiphenomena challenge. Fundamental understanding and highly accurate predictive methods are critical to successful manufacturing of nanostructured materials, bio/mechanical devices and systems. In biomedical engineering, and in the mechanical analysis of biological tissues, classical continuum approaches are routinely utilized, even if these disregard the discrete nature of tissues, that are an interpenetrating network of a matrix (the extra cellular matrix, ECM) and a generally large but finite number of cells with a size falling in the micrometer range. Here, we introduce a nano-mechanical theory that accounts for the-non continuum nature of bio systems and other discrete systems. This discrete field theory, doublet mechanics (DM), is a technique to model the mechanical behavior of materials over multiple scales, ranging from some millimeters down to few nanometers. In the paper, we use this theory to predict the response of a granular material to an external applied load. Such a representation is extremely attractive in modeling biological tissues which may be considered as a spatial set of a large number of particulate (cells) dispersed in an extracellular matrix. Possibly more important of this, using digital image correlation (DIC) optical methods, we provide an experimental verification of the model.

  18. Modeling dental composite shrinkage by digital image correlation and finite element methods

    Chen, Terry Yuan-Fang; Huang, Pin-Sheng; Chuang, Shu-Fen


    Dental composites are light-curable resin-based materials with an inherent defect of polymerization shrinkage which may cause tooth deflection and debonding of restorations. This study aimed to combine digital image correlation (DIC) and finite element analysis (FEA) to model the shrinkage behaviors under different light curing regimens. Extracted human molars were prepared with proximal cavities for composite restorations, and then divided into three groups to receive different light curing protocols: regular intensity, low intensity, and step-curing consisting of low and high intensities. For each tooth, the composite fillings were consecutively placed under both unbonded and bonded conditions. At first, the shrinkage of the unbonded restorations was analyzed by DIC and adopted as the setting of FEA. The simulated shrinkage behaviors obtained from FEA were further validated by the measurements in the bonded cases. The results showed that different light curing regimens affected the shrinkage in unbonded restorations, with regular intensity showing the greatest shrinkage strain on the top surface. The shrinkage centers in the bonded cases were located closer to the cavity floor than those in the unbonded cases, and were less affected by curing regimens. The FEA results showed that the stress was modulated by the accumulated light energy density, while step-curing may alleviate the tensile stress along the cavity walls. In this study, DIC provides a complete description of the polymerization shrinkage behaviors of dental composites, which may facilitate the stress analysis in the numerical investigation.

  19. Experimental Investigation on the Mechanical Behavior of Bovine Bone Using Digital Image Correlation Technique

    Yuxi Chen


    Full Text Available In order to understand the fracture mechanisms of bone subjected to external force well, an experimental study has been performed on the bovine bone by carrying out the three-point bending test with 3D digital image correlation (DIC method, which provides a noncontact and full field of displacement measurement. The local strain and damage evolution of the bone has been recorded real time. The results show that the deflection measured by DIC agrees well with that obtained by the displacement sensor of the mechanical testing machine. The relationship between the deflection and the force is nearly linear prior to reaching the peak strength which is about 16 kN for the tested bovine tibia. The full-field strain contours of the bone show that the strain distribution depends on not only the force direction, but also the natural bone shape. The natural arched-shape bovine tibia bone could bear a large force, due to the tissue structure with high strength, and the fracture propagation process of the sample initiates at the inner side of the bone first and propagates along the force direction.

  20. Systematic errors in two-dimensional digital image correlation due to lens distortion

    Pan, Bing; Yu, Liping; Wu, Dafang; Tang, Liqun


    Lens distortion practically presents in a real optical imaging system causing non-uniform geometric distortion in the recorded images, and gives rise to additional errors in the displacement and strain results measured by two-dimensional digital image correlation (2D-DIC). In this work, the systematic errors in the displacement and strain results measured by 2D-DIC due to lens distortion are investigated theoretically using the radial lens distortion model and experimentally through easy-to-implement rigid body, in-plane translation tests. Theoretical analysis shows that the displacement and strain errors at an interrogated image point are not only in linear proportion to the distortion coefficient of the camera lens used, but also depend on its distance relative to distortion center and its magnitude of displacement. To eliminate the systematic errors caused by lens distortion, a simple linear least-squares algorithm is proposed to estimate the distortion coefficient from the distorted displacement results of rigid body, in-plane translation tests, which can be used to correct the distorted displacement fields to obtain unbiased displacement and strain fields. Experimental results verify the correctness of the theoretical derivation and the effectiveness of the proposed lens distortion correction method.

  1. Improvements in thermoforming simulation by use of 3D digital image correlation

    B. Van Mieghem


    Full Text Available Numerical simulation tools for the thermoforming of unfilled thermoplastic polymers already exist for a while, but are seldom used to full extent in industry. When it is used, it is mostly only for comparative studies and prediction of relative wall thickness. One of the major reasons is the difficulty to correctly calibrate and integrate all necessary material and process parameters into the simulation software. This paper introduces and validates a methodology, in which digital image correlation (DIC is used as the key enabling technology that improves the knowledge of the process parameters and optimizes simulation accuracy by taking away a number of uncertainties and assumptions. DIC in combination with infrared thermal measurements and pressure monitoring is used to track sheet sagging and bubble inflation of a HIPS sheet, the two main process steps in the thermoforming of positive (male products or the only two steps in the case of free forming. The results of these in-situ measurements are used as a guideline for selecting the correct input parameters in the commercial thermoforming simulation software T-SIM®. A similar methodology can be further implemented for subsequent process steps such as forming and cooling or even to validate the material data used in the simulation software.

  2. Real-time three-dimensional digital image correlation for biomedical applications

    Wu, Rong; Wu, Hua; Arola, Dwayne; Zhang, Dongsheng


    Digital image correlation (DIC) has been successfully applied for evaluating the mechanical behavior of biological tissues. A three-dimensional (3-D) DIC system has been developed and applied to examining the motion of bones in the human foot. To achieve accurate, real-time displacement measurements, an algorithm including matching between sequential images and image pairs has been developed. The system was used to monitor the movement of markers which were attached to a precisely motorized stage. The accuracy of the proposed technique for in-plane and out-of-plane measurements was found to be -0.25% and 1.17%, respectively. Two biomedical applications were presented. In the experiment involving the foot arch, a human cadaver lower leg and foot specimen were subjected to vertical compressive loads up to 700 N at a rate of 10 N/s and the 3-D motions of bones in the foot were monitored in real time. In the experiment involving distal tibio fibular syndesmosis, a human cadaver lower leg and foot specimen were subjected to a monotonic rotational torque up to 5 Nm at a speed of 5 deg per min and the relative displacements of the tibia and fibula were monitored in real time. Results showed that the system could reach a frequency of up to 16 Hz with 6 points measured simultaneously. This technique sheds new lights on measuring 3-D motion of bones in biomechanical studies.

  3. Modified digital image correlation for balancing the influence of subset size choice

    Li, Bang-Jian; Wang, Quanbao; Duan, Deng-Ping; Chen, Ji-An


    A modified digital image correlation (DIC) method is presented to balance the influence of subset size choice, improve the calculation efficiency, and enhance the measurement accuracy. The relations between pixels and the central pixel are investigated. A relatively large subset size is selected in the method and all the pixels in a subset are treated nonuniformly. Weight is assigned to each pixel dependent on the significance of the pixel to track a subset from deformed images, and weights are computed by Butterworth function based on the distances between the pixels and the central pixel in the subset. Compared with classical DIC, the proposed method is a compromise between a small and a large subset. The choice of subset size for classical DIC is displaced by choice of parameters of Butterworth function in the presented method. The influence of subset size is reduced, and the calculation efficiency is improved with enhanced measurement accuracy by the modified method. Computer-simulated speckle patterns and real experiments are applied to verify the proposed method.

  4. Developing Dynamic Digital Image Correlation Technique to Monitor Structural Damage of Old Buildings under External Excitation

    Ming-Hsiang Shih


    Full Text Available The capacity of buildings to resist external excitation is an important factor to consider for the structural design of buildings. When subject to external excitation, a building may suffer a certain degree of damages, and its residual capacity to resist external excitation cannot be evaluated. In this research, dynamic digital image correlation method combined with parameter evaluation available in system identification is used to evaluate the structural capacity to resist external excitation. The results reveal possible building latent safety problems so that timely structural reinforcement or dismantling of the building can be initiated to alleviate further damages. The results of experiments using the proposed method conform to the results obtained using the conventional method, but this method is more convenient and rapid than the latter in the subsequent procedure of data processing. If only the frequency change is used, the damages suffered by the building can be detected, but the damage location is not revealed. The interstory drift mode shape (IDMS based on the characteristic of story drift has higher sensitivity than the approximate story damage index (ADSI method based on modal frequency and vibration type; however, both indices can be used to determine the degree and location of building damages.

  5. Robust full-field measurement considering rotation using digital image correlation

    Wu, Rong; Qian, Hao; Zhang, Dongsheng


    Digital image correlation (DIC) has been widely accepted as a method for displacement and strain measurement and is applied in a variety of engineering fields. Most DIC algorithms encounter errors in measuring the deformation in conditions that involve rotation since they are designed without considering rotation of the deformed object. In this paper, a robust and automated DIC method capable of determining full-field displacement and strain components with random rotations has been presented. The algorithm starts with the determination of the initial position of the seed point in the integer-pixel domain. An approximate rotational angle between the reference and the deformed subset is estimated using an automated feature matching technology. A two-step Newton-Raphson algorithm has been developed for optimizing a suite of variables including displacement, strain and the rotational angle to achieve subpixel accuracy. A reliable propagation scheme, which enables rapid determination of the initial guess for full-field analysis is also proposed. Results from numerical simulations are used to validate the feasibility of the proposed DIC method. An application to 3-point bending with large deflection shows that the algorithm can be employed to measure displacement or strain parameters of the deformed object with arbitrary angles of rotation.

  6. An efficient and accurate 3D displacements tracking strategy for digital volume correlation

    Pan, Bing


    Owing to its inherent computational complexity, practical implementation of digital volume correlation (DVC) for internal displacement and strain mapping faces important challenges in improving its computational efficiency. In this work, an efficient and accurate 3D displacement tracking strategy is proposed for fast DVC calculation. The efficiency advantage is achieved by using three improvements. First, to eliminate the need of updating Hessian matrix in each iteration, an efficient 3D inverse compositional Gauss-Newton (3D IC-GN) algorithm is introduced to replace existing forward additive algorithms for accurate sub-voxel displacement registration. Second, to ensure the 3D IC-GN algorithm that converges accurately and rapidly and avoid time-consuming integer-voxel displacement searching, a generalized reliability-guided displacement tracking strategy is designed to transfer accurate and complete initial guess of deformation for each calculation point from its computed neighbors. Third, to avoid the repeated computation of sub-voxel intensity interpolation coefficients, an interpolation coefficient lookup table is established for tricubic interpolation. The computational complexity of the proposed fast DVC and the existing typical DVC algorithms are first analyzed quantitatively according to necessary arithmetic operations. Then, numerical tests are performed to verify the performance of the fast DVC algorithm in terms of measurement accuracy and computational efficiency. The experimental results indicate that, compared with the existing DVC algorithm, the presented fast DVC algorithm produces similar precision and slightly higher accuracy at a substantially reduced computational cost. © 2014 Elsevier Ltd.

  7. Hygroscopic Swelling Determination of Cellulose Nanocrystal (CNC) Films by Polarized Light Microscopy Digital Image Correlation.

    Shrestha, Shikha; Diaz, Jairo A; Ghanbari, Siavash; Youngblood, Jeffrey P


    The coefficient of hygroscopic swelling (CHS) of self-organized and shear-oriented cellulose nanocrystal (CNC) films was determined by capturing hygroscopic strains produced as result of isothermal water vapor intake in equilibrium. Contrast enhanced microscopy digital image correlation enabled the characterization of dimensional changes induced by the hygroscopic swelling of the films. The distinct microstructure and birefringence of CNC films served in exploring the in-plane hygroscopic swelling at relative humidity values ranging from 0% to 97%. Water vapor intake in CNC films was measured using dynamic vapor sorption (DVS) at constant temperature. The obtained experimental moisture sorption and kinetic profiles were analyzed by fitting with Guggenheim, Anderson, and deBoer (GAB) and Parallel Exponential Kinetics (PEK) models, respectively. Self-organized CNC films showed isotropic swelling, CHS ∼0.040 %strain/%C. By contrast, shear-oriented CNC films exhibited an anisotropic swelling, resulting in CHS ∼0.02 and ∼0.30 %strain/%C, parallel and perpendicular to CNC alignment, respectively. Finite element analysis (FEA) further predicted moisture diffusion as the predominant mechanism for swelling of CNC films.

  8. Towards high velocity deformation characterisation of metals and composites using Digital Image Correlation

    Dulieu-Barton J.M.


    Full Text Available Characterisation of materials subject to high velocity deformation is necessary as many materials behave differently under such conditions. It is particularly important for accurate numerical simulation of high strain rate events. High velocity servo-hydraulic test machines have enabled material testing in the strain rate regime from 1 – 500 ε/s. The range is much lower than that experienced under ballistic, shock or impact loads, nevertheless it is a useful starting point for the application of optical techniques. The present study examines the possibility of using high speed cameras to capture images and then extracting deformation data using Digital Image Correlation (DIC from tensile testing in the intermediate strain rate regime available with the test machines. Three different materials, aluminium alloy 1050, S235 steel and glass fibre reinforced plastic (GFRP were tested at different nominal strain rates ranging from quasi static to 200 ε/s. In all cases DIC was able to analyse data collected up to fracture and in some cases post fracture. The use of highspeed DIC made it possible to capture phenomena such as multiple necking in the aluminium specimens and post compression failure in GFRP specimens.

  9. Stress-wave induced fracture of unidirectional composites: an experimental study using digital image correlation method

    Lee, Dongyeon; Tippur, Hareesh V.


    In this work, fracture behavior of unidirectional graphite/epoxy composite materials is optically investigated. Single-edge notched coupons are studied under geometrically symmetric impact loading. The notch orientation parallel to or at an angle relative to the fiber orientation is considered to produce mode-I as well as mixed-mode fracture. Stress-wave induced crack initiation and rapid crack growth events are studied using a digital correlation technique and high-speed photography. Surface deformations histories in the crack-tip vicinity are obtained by analyzing decorated speckle recordings. Measured deformation fields are used to extract fracture parameters and examine the effect of fiber orientation on crack initiation and growth behaviors. The maximum crack speed observed is the highest for mode-I dominant conditions and decreases with increasing fiber orientation angle. With increasing fiber orientation angle, crack takes longer to attain the maximum speed upon initiation. The crack initiation toughness values decrease with increasing degree-of-anisotropy.

  10. Investigation of Rock Failure Pattern in Creep by Digital Speckle Correlation Method

    Yunliang Tan


    Full Text Available In order to study the mechanical characteristics from creep deformation to failure of rock, the tests of uniaxial compression and pushing steel-plate anchored in rock were performed, by using RLJW-2000 servo test synchronizing with Digital Speckle Correlation Method (DSCM. The investigations showed that for a uniaxial compressive specimen, when load arrived at 0.5σc, displacement clusters orderly formed, which was ahead of the macrocreep strain occurring in a slight jump mode when load arrived at 0.7σc. When the load level arrived at 0.8σc, displacement clusters gathered to be a narrow band. After that, the specimen abruptly fractured in a shear mode. In the creep pushing steel-plate test, when pushing force arrived at 25 kN, crack began to occur, the horizontal displacement field as well as shear strain field concentrated continuously along the interface between steel-plate and rock, and a new narrow concentrating band gathered in the upper layer. When pushing force arrived at 27.5 kN, another new narrow shear deformation band formed in the lower layer. Then, the steel-plate was pushed out quickly accompanying strong creep deformation.

  11. Digital image correlation for full-field time-resolved assessment of arterial stiffness

    Campo, Adriaan; Soons, Joris; Heuten, Hilde; Ennekens, Guy; Goovaerts, Inge; Vrints, Christiaan; Lava, Pascal; Dirckx, Joris


    Pulse wave velocity (PWV) of the arterial system is a very important parameter to evaluate cardiovascular health. Currently, however, there is no golden standard for PWV measurement. Digital image correlation (DIC) was used for full-field time-resolved assessment of displacement, velocity, acceleration, and strains of the skin in the neck directly above the common carotid artery. By assessing these parameters, propagation of the pulse wave could be tracked, leading to a new method for PWV detection based on DIC. The method was tested on five healthy subjects. As a means of validation, PWV was measured with ultrasound (US) as well. Measured PWV values were between 3.68 and 5.19 m/s as measured with DIC and between 5.14 and 6.58 m/s as measured with US, with a maximum absolute difference of 2.78 m/s between the two methods. DIC measurements of the neck region can serve as a test base for determining a robust strategy for PWV detection, they can serve as reference for three-dimensional fluid-structure interaction models, or they may even evolve into a screening method of their own. Moreover, full-field, time-resolved DIC can be adapted for other applications in biomechanics.

  12. Evaluating the bending response of two osseointegrated transfemoral implant systems using 3D digital image correlation.

    Thompson, Melanie L; Backman, David; Branemark, Rickard; Mechefske, Chris K


    Osseointegrated transfemoral implants have been introduced as a prosthetic solution for above knee amputees. They have shown great promise, providing an alternative for individuals who could not be accommodated by conventional, socket-based prostheses; however, the occurrence of device failures is of concern. In an effort to improve the strength and longevity of the device, a new design has been proposed. This study investigates the mechanical behavior of the new taper-based assembly in comparison to the current hex-based connection for osseointegrated transfemoral implant systems. This was done to better understand the behavior of components under loading, in order to optimize the assembly specifications and improve the useful life of the system. Digital image correlation was used to measure surface strains on two assemblies during static loading in bending. This provided a means to measure deformation over the entire sample and identify critical locations as the assembly was subjected to a series of loading conditions. It provided a means to determine the effects of tightening specifications and connection geometry on the material response and mechanical behavior of the assemblies. Both osseoinegrated assemblies exhibited improved strength and mechanical performance when tightened to a level beyond the current specified tightening torque of 12 N m. This was shown by decreased strain concentration values and improved distribution of tensile strain. Increased tightening torque provides an improved connection between components regardless of design, leading to increased torque retention, decreased peak tensile strain values, and a more gradual, primarily compressive distribution of strains throughout the assembly.

  13. Advanced digital speckle correlation method for strain measurement and nondestructive testing

    Jin, Guan-chang; Bao, Nai-Keng; Chung, Po Sheun


    An advanced digital speckle correlation method (DSCM) is presented in this paper. The advantages of this method will not only improve the processing speed but also increase the measuring accuracy. Some mathematics tools are derived and a powerful computing program is developed for further applications. A new feature of the measuring sensitivity of DSCM that can be varied by different amplification of the optical arrangement is first presented. This advantage may be superior to those available in other optical metrology methods like Electronic Speckle Pattern Interferometry (ESPI) in micro-deformation measurements. The applications of strain measurement and nondestructive testing are described and the advantages of DSCM are obvious. Some examples of material behavior measurement and plastic strain measurement are presented. Due to the high sensitivity of DSCM, another potential application in nondestructive testing (NDT) is also described in this paper. From the application examples given, this advanced DSCM proves to be a new and effective optical strain sensing technique especially for small objects or micro-deformation measurements.

  14. Accurate B-spline-based 3-D interpolation scheme for digital volume correlation

    Ren, Maodong; Liang, Jin; Wei, Bin


    An accurate and efficient 3-D interpolation scheme, based on sampling theorem and Fourier transform technique, is proposed to reduce the sub-voxel matching error caused by intensity interpolation bias in digital volume correlation. First, the influence factors of the interpolation bias are investigated theoretically using the transfer function of an interpolation filter (henceforth filter) in the Fourier domain. A law that the positional error of a filter can be expressed as a function of fractional position and wave number is found. Then, considering the above factors, an optimized B-spline-based recursive filter, combining B-spline transforms and least squares optimization method, is designed to virtually eliminate the interpolation bias in the process of sub-voxel matching. Besides, given each volumetric image containing different wave number ranges, a Gaussian weighting function is constructed to emphasize or suppress certain of wave number ranges based on the Fourier spectrum analysis. Finally, a novel software is developed and series of validation experiments were carried out to verify the proposed scheme. Experimental results show that the proposed scheme can reduce the interpolation bias to an acceptable level.

  15. Cyclic tension compression testing of AHSS flat specimens with digital image correlation system

    Knoerr, Lay; Sever, Nimet; McKune, Paul; Faath, Timo


    A cyclic tension-compression testing program was conducted on flat specimens of TPN-W®780 (Three Phase Nano) and DP980 (Dual Phase) Advanced High Strength Steels (AHSS). This experimental method was enabled utilizing an anti-buckling clamping device performed in a test machine, and the surface strains along the thickness edge are measured with a three-dimensional Digital Image Correlation (DIC) system. The in-plane pre-strain and reversed strain values, at specified strain rates, are investigated to observe the potential plastic flow and the nonlinear strain hardening behavior of the materials. The validity of the test results is established with the monotonic tension tests, to substantiate the true stress-strain curves corrected for the frictional and biaxial stresses induced by the clamping device. A process method for analyzing the correction using a macro script is shown to simplify the output of the true stress-strain results for material model calibration. An in progress study to validate the forming and spring-back predictive capabilities of a calibrated TPN-W®780 complex material model to an actual stamping of an automotive component will demonstrate the usefulness of the experimental cyclic test method. Suggestions to improve the testing, strain analysis and calibration of the model parameters are proposed for augmented use of this test method.

  16. Noise-induced bias for convolution-based interpolation in digital image correlation.

    Su, Yong; Zhang, Qingchuan; Gao, Zeren; Xu, Xiaohai


    In digital image correlation (DIC), the noise-induced bias is significant if the noise level is high or the contrast of the image is low. However, existing methods for the estimation of the noise-induced bias are merely applicable to traditional interpolation methods such as linear and cubic interpolation, but are not applicable to generalized interpolation methods such as BSpline and OMOMS. Both traditional interpolation and generalized interpolation belong to convolution-based interpolation. Considering the widely use of generalized interpolation, this paper presents a theoretical analysis of noise-induced bias for convolution-based interpolation. A sinusoidal approximate formula for noise-induced bias is derived; this formula motivates an estimating strategy which is with speed, ease, and accuracy; furthermore, based on this formula, the mechanism of sophisticated interpolation methods generally reducing noise-induced bias is revealed. The validity of the theoretical analysis is established by both numerical simulations and actual subpixel translation experiment. Compared to existing methods, formulae provided by this paper are simpler, briefer, and more general. In addition, a more intuitionistic explanation of the cause of noise-induced bias is provided by quantitatively characterized the position-dependence of noise variability in the spatial domain.

  17. Comparison of leaf color chart observations with digital photographs and spectral measurements for estimating maize leaf chlorophyll content

    Crop nitrogen management is important world-wide, as much for small fields as it is for large operations. Developed as a non-destructive aid for estimating nitrogen content in rice crops, leaf color charts (LCC) are a numbered series of plastic panels that range from yellowgreen to dark green. By vi...

  18. Digital Spectro-Correlator System for the Atacama Compact Array of the Atacama Large Millimeter/submillimeter Array

    Kamazaki, T; Chikada, Y; Okuda, T; Kurono, Y; Iguchi, S; Mitsuishi, S; Murakami, Y; Nishimuta, N; Mita, H; Sano, R


    We have developed an FX-architecture digital spectro-correlator for the Atacama Compact Array (ACA) of the Atacama Large Millimeter/submillimeter Array. The correlator is able to simultaneously process four pairs of dual polarization signals with the bandwidth of 2 GHz, which are received by up to sixteen antennas. It can calculate auto- and cross-correlation spectra including cross-polarization in all combinations of all the antennas, and output correlation spectra with flexible spectral configuration such as multiple frequency ranges and multiple frequency resolutions. Its spectral dynamic range is estimated to be higher than 10^4 relative to Tsys from processing results of thermal noise for eight hours with a typical correlator configuration. The sensitivity loss is also confirmed to be 0.9 % with the same configuration. In this paper, we report the detailed design of the correlator and the verification results of the developed hardware.

  19. Precision of Synesthetic Color Matching Resembles That for Recollected Colors Rather than Physical Colors

    Arnold, Derek H.; Wegener, Signy V.; Brown, Francesca; Mattingley, Jason B.


    Grapheme-color synesthesia is an atypical condition in which individuals experience sensations of color when reading printed graphemes such as letters and digits. For some grapheme-color synesthetes, seeing a printed grapheme triggers a sensation of color, but "hearing" the name of a grapheme does not. This dissociation allowed us to…

  20. Precision of Synesthetic Color Matching Resembles That for Recollected Colors Rather than Physical Colors

    Arnold, Derek H.; Wegener, Signy V.; Brown, Francesca; Mattingley, Jason B.


    Grapheme-color synesthesia is an atypical condition in which individuals experience sensations of color when reading printed graphemes such as letters and digits. For some grapheme-color synesthetes, seeing a printed grapheme triggers a sensation of color, but "hearing" the name of a grapheme does not. This dissociation allowed us to…

  1. Quantitation of chlorophylls and 22 of their colored degradation products in culinary aromatic herbs by HPLC-DAD-MS and correlation with color changes during the dehydration process.

    Lafeuille, Jean-Louis; Lefèvre, Stéphane; Lebuhotel, Julie


    Chlorophylls and their green and olive-brown derivatives were successfully separated from culinary herb extracts by HPLC with photodiode-array and mass spectrometry detection. The method involved a ternary gradient elution and reverse-phase separation conditions capable of resolving 24 different pigments (2 chlorophylls and 22 of their derivatives) of different polarities within 28 min. The method was applied to monitor color changes in 50 samples of culinary aromatic herbs subjected to five different drying treatments. Of the 24 pigments, 14 were key to understanding the differences between the primary degradation pathways of chlorophyll a and chlorophyll b in culinary herbs during drying processes. A color degradation ladder based on the total molar percentage of all the remaining green pigments was also proposed as a tool to measure the impact of drying treatments on aromatic herb visual aspects.

  2. Diamond nanocrystals hosting single nitrogen-vacancy color centers sorted by photon-correlation near-field microscopy.

    Sonnefraud, Yannick; Cuche, Aurélien; Faklaris, Orestis; Boudou, Jean-Paul; Sauvage, Thierry; Roch, Jean-François; Treussart, François; Huant, Serge


    Diamond nanocrystals containing highly photoluminescent color centers are attractive, nonclassical, and near-field light sources. For near-field applications, the size of the nanocrystal is crucial, since it defines the optical resolution. Nitrogen-vacancy (NV) color centers are efficiently created by proton irradiation and annealing of a nanodiamond powder. Using near-field microscopy and photon statistics measurements, we show that nanodiamonds with sizes down to 25 nm can hold a single NV color center with bright and stable photoluminescence.

  3. Optimization of Exactness of Direct Digital Correlation-Interferometer Direction-finder with Double Сorrelation Processing

    V. V. Tsyporenko


    Full Text Available Introduction. In this paper considered unsolved part of general issue of research of direct digital methods of correlation-interferometer radio direction-finding. The purpose of the article is optimization of exactness of direct digital correlation-interferometer direction-finder with double сorrelation processing. Fundamentals of researches. As a result of the conducted researches was defined that the basic parameter of equalization of dispersion of error of estimation of direction on the source of radio radiation for the direct digital correlation-interferometric direction-finder with double correlation processing, which it is expedient to optimize, there is the size of frequency converting change. Optimization. It was conducted parametrical optimization of the explored direction-finder for the selective model of frequency change. As a result of design was obtained dependence of middle deviation of estimation of direction from the relation of signal/noise at the action of normal gaussian noise for the different possible values of circular frequency converting shift. Conclusions. Analytical calculations and results of design coincided fully, that confirmed the rightness of the conducted researches and authenticity of results of optimization.


    Rajendra Kumar


    Full Text Available The objective of this study was to assess the utility of gray scale and color Doppler Ultrasonographic (US findings in characterization of benign and malignant thyroid nodules in correlation with the pathological diagnosis. METHODS: From January 2013 through December 2013, a total of 70 patients with solitary thyroid nodule underwent thyroid US with 7.5 – 12 MHz, linear array transducer of ESOATE MYLAB 40 . The following characteristics of each nodule were determined: Nodule diameter, Shape , Margins, Internal Contents , Echo texture, Halo, Presence and pattern of calcification, Pattern of vascularity, resistive index (RI of Intranodular/Peripheral vessels, and Association of cervical lymphadenopathy. Sensitivity, specificity, and positive and negative predictive values were obtained. The results were then compared to the fine needle aspira tion (FNA/Histopathological diagnosis. Diagnostic accuracy of US was determined using multiple logistic regression analysis. RESULTS: Statistically significant ( P peripheral pattern of vascularity and associated cervical lymphadenopathy. The overall diagnostic accuracy of thyroid US for differentiating a malignant lesion from a benign one was found to be 84.3%. CONCLUSION: Taller - than - wide shape, Lobulated/poorly defined margins, Hypoechogenicity and Marked hypoechogenicity, Microcalcifications and Central/central >peripheral pattern of vascularity are helpful criteria for the discrimination of malignant from benign nodules. Thyroid US achieved a good overall diagnostic accuracy in the categorization of benign and malignant thyroid nodules.

  5. Small-strain measurement in bridge connections using the digital image correlation (DIC) technique

    Desai, Niranjan


    Structural health monitoring (SHM) is emerging as a vital tool to help civil engineers improve the safety, maintainability, and reliability of critical structures and assists infrastructure owners with timely information for the continued safe and economic operation of their structure. SHM involves implementing a strategy that identifies and characterizes damage or undesirable performance in engineering structures. The goal of this research project was to determine the smallest strains measurable using standard digital image correlation (DIC) based SHM equipment. This practical investigation that had strong ties to the industry was motivated by damage observed in a real-world bridge, which was initially undetected. Its early detection would have led to reduced repair costs. To accomplish the aforementioned goal, tests were performed on a laboratory specimen that replicated a steel beam-to-column connection of the concerned bridge, involving progressively loading it in a manner in which it was loaded in the actual bridge, while simultaneously measuring the strains that developed in it using the aforementioned DIC-based equipment and software. Under the controlled conditions in the laboratory, the minimum resolution of the state-of-the-art system used in this investigation was determined. Due to the challenges faced in making these small-strain measurements even under highly controlled laboratory conditions, it was concluded that it is currently unrealistic to use the existing DIC technology in a real-world situation to measure strains as small as those that would need to be measured to detect the onset of damage in bridge connections. More work needs to be done in this area.

  6. Whole-field thickness strain measurement using multiple camera digital image correlation system

    Li, Junrui; Xie, Xin; Yang, Guobiao; Zhang, Boyang; Siebert, Thorsten; Yang, Lianxiang.


    Three Dimensional digital image correlation(3D-DIC) has been widely used by industry, especially for strain measurement. The traditional 3D-DIC system can accurately obtain the whole-field 3D deformation. However, the conventional 3D-DIC system can only acquire the displacement field on a single surface, thus lacking information in the depth direction. Therefore, the strain in the thickness direction cannot be measured. In recent years, multiple camera DIC (multi-camera DIC) systems have become a new research topic, which provides much more measurement possibility compared to the conventional 3D-DIC system. In this paper, a multi-camera DIC system used to measure the whole-field thickness strain is introduced in detail. Four cameras are used in the system. two of them are placed at the front side of the object, and the other two cameras are placed at the back side. Each pair of cameras constitutes a sub stereo-vision system and measures the whole-field 3D deformation on one side of the object. A special calibration plate is used to calibrate the system, and the information from these two subsystems is linked by the calibration result. Whole-field thickness strain can be measured using the information obtained from both sides of the object. Additionally, the major and minor strain on the object surface are obtained simultaneously, and a whole-field quasi 3D strain history is acquired. The theory derivation for the system, experimental process, and application of determining the thinning strain limit based on the obtained whole-field thickness strain history are introduced in detail.

  7. Image pre-filtering for measurement error reduction in digital image correlation

    Zhou, Yihao; Sun, Chen; Song, Yuntao; Chen, Jubing


    In digital image correlation, the sub-pixel intensity interpolation causes a systematic error in the measured displacements. The error increases toward high-frequency component of the speckle pattern. In practice, a captured image is usually corrupted by additive white noise. The noise introduces additional energy in the high frequencies and therefore raises the systematic error. Meanwhile, the noise also elevates the random error which increases with the noise power. In order to reduce the systematic error and the random error of the measurements, we apply a pre-filtering to the images prior to the correlation so that the high-frequency contents are suppressed. Two spatial-domain filters (binomial and Gaussian) and two frequency-domain filters (Butterworth and Wiener) are tested on speckle images undergoing both simulated and real-world translations. By evaluating the errors of the various combinations of speckle patterns, interpolators, noise levels, and filter configurations, we come to the following conclusions. All the four filters are able to reduce the systematic error. Meanwhile, the random error can also be reduced if the signal power is mainly distributed around DC. For high-frequency speckle patterns, the low-pass filters (binomial, Gaussian and Butterworth) slightly increase the random error and Butterworth filter produces the lowest random error among them. By using Wiener filter with over-estimated noise power, the random error can be reduced but the resultant systematic error is higher than that of low-pass filters. In general, Butterworth filter is recommended for error reduction due to its flexibility of passband selection and maximal preservation of the allowed frequencies. Binomial filter enables efficient implementation and thus becomes a good option if computational cost is a critical issue. While used together with pre-filtering, B-spline interpolator produces lower systematic error than bicubic interpolator and similar level of the random

  8. Force-independent distribution of correlated neural inputs to hand muscles during three-digit grasping.

    Poston, Brach; Danna-Dos Santos, Alessander; Jesunathadas, Mark; Hamm, Thomas M; Santello, Marco


    The ability to modulate digit forces during grasping relies on the coordination of multiple hand muscles. Because many muscles innervate each digit, the CNS can potentially choose from a large number of muscle coordination patterns to generate a given digit force. Studies of single-digit force production tasks have revealed that the electromyographic (EMG) activity scales uniformly across all muscles as a function of digit force. However, the extent to which this finding applies to the coordination of forces across multiple digits is unknown. We addressed this question by asking subjects (n = 8) to exert isometric forces using a three-digit grip (thumb, index, and middle fingers) that allowed for the quantification of hand muscle coordination within and across digits as a function of grasp force (5, 20, 40, 60, and 80% maximal voluntary force). We recorded EMG from 12 muscles (6 extrinsic and 6 intrinsic) of the three digits. Hand muscle coordination patterns were quantified in the amplitude and frequency domains (EMG-EMG coherence). EMG amplitude scaled uniformly across all hand muscles as a function of grasp force (muscle x force interaction: P = 0.997; cosines of angle between muscle activation pattern vector pairs: 0.897-0.997). Similarly, EMG-EMG coherence was not significantly affected by force (P = 0.324). However, coherence was stronger across extrinsic than that across intrinsic muscle pairs (P = 0.0039). These findings indicate that the distribution of neural drive to multiple hand muscles is force independent and may reflect the anatomical properties or functional roles of hand muscle groups.

  9. SPIDER - IV. Optical and NIR color gradients in Early-type galaxies: New Insights into Correlations with Galaxy Properties

    La Barbera, F; de la Rosa, I G; Gal, R R; Swindle, R; Lopes, P A A


    We present an analysis of stellar population gradients in 4,546 Early-Type Galaxies with photometry in $grizYHJK$ along with optical spectroscopy. A new approach is described which utilizes color information to constrain age and metallicity gradients. Defining an effective color gradient, $\

  10. Identification of viscoplastic parameters and characterization of Lüders behaviour using digital image correlation and the virtual fields method

    Avril, Stéphane; Pierron, Fabrice; Sutton, Michael A.; Yan, Junhui


    In this study, tensile loading experiments are performed on notched steel bars at an average applied strain rate of 1s-1. Displacement fields are measured across the specimen by coupling digital image correlation (DIC) with imaging using high speed CCD cameras (4796 fps). Results from the experiments indicate the presence of local strain rates ranging from 0.1 to 10s-1 in the notched specimens. The heterogeneity of the strain rate fields provides suitable conditions for determining simultaneo...

  11. Application of digital image correlation to full-field measurement of shrinkage strain of dental composites

    Jian-ying LI; Andrew LAU; Alex S.L.FOK


    Objectives:Polymerization shrinkage of dental composites remains a major concern in restorative dentistry because it can lead to micro-cracking of the tooth and debonding at the tooth-restoration interface.The aim of this study was to measure the full-field polymerization shrinkage of dental composites using the optical digital image correlation (DIC) method and to evaluate how the measurement is influenced by the factors in experiment setup and image analysis.Methods:Four commercial dental composites,Premise Dentine,Z100,Z250 and Tetric EvoCeram,were tested.Composite was first placed into a slot mould to form a bar specimen with rectangular-section of 4 mm×2 mm,followed by the surface painting to create irregular speckles.Curing was then applied at one end of the specimen while the other part were covered against curing light for simulating the clinical curing condition of composite in dental cavity.The painted surface was recorded by a charge-coupled device (CCD) camera before and after curing.Subsequently,the volumetric shrinkage of the specimen was calculated with specialist DIC software based on image cross correlation.In addition,a few factors that may influence the measuring accuracy,including the subset window size,speckle size,illumination light and specimen length,were also evaluated.Results:The volumetric shrinkage of the specimen generally decreases with increasing distance from the irradiated surface with a conspicuous exception being the composite Premise Dentine as its maximum shrinkage occurred at a subsurface distance of about 1 mm instead of the irradiated surface.Zl00 had the greatest maximum shrinkage strain,followed by Z250,Tetric EvoCeram and then Premise Dentine.Larger subset window size made the shrinkage strain contour smoother.But the cost was that some details in the heterogeneity of the material were lost.Very small subset window size resulted in a lot of noise in the data,making it difficult to discern the general pattern in the strain

  12. Advanced optical correlation and digital methods for pattern matching—50th anniversary of Vander Lugt matched filter

    Millán, María S.


    On the verge of the 50th anniversary of Vander Lugt’s formulation for pattern matching based on matched filtering and optical correlation, we acknowledge the very intense research activity developed in the field of correlation-based pattern recognition during this period of time. The paper reviews some domains that appeared as emerging fields in the last years of the 20th century and have been developed later on in the 21st century. Such is the case of three-dimensional (3D) object recognition, biometric pattern matching, optical security and hybrid optical-digital processors. 3D object recognition is a challenging case of multidimensional image recognition because of its implications in the recognition of real-world objects independent of their perspective. Biometric recognition is essentially pattern recognition for which the personal identification is based on the authentication of a specific physiological characteristic possessed by the subject (e.g. fingerprint, face, iris, retina, and multifactor combinations). Biometric recognition often appears combined with encryption-decryption processes to secure information. The optical implementations of correlation-based pattern recognition processes still rely on the 4f-correlator, the joint transform correlator, or some of their variants. But the many applications developed in the field have been pushing the systems for a continuous improvement of their architectures and algorithms, thus leading towards merged optical-digital solutions.

  13. The correlation between dual-color chromogenic in situ hybridization and fluorescence in situ hybridization in assessing HER2 gene amplification in breast cancer

    Pedersen, Marianne; Rasmussen, Birgitte Bruun


    obtained by the 2 methods showed excellent correlation (correlation coefficient 0.95). In conclusion, it is possible by dual-color CISH method to demonstrate HER2 genes and chromosome 17 genes, in the same tissue section and reliably assess HER2 status. The CISH method is a very promising alternative...... invasive breast carcinomas, both FISH and CISH detected HER2 amplification in 24 cases and nonamplification was detected in 47 cases. One case showed a discrepancy between FISH and CISH. The concordance between CISH and FISH was found to be almost perfect (98.6%). The correlation between the HER2 ratios...

  14. Color digital image watermarking based on Contourlet transform domain%一种Contourlet变换域彩色图像数字水印算法



    As an important means of copyright protection,digital watermarking technology has been widely used,but the practical watermark algorithm is scant,especially the relevant algorithm of color image and video image processing. Taking fully into account of the characteristics of human visual system,a binary watermark image is embedded into the low frequency compo-nent(after DWT transform)of the protected image in the color space according to the feature of carrier image,the quantity of the embedded binary watermark information can be adaptively increased according to the actual requirement. Based on the digi-tal watermark embedding algorithm research in Contourlet domain,the embedded process and watermark extraction process of the algorithm are implemented through Matlab software emulation. The emulation result proves that the proposed algorithm can improve the practical application of digital watermarking technology in the real life.%数字水印技术作为版权保护的一种有效手段,在信息安全领域已有一定的实际应用,但实用性的水印算法还较少,特别是与彩色图像及视频图像处理的相关算法凤毛麟角.依靠人类的视觉敏感特性,在彩色图像空间上将一幅二值水印图像根据载体图像的特征,选择性的嵌入到受保护图像的DWT变换后的低频分量中,所嵌入的二值水印信息量可以根据实际需要自适应的增加.在Contourlet域水印的嵌入算法研究基础上,提出并通过Matlab软件仿真完成算法的嵌入过程和水印提取过程.仿真实验证明所提出的算法能够有效提高数字水印技术在现实生活中的实际应用.

  15. The application of digitization of "HSB color model" in pigment teeth's prosthetic restoration%“HSB色彩模型”的数字化在色素牙修复中的应用研究

    章加宇; 孙应明; 张梦洁; 吴梦


    目的:运用“HSB色彩模型”的数字化,提高临床色素牙修复的协调性与精确度.方法:选取2001年6月~2010年6月我科32例色素牙修复患者,共48颗瓷修复体.运用数码相机采集与患者色素牙相近明度的Vita 3D-Master26色比色板中的标准色片的数码照.依据孟塞尔(Munse11)颜色系统,通过“HSB色彩模型”H、S、B数字化,确定最小色差的特定色色片组合,指导瓷粉重组与调配,并对修复体色质效果满意度评价.结果:48颗色素牙修复体中,46颗色质良好,与邻牙色质协调,成功率96%.经卡方检验,x2=23.85,P<0.05,运用“HSB色彩模型”的数字化指导瓷粉重组修复与标准色片比色修复的满意程度有显著差异.结论:运用“HSB色彩模型”的数字化,通过最小色差的组合色片指导瓷粉重组,修复体能完全覆盖所有色素牙的颜色区域,该方法科学、量化、方便、精确.%Objective The aim of this study is to improve coordination and accuracy of clinical pigment teeth in dental restoration by using the digitization of "the HSB color model". Methods 32 cases of pigment in patients with dental restoration were chosen during June 2001 to June 2010 with a total of 48 ceramic restorations.The digital photos of the brightness of the standard color chip in Vita 3D-Master26 color swatch which were similar to patient's pigment teeth were collected by digital camera.The combination of minimum chromatic aberration color film was determined and guide the porcelain powder reorganization and deployment by the digitization of HSB color model according to Munsell (Munsell) color system,then the satisfactory of dental prosthetic restoration's color quality was evaluated. Results 46 dental prosthetic restorations' color quality were in coordination with adjacent teeth's color quality during 48 dental prosthetic restorations.The success rate was 96% There were significant differences of satisfaction between porcelain powder

  16. Evaluation of degree of blending colored diluents using color difference signal method.

    Miyazaki, Yasunori; Uchino, Tomonobu; Kagawa, Yoshiyuki


    We developed a color difference signal method to evaluate the degree of blending powdered medicines in pharmacies. In the method, the degree of blending is expressed as the relative standard deviation of the color difference signal value (Cb or Cr) of the YCbCr color space after digital photos of the blended medicines are analyzed by image processing. While the method is effective to determine the degree of blending colored medicines, it remains unknown whether it can be applied to uncolored or white-colored medicines. To investigate this, we examined colored diluents to identify an indicator of the degree mixtures are blended. In this study, we applied this method to Pontal® and Prednisolone® powders, which were used as uncolored and white-colored medicines, respectively. Each of these medicines was blended with the colored lactose using a pestle and mortar, and then the uniformity of blending was evaluated. The degree of blending was well-monitored in both mixtures with various blending ratios (1 : 9-9 : 1), showing a sufficient uniformity at 60 rotations of the pestle. Moreover, the Cr values of the mixtures with various blending ratios were correlated with the concentration of active pharmaceutical ingredients in these medicines, which was determined using HPLC. This indicated the usefulness of the color difference signal method for the quantitative determination of medicines. Thus, we demonstrated the applicability and effectiveness of this method to check dispensing powders.

  17. An Application of Image Analysis and Colorimetric Methods on Color Change of Dehydrated Asparagus (Asparagus maritimus L.

    Jasmina Lukinac


    Full Text Available Shape and color are key factors in quality evaluation of fresh asparagus (Asparagus maritimus L.. Typical green color of asparagus comes from the chlorophyll, pigment which has been degradated during drying process. The aim of this paper was to compare color changes of asparagus dried in laboratory tray drier equipment at different temperatures (40 °C, 50 °C, 60 °C and 70 °C at airflow velocity of 2.75 ms-1. Color changes were obtained by digital image analysis in RGB color model and by chromameter in L*a*b* color model. Basic elements of image analysis system were low voltage halogen lamps with reflector, digital camera and programs for image pre-processing and analysis.Mean values of color parameters, color changes and correlation coefficients for asparagus were calculated for both color models. An analysis showed statistically significant influence of drying temperature on hue angle and total color change for both chosen color models of dehydrated asparagus. Represented results show that there was no statistically significant difference according to color changes between drying at 50 °C and 60 °C. Calculated correlation coefficient between color changes for used models was found to be 0.9167.

  18. 基于彩色图像的灰度仿真数码提花织物设计%Grey simulative design of digital jacquard fabric based on colorful image

    周赳; 唐澜倩


    In order to keep the color information of digital image during grey simulative design of jacquard fabric, this paper puts forword a new method of grey simulative effect digital jacquard fabric with multiple set of weft yarns. Applying to layered-combination mode, full-color weave points and weave structure, colorful digital pattern can be directly used in grey simulative jacquard fabric, and using multiple set of weft grey yarns, grey simulative fabric based on colorful digital pattern can be done. Moreover, the fabric structure has kept color information. Using colorful yarns, the color of the pattern can be simulated in the meantime. This method meets the requirement of simulative digital pattern in fabric, and the process, which can do the business of massive production system, opens up the field of digital jacquard fabric design innovation.%为了在灰度仿真提花织物设计中保留数码图像的色彩信息,提出一种基于多组纬的灰度仿真提花织物的设计原理和方法.结合数码提花织物分层组合模式和全显色组合结构设计方法,通过分色然后组合的方法,可以将彩色效果的数码图像直接用于灰度仿真提花织物的设计.该方法采用多组灰度效果的纱线来还原数码图像的灰度效果,实现了提花织物对数码图像灰度效果的仿真设计.另外,由于获得的灰度仿真提花织物的分层结构保留了分色信息,若将灰度纱线换成有色纱线,则可以设计各种彩色效果的数码提花织物.采用该方法设计的织物能满足大批量生产的技术要求,为数码提花织物的设计创新提供借鉴.

  19. Mapping soil deformation around plant roots using in vivo 4D X-ray Computed Tomography and Digital Volume Correlation.

    Keyes, S D; Gillard, F; Soper, N; Mavrogordato, M N; Sinclair, I; Roose, T


    The mechanical impedance of soils inhibits the growth of plant roots, often being the most significant physical limitation to root system development. Non-invasive imaging techniques have recently been used to investigate the development of root system architecture over time, but the relationship with soil deformation is usually neglected. Correlative mapping approaches parameterised using 2D and 3D image data have recently gained prominence for quantifying physical deformation in composite materials including fibre-reinforced polymers and trabecular bone. Digital Image Correlation (DIC) and Digital Volume Correlation (DVC) are computational techniques which use the inherent material texture of surfaces and volumes, captured using imaging techniques, to map full-field deformation components in samples during physical loading. Here we develop an experimental assay and methodology for four-dimensional, in vivo X-ray Computed Tomography (XCT) and apply a Digital Volume Correlation (DVC) approach to the data to quantify deformation. The method is validated for a field-derived soil under conditions of uniaxial compression, and a calibration study is used to quantify thresholds of displacement and strain measurement. The validated and calibrated approach is then demonstrated for an in vivo test case in which an extending maize root in field-derived soil was imaged hourly using XCT over a growth period of 19h. This allowed full-field soil deformation data and 3D root tip dynamics to be quantified in parallel for the first time. This fusion of methods paves the way for comparative studies of contrasting soils and plant genotypes, improving our understanding of the fundamental mechanical processes which influence root system development.

  20. Interpreting digit ratio (2D:4D)-behavior correlations: 2D:4D sex difference, stability, and behavioral correlates and their replicability in young children.

    Wong, Wang I; Hines, Melissa


    The popularity of using the ratio of the second to the fourth digit (2D:4D) to study influences of early androgen exposure on human behavior relies, in part, on a report that the ratio is sex-dimorphic and stable from age 2 years (Manning etal., 1998). However, subsequent research has rarely replicated this finding. Moreover, although 2D:4D has been correlated with many behaviors, these correlations are often inconsistent. Young children's 2D:4D-behavior correlations may be more consistent than those of older individuals, because young children have experienced fewer postnatal influences. To evaluate the usefulness of 2D:4D as a biomarker of prenatal androgen exposure in studies of 2D:4D-behavior correlations, we assessed its sex difference, temporal stability, and behavioral correlates over a 6- to 8-month period in 126, 2- to 3-year-old children, providing a rare same-sample replicability test. We found a moderate sex difference on both hands and high temporal stability. However, between-sex overlap and within-sex variability were also large. Only 3 of 24 correlations with sex-typed behaviors-scores on the Preschool Activities Inventory (PSAI), preference for a boy-typical toy, preference for a girl-typical toy, were significant and in the predicted direction, all of which involved the PSAI, partially confirming findings from another study. Correlation coefficients were larger for behaviors that showed larger sex differences. But, as in older samples, the overall pattern showed inconsistency across time, sex, and hand. Therefore, although sex-dimorphic and stable, 2D:4D-behavior correlations are no more consistent for young children than for older samples. Theoretical and methodological implications are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. A Digital Correlation Spectrometer Chip with 1 GHz Bandwidth, 4096 Spectral Channels, and 4 W Power Consumption for Passive Microwave Remote Sensing Instruments Project

    National Aeronautics and Space Administration — The scope of this project is to provide a digital auto-correlation spectrometer fabricated on a single integrated circuit for NASA's future Earth-Sun System missions...

  2. Photopolarimetric Monitoring of Blazars in the Optical and Near-Infrared Bands with the Kanata Telescope: I. Correlations between Flux, Color, and Polarization

    Ikejiri, Yuki; Sasada, Mahito; Ito, Ryosuke; Yamanaka, Masayuki; Sakimoto, Kiyoshi; Arai, Akira; Fukazawa, Yasushi; Ohsugi, Takashi; Kawabata, Koji S; Yoshida, Michitoshi; Sato, Shuji; Kino, Masaru


    We report on the correlation between flux, color and polarization variations on time scales of days-months in blazars, and discuss their universal aspects. We performed monitoring of 42 blazars in the optical and near-infrared bands from 2008 to 2010 using TRISPEC attached to the "Kanata" 1.5-m telescope. We found that 28 blazars exhibited "bluer-when-brighter" trends in their whole or a part of time-series data sets. This corresponds to 88% of objects that were observed for >10 days. Thus, our observation unambiguously confirmed that the "bluer-when-brighter" trend is common in the emission from blazar jets. This trend was apparently generated by a variation component with a constant and relatively blue color and an underlying red component. Prominent short-term flares on time scales of days-weeks tended to exhibit a spectral hysteresis; their rising phases were bluer than their decay phases around the flare maxima. In contrast to the strong flux-color correlation, the correlation of the flux and polarizatio...

  3. Benchmarking of depth of field for large out-of-plane deformations with single camera digital image correlation

    Van Mieghem, Bart; Ivens, Jan; Van Bael, Albert


    A problem that arises when performing stereo digital image correlation in applications with large out-of-plane displacements is that the images may become unfocused. This unfocusing could result in correlation instabilities or inaccuracies. When performing DIC measurements and expecting large out-of-plane displacements researchers either trust on their experience or use the equations from photography to estimate the parameters affecting the depth of field (DOF) of the camera. A limitation of the latter approach is that the definition of sharpness is a human defined parameter and that it does not reflect the performance of the digital image correlation system. To get a more representative DOF value for DIC applications, a standardised testing method is presented here, making use of real camera and lens combinations as well as actual image correlation results. The method is based on experimental single camera DIC measurements of a backwards moving target. Correlation results from focused and unfocused images are compared and a threshold value defines whether or not the correlation results are acceptable even if the images are (slightly) unfocused. By following the proposed approach, the complete DOF of a specific camera/lens combination as function of the aperture setting and distance from the camera to the target can be defined. The comparison between the theoretical and the experimental DOF results shows that the achievable DOF for DIC applications is larger than what theoretical calculations predict. Practically this means that the cameras can be positioned closer to the target than what is expected from the theoretical approach. This leads to a gain in resolution and measurement accuracy.

  4. Measurement of Full Field Strains in Filament Wound Composite Tubes Under Axial Compressive Loading by the Digital Image Correlation (DIC) Technique


    McNeill , S. R. Determination of Displacements Using an Improved Digital Image Correlation Method. Computer Vision August 1983. 13 12. Bruck, H. A... McNeill , S. R.; Russell, S. S.; Sutton, M. A. Use of Digital Image Correlation for Determination of Displacements and Strains. Non-Destructive...Evaluation for Aerospace Requirements, 1989. 13. Sutton, M. A.; McNeill , S. R.; Helm, J. D.; Schreier, H. Full-field Non-Contacting Measurement of

  5. Color-coded digital subtraction angiography in the management of a rare case of middle cerebral artery pure arterial malformation. A technical and case report.

    Feliciano, Caleb E; Pamias-Portalatin, Eva; Mendoza-Torres, Jorge; Effio, Euclides; Moran, Yadira; Rodriguez-Mercado, Rafael


    The advent of flow dynamics and the recent availability of perfusion analysis software have provided new diagnostic tools and management possibilities for cerebrovascular patients. To this end, we provide an example of the use of color-coded angiography and its application in a rare case of a patient with a pure middle cerebral artery (MCA) malformation. A 42-year-old male chronic smoker was evaluated in the emergency room due to sudden onset of severe headache, nausea, vomiting and left-sided weakness. Head computed tomography revealed a right basal ganglia hemorrhage. Cerebral digital subtraction angiography (DSA) showed a right middle cerebral artery malformation consisting of convoluted and ectatic collateral vessels supplying the distal middle cerebral artery territory-M1 proximally occluded. An associated medial lenticulostriate artery aneurysm was found. Brain single-photon emission computed tomography with and without acetazolamide failed to show problems in vascular reserve that would indicate the need for flow augmentation. Twelve months after discharge, the patient recovered from the left-sided weakness and did not present any similar events. A follow-up DSA and perfusion study using color-coded perfusion analysis showed perforator aneurysm resolution and adequate, albeit delayed perfusion in the involved vascular territory. We propose a combined congenital and acquired mechanism involving M1 occlusion with secondary dysplastic changes in collateral supply to the distal MCA territory. Angiographic and cerebral perfusion work-up was used to exclude the need for flow augmentation. Nevertheless, the natural course of this lesion remains unclear and long-term follow-up is warranted.

  6. Effect's of Cross-Correlation Between Real and Imaginary Parts of Colored Pump Noise in Transient Process of Single-Mode Laser

    ZHANG Li; CAO Li; WU Da-Jin


    A two-dimensional single-mode laser model with cross-correlation between the real and imaginary parts of the colored quadric pump noise is investigated. A novel laser amplitude Langevin equation is obtained, in which the cross-correlation λp between the real and imaginary parts of the pump noise appears. The mean, variance, and skewness of first-passage-time are calculated. It is shown that the mean, variance, and skewness of first-passage-time are strongly affected by λp.

  7. Image composition with color harmonization

    Congde Wang; Rong Zhang; Fan Deng


    Image matting and color transfer are combined to achieve image composition.Firstly,digital matting is used to pull out the region of interest.Secondly,taking color harmonization into account,color transfer techniques are introduced in pasting the region onto the target image.Experimental results show that the proposed approach generates visually plea.sing composite images.

  8. Quasi-static tensile deformation and fracture behavior of a highly particle-filled composite using digital image correlation method


    Polymer bonded explosives (PBXs) are highly particle-filled composite materials.This paper experimentally studies the tensile deformation and fracture behavior of a PBX simulation by using the semi-circular bending (SCB) test.The deformation and fracture process of a pre-notched SCB sample with a random speckle pattern is recorded by a charge coupled device camera.The displacement and strain fields on the observed surface during the loading process are obtained by using the digital image correlation method....

  9. Validation of Shape Context Based Image Registration Method Using Digital Image Correlation Measurement on a Rat Stomach

    Liao, Donghua; Wang, P; Zhao, Jingbo


    needs to be further verified by using a feature tracking measurement. Hence, the aim of this study was to verify the SC method-based calculation by using digital image correlation (DIC) measurement on a rat stomach. The rat stomach exposed to distension pressures 0.0, 0.2, 0.4, and 0.6 kPa were studied...... and quantitative agreement on the surfaces with small dissimilarity and small sample count difference between the reference surface and the target surface. In conclusion, this is the first study to validate the 3D SC-based image registration method by using unique tracking features measurement. The developed...

  10. Spectrum Optimization of Bi-color and Tri-color Phosphor-converted White LEDs in Neutral Correlated Color Temperature System%中性色温下两基色、三基色荧光粉转换白光 LED 的光谱优化

    戴树春; 郭自泉; 吕毅军; 陈忠


    针对中性色温4870 K,考虑斯托克斯损失,研究了两基色、三基色的白光LED的光谱优化.结果表明:InGaN/GaN基蓝光LED激发YAG荧光粉合成的白光光视效能可高达483.5 lm/W,但显色性较差,计算的斯托克斯效率为83.9%.加入窄带红色荧光粉或红光LED,优化后的光视效能降低为343 lm/W,但显色指数升至94.7,同时计算得到该LED的斯托克斯效率为84.4%.对该优化的三基色LED光谱进行可调色温白光的特性分析,发现较高色温( >4000 K)对应的显色指数普遍高于低色温( <4000 K)的显色指数.%The spectra of the bi-color and tri-color phosphor-converted white LED were optimized in the neutral correlated color temperature of 4 870 K with consideration of Stokes shift energy loss. The results showed that a high luminous efficacy of radiation up to 483 lm/W could be attained in the case of the white LED composed of blue chip and YAG phosphor but with a poor color quality and 83.9% Stokes efficiency. When a narrow-band red phosphor or LED chip was added to the bi-color white LED, a good color rendering index of 94. 7 was gained with a reduced luminous efficacy of radiation 343 lm/W and a Stokes efficiency of 84.4%. Later, we characterized the performance of tunable-color-temperature tri-color white LED. It was found that the color rendering index was better when the correlated color temperature exceeded 4 000 K.

  11. Social Media Usage In European Clubs Football Industry. Is Digital Reach Better Correlated With Sports Or Financial Performane?

    Teodor Dima


    Full Text Available Social media is likely the marketing and communication channel which grew fastest from "unique and modern" to "mandatory". Presented as a solution for the future, usage of media channels has already become a key part of any brand promoting campaign or business expansion effort. And football clubs line up with this trend. Development of the new media elements solves two fundamental needs for business units specialized in sports: the need for faster and more efficient communication with fans - a true two-way relationship - and the need to expand the base of supporters using marketing tools. This paper presents the usage of social media networks in European club football industry, the mix of channels used and the increase of digital supporters for the top teams. This academic approach also examines the correlation between the digital reach of the richest clubs in the world and their sports and financial results. This study shows the growing importance that social media plays in the sports industry, initiating a debate on the relationship between the digital expansion of a football club and its sports and financials indicators.

  12. Color-induced graph colorings

    Zhang, Ping


    A comprehensive treatment of color-induced graph colorings is presented in this book, emphasizing vertex colorings induced by edge colorings. The coloring concepts described in this book depend not only on the property required of the initial edge coloring and the kind of objects serving as colors, but also on the property demanded of the vertex coloring produced. For each edge coloring introduced, background for the concept is provided, followed by a presentation of results and open questions dealing with this topic. While the edge colorings discussed can be either proper or unrestricted, the resulting vertex colorings are either proper colorings or rainbow colorings. This gives rise to a discussion of irregular colorings, strong colorings, modular colorings, edge-graceful colorings, twin edge colorings and binomial colorings. Since many of the concepts described in this book are relatively recent, the audience for this book is primarily mathematicians interested in learning some new areas of graph colorings...

  13. New measuring concepts using integrated online analysis of color and monochrome digital high-speed camera sequences

    Renz, Harald


    High speed sequences allow a subjective assessment of very fast processes and serve as an important basis for the quantitative analysis of movements. Computer systems help to acquire, handle, display and store digital image sequences as well as to perform measurement tasks automatically. High speed cameras have been used since several years for safety tests, material testing or production optimization. To get the very high speed of 1000 or more images per second, three have been used mainly 16 mm film cameras, which could provide an excellent image resolution and the required time resolution. But up to now, most results have been only judged by viewing. For some special applications like safety tests using crash or high-g sled tests in the automobile industry there have been used image analyzing techniques to measure also the characteristic of moving objects inside images. High speed films, shot during the short impact, allow judgement of the dynamic scene. Additionally they serve as an important basis for the quantitative analysis of the very fast movements. Thus exact values of the velocity and acceleration, the dummies or vehicles are exposed to, can be derived. For analysis of the sequences the positions of signalized points--mostly markers, which are fixed by the test engineers before a test--have to be measured frame by frame. The trajectories show the temporal sequence of the test objects and are the base for calibrated diagrams of distance, velocity and acceleration. Today there are replaced more and more 16 mm film cameras by electronic high speed cameras. The development of high-speed recording systems is very far advanced and the prices of these systems are more and more comparable to those of traditional film cameras. Also the resolution has been increased very greatly. The new cameras are `crashproof' and can be used for similar tasks as the 16 mm film cameras at similar sizes. High speed video cameras now offer an easy setup and direct access to

  14. De-noising of digital image correlation based on stationary wavelet transform

    Guo, Xiang; Li, Yulong; Suo, Tao; Liang, Jin


    In this paper, a stationary wavelet transform (SWT) based method is proposed to de-noise the digital image with the light noise, and the SWT de-noise algorithm is presented after the analyzing of the light noise. By using the de-noise algorithm, the method was demonstrated to be capable of providing accurate DIC measurements in the light noise environment. The verification, comparative and realistic experiments were conducted using this method. The result indicate that the de-noise method can be applied to the full-field strain measurement under the light interference with a high accuracy and stability.

  15. Macro-carriers of plastic deformation of steel surface layers detected by digital image correlation

    Kopanitsa, D. G., E-mail:; Ustinov, A. M., E-mail: [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); Potekaev, A. I., E-mail: [National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Klopotov, A. A., E-mail: [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Kopanitsa, G. D., E-mail: [National Research Tomsk Polytechnic University, 30 Lenin Ave., Tomsk, 634050 (Russian Federation)


    This paper presents a study of characteristics of an evolution of deformation fields in surface layers of medium-carbon low-alloy specimens under compression. The experiments were performed on the “Universal Testing Machine 4500” using a digital stereoscopic image processing system Vic-3D. A transition between stages is reflected as deformation redistribution on the near-surface layers. Electronic microscopy shows that the structure of the steel is a mixture of pearlite and ferrite grains. A proportion of pearlite is 40% and ferrite is 60%.

  16. Applications of digital image processing techniques to problems of data registration and correlation

    Green, W. B.


    An overview is presented of the evolution of the computer configuration at JPL's Image Processing Laboratory (IPL). The development of techniques for the geometric transformation of digital imagery is discussed and consideration is given to automated and semiautomated image registration, and the registration of imaging and nonimaging data. The increasing complexity of image processing tasks at IPL is illustrated with examples of various applications from the planetary program and earth resources activities. It is noted that the registration of existing geocoded data bases with Landsat imagery will continue to be important if the Landsat data is to be of genuine use to the user community.

  17. In-situ strain localization analysis in low density transformation-twinning induced plasticity steel using digital image correlation

    Eskandari, M.; Yadegari-Dehnavi, M. R.; Zarei-Hanzaki, A.; Mohtadi-Bonab, M. A.; Basu, R.; Szpunar, J. A.


    The effect of deformation temperature on the strain localization has been evaluated by an adapted digital image correlation (DIC) technique during tensile deformation. The progress of strain localization was traced by the corresponding strain maps. The electron backscatter diffraction analysis and tint etching technique were utilized to determine the impact of martensitic transformation and deformation twinning on the strain localization in both elastic and plastic regimes. In elastic regime the narrow strain bands which are aligned perpendicular to the tension direction were observed in temperature range of 25 to 180 °C due to the stress-assisted epsilon martensite. The strain bands were disappeared by increasing the temperature to 300 °C and reappeared at 400 °C due to the stress-assisted deformation twinning. In plastic regime strain localization continued at 25 °C and 180 °C due to the strain-induced alfa-martensite and deformation twinning, respectively. The intensity of plastic strain localization was increased by increasing the strain due to the enhancement of martensite and twin volume fraction. The plastic strain showed more homogeneity at 300 °C due to the lack of both strain-induced martensite and deformation twinning. Effect of deformation mechanism by changing temperature on strain localization is investigated by digital image correlation. EBSD technique is served to validate deformation mechanism as well as microstructural evolution. Strain induced martensite as well as deformation twinning is activated in the present steel affecting strain localization.

  18. Steady-State Analysis of a Single-Mode Laser Driven by Colored Pump Noise withCross-Correlation Between Real and Imaginary Parts of Quantum Noise

    ZHANGLi; CAOLi; WUDa-Jin


    Applying the method of the unified colored noise approximation and phase lock, we study in this paper the stationary intensity distribution of the single-mode laser driven by colored pump noise with cross-correlation between the real and imaginary parts of the quantum noise. We present a thorough discussion of how the cross-correlation λq between the real and imaginary parts of the quantum noise and the self-correlation time τ of the pump noise determine the behaviors of the stationary distribution Qst(I), the mean (I), and the variance λ2(0) of the laser intensity. It is shown that cross-correlation intensity λq of the complex quantum noise can induce a first-order-like transition. When the pump noise is colored noise (τ≠0), improving the pump parameters monotonously will make the curves of Qst(I) exhibit reentrant phase transition. The fluctuations of laser intensity are strongly influenced by λq and τ when the laser is operated near or below threshold. Especially when τ≠0, the heights of the peaks of the curves of λ2(0)-α0 and α3(0)-α0, (here a0 is the net gain coefficient) go up as λq increases. However the entire curves λ2(0)-α0 and λ3(0)-α0 are abruptly suppressed when λq = 1, in similarity to phase transition of stationary intensity distribution.

  19. Steady-State Analysis of a Single-Mode Laser Driven by Colored Pump Noise with Cross-Correlation Between Real and Imaginary Parts of Quantum Noise

    ZHANG Li; CAO Li; WU Da-Jin


    Applying the method of the unified colored noise approximation and phase lock, we study in this paper the stationary intensity distribution of the single-mode laser driven by colored pump noise with cross-correlation between the real and imaginary parts of the quantum noise. We present a thorough discussion of how the cross-correlation λq between the realand imaginary parts of the quantum noise and the self-correlation time τ of the pump noise determine the behaviors of the stationary distribution Qst(I), the mean (I), and the variance λ2(0) of the laser intensity. It is shown that cross-correlation intensity λq of the complex quantum noise can induce a first-order-like transition. When the pump noise is colored noise (τ≠ 0), improving the pump parameters monotonously will make the curves of Qst(I)exhibit reentrant phase transition. The fluctuations of laser intensity are strongly influenced by λq and τ when the laser is operated near or below threshold. Especially when τ≠ 0, the heights of the peaks of the curves of λ2(0)-a0 and λ3(0)-a0, (here a0 is the net gain coefficient) go up as λq increases. However the entire curves of λ2(0)-a0 and λ3(0)-a0are abruptly suppressed when λq = 1, in similarity to phase transition of stationary intensity distribution.

  20. Reproduction of various colors on Jacquard textiles by only eight kinds of color wefts

    Osaki, Keiji


    By making use of the information of the textile color blocks, reproduction of high-precision colors on fabrics that we call 'Color Image Fabrics' could be woven by Jacquard loom. Color components for each pixel on digitized original image are transformed into weaving data on textile by minimizing the color difference in CIEL*a*b* representation between the original image color and the simulated textile color.

  1. Prevalence of carotid and pulp calcifications: a correlation using digital panoramic radiographs

    Clark, Stephen J. [School of Dentistry, University of Louisville, Department of Periodontics, Endodontics and Dental Hygiene, Louisville, KY (United States); Scheetz, James P.; Khan, Zafrulla [University of Louisville, Department of Diagnostic Sciences, Prosthodontics and Restorative Dentistry, School of Dentistry, Louisville, KY (United States); Farman, Allan G. [School of Dentistry, University of Louisville, Department of Periodontics, Endodontics and Dental Hygiene, Louisville, KY (United States); Horsley, Scott H.; Beckstrom, Brice


    To compare the prevalence of pulp calcification with that of carotid calcification using digital panoramic dental radiographs. Digital panoramic radiographs of patients at a dental oncology clinic were included if (1) the carotid artery bifurcation region was visible bilaterally and (2) the patient had non-restored or minimally restored molars and/or canines. An endodontist evaluated the images for pulpal calcifications in the selected teeth. An oral and maxillofacial radiologist independently evaluated the same images for calcifications in the carotid bifurcation region. Odds-ratio and Pearson {chi}{sup 2} were used for data analysis. Presence of pulpal calcification was also evaluated as a screening test for the presence of carotid calcification. A total of 247 panoramic radiographs were evaluated. 32% (n=80) had pulpal calcifications and 25% (n=61) had carotid calcifications with 12% (n=29) having both carotid and pulp calcifications. A significantly higher prevalence of both pulp and carotid calcification was found in subjects older than age 60 years compared to younger age groups. Accuracy of pulpal calcification in screening for carotid calcification was 66.4%. Both pulp and carotid calcifications were more prevalent in older individuals. The presence of pulp calcification was not a strong predictor for the presence of carotid calcification. (orig.)

  2. Sensory Drive, Color, and Color Vision.

    Price, Trevor D


    Colors often appear to differ in arbitrary ways among related species. However, a fraction of color diversity may be explained because some signals are more easily perceived in one environment rather than another. Models show that not only signals but also the perception of signals should regularly evolve in response to different environments, whether these primarily involve detection of conspecifics or detection of predators and prey. Thus, a deeper understanding of how perception of color correlates with environmental attributes should help generate more predictive models of color divergence. Here, I briefly review our understanding of color vision in vertebrates. Then I focus on opsin spectral tuning and opsin expression, two traits involved in color perception that have become amenable to study. I ask how opsin tuning is correlated with ecological differences, notably the light environment, and how this potentially affects perception of conspecific colors. Although opsin tuning appears to evolve slowly, opsin expression levels are more evolutionarily labile but have been difficult to connect to color perception. The challenge going forward will be to identify how physiological differences involved in color vision, such as opsin expression levels, translate into perceptual differences, the selection pressures that have driven those differences, and ultimately how this may drive evolution of conspecific colors.

  3. Performance analysis and acceleration of cross-correlation computation using FPGA implementation for digital signal processing

    Selma, R.


    Paper describes comparison of cross-correlation computation speed of most commonly used computation platforms (CPU, GPU) with an FPGA-based design. It also describes the structure of cross-correlation unit implemented for testing purposes. Speedup of computations was achieved using FPGA-based design, varying between 16 and 5400 times compared to CPU computations and between 3 and 175 times compared to GPU computations.

  4. Full-field wing deformation measurement scheme for in-flight cantilever monoplane based on 3D digital image correlation

    Li, Lei-Gang; Liang, Jin; Guo, Xiang; Guo, Cheng; Hu, Hao; Tang, Zheng-Zong


    In this paper, a new non-contact scheme, based on 3D digital image correlation technology, is presented to measure the full-field wing deformation of in-flight cantilever monoplanes. Because of the special structure of the cantilever wing, two conjugated camera groups, which are rigidly connected and calibrated to an ensemble respectively, are installed onto the vertical fin of the aircraft and record the whole measurement. First, a type of pre-stretched target and speckle pattern are designed to adapt the oblique camera view for accurate detection and correlation. Then, because the measurement cameras are swinging with the aircraft vertical trail all the time, a camera position self-correction method (using control targets sprayed on the back of the aircraft), is designed to orientate all the cameras’ exterior parameters to a unified coordinate system in real time. Besides, for the excessively inclined camera axis and the vertical camera arrangement, a weak correlation between the high position image and low position image occurs. In this paper, a new dual-temporal efficient matching method, combining the principle of seed point spreading, is proposed to achieve the matching of weak correlated images. A novel system is developed and a simulation test in the laboratory was carried out to verify the proposed scheme.

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

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


    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. Laser color recording unit

    Jung, E.


    A color recording unit was designed for output and control of digitized picture data within computer controlled reproduction and picture processing systems. In order to get a color proof picture of high quality similar to a color print, together with reduced time and material consumption, a photographic color film material was exposed pixelwise by modulated laser beams of three wavelengths for red, green and blue light. Components of different manufacturers for lasers, acousto-optic modulators and polygon mirrors were tested, also different recording methods as (continuous tone mode or screened mode and with a drum or flatbed recording principle). Besides the application for the graphic arts - the proof recorder CPR 403 with continuous tone color recording with a drum scanner - such a color hardcopy peripheral unit with large picture formats and high resolution can be used in medicine, communication, and satellite picture processing.

  7. Single-step scanner-based digital image correlation (SB-DIC) method for large deformation mapping in rubber

    Goh, C. P.; Ismail, H.; Yen, K. S.; Ratnam, M. M.


    The incremental digital image correlation (DIC) method has been applied in the past to determine strain in large deformation materials like rubber. This method is, however, prone to cumulative errors since the total displacement is determined by combining the displacements in numerous stages of the deformation. In this work, a method of mapping large strains in rubber using DIC in a single-step without the need for a series of deformation images is proposed. The reference subsets were deformed using deformation factors obtained from the fitted mean stress-axial stretch ratio curve obtained experimentally and the theoretical Poisson function. The deformed reference subsets were then correlated with the deformed image after loading. The recently developed scanner-based digital image correlation (SB-DIC) method was applied on dumbbell rubber specimens to obtain the in-plane displacement fields up to 350% axial strain. Comparison of the mean axial strains determined from the single-step SB-DIC method with those from the incremental SB-DIC method showed an average difference of 4.7%. Two rectangular rubber specimens containing circular and square holes were deformed and analysed using the proposed method. The resultant strain maps from the single-step SB-DIC method were compared with the results of finite element modeling (FEM). The comparison shows that the proposed single-step SB-DIC method can be used to map the strain distribution accurately in large deformation materials like rubber at much shorter time compared to the incremental DIC method.

  8. Measurement of transient deformation by color encoding.

    Mares, C; Barrientos, B; Blanco, A


    We present a method based on color encoding for measurement of transient 3D deformation in diffuse objects. The object is illuminated by structured light that consists of a fringe pattern with cyan fringes embedded in a white background. Color images are registered and information on each color channel is then separated. Surface features appear on the blue channel while fringes on the red channel. The in-plane components of displacement are calculated via digital correlation of the texture images. Likewise, the resulting fringes serve for the measuring of the out-of-plane component. As crossing of information between signals is avoided, the accuracy of the method is high. This is confirmed by a series of displacement measurements of an aluminum plate.

  9. New techniques in digital holography

    Picart, Pascal


    A state of the art presentation of important advances in the field of digital holography, detailing advances related to fundamentals of digital holography, in-line holography applied to fluid mechanics, digital color holography, digital holographic microscopy, infrared holography, special techniques in full field vibrometry and inverse problems in digital holography

  10. Characterization of invisible breast cancers in digital mammography and tomosynthesis: radio-pathological correlation.

    Aguilar Angulo, P M; Romero Castellano, C; Ruiz Martín, J; Sánchez-Camacho González-Carrato, M P; Cruz Hernández, L M


    To review the radio-pathologic features of symptomatic breast cancers not detected at digital mammography (DM) and digital breast tomosynthesis (DBT). Retrospective analysis of 169 lesions from symptomatic patients with breast cancer that were studied with DM, DBT, ultrasound (US) and magnetic resonance (MR). We identified occult lesions (true false negatives) in DM and DBT. Clinical data, density, US and MR findings were analyzed as well as histopathological results. We identified seven occult lesions in DM and DBT. 57% (4/7) of the lesions were identified in high-density breasts (type c and d), and the rest of them in breasts of density type b. Six carcinomas were identified at US and MR (BI-RADS 4 masses); the remaining lesion was only identified at MR. The tumor size was larger than 3cm at MRI in 57% of the lesions. All tumors were ductal infiltrating carcinomas, six of them with high stromal proportion. According to molecular classification, we found only one triple-negative breast cancer, the other lesions were luminal-type. We analyzed the tumor margins of two resected carcinomas that were not treated with neoadjuvant chemotherapy, both lesions presented margins that displaced the adjacent parenchyma without infiltrating it. Occult breast carcinomas in DM and DBT accounted for 4% of lesions detected in patients with symptoms. They were mostly masses, all of them presented the diagnosis of infiltrating ductal carcinoma (with predominance of the luminal immunophenotype) and were detected in breasts of density type b, c and d. Copyright © 2017 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

  11. Color Blindness

    ... rose in full bloom. If you have a color vision defect, you may see these colors differently than most people. There are three main kinds of color vision defects. Red-green color vision defects are the most ...

  12. Vibration of low amplitude imaged in amplitude and phase by sideband versus carrier correlation digital holography

    Verrier, N; Gross, M


    Sideband holography can be used to get fields images (E0 and E1) of a vibrating object for both the carrier (E0) and the sideband (E1) frequency with respect to vibration. We propose here to record E0 and E1 sequentially, and to image the correlation E1E * 0 . We show that this correlation is insensitive the phase related to the object roughness and directly reflect the phase of the mechanical motion. The signal to noise can be improved by averaging the correlation over neighbor pixel. Experimental validation is made with vibrating cube of wood and with a clarinet reed. At 2 kHz, vibrations of amplitude down to 0.01 nm are detected.

  13. Effects of melamine formaldehyde resin and CaCO3 diffuser-loaded encapsulation on correlated color temperature uniformity of phosphor-converted LEDs.

    Yang, Liang; Lv, Zhicheng; Jiaojiao, Yuan; Liu, Sheng


    Phosphor-free dispensing is the most widely used LED packaging method, but this method results in poor quality in angular CCT uniformity. This study proposes a diffuser-loaded encapsulation to solve the problem; the effects of melamine formaldehyde (MF) resin and CaCO3 loaded encapsulation on correlated color temperature (CCT) uniformity and luminous efficiency reduction of the phosphor-converted LEDs are investigated. Results reveal that MF resin loaded encapsulation has better light diffusion performance compared to MF resin loaded encapsulation at the same diffuser concentration, but CaCO3 loaded encapsulation has better luminous efficiency maintenance. The improvements in angular color uniformity for the LEDs emitting with MF resin and CaCO3 loaded encapsulation can be explained by the increase in photon scattering. The utility of this low cost and controllable mineral diffuser packaging method provides a practical approach for enhancing the angular color uniformity of LEDs. The diffuser mass ratio of 1% MF resin or 10% CaCO3 is the optimum condition to obtain low angular CCT variance and high luminous efficiency.

  14. The Correlation Between Atmospheric Dust Deposition to the Surface Ocean and SeaWiFS Ocean Color: A Global Satellite-Based Analysis

    Erickson, D. J., III; Hernandez, J.; Ginoux, P.; Gregg, W.; Kawa, R.; Behrenfeld, M.; Esaias, W.; Einaudi, Franco (Technical Monitor)


    Since the atmospheric deposition of iron has been linked to primary productivity in various oceanic regions, we have conducted an objective study of the correlation of dust deposition and satellite remotely sensed surface ocean chlorophyll concentrations. We present a global analysis of the correlation between atmospheric dust deposition derived from a satellite-based 3-D atmospheric transport model and SeaWiFs estimates of ocean color. We use the monthly mean dust deposition fields of Ginoux et al. which are based on a global model of dust generation and transport. This model is driven by atmospheric circulation from the Data Assimilation Office (DAO) for the period 1995-1998. This global dust model is constrained by several satellite estimates of standard circulation characteristics. We then perform an analysis of the correlation between the dust deposition and the 1998 SeaWIFS ocean color data for each 2.0 deg x 2.5 deg lat/long grid point, for each month of the year. The results are surprisingly robust. The region between 40 S and 60 S has correlation coefficients from 0.6 to 0.95, statistically significant at the 0.05 level. There are swaths of high correlation at the edges of some major ocean current systems. We interpret these correlations as reflecting areas that have shear related turbulence bringing nitrogen and phosphorus from depth into the surface ocean, and the atmospheric supply of iron provides the limiting nutrient and the correlation between iron deposition and surface ocean chlorophyll is high. There is a region in the western North Pacific with high correlation, reflecting the input of Asian dust to that region. The southern hemisphere has an average correlation coefficient of 0.72 compared that in the northern hemisphere of 0.42 consistent with present conceptual models of where atmospheric iron deposition may play a role in surface ocean biogeochemical cycles. The spatial structure of the correlation fields will be discussed within the context

  15. Color Doppler ultrasound detection of uterine artery S/D, PI and RI in patients with preeclampsia and their correlation with disease severity

    Yan-Ping Zhao


    Objective:To study color Doppler ultrasound detection of uterine artery S/D, PI and RI in patients with preeclampsia and their correlation with disease severity.Methods:Pregnant women with preeclampsia were selected as PE group, healthy pregnant women were the NOR group, color Doppler ultrasound detection was conducted to detect uterine artery S/D, PI and RI, serum was collected to detect the contents of angiogenesis-related cytokines, and placenta tissue was collected to detect the contents of proteases as well as inhibitors, oxidative stress molecules and anti-apoptotic molecules.Results: S/D, PI and RI of PE group were significantly higher than those of NOR group; serum PIGF, VEGF and PAPP-A contents of PE group were significantly lower than those of NOR group and negatively correlated with S/D, PI and RI while sVEGFR-1 and Kisspeptin-10 contents were significantly higher than those of NOR group and positively correlated with S/D, PI and RI; CTSB, CTSL, MMP3, MMP9, SOD, GST, VitC, VitE and coenzyme Q10 as well as Xiap and Survivin contents in placenta tissue of PE group were lower than those of NOR group and negatively correlated with S/D, PI and RI while TIMP1, TIMP2, TIMP3 and RECK contents were higher than those of NOR group and positively correlated with S/D, PI and RI.Conclusion: Uterine artery S/D, PI and RI significantly increase in patients with preeclampsia, and can assess the angiogenesis, cell invasion, anti-apoptosis and oxidative stress in patients.

  16. Cerebral Circulation Time is Prolonged and Not Correlated with EDSS in Multiple Sclerosis Patients: A Study Using Digital Subtracted Angiography

    Monti, Lucia; Donati, Donatella; Menci, Elisabetta; Cioni, Samuele; Bellini, Matteo; Grazzini, Irene; Leonini, Sara; Galluzzi, Paolo; Severi, Sauro; Burroni, Luca; Casasco, Alfredo; Morbidelli, Lucia; Santarnecchi, Emiliano; Piu, Pietro


    Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis. In this study, digital subtraction angiography (DSA) was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS). DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered. A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27s) and control group (mean = 2.8s; sd = 0.51s) was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS patients. Significantly increased CCT value in MS patients suggests the presence of microvascular dysfunctions, which do not depend on clinical and MRI findings. Hemodynamic changes may not be exclusively the result of a late chronic inflammatory process. PMID:25679526

  17. Cerebral circulation time is prolonged and not correlated with EDSS in multiple sclerosis patients: a study using digital subtracted angiography.

    Lucia Monti

    Full Text Available Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis. In this study, digital subtraction angiography (DSA was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS. DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered. A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27 s and control group (mean = 2.8s; sd = 0.51 s was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS patients. Significantly increased CCT value in MS patients suggests the presence of microvascular dysfunctions, which do not depend on clinical and MRI findings. Hemodynamic changes may not be exclusively the result of a late chronic inflammatory process.

  18. Cerebral circulation time is prolonged and not correlated with EDSS in multiple sclerosis patients: a study using digital subtracted angiography.

    Monti, Lucia; Donati, Donatella; Menci, Elisabetta; Cioni, Samuele; Bellini, Matteo; Grazzini, Irene; Leonini, Sara; Galluzzi, Paolo; Bracco, Sandra; Severi, Sauro; Burroni, Luca; Casasco, Alfredo; Morbidelli, Lucia; Santarnecchi, Emiliano; Piu, Pietro


    Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis. In this study, digital subtraction angiography (DSA) was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS). DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered. A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27 s) and control group (mean = 2.8s; sd = 0.51 s) was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS patients. Significantly increased CCT value in MS patients suggests the presence of microvascular dysfunctions, which do not depend on clinical and MRI findings. Hemodynamic changes may not be exclusively the result of a late chronic inflammatory process.

  19. Accurate kinematic measurement at interfaces between dissimilar materials using conforming finite-element-based digital image correlation

    Tao, Ran


    Digital image correlation (DIC) is now an extensively applied full-field measurement technique with subpixel accuracy. A systematic drawback of this technique, however, is the smoothening of the kinematic field (e.g., displacement and strains) across interfaces between dissimilar materials, where the deformation gradient is known to be large. This can become an issue when a high level of accuracy is needed, for example, in the interfacial region of composites or joints. In this work, we described the application of global conforming finite-element-based DIC technique to obtain precise kinematic fields at interfaces between dissimilar materials. Speckle images from both numerical and actual experiments processed by the described global DIC technique better captured sharp strain gradient at the interface than local subset-based DIC. © 2016 Elsevier Ltd. All rights reserved.

  20. Digital image correlation and finite element modelling as a method to determine mechanical properties of human soft tissue in vivo

    Moerman, Kevin M; Evans, Sam L; Simms, Ciaran K


    The mechanical properties of human soft tissue are crucial for impact biomechanics, rehabilitation engineering and surgical simulation. Validation of these constitutive models using human data remains challenging and often requires the use of non-invasive imaging and inverse finite element (FE) analysis. Post processing data from imaging methods such as tagged magnetic resonance imaging (MRI) can be challenging. Digital Image Correlation (DIC) however is a relatively straightforward imaging method and thus the goal of this study was to assess the use of DIC in combination with FE modelling to determine the bulk material properties of human soft tissue. Indentation experiments were performed on a silicone gel soft tissue phantom. A two camera DIC setup was then used to record the 3D surface deformation. The experiment was then simulated using a FE model.

  1. Strain distribution in the intervertebral disc under unconfined compression and tension load by the optimized digital image correlation technique.

    Liu, Qing; Wang, Tai-Yong; Yang, Xiu-Ping; Li, Kun; Gao, Li-Lan; Zhang, Chun-Qiu; Guo, Yue-Hong


    The unconfined compression and tension experiments of the intervertebral disc were conducted by applying an optimized digital image correlation technique, and the internal strain distribution was analysed for the disc. It was found that the axial strain values of different positions increased obviously with the increase in loads, while inner annulus fibrosus and posterior annulus fibrosus experienced higher axial strains than the outer annulus fibrosus and anterior annulus fibrosus. Deep annulus fibrosus exhibited higher compressive and tensile axial strains than superficial annulus fibrosus for the anterior region, while there was an opposite result for the posterior region. It was noted that all samples demonstrated a nonlinear stress-strain profile in the process of deforming, and an elastic region was shown once the sample was deformed beyond its toe region.

  2. Validation of Shape Context Based Image Registration Method Using Digital Image Correlation Measurement on a Rat Stomach

    Liao, Donghua; Wang, P; Zhao, Jingbo


    Recently we developed analysis for 3D visceral organ deformation by combining the shape context (SC) method with a full-field strain (strain distribution on a whole 3D surface) analysis for calculating distension-induced rat stomach deformation. The surface deformation detected by the SC method...... needs to be further verified by using a feature tracking measurement. Hence, the aim of this study was to verify the SC method-based calculation by using digital image correlation (DIC) measurement on a rat stomach. The rat stomach exposed to distension pressures 0.0, 0.2, 0.4, and 0.6 kPa were studied...... using both 3D DIC system and SC-based image registration calculation. Three different surface sample counts between the reference and the target surfaces were usedto gauge the effect of the surface sample counts on the calculation. Each pair of the surface points between the DIC measured target surface...

  3. Damage law identification of a quasi brittle ceramic from a b ending test using digital image correlation

    Meille S.


    Full Text Available The quasi brittle ceramics show a non linear mechanical behaviour resulting most of the time in a dissymetry between their tensile and compressive stress-strain laws. The characterization of their fracture strengths might be biased if elastic linear formulae are used to analyze classical tests like bending tests. Based on Digital Image Correlation (DIC, a methodology is proposed to characterize materials with dissymmetric behaviours. Applying specific DIC decomposition functions for bending, compressive and tensile tests, a stress-strain model and its damage law are identified for aluminium titanate, a damageable micro cracked ceramic. This identification method using DIC can obviously be applied to other quasi brittle materials.

  4. Digital image correlation analysis of local strain fields on Ti6Al4V manufactured by electron beam melting

    Karlsson, Joakim, E-mail: [SP Technical Research Institute of Sweden, Box 857, SE-501 15, Borås (Sweden); Division of Applied Materials Science, Department of Engineering Sciences, Ångström Laboratory, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Sjögren, Torsten [SP Technical Research Institute of Sweden, Box 857, SE-501 15, Borås (Sweden); Snis, Anders [Arcam AB, Krokslätts fabriker 27 A, SE-431 37, Mölndal (Sweden); Engqvist, Håkan [Division of Applied Materials Science, Department of Engineering Sciences, Ångström Laboratory, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Lausmaa, Jukka [SP Technical Research Institute of Sweden, Box 857, SE-501 15, Borås (Sweden)


    Additive manufacturing, or 3D-printing as it is often called, build parts in a layer-by-layer fashion. A common concern, regardless of the specific additive manufacturing technique used, is the risk of inadequate fusion between the adjacent layers which in turn may cause inferior mechanical properties. In this work, the local strain properties of titanium parts produced by Electron Beam Melting (EBM{sup ®}) were studied in order to gain information about the quality of fusion of the stock powder material used in the process. By using Digital Image Correlation (DIC) the strain fields in the individual layers were analyzed, as well as the global strain behavior of the bulk material. The results show that fully solid titanium parts manufactured by EBM are homogenous and do not experience local deformation behavior, neither on local nor on a global level.

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

    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.

  6. Cross-modal, bidirectional priming in grapheme-color synesthesia

    Paffen, Chris L E; Van der Smagt, Maarten J; Nijboer, Tanja C W


    Grapheme-color synesthetes perceive achromatic graphemes to be inherently colored. In this study grapheme-color synesthetes and non-synesthetes discriminated (1) the color of visual targets presented along with aurally presented digit primes, and (2) the identity of aurally presented digit targets p

  7. Full-field modal analysis during base motion excitation using high-speed 3D digital image correlation

    Molina-Viedma, Ángel J.; López-Alba, Elías; Felipe-Sesé, Luis; Díaz, Francisco A.


    In recent years, many efforts have been made to exploit full-field measurement optical techniques for modal identification. Three-dimensional digital image correlation using high-speed cameras has been extensively employed for this purpose. Modal identification algorithms are applied to process the frequency response functions (FRF), which relate the displacement response of the structure to the excitation force. However, one of the most common tests for modal analysis involves the base motion excitation of a structural element instead of force excitation. In this case, the relationship between response and excitation is typically based on displacements, which are known as transmissibility functions. In this study, a methodology for experimental modal analysis using high-speed 3D digital image correlation and base motion excitation tests is proposed. In particular, a cantilever beam was excited from its base with a random signal, using a clamped edge join. Full-field transmissibility functions were obtained through the beam and converted into FRF for proper identification, considering a single degree-of-freedom theoretical conversion. Subsequently, modal identification was performed using a circle-fit approach. The proposed methodology facilitates the management of the typically large amounts of data points involved in the DIC measurement during modal identification. Moreover, it was possible to determine the natural frequencies, damping ratios and full-field mode shapes without requiring any additional tests. Finally, the results were experimentally validated by comparing them with those obtained by employing traditional accelerometers, analytical models and finite element method analyses. The comparison was performed by using the quantitative indicator modal assurance criterion. The results showed a high level of correspondence, consolidating the proposed experimental methodology.

  8. Digital holography

    Picart, Pascal


    This book presents a substantial description of the principles and applications of digital holography.The first part of the book deals with mathematical basics and the linear filtering theory necessary to approach the topic. The next part describes the fundamentals of diffraction theory and exhaustively details the numerical computation of diffracted fields using FFT algorithms. A thorough presentation of the principles of holography and digital holography, including digital color holography, is proposed in the third part.A special section is devoted to the algorithms and method

  9. Stochastic Resonance in a Single-Mode Laser Driven by Quadratic Colored Pump Noise and Quantum Noise with Cross-Correlation Between Real and Imaginary Parts of Noise

    Xu, De-Sheng; Cao, Li; Wu, Da-Jin

    Based on the single-mode laser noise model driven by quadratic colored pump noise and quantum noise with cross-correlation between real and imaginary parts of noise proposed in International Journal of Modern Physics B 20, 5383 (2006) and Phys. Rev. E 73, 023802 (2006), the stochastic resonance (SR) of laser intensity is investigated by virtue of the linearized approximation. The analytic expression of signal-to-noise ratio (SNR) is calculated. It is found that the phenomena of stochastic resonance respectively exist in the curves of the SNR versus the noise cross-correlation coefficient λp and the SNR versus the pump parameter a, as well as the SNR versus the signal frequency bar {ω } for the model. It is shown that there are three different types of SR in the model: the conventional form of SR, the SR in the broad sense and the bona fide SR.

  10. Laboratory Earthquake Measurements with the High-speed Digital Image Correlation Method and Applications to Super-shear Transition

    Rubino, V.; Lapusta, N.; Rosakis, A.


    Mapping full-field displacements and strains on the Earth's surface during an earthquake is of paramount importance to enhance our understanding of earthquake mechanics. In this study, the feasibility of such measurements using image correlation methods is investigated in a laboratory earthquake setup. Earthquakes are mimicked in the laboratory by dynamic rupture propagating along an inclined frictional interface formed by two Homalite plates under compression, using the configuration developed by Rosakis and coworkers (e.g., Rosakis et al., 2007). In our study, the interface is partially glued, in order to confine the rupture before it reaches the ends of the specimen. The specimens are painted with a speckle pattern to provide the surface with characteristic features for image matching. Images of the specimens are taken before and after dynamic rupture with a 4 Megapixels resolution CCD camera. The digital images are analyzed with two software packages: VIC-2D (Correlated Solutions Inc.) and COSI-Corr (Leprince et. al, 2007). Both VIC-2D and COSI-Corr are able to characterize the full-field static displacement of a dynamic crack. For example, in a case with secondary mode I cracks, the correlation analysis performed with either software clearly shows (i) the relative displacement (slip) along the frictional interface, (ii) the rupture arrest on the glued boundaries, and (iii) the presence of two wing cracks. The obtained displacement measurements are converted to strains, using de-noising techniques. The digital image correlation method is then used in combination with high-speed photography. We will report our progress on the study of a spontaneously expanding sub-Rayleigh shear crack advancing along an interface containing a patch of favorable heterogeneity, such as a preexisting subcritical crack or a patch with higher prestress. According to the predictions of Liu and Lapusta (2008), intersonic transition and propagation can be achieved in the presence of a

  11. Natural-color maps via coloring of bivariate grid data

    Darbyshire, Jane E.; Jenny, Bernhard


    Natural ground color is useful for maps where a representation of the Earth's surface matters. Natural color schemes are less likely to be misinterpreted, as opposed to hypsometric color schemes, and are generally preferred by map readers. The creation of natural-color maps was once limited to manual cartographic techniques, but they can now be created digitally with the aid of raster graphics editing software. However, the creation of natural-color maps still requires many steps, a significant time investment, and fairly detailed digital land cover information, which makes this technique impossible to apply to global web maps at medium and large scales. A particular challenge for natural-color map creation is adjusting colors with location to create smoothly blending transitions. Adjustments with location are required to show land cover transitions between climate zones with a natural appearance. This study takes the first step in automating the process in order to facilitate the creation of medium- and large-scale natural-color maps covering large areas. A coloring method based on two grid inputs is presented. Here, we introduce an algorithmic method and prototype software for creating maps with this technique. The prototype software allows the map author to interactively assign colors to design the appearance of the map. This software can generate web map tiles at a global level for medium and large scales. Example natural-color web maps created with this coloring technique are provided.

  12. Multi-wavelengths digital holography: reconstruction, synthesis and display of holograms using adaptive transformation.

    Memmolo, P; Finizio, A; Paturzo, M; Ferraro, P; Javidi, B


    A method based on spatial transformations of multiwavelength digital holograms and the correlation matching of their numerical reconstructions is proposed, with the aim to improve superimposition of different color reconstructed images. This method is based on an adaptive affine transform of the hologram that permits management of the physical parameters of numerical reconstruction. In addition, we present a procedure to synthesize a single digital hologram in which three different colors are multiplexed. The optical reconstruction of the synthetic hologram by a spatial light modulator at one wavelength allows us to display all color features of the object, avoiding loss of details.

  13. Characterization of color texture: color texture based sorting of tiles

    Bourada, Y.; Lafon, Dominique; Eterradossi, O.


    Many materials used by the building industry show a color texture which affects the product commercial value. This texture can be seen as the spatial arrangement of regions of acceptable color differences. This work describes an appearance based automated sorting via color texture analysis, using ceramic tiles as example. Textural analysis of the tiles digital images expressed in CIEL*a*b* color system is performed through the analysis of intrinsic features of each region and relationships between regions. Results obtained through the automated process are compared to a visual sorting which leads to calculation of application dependant color and texture tolerances.

  14. An Color Image Digital Watermarking Algorithm Based on Wavelet Lifting%一种基于小波提升的彩色图像水印算法



    提出一种基于小波提升的水印算法,将载体图像的亮度分量进行一级提升小波分解,分解之后再对其部分DCT系数进行一定的量化调制,将水印信息通过量化过程嵌入到载体图像中.由于对水印图像进行了置乱变换,消除了像素间的空间相关性,进一步提高了水印算法的安全性和抗攻击能力.%In this paper, the scrambled watermark is embedded in DCT coefficients of low-frequency sub image of the Brightness Component of original color image after lifting wavelet transformation. Before embedding the watermark, the image confusion method is used to eliminate the space correlation of the pixels and improvs the security and robustness.

  15. Preliminary evaluation of a fully automated quantitative framework for characterizing general breast tissue histology via color histogram and color texture analysis

    Keller, Brad M.; Gastounioti, Aimilia; Batiste, Rebecca C.; Kontos, Despina; Feldman, Michael D.


    Visual characterization of histologic specimens is known to suffer from intra- and inter-observer variability. To help address this, we developed an automated framework for characterizing digitized histology specimens based on a novel application of color histogram and color texture analysis. We perform a preliminary evaluation of this framework using a set of 73 trichrome-stained, digitized slides of normal breast tissue which were visually assessed by an expert pathologist in terms of the percentage of collagenous stroma, stromal collagen density, duct-lobular unit density and the presence of elastosis. For each slide, our algorithm automatically segments the tissue region based on the lightness channel in CIELAB colorspace. Within each tissue region, a color histogram feature vector is extracted using a common color palette for trichrome images generated with a previously described method. Then, using a whole-slide, lattice-based methodology, color texture maps are generated using a set of color co-occurrence matrix statistics: contrast, correlation, energy and homogeneity. The extracted features sets are compared to the visually assessed tissue characteristics. Overall, the extracted texture features have high correlations to both the percentage of collagenous stroma (r=0.95, phistological processes in digitized histology specimens.

  16. Resonant loading of aircraft secondary structure panels for use with thermoelastic stress analysis and digital image correlation

    Waugh, Rachael C.; Dulieu-Barton, Janice M.; Quinn, S.


    Thermoelastic stress analysis (TSA) is an established active thermographic approach which uses the thermoelastic effect to correlate the temperature change that occurs as a material is subjected to elastic cyclic loading to the sum of the principal stresses on the surface of the component. Digital image correlation (DIC) tracks features on the surface of a material to establish a displacement field of a component subjected to load, which can then be used to calculate the strain field. The application of both DIC and TSA on a composite plate representative of aircraft secondary structure subject to resonant frequency loading using a portable loading device, i.e. `remote loading' is described. Laboratory based loading for TSA and DIC is typically imparted using a test machine, however in the current work a vibration loading system is used which is able to excite the component of interest at resonant frequency which enables TSA and DIC to be carried out. The accuracy of the measurements made under remote loading of both of the optical techniques applied is discussed. The data are compared to extract complimentary information from the two techniques. This work forms a step towards a combined strain based non-destructive evaluation procedure able to identify and quantify the effect of defects more fully, particularly when examining component performance in service applications.

  17. Use of Multimodal Technology to Identify Digital Correlates of Violence Among Inpatients With Serious Mental Illness: A Pilot Study.

    Ben-Zeev, Dror; Scherer, Emily A; Brian, Rachel M; Mistler, Lisa A; Campbell, Andrew T; Wang, Rui


    The study examined multimodal technologies to identify correlates of violence among inpatients with serious mental illness. Twenty-eight high-risk inpatients were provided with smartphones adapted for data collection. Participants recorded their thoughts and behaviors by using self-report software. Sensors embedded in each device (microphone and accelerometers) and throughout the inpatient unit (Bluetooth beacons) captured patients' activity and location. Self-reported delusions were associated with violent ideation (odds ratio [OR]=3.08), damaging property (OR=8.24), and physical aggression (OR=12.39). Alcohol and cigarette cravings were associated with violent ideation (OR=5.20 and OR=6.08, respectively), damaging property (OR=3.71 and OR=4.26, respectively), threatening others (OR=3.62 and OR=3.04, respectively), and physical aggression (OR=6.26, and OR=8.02, respectively). Drug cravings were associated with violent ideation (OR=2.76) and damaging property (OR=5.09). Decreased variability in physical activity and noisy ward conditions were associated with violent ideation (OR=.71 and OR=2.82, respectively). Identifiable digital correlates may serve as indicators of increased risk of violence.

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

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


    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.

  19. Design and Establishment of Color System for 1: 1 000 000 Digital Geomorphologic Map of China%中国1: 100万地貌图色彩系统的设计与建库

    钱金凯; 宋阳; 程维明


    Based on analysis and research on regional geomorphologic characteristics and spatial distribution pattern in China, according to the physical color model of geomorphologic map of China, different transformation and combination of three basic features of color (hue, intensity and saturation), adding people's physical or psychological characters into their feeling with color and the quantitative analysis on more than 2000 color types used in 1: 1 000 000 geomorphic map of China, this paper establishes a complete color system of geomorphologic types by taking account of the relation between the color value and unique geomorphologic type which is constructed by the four color value (C, M, Y, K) of modern digital map printing technology. The rules of different color value correspond to geomorphologic genesis types. Sea bottom landform using blue color and the color value can change from continental shelf landform to continental slope landform, to marginal sea basin landform, until to abyssal basin landform. Marine landform using blue color; lacustrine landform, blue-green; among fluvial landform, plain and tableland, using green color, and hill and mountain landforms, brown; among arid landform, plain and tableland using light yellow-brown color; hill and mountain landform, dark orange-brown; aeolian landform, yellow; loess landform, soil yellow color; karst landform, dark brown; peri-glacial landform, blue-purple; glacial landform, purple; and volcanic and lava landform using red color, etc. The 1: 1 000 000 geomorphic map of China which is achieved based on the above can not only represent general rule of Chinese geomorphology completely, but also the difference among different geomorphologic types.%中国1: 100万地貌图的色彩设计是在对中国地貌特征分析研究的基础上,通过中国地貌图物理色彩模型,根据颜色三个基本特征:即色相、亮度和饱和度的不同变化与组合,结合人们对色彩感受的物理与心理特

  20. Digital printing

    Sobotka, Werner K.


    Digital printing is described as a tool to replace conventional printing machines completely. Still this goal was not reached until now with any of the digital printing technologies to be described in the paper. Productivity and costs are still the main parameters and are not really solved until now. Quality in digital printing is no problem anymore. Definition of digital printing is to transfer digital datas directly on the paper surface. This step can be carried out directly or with the use of an intermediate image carrier. Keywords in digital printing are: computer- to-press; erasable image carrier; image carrier with memory. Digital printing is also the logical development of the new digital area as it is pointed out in Nicholas Negropotes book 'Being Digital' and also the answer to networking and Internet technologies. Creating images text and color in one country and publishing the datas in another country or continent is the main advantage. Printing on demand another big advantage and last but not least personalization the last big advantage. Costs and being able to coop with this new world of prepress technology is the biggest disadvantage. Therefore the very optimistic growth rates for the next few years are really nonexistent. The development of complete new markets is too slow and the replacing of old markets is too small.

  1. Studies of Diffuse Interstellar Bands. V. Pairwise Correlations of Eight Strong DIBs and Neutral Hydrogen, Molecular Hydrogen, and Color Excess

    Friedman, Scott D; McCall, Benjamin J; Dahlstrom, Julie; Sonnentrucker, Paule; Welty, Daniel E; Drosback, Meredith M; Hobbs, L M; Rachford, Brian L; Snow, Theodore P


    We establish correlations between equivalent widths of eight diffuse interstellar bands (DIBs), and examine their correlations with atomic hydrogen, molecular hydrogen, and EB-V . The DIBs are centered at \\lambda\\lambda 5780.5, 6204.5, 6283.8, 6196.0, 6613.6, 5705.1, 5797.1, and 5487.7, in decreasing order of Pearson’s correlation coefficient with N(H) (here defined as the column density of neutral hydrogen), ranging from 0.96 to 0.82. We find the equivalent width of \\lambda 5780.5 is better correlated with column densities of H than with E(B-V) or H2, confirming earlier results based on smaller datasets. We show the same is true for six of the seven other DIBs presented here. Despite this similarity, the eight strong DIBs chosen are not well enough correlated with each other to suggest they come from the same carrier. We further conclude that these eight DIBs are more likely to be associated with H than with H2 , and hence are not preferentially located in the densest, most UV shielded parts of interste...

  2. Pre-Peak and Post-Peak Rock Strain Characteristics During Uniaxial Compression by 3D Digital Image Correlation

    Munoz, H.; Taheri, A.; Chanda, E. K.


    A non-contact optical method for strain measurement applying three-dimensional digital image correlation (3D DIC) in uniaxial compression is presented. A series of monotonic uniaxial compression tests under quasi-static loading conditions on Hawkesbury sandstone specimens were conducted. A prescribed constant lateral-strain rate to control the applied axial load in a closed-loop system allowed capturing the complete stress-strain behaviour of the rock, i.e. the pre-peak and post-peak stress-strain regimes. 3D DIC uses two digital cameras to acquire images of the undeformed and deformed shape of an object to perform image analysis and provides deformation and motion measurements. Observations showed that 3D DIC provides strains free from bedding error in contrast to strains from LVDT. Erroneous measurements due to the compliance of the compressive machine are also eliminated. Furthermore, by 3D DIC technique relatively large strains developed in the post-peak regime, in particular within localised zones, difficult to capture by bonded strain gauges, can be measured in a straight forward manner. Field of strains and eventual strain localisation in the rock surface were analysed by 3D DIC method, coupled with the respective stress levels in the rock. Field strain development in the rock samples, both in axial and shear strain domains suggested that strain localisation takes place progressively and develops at a lower rate in pre-peak regime. It is accelerated, otherwise, in post-peak regime associated with the increasing rate of strength degradation. The results show that a major failure plane, due to strain localisation, becomes noticeable only long after the peak stress took place. In addition, post-peak stress-strain behaviour was observed to be either in a form of localised strain in a shearing zone or inelastic unloading outside of the shearing zone.

  3. Color control of the multi-color printing device

    WANG Xiao-hua; XIU Xiao-jie; ZHU Wen-hua; TANG Hong-jun


    Conventional color-printing systems often use inks of three hues, such as CMY, CMYK and CMYKLcLm, but in order to obtain more realistic color reproductions, the ink set of more than three hues has been adopted by some color-printing systems. It is difficult, however, to model the composed color with the multiple inks when the number of the output ink hues exceeds three due to the none-unique mapping between the color spaces of the CIE Lab and the multi-color printing device. In this paper, we propose a fine color-printing method for multi-color printing device with the ink set of more than three hues. The proposed approach has good color expression ability and provides fine control of the printed color. By dividing the output color space into several subspaces, our method allows one-to-one mapping between the standard color space and the multi-color output color space. It has been proved effective when applied to the digital inkjet printer-Mutoh8000.

  4. Research on Digital Watermarking Algorithm Based on Color Two-dimensional Code Image%基于彩色二维码图像的数字水印算法研究

    吕慧中; 蓝凤华; 李宏昌


    This paper introduces the color two-dimensional code on the basis of introducing the traditional black and white two-dimensional code. The two dimensional code is changed into color to provide more watermark embedding position and higher visibility. The MATLAB simulation experiment proves the feasibility of embedding the watermark information in the two-dimensional code. Based on characteristics of color two-dimensional code, this paper studies the application of digital watermark in color two-dimensional code. By embedding watermark through through R, G, B color component translation and rotation, this paper designs a watermarking algorithm based on the color two-dimensional code, which can resist geometric attacks and improve the security and practicability of two-dimensional code.%在介绍了传统黑白二维码的基础上,对彩色二维码进行了介绍.将二维码变成彩色,提供了更多的水印嵌入位置和更高的不可见性.通过Matlab仿真实验,验证了在彩色二维码中嵌入水印信息的可行性,并结合彩色二维码的特点,对数字水印在彩色二维码中的应用进行研究,采用R、G和B三种颜色分量分别平移和旋转的方法嵌入水印,设计出了一种可抵抗几何攻击的彩色二维码水印算法,提高了二维码的安全性和实用性.

  5. Priming Letters by Colors: Evidence for the Bidirectionality of Grapheme-Color Synesthesia

    Weiss, Peter H.; Kalckert, Andreas; Fink, Gereon R.


    In synesthesia, stimulation of one sensory modality leads to a percept in another nonstimulated modality, for example, graphemes trigger an additional color percept in grapheme-color synesthesia, which encompasses the variants letter-color and digit-color synesthesia. Until recently, it was assumed that synesthesia occurs strictly unidirectional:…

  6. Priming Letters by Colors: Evidence for the Bidirectionality of Grapheme-Color Synesthesia

    Weiss, Peter H.; Kalckert, Andreas; Fink, Gereon R.


    In synesthesia, stimulation of one sensory modality leads to a percept in another nonstimulated modality, for example, graphemes trigger an additional color percept in grapheme-color synesthesia, which encompasses the variants letter-color and digit-color synesthesia. Until recently, it was assumed that synesthesia occurs strictly unidirectional:…

  7. Neoangiogenesis in early cervical cancer: Correlation between color Doppler findings and risk factors. A prospective observational study

    Mazaira Jesús


    Full Text Available Abstract Background The aim of the present article was to evaluate whether angiogenic parameters as assessed by transvaginal color Doppler ultrasound (TVCD may predict those prognostic factors related to recurrence. Methods A total of 27 patients (mean age: 51.3 years, range: 29 to 85 with histologically proven early stage invasive cervical cancer were evaluated by TVCD prior to surgery. Subjective assessment of the amount of vessels within the tumor (scanty-moderate or abundant and pulsatility index (PI were recorded. All patients underwent radical hysterectomy and pelvic lymph node dissection. Postoperative treatment (RT or chemoradiotherapy was given according to risk factors (positive lymph nodes, parametrial and vaginal margin involvement, depth stromal invasion, lymph-vascular space involvement Results Tumors with "abundant" vascularization were significantly associated with pelvic lymph node metastases, depth stromal invasion > 10 mm, lymph-vascular space involvement, tumor diameter > 17.5 mm, and parametrial involvement. Postoperative treatment was significantly more frequent in patients with "abundant" vascularization (OR: 20.8, 95% CIs: 2 to 211. The presence of scanty-moderate vascularization with a PI 0.82 or PI Conclusion The results are consistent with a relationship between tumor angiogenesis and prognostic factors for recurrence in early cervical cancer. "Abundant" vascularization and PI

  8. Clinico-anatomical correlations of left posterior cerebral artery occlusion. Alexia without agraphia, color anomia, and memory disturbance

    Isono, Osamu; Shiota, Junichi; Kawamura, Mitsuru; Hirayama, Keizou; Maki, Toshiyuki.


    The relation between neurological signs and symptoms and computed tomography (CT) and magnetic resonance imaging (MRI) was examined in 11 cases of occlusion of the left posterior cerebral artery. All the patients were righthanded. Right homonimous hemianopia was noted in 8 cases, right upper quadrantanopia in 2 cases, and right lower quadrantanopia in 1 case. Of the 11 cases, alexia without agraphia was noted in 9 cases, all 9 of which showed lesions of inferior occipital cortex (lingual and fusiform gyri) and subjacent white matter. Lesions of splenium were found in only 5 of the cases of alexia without agraphia. In 2 cases with neither alexia nor agraphia, lesions were seen in the medial occipital cortex and the subjacent white matter but not in the inferior occipital lobe. Three patients had color anomia which was accompanied by memory disturbances and alexia without agraphia. In 2 of these 3, lesions were widespread in the region of the left posterior cerebral artery. Memory disturbances were observed in 6 cases, all of which also showed alexia without agraphia. The lesions extended not only of the inferior surface of the occipital lobe and along the interhemispheric fissure, but also of hippocampal and parahippocampal gyri. In 3 cases of alexia without agraphia in which no memory distrubance was found, the symptoms of alexia were slight and disappeared at an early stage. (J.P.N.).

  9. 利用数码相机测定面部皮肤颜色的初步研究%A study of measurement of facial skin color using digital camera

    陈江飞; 赵铱民


    目的:利用数码相机进行面部皮肤颜色测定的可行性与合理性的研究.方法:在进行颜色采集之前,首先测定实验光源的稳定性.使用Canon EOS 20D单反数码相机,在实验光源稳定的时间内,以相同的拍摄参数(快门1/25 s,光圈4.5 自定义白平衡,ISO 800)采集122 例22~32 岁受试人群颌面部的皮肤颜色,拍摄文档保存为Jpeg格式.图像经Adobe photoshop7.0统一校色后,拾取皮肤CIE L*a*b*色度学空间颜色数据,利用SPSS 10.0做统计描述.结果:实验光源在21~70 min内是稳定的,可以达到比色要求.实验测得皮肤的L*a*b*色度学参数范围为:L* 49~66,a* 7~18,b* 5~22.结论:面部皮肤色度参数与测色手段和方式密切相关,数码相机作为面部赝复体的比色方法,在面部皮肤色彩信息全面采集、色彩信息准确传递方面,具有独特优势.%Objective; To evaluate the reliability and reasonability of maxillofacial skin color match using the digital camera. Methods; The stability of the experimental light source was evaluated before establishing the color measurement. 122 volunteers aged from 22 to 32 years were recorded by a Canon EOS 20D digital camera in studio environment when the light source was stable. Photographs were taken under a set exposure parameters(f/4.5,1/25 s,custom white balance,ISO 800) and saved as JPEG format. The CIE L~* a~* b~* color values were obtained from the digital images using Adobe Photoshop7.0 after color correction. All data were analyzed using SPSS 10. 0. Results;The experimental light source was stable in 21 to 70 minutes. It was suitable for color measurement during this period. The color parameters of all tested maxillofacial skin were:L~*49~66,a~*7 - 18,b~*5 -22. Conclusion;The assessment of maxillofacial skin color depend on method of measurement and instrument. The method of maxillofacial skin color matching by digital camera seems reliable.

  10. [Correlation of noises in the channels of digital X-ray receiver-transformer and the evaluation of registration's quant efficiency].

    Porosev, V V; Shekhtman, L I; Zelikman, M I; Blinov Jr, N N


    Theoretical and experimental research results related with the influence of correlation of signals in neighboring elements of digital X-ray receiver-transformer produced on the evaluation of the output ratio noise/signal and, as a consequence, on the evaluation of quantum registration efficiency are described in the paper.

  11. A Color Image Watermarking Scheme Resistant against Geometrical Attacks

    Y. Xing


    Full Text Available The geometrical attacks are still a problem for many digital watermarking algorithms at present. In this paper, we propose a watermarking algorithm for color images resistant to geometrical distortions (rotation and scaling. The singular value decomposition is used for watermark embedding and extraction. The log-polar map- ping (LPM and phase correlation method are used to register the position of geometrical distortion suffered by the watermarked image. Experiments with different kinds of color images and watermarks demonstrate that the watermarking algorithm is robust to common image processing attacks, especially geometrical attacks.

  12. Sugar and Acid Content and Their Genotypic Correlations of Unselected P.Persica x P.Davidiana Progenies as Affected by Hairness and Flesh Color

    WU Ben-hong; LI Shao-hua; Quilot Bénédicte; Génard Michel; Kervella Jocelyne


    Fruit sugar and acid content were determined in a group of hybrids from one family,including 22 peach and 85 nectarine genotypes, or 75 white-fleshed and 32 yellow-fleshed genotypes. Sucrose accounted for about 65% of the total sugar, and malate for about 50%of the total acid. Mean sucrose, fructose, sorbitol, total sugar, soluble solid and quinate content were significantly higher in nectarines than in peaches, while no significant difference was found in mean malate, citrate and total acid content between nectarines and peaches. Shikimate content was very low and ranged from 0.011-0.046 meq 100 g-1 FW in all genotypes studied. Flesh color did not affect sugar and acid content.Glucose and fructose had a close positive correlation (r=0.63***). Malate had positive correlations with sucrose, sorbitol, total sugar and soluble solid content. The correlation between citrate and sugars were not significant. Glucose, fructose, sorbitol and malate content seemed to be higher in late-maturing genotypes. Sucrose, total sugar and total acid content had a parabolic relationship with developmental period (from full blooming date to maturity date).

  13. Watermarking on Colored Images


    The great success of internet and the ease of copying anddistributing the electronic data has presented a new challenge of how to protect the digital data. Digital watermarks have been proposed as a means for copyright protection of multimedia. Unlike the traditional visible watermark, the challenge here is to introduce a digital watermark that does not alter the quality of electronic content, while being extremely robust to attack. From the angle of signal processing, the two basic requirements for an effective watermarking scheme, robustness and transparency conflict with each other. So the digital watermark is information that is imperceptibly and robustly embedded in the host data such that it can not be removed without important degradation of images quality. This paper consists of two parts. In the first part, an authentication technique by embedding digital “watermarks” into colored images is proposed. In our approach, we embed the “watermarks” with visually recognizable patterns into the images by selectively modifying the middle-frequency coefficients of the image. In the second part, the technique of hiding a colored image into another colored one is proposed. The experimental results show that the proposed techniques successfully survive image processing operations, image cropping and the JPEG lossy compression.

  14. Digital Inkjet Textile Printing

    Wang, Meichun


    Digital inkjet textile printing is an emerging technology developed with the rise of the digital world. It offers a possibility to print high-resolution images with unlimited color selection on fabrics. Digital inkjet printing brings a revolutionary chance for the textile printing industry. The history of textile printing shows the law how new technology replaces the traditional way of printing. This indicates the future of digital inkjet textile printing is relatively positive. Differen...

  15. Application of the digital volume correlation technique for the measurement of displacement and strain fields in bone: a literature review.

    Roberts, Bryant C; Perilli, Egon; Reynolds, Karen J


    Digital volume correlation (DVC) provides experimental measurements of displacements and strains throughout the interior of porous materials such as trabecular bone. It can provide full-field continuum- and tissue-level measurements, desirable for validation of finite element models, by comparing image volumes from subsequent µCT scans of a sample in unloaded and loaded states. Since the first application of DVC for measurement of strain in bone tissue, subsequent reports of its application to trabecular bone cores up to whole bones have appeared within the literature. An "optimal" set of procedures capable of precise and accurate measurements of strain, however, still remains unclear, and a systematic review focussing explicitly on the increasing number of DVC algorithms applied to bone or structurally similar materials is currently unavailable. This review investigates the effects of individual parameters reported within individual studies, allowing to make recommendations for suggesting algorithms capable of achieving high accuracy and precision in displacement and strain measurements. These recommendations suggest use of subsets that are sufficiently large to encompass unique datasets (e.g. subsets of 500 µm edge length when applied to human trabecular bone cores, such as cores 10mm in height and 5mm in diameter, scanned at 15 µm voxel size), a shape function that uses full affine transformations (translation, rotation, normal strain and shear strain), the robust normalized cross-correlation coefficient objective function, and high-order interpolation schemes. As these employ computationally burdensome algorithms, researchers need to determine whether they have the necessary computational resources or time to adopt such strategies. As each algorithm is suitable for parallel programming however, the adoption of high precision techniques may become more prevalent in the future.

  16. A novel 2nd-order shape function based digital image correlation method for large deformation measurements

    Bai, Ruixiang; Jiang, Hao; Lei, Zhenkun; Li, Weikang


    Compared with the traditional forward compositional matching strategy, the inverse compositional matching strategy has almost the same accuracy, but has an obviously higher efficiency than the former in digital image correlation (DIC) algorithms. Based on the inverse compositional matching strategy and the auxiliary displacement functions, a more accurate inverse compositional Gauss-Newton (IC-GN2) algorithm with a new second-order shape operator is proposed for nonuniform and large deformation measurements. A theoretical deduction showed that the new proposed second-order shape operator is invertible and can steadily attain second-order precision. The result of the numerical simulation showed that the matching accuracy of the new IC-GN2 algorithm is the same as that of the forward compositional Gauss-Newton (FC-GN2) algorithm and is relatively better than in IC-GN2 algorithm. Finally, a rubber tension experiment with a large deformation of 27% was performed to validate the feasibility of the proposed algorithm.

  17. Determining mode I cohesive law of Pinus pinaster by coupling double cantilever beam test with digital image correlation

    J. Xavier


    Full Text Available The direct identification of the cohesive law in pure mode I of Pinus pinaster is addressed. The approach couples the double cantilever beam (DCB test with digital image correlation (DIC. Wooden beam specimens loaded in the radial-longitudinal (RL fracture propagation system are used. The strain energy release rate in mode I ( is uniquely determined from the load-displacement ( curve by means of the compliance-based beam method (CBBM. This method relies on the concept of equivalent elastic crack length ( and therefore does not require the monitoring of crack propagation during test. The crack tip opening displacement in mode I is determined from the displacement field at the initial crack tip. The cohesive law in mode I is then identified by numerical differentiation of the relationship. Moreover, the proposed procedure is validated by finite element analyses including cohesive zone modelling. It is concluded that the proposed data reduction scheme is adequate for assessing the cohesive law in pure mode I of P. pinaster

  18. Experimental validation for the determination of particle positions by the correlation coefficient method in digital particle holography.

    Yang, Yan; Kang, Bo-seon


    The feasibility and the accuracy of the correlation coefficient (CC) method for the determination of particle positions along the optical axis in digital particle holography were verified by validation experiments. A translation system capable of high precision was used to move the particle objects by exact known distances between several different positions. The particle positions along the optical axis were calculated by the CC method and compared with their exact values to obtain the errors of the focus plane determination. The tested particles were two-dimensional (2D) dots in a calibration target along with different-sized glass beads and droplets that reflected and caused a three-dimensional (3D) effect. The results show that the CC method can work well for both the 2D dots and the 3D particles. The effect of other particles on the focus plane determination was also investigated. The CC method can locate the focus plane of particles with high precision, regardless of the existence of other particles.

  19. Spatial resolution and measurement uncertainty of strains in bone and bone-cement interface using digital volume correlation.

    Zhu, Ming-Liang; Zhang, Qing-Hang; Lupton, Colin; Tong, Jie


    The measurement uncertainty of strains has been assessed in a bone analogue (sawbone), bovine trabecular bone and bone-cement interface specimens under zero load using the Digital Volume Correlation (DVC) method. The effects of sub-volume size, sample constraint and preload on the measured strain uncertainty have been examined. There is generally a trade-off between the measurement uncertainty and the spatial resolution. Suitable sub-volume sizes have been be selected based on a compromise between the measurement uncertainty and the spatial resolution of the cases considered. A ratio of sub-volume size to a microstructure characteristic (Tb.Sp) was introduced to reflect a suitable spatial resolution, and the measurement uncertainty associated was assessed. Specifically, ratios between 1.6 and 4 appear to give rise to standard deviations in the measured strains between 166 and 620 με in all the cases considered, which would seem to suffice for strain analysis in pre as well as post yield loading regimes. A microscale finite element (μFE) model was built from the CT images of the sawbone, and the results from the μFE model and a continuum FE model were compared with those from the DVC. The strain results were found to differ significantly between the two methods at tissue level, consistent in trend with the results found in human bones, indicating mainly a limitation of the current DVC method in mapping strains at this level.

  20. Deformation behavior of lead zirconate titanate ceramics under uniaxial compression measured by the digital image correlation method

    Chen, Di; Carter, Emma; Kamlah, Marc


    The deformation behavior of lead zirconate titanate bulk ceramic specimen under uniaxial compression was monitored by the digital image correlation method and the homogeneity of the deformation was discussed. Combined with using a Sawyer-Tower circuit, the depolarization curve was also obtained. Because of the friction at both the top and bottom surfaces of the lead zirconate titanate ceramic specimen, the distribution of deformation under large uniaxial compressive stresses usually shows a barrel shape. By focusing on correspondingly selected regions of interest and calculating the values of strain components there, the barreling behavior was proved. This barreling behavior is due to elastic strains, in the first place, while the remnant strains are less affected by this phenomenon. All these findings are the experimental justifications for the selection of an aspect ratio of 3:1 for our specimens, where only the central cubic region of a specimen represents the desired purely uniaxial stress state. Only from this region, true uniaxial stress-strain results can be obtained to develop constitutive models.

  1. Durability Analysis and Experimental Validation of Environmental Barrier Coating (EBC Performance Using Combined Digital Image Correlation and NDE

    Ali Abdul-Aziz


    Full Text Available To understand the failure mechanism or to predict the spallation life of environmental barrier coatings (EBC on fiber reinforced ceramic matrix composites, the fracture strength of EBC and the process of the crack growth in EBC layers need to be experimentally determined under standard or simulated engine operating conditions. The current work considers a multi layered barium strontium aluminum silicate (BSAS-based EBC-coated, melt infiltrated silicon carbide fiber reinforced silicon carbide matrix composite (MI SiC/SiC specimen that was tensile tested at room temperature. Numerous tests were performed under tensile loading conditions, and the specimen was loaded until failure under pre-determined stress levels. The specimen was examined with optical microscopy, scanning electron microscopy (SEM, computed tomography (CT scan, and digital image correlation (DIC camera. Observation from the computed tomography scanning, the SEM, and the optical microscopy did not offer conclusive information concerning the cracks that spawned during the tests. However, inspection with the DIC camera offered some indication that cracks had developed and allowed their detection and the location of their initiation site. Thus, this study provides detailed discussion of the results obtained from the experimental investigation and the nondestructive evaluation (NDE, and it also includes assessment of the stress response predicted by analytical modeling and their impact on EBC durability and crack growth formation under complex loading settings.

  2. Measurement of high temperature full-field strain up to 2000 °C using digital image correlation

    Wang, Wei; Xu, Chenghai; Jin, Hua; Meng, Songhe; Zhang, Yumin; Xie, Weihua


    Understanding the deformation and strain at elevated temperature is a critical factor for the stability of aerodynamic shape, and an important consideration for the thermal protection system design. However, accurate measurement of deformation and strain at high temperatures is a challenge. Here, we present a measurement study for full-field strain mapping up to 2000 °C using digital image correlation (DIC) method, which mainly depends on the quality of speckle patterns on the specimen surface. In our study, the strain values are analyzed by DIC method while specimens are heated using a large electric current. Improvements in filtering and speckling allow the measured temperatures using this method to reach 2000 °C. We confirmed the validity of this method by comparison of measured Young’s modulus values with reference data for Inconel 718 Ni-based superalloy and graphite at different temperatures. Additionally, the full-field strain and Young’s modulus were demonstrated for a carbon fiber-reinforced carbon (C/C) composite uniaxial tensile specimen at 2000 °C.

  3. Detecting the Activation of a Self-Healing Mechanism in Concrete by Acoustic Emission and Digital Image Correlation

    E. Tsangouri


    Full Text Available Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process.

  4. Detecting the activation of a self-healing mechanism in concrete by acoustic emission and digital image correlation.

    Tsangouri, E; Aggelis, D G; Van Tittelboom, K; De Belie, N; Van Hemelrijck, D


    Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process.

  5. Characterizing the Mechanical Properties of Actual SAC105, SAC305, and SAC405 Solder Joints by Digital Image Correlation

    Nguyen, T. T.; Yu, D.; Park, S. B.


    This paper presents the characterization of the mechanical properties of three lead-free solder alloys 95.5Sn-4.0Ag-0.5Cu (SAC405), 96.5Sn-3.0Ag-0.5Cu (SAC305), and 98.5Sn-1.0Ag-0.5Cu (SAC105) at the solder joint scale. Several actual ChipArray ® ball grid array (CABGA) packages were cross-sectioned, polished, and used as test vehicles. Compressive tests were performed using a nanocharacterization system over the temperature range of 25°C to 105°C. Images of the cross-sectioned solder joints were recorded by microscope during the tests. The recorded images were then processed by using a digital image correlation (DIC) program to calculate the displacement and strain fields on the solder joints. Finite-element method (FEM) modeling was used to extract the Poisson's ratio, Young's modulus, and coefficient of thermal expansion (CTE) of the solder alloys over the temperature range. The methodology developed in this paper enables characterization of the mechanical properties of the actual solder joints at low strain range with high accuracy.

  6. Direct Numerical Simulation of Fracture Behaviour for Random Short Wood Fibres Reinforced Composites, Comparison with Digital Image Correlation Experiments

    Shen, M.; Touchard, F.; Bezine, G.; Brillaud, J.


    The work is to predict fracture behaviour of bio-composites from the tensile properties of its components. In this work, we have realized a direct numerical simulation of fracture behaviour for random short spruce fibers reinforced composites. For calculations, wood fibers have been considered as linear elastic bodies, polypropylene matrix as an elastic-plastic material. Then, numerical results have been compared with experimental results that have been obtained by digital image correlation. This comparison indicates that random fiber FE model of random short spruce fibers reinforced composites can be able to fairly reflect the influence of random fibers microstructure in the composite on its fracture behavior. The calculation of both random fiber and homogeneous FE model and their comparison with experiments show that the average values of J-integral in a region in the front of the crack tip from both numerical FE models are in good agreement with the average J value of DIC experiment in the same region when the numerical and experimental CT specimens of the short spruce fiber reinforced composite are subjected to the same extension at their loading point.

  7. Direct Numerical Simulation of Fracture Behaviour for Random Short Wood Fibres Reinforced Composites, Comparison with Digital Image Correlation Experiments

    Brillaud J.


    Full Text Available The work is to predict fracture behaviour of bio-composites from the tensile properties of its components. In this work, we have realized a direct numerical simulation of fracture behaviour for random short spruce fibers reinforced composites. For calculations, wood fibers have been considered as linear elastic bodies, polypropylene matrix as an elastic-plastic material. Then, numerical results have been compared with experimental results that have been obtained by digital image correlation. This comparison indicates that random fiber FE model of random short spruce fibers reinforced composites can be able to fairly reflect the influence of random fibers microstructure in the composite on its fracture behavior. The calculation of both random fiber and homogeneous FE model and their comparison with experiments show that the average values of J-integral in a region in the front of the crack tip from both numerical FE models are in good agreement with the average J value of DIC experiment in the same region when the numerical and experimental CT specimens of the short spruce fiber reinforced composite are subjected to the same extension at their loading point.

  8. Effect of Sr-modification on the bendability of cast aluminum alloy A356 using digital image correlation method

    Marzouk, M.; Jain, M., E-mail:; Shankar, S.


    The effect of cast microstructure on bendability of automotive cast aluminum alloy A356 has been studied by machining sheet specimens and conducting V-bend tests. Specimens in the loaded condition are observed from the through-thickness section using a CCD camera and also using a scanning electron microscope (SEM). The latter allowed recording of high magnification images from the through-thickness region of the bend to determine aspects of strain localization and particle induced damage in the microstructure. In addition, the initial microstructure is utilized as a speckle pattern for further analysis of through-thickness strain development in the bent region using digital image correlation (DIC) method. The method is applied to unmodified and Sr-modified A356 compositions. The results indicate superior bendability of Sr modified A356 alloy compared to the unmodified alloy. The differences in bendability are attributed to the size and morphology of eutectic Si phase particles that undergo significant cracking in the tensile region of specimen during bending. The results demonstrate that high magnification SEM imaging of bent specimens coupled with DIC based strain analysis offers a useful method of analyzing the effect of microstructure on bendability of cast materials.

  9. Color planner for designers based on color emotions

    Cheng, Ka-Man; Xin, John H.; Taylor, Gail


    During the color perception process, an associated feeling or emotion is induced in our brains, and this kind of emotion is termed as 'color emotion.' The researchers in the field of color emotions have put many efforts in quantifying color emotions with the standard color specifications and evaluating the influence of hue, lightness and chroma to the color emotions of human beings. In this study, a color planner was derived according to these findings so that the correlation of color emotions and standard color specifications was clearly indicated. Since people of different nationalities usually have different color emotions as different cultural and traditional backgrounds, the subjects in this study were all native Hong Kong Chinese and the color emotion words were all written in Chinese language in the visual assessments. Through the color planner, the designers from different areas, no matter fashion, graphic, interior or web site etc., can select suitable colors for inducing target color emotions to the customers or product-users since different colors convey different meanings to them. In addition, the designers can enhance the functionality and increase the attractiveness of their designed products by selecting suitable colors.

  10. Correlations between contrast enhanced color Doppler US and neoangiogenesis in small prostate carcinomas; Correlazioni tra color Doppler con uso di mezzo di contrasto e neoangiogenesi dei piccoli carcinomi prostatici

    Lagalla, R.; Caruso, G.; Caruso, R.; Bizzini, G. [Policlinico Universitario P. Giaccone, Palermo (Italy). Ist. di Radiologia; Marasa' , L. [Ospedale Oncologico M. Ascoli, Palermo (Italy). Servizio di Anatomia Patologica; Miceli, V. [Policlinico Universitario P. Giaccone, Palermo (Italy). Ist. di Clinica Urologica


    Aim of the work was to investigate if the use of a contrast agent (Levovist) improves the specificity of ultrasonography in the diagnosis of prostate carcinoma, having the results of prostate biopsy as the gold standard. The results have been compared with the microscopic angiogenesis grading system (MAGS) index; they exceed 30 in 11 avascular lesions value indicates microangiogenesis. In the other two cases a minor value of 30 was correlated with a different type of tumor vascularisation typical of macroangiogenesis. [Italian] Scopo del lavoro e' verificare se l'impiego del mezzo di contrasto Levovist (Schering, Berlino) consente di migliorare la specificta' dell'esame ecografico nella diagnosi del carcinoma prostatico, avendo come riferimento i risultati della biopsia prostatica. Trenta pazienti con esame obiettivo sospetto per carcinoma prostatico e antigene prostatico specifico (PSA) compreso tra 5 e 15 ng/ml, sono stati studiati con ecografia transrettale integrata da esame color Doppler e somministrazione di mdc. I risultati ottenuti sono stati confrontati con l'indice Microscopic Angiogenesis Grading System (MAGS) che nelle sezioni istologiche degli 11 casi con aspetto avascolare e' stato superato a 30, espressione di microgenesi; negli altri due casi, il valore inferiore a 30 e' conciso con un differente modello di vascolarizzazione neoplastica proprio della microangiogenesi.

  11. Color Blindness



    About one in 12 boys is color-blind, and one in every 400 girls, so in each school class there are likely to be at least one or two people who are color-blind. Because they are color- blind from birth, most people do not know that they are color-

  12. 一种简单的六色打印数字半调算法%A Simple Digital Halftone Algorithm for Six Color Inkjet Printer

    田玉敏; 吴自力; 柯丽芳


    Traditional ink-jet printer with CMYK inks has limited color gamut. To improve the quality of printing images, many plotters added two inter-grade colors Lc and Lm, which makes it more color-levels achieved.The color images printed with six-color printer have less artificial textures produced by halftone. The advantages of six-color printing are introduced. A new pattern and halftone algorithm for six-color printer is presented. Research has proved that the algorithm is simple and practical.%传统的喷墨打印机通常采用四色墨水(CMYK)打印,但CMYK四色墨水所能提供的色彩有限,为进一步提高彩色图像的输出质量,目前很多新型打印机在原有CMYK墨水的基础上增加了浅品红(Lm)和浅青墨水(Lc),从而使打印机可实现的色阶更加丰富.使用六色墨水打印不仅提高了输出图像的分辨率和清晰度,增强了图像细节,而且还使图像的色调过渡更平滑,降低了半调技术产生的图样干扰,极大地提高了打印图像质量.简单介绍了六色打印的优点,提出了一种适用六色打印的模板和误差分散数字半调算法,实验表明,该算法简单实用.

  13. Z86E33 Based Neoteric Digital Light Source--Magic Color Light%数字化新颖光源的实现

    姚萌; 蒋洋; 秦敏


    用GaAs/Si高亮聚光LED的Digital Light实现魔幻彩灯,简述了CIE计色制、Digital Light工作原理,论述了软件PWM实现方法,给出了系统框图,说明了系统特点和与传统光源比较的系统优越性.

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

    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.

  15. Characterization of the bone-metal implant interface by Digital Volume Correlation of in-situ loading using neutron tomography.

    Le Cann, Sophie; Tudisco, Erika; Perdikouri, Christina; Belfrage, Ola; Kaestner, Anders; Hall, Stephen; Tägil, Magnus; Isaksson, Hanna


    Metallic implants are commonly used as surgical treatments for many orthopedic conditions. The long-term stability of implants relies on an adequate integration with the surrounding bone. Unsuccessful integration could lead to implant loosening. By combining mechanical loading with high-resolution 3D imaging methods, followed by image analysis such as Digital Volume Correlation (DVC), we aim at evaluating ex vivo the mechanical resistance of newly formed bone at the interface. X-rays tomography is commonly used to image bone but induces artefacts close to metallic components. Utilizing a different interaction with matter, neutron tomography is a promising alternative but has not yet been used in studies of bone mechanics. This work demonstrates that neutron tomography during in situ loading is a feasible tool to characterize the mechanical response of bone-implant interfaces, especially when combined with DVC. Experiments were performed where metal screws were implanted in rat tibiae during 4 weeks. The screws were pulled-out while the samples were sequentially imaged in situ with neutron tomography. The images were analyzed to quantify bone ingrowth around the implants. DVC was used to track the internal displacements and calculate the strain fields in the bone during loading. The neutron images were free of metal-related artefacts, which enabled accurate quantification of bone ingrowth on the screw (ranging from 60% to 71%). DVC allowed successful identification of the deformation and cracks that occurred during mechanical loading and led to final failure of the bone-implant interface. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Comparison of subset-based local and FE-based global digital image correlation: Theoretical error analysis and validation

    Pan, B.; Wang, B.; Lubineau, G.


    Subset-based local and finite-element-based (FE-based) global digital image correlation (DIC) approaches are the two primary image matching algorithms widely used for full-field displacement mapping. Very recently, the performances of these different DIC approaches have been experimentally investigated using numerical and real-world experimental tests. The results have shown that in typical cases, where the subset (element) size is no less than a few pixels and the local deformation within a subset (element) can be well approximated by the adopted shape functions, the subset-based local DIC outperforms FE-based global DIC approaches because the former provides slightly smaller root-mean-square errors and offers much higher computation efficiency. Here we investigate the theoretical origin and lay a solid theoretical basis for the previous comparison. We assume that systematic errors due to imperfect intensity interpolation and undermatched shape functions are negligibly small, and perform a theoretical analysis of the random errors or standard deviation (SD) errors in the displacements measured by two local DIC approaches (i.e., a subset-based local DIC and an element-based local DIC) and two FE-based global DIC approaches (i.e., Q4-DIC and Q8-DIC). The equations that govern the random errors in the displacements measured by these local and global DIC approaches are theoretically derived. The correctness of the theoretically predicted SD errors is validated through numerical translation tests under various noise levels. We demonstrate that the SD errors induced by the Q4-element-based local DIC, the global Q4-DIC and the global Q8-DIC are 4, 1.8-2.2 and 1.2-1.6 times greater, respectively, than that associated with the subset-based local DIC, which is consistent with our conclusions from previous work.

  17. Blood Pool Contrast-enhanced Magnetic Resonance Angiography with Correlation to Digital Subtraction Angiography: A Pictorial Review

    Martha-Grace Knuttinen


    Full Text Available Magnetic resonance angiography (MRA provides noninvasive visualization of the vascular supply of soft tissue masses and vascular pathology, without harmful radiation. This is important for planning an endovascular intervention, and helps to evaluate the efficiency and effectiveness of the treatment. MRA with conventional extracellular contrast agents relies on accurate contrast bolus timing, limiting the imaging window to first-pass arterial phase. The recently introduced blood pool contrast agent (BPCA, gadofosveset trisodium, reversibly binds to human serum albumin, resulting in increased T1 relaxivity and prolonged intravascular retention time, permitting both first-pass and steady-state phase high-resolution imaging. In our practice, high-quality MRA serves as a detailed "roadmap" for the needed endovascular intervention. Cases of aortoiliac occlusive disease, inferior vena cava thrombus, pelvic congestion syndrome, and lower extremity arteriovenous malformation are discussed in this article. MRA was acquired at 1.5 T with an 8-channel phased array coil after intravenous administration of gadofosveset (0.03 mmol/kg body weight, at the first-pass phase. In the steady-state, serial T1-weighted 3D spoiled gradient echo images were obtained with high resolution. All patients underwent digital subtraction angiography (DSA and endovascular treatment. MRA and DSA findings of vascular anatomy and pathology are discussed and correlated. BPCA-enhanced MRA provides high-quality first-pass and steady-state vascular imaging. This could increase the diagnostic accuracy and create a detailed map for pre-intervention planning. Understanding the pharmacokinetics of BPCA and being familiar with the indications and technique of MRA are important for diagnosis and endovascular intervention.

  18. Volume digital image correlation to assess displacement field in compression loaded bread crumb under X-ray microtomography

    Moussawi, Ali


    In this study, we present an original approach to assess structural changes during bread crumb compression using a mechanical testing bench coupled to 3D X-ray microtomography. X-ray images taken at different levels of compression of the bread crumb are processed using image analysis. A subset-based digital volume correlation method is used to achieve the 3D displacement field. Within the limit of the approach, deterministic search strategy is implemented for solving subset displacement in each deformed image with regards to the undeformed one. The predicted displacement field in the transverse directions shows differences that depend on local cell arrangement as confirmed by finite element analysis. The displacement component in the loading direction is affected by the magnitude of imposed displacement and shows more regular change. Large displacement levels in the compression direction are in good agreement with the imposed experimental displacement. The results presented here are promising in a sense of possible identification of local foam properties. New insights are expected to achieve better understanding of structural heterogeneities in the overall perception of the product. Industrial relevance: Texture evaluation of cereal product is an important aspect for testing consumer acceptability of new designed products. Mechanical evaluation of backed products is a systemic route for determining texture of cereal based product. From the industrial viewpoint, mechanical evaluation allows saving both time and cost compared to panel evaluation. We demonstrate that better understanding of structural changes during texture evaluation can be achieved in addition to texture evaluation. Sensing structural changes during bread crumb compression is achievable by combining novel imaging technique and processing based on image analysis. We present thus an efficient way to predict displacements during compression of freshly baked product. This method can be used in different

  19. Experimental validation of 3D printed patient-specific implants using digital image correlation and finite element analysis.

    Sutradhar, Alok; Park, Jaejong; Carrau, Diana; Miller, Michael J


    With the dawn of 3D printing technology, patient-specific implant designs are set to have a paradigm shift. A topology optimization method in designing patient-specific craniofacial implants has been developed to ensure adequate load transfer mechanism and restore the form and function of the mid-face. Patient-specific finite element models are used to design these implants and to validate whether they are viable for physiological loading such as mastication. Validation of these topology optimized finite element models using mechanical testing is a critical step. Instead of inserting the implants into a cadaver or patient, we embed the implants into the computer-aided skull model of a patient and, fuse them together to 3D print the complete skull model with the implant. Masticatory forces are applied in the molar region to simulate chewing and measure the stress-strain trajectory. Until recently, strain gages have been used to measure strains for validation. Digital Image Correlation (DIC) method is a relatively new technique for full-field strain measurement which provides a continuous deformation field data. The main objective of this study is to validate the finite element model of patient-specific craniofacial implants against the strain data from the DIC obtained during the mastication simulation and show that the optimized shapes provide adequate load-transfer mechanism. Patient-specific models are obtained from CT scans. The principal maximum and minimum strains are compared. The computational and experimental approach to designing patient-specific implants proved to be a viable technique for mid-face craniofacial reconstruction.

  20. Unmanned aerial vehicle acquisition of three-dimensional digital image correlation measurements for structural health monitoring of bridges

    Reagan, Daniel; Sabato, Alessandro; Niezrecki, Christopher


    Civil engineering structures such as bridges, buildings, and tunnels continue to be used despite aging and deterioration well past their design life. In 2013, the American Society of Civil Engineers (ASCE) rated the state of the U.S. bridges as mediocre, despite the $12.8 billion USD annually invested. Traditional inspection and monitoring techniques may produce inconsistent results, are labor intensive and too time-consuming to be considered effective for large-scale monitoring. Therefore, new structural health monitoring systems must be developed that are automated, highly accurate, minimally invasive, and cost effective. Three-dimensional (3D) digital image correlation (DIC) systems possess the capability of extracting full-field strain, displacement, and geometry profiles. Furthermore, as this measurement technique is implemented within an Unmanned Aerial Vehicle (UAV) the capability to expedite the optical-based measurement process is increased as well as the infrastructure downtime being reduced. These resulting integrity maps of the structure of interest can be easily interpreted by trained personal. Within this paper, the feasibility of performing DIC measurements using a pair of cameras installed on a UAV is shown. Performance is validated with in-flight measurements. Also, full-field displacement monitoring, 3D measurement stitching, and 3D point-tracking techniques are employed in conjunction with 3D mapping and data management software. The results of these experiments show that the combination of autonomous flight with 3D DIC and other non-contact measurement systems provides a highly valuable and effective civil inspection platform.

  1. Comparison of subset-based local and FE-based global digital image correlation: Theoretical error analysis and validation

    Pan, B.


    Subset-based local and finite-element-based (FE-based) global digital image correlation (DIC) approaches are the two primary image matching algorithms widely used for full-field displacement mapping. Very recently, the performances of these different DIC approaches have been experimentally investigated using numerical and real-world experimental tests. The results have shown that in typical cases, where the subset (element) size is no less than a few pixels and the local deformation within a subset (element) can be well approximated by the adopted shape functions, the subset-based local DIC outperforms FE-based global DIC approaches because the former provides slightly smaller root-mean-square errors and offers much higher computation efficiency. Here we investigate the theoretical origin and lay a solid theoretical basis for the previous comparison. We assume that systematic errors due to imperfect intensity interpolation and undermatched shape functions are negligibly small, and perform a theoretical analysis of the random errors or standard deviation (SD) errors in the displacements measured by two local DIC approaches (i.e., a subset-based local DIC and an element-based local DIC) and two FE-based global DIC approaches (i.e., Q4-DIC and Q8-DIC). The equations that govern the random errors in the displacements measured by these local and global DIC approaches are theoretically derived. The correctness of the theoretically predicted SD errors is validated through numerical translation tests under various noise levels. We demonstrate that the SD errors induced by the Q4-element-based local DIC, the global Q4-DIC and the global Q8-DIC are 4, 1.8-2.2 and 1.2-1.6 times greater, respectively, than that associated with the subset-based local DIC, which is consistent with our conclusions from previous work. © 2016 Elsevier Ltd. All rights reserved.

  2. Single-camera stereo-digital image correlation with a four-mirror adapter: optimized design and validation

    Yu, Liping; Pan, Bing


    A low-cost, easy-to-implement but practical single-camera stereo-digital image correlation (DIC) system using a four-mirror adapter is established for accurate shape and three-dimensional (3D) deformation measurements. The mirrors assisted pseudo-stereo imaging system can convert a single camera into two virtual cameras, which view a specimen from different angles and record the surface images of the test object onto two halves of the camera sensor. To enable deformation measurement in non-laboratory conditions or extreme high temperature environments, an active imaging optical design, combining an actively illuminated monochromatic source with a coupled band-pass optical filter, is compactly integrated to the pseudo-stereo DIC system. The optical design, basic principles and implementation procedures of the established system for 3D profile and deformation measurements are described in detail. The effectiveness and accuracy of the established system are verified by measuring the profile of a regular cylinder surface and displacements of a translated planar plate. As an application example, the established system is used to determine the tensile strains and Poisson's ratio of a composite solid propellant specimen during stress relaxation test. Since the established single-camera stereo-DIC system only needs a single camera and presents strong robustness against variations in ambient light or the thermal radiation of a hot object, it demonstrates great potential in determining transient deformation in non-laboratory or high-temperature environments with the aid of a single high-speed camera.

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

    贾晓芬; 赵佰亭; 周孟然; 陈兆权


    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.

  4. 3DMADMAC|SPECTRAL: Hardware and Software Solution for Integrated Digitization of 3D Shape, Multispectral Color and BRDF for Cultural Heritage Documentation

    Robert Sitnik


    Full Text Available In this article a new 3D measurement system along with the study on 3D printing technology is presented from the perspective of quality of reproduction. In the first part of the paper the 3DMADMAC|SPECTRAL system which integrates 3D shape with additional color and angular reflectance measurement capabilities is presented (see Figure 1. The shape measurement system is based on structured light projection with the use of a DLP projector. The 3D shape measurement method is based on sinusoidal fringes and Gray codes projection. Color is being measured using multispectral images with a set of interference filters to separate spectral channels. Additionally the set up includes an array of compact light sources for measuring angular reflectance based on image analysis and 3D data processing. All three components of the integrated system use the same greyscale camera as a detector. The purpose of the system is to obtain complete information about shape, color and reflectance characteristic of mea sured surface, especially for cultural heritage objects - in order to create high quality 3D documentation. In the second part of the paper the 3D printing technology will be tested on real measured cultural heritage objects. Tests allow to assess measurement and color accuracy of reproduction by selected 3D printing technology and shed some light on how current 3D printing technology can be applied into cultural heritage.

  5. Ocean Color

    National Aeronautics and Space Administration — Satellite-derived Ocean Color Data sets from historical and currently operational NASA and International Satellite missions including the NASA Coastal Zone Color...

  6. Entropy, color, and color rendering.

    Price, Luke L A


    The Shannon entropy [Bell Syst. Tech J.27, 379 (1948)] of spectral distributions is applied to the problem of color rendering. With this novel approach, calculations for visual white entropy, spectral entropy, and color rendering are proposed, indices that are unreliant on the subjectivity inherent in reference spectra and color samples. The indices are tested against real lamp spectra, showing a simple and robust system for color rendering assessment. The discussion considers potential roles for white entropy in several areas of color theory and psychophysics and nonextensive entropy generalizations of the entropy indices in mathematical color spaces.

  7. Effects of white light-emitting diode (LED) light exposure with different correlated color temperatures (CCTs) on human lens epithelial cells in culture.

    Xie, Chen; Li, Xiuyi; Tong, Jianping; Gu, Yangshun; Shen, Ye


    Cataract is the major cause for legal blindness in the world. Oxidative stress on the lens epithelial cells (hLECs) is the most important factor in cataract formation. Cumulative light-exposure from widely used light-emitting diodes (LEDs) may pose a potential oxidative threat to the lens epithelium, due to the high-energy blue light component in the white-light emission from diodes. In the interest of perfecting biosafety standards for LED domestic lighting, this study analyzed the photobiological effect of white LED light with different correlated color temperatures (CCTs) on cultured hLECs. The hLECs were cultured and cumulatively exposed to multichromatic white LED light with CCTs of 2954, 5624, and 7378 K. Cell viability of hLECs was measured by Cell Counting Kit-8 (CCK-8) assay. DNA damage was determined by alkaline comet assay. Intracellular reactive oxygen species (ROS) generation, cell cycle, and apoptosis were quantified by flow cytometry. Compared with 2954 and 5624 K LED light, LED light having a CCT of 7378 K caused overproduction of intracellular ROS and severe DNA damage, which triggered G2 /M arrest and apoptosis. These results indicate that white LEDs with a high CCT could cause significant photobiological damage to hLECs. © 2014 The American Society of Photobiology.

  8. Correlations between mean echogenicity and material properties of normal and diseased equine superficial digital flexor tendons: an in vitro segmental approach.

    Crevier-Denoix, N; Ruel, Y; Dardillat, C; Jerbi, H; Sanaa, M; Collobert-Laugier, C; Ribot, X; Denoix, J-M; Pourcelot, P


    The objective of this study was to test the hypothesis that tendon echogenicity is associated with the material properties of the corresponding tendon site, especially in case of lesions, due to local changes in tendon matrix composition. Four normal and nine spontaneously injured equine superficial digital flexor tendons (SDFT) were isolated then ultrasonographically examined under tension, in a special device placed in a water bath. Ultrasonographic transversal images (7.5MHz linear transducer) of five segments along each tendon were digitized, and analyzed in order to measure the mean cross-sectional area (MCSA) and mean echogenicity (ME) of each segment. The tendons were then tested in traction until rupture in a testing machine. For each segment, stress and strain were determined throughout the test, and the elastic modulus (EM) was evaluated. The tendon lesions were also documented by histology. No correlation was found between ME and the material properties of normal tendon segments. At the rupture sites of the nine diseased tendons, ME was positively correlated with maximal stress and EM, whereas no correlation was demonstrated with maximal strain. Besides, a positive correlation was demonstrated between ME and both MCSA and EM, when the three metacarpal segments of the diseased tendons were considered. Although ME gives only rough information about tendon matrix structure, it does show, under these in vitro conditions, significant correlations with material properties of pathological tendon segments, which may improve the functional significance and therefore the prognostic value of the ultrasonographic examination of tendon lesions.

  9. Color invariance

    Geusebroek, J.M.; van den Boomgaard, R.; Smeulders, A.W.M.; Geerts, H.


    This paper presents the measurement of colored object reflectance, under different, general assumptions regarding the imaging conditions. We exploit the Gaussian scale-space paradigm for color images to define a framework for the robust measurement of object reflectance from color images. Object ref

  10. Color Algebras

    Mulligan, Jeffrey B.


    A color algebra refers to a system for computing sums and products of colors, analogous to additive and subtractive color mixtures. We would like it to match the well-defined algebra of spectral functions describing lights and surface reflectances, but an exact correspondence is impossible after the spectra have been projected to a three-dimensional color space, because of metamerism physically different spectra can produce the same color sensation. Metameric spectra are interchangeable for the purposes of addition, but not multiplication, so any color algebra is necessarily an approximation to physical reality. Nevertheless, because the majority of naturally-occurring spectra are well-behaved (e.g., continuous and slowly-varying), color algebras can be formulated that are largely accurate and agree well with human intuition. Here we explore the family of algebras that result from associating each color with a member of a three-dimensional manifold of spectra. This association can be used to construct a color product, defined as the color of the spectrum of the wavelength-wise product of the spectra associated with the two input colors. The choice of the spectral manifold determines the behavior of the resulting system, and certain special subspaces allow computational efficiencies. The resulting systems can be used to improve computer graphic rendering techniques, and to model various perceptual phenomena such as color constancy.

  11. Methodological Research on Color Digitalization of Glycyrrhizae Radix et Rhizoma Based on Colorimetry Theory%基于色度学理论的甘草颜色数字化方法学研究*

    邹慧琴; 李硕; 林相龙; 苏玉贞; 吴浩忠; 闫永红


    目的:基于色度学理论,引入分光测色计,建立甘草断面及表皮颜色指标数字化的方法。为传统中药性状鉴别中感官颜色的客观化、数字化提供新方法、新思路。方法:基于CIE1976L*a*b*均匀色空间系统,以甘草为研究对象,针对样品断面及表皮的具体情况,选用2种分光测色计分别制订了甘草断面和表皮颜色的测量方法。结果:确定了去皮打粉的断面颜色量化方法和以直接测量为主、湿法施压剥皮测量为辅的表皮颜色量化方法,摸索并确定了RSD和dE*ab双指标评价方法。结果表明此方法有效、可行。结论:本颜色测量方法简便、可靠,测量结果可以如实的反映药材颜色情况,并将主观的颜色描述用客观的数据表示,为揭示中药传统性状鉴别深层内涵提供了实验依据。%This study was aimed to establish a method for sensorial color digitalization of Chinese herbal medicines (CHMs) with the application of spectrocolorimeter. The discussion was focused on difficulties of distinguishing surface and section color of CHMs. Based on uniform color space system of CIE1976L*a*b*, two methods for determination of section and surface color were constructed with two different kinds of spectrocolorimeters taking Glycyrrhizae Radix et Rhizoma as the experimental objective. In this paper, different kinds of sample preparation methods were used. Based on results, the method of scraping and grinding was proposed to prepare samples for section color determination. The method of wet pressing and peeling was proposed to prepare samples for surface color determination. Besides, RSD and dE*ab were served as evaluation indexes. This paper provided a simple, rapid and reliable analysis method for the color determination of CHMs. It also gave insight to future research on digitalization and modernization of CHMs' organoleptic characteristics based on traditional macroscopic identification.

  12. Measurement of J-integral in CAD/CAM dental ceramics and composite resin by digital image correlation.

    Jiang, Yanxia; Akkus, Anna; Roperto, Renato; Akkus, Ozan; Li, Bo; Lang, Lisa; Teich, Sorin


    Ceramic and composite resin blocks for CAD/CAM machining of dental restorations are becoming more common. The sample sizes affordable by these blocks are smaller than ideal for stress intensity factor (SIF) based tests. The J-integral measurement calls for full field strain measurement, making it challenging to conduct. Accordingly, the J-integral values of dental restoration materials used in CAD/CAM restorations have not been reported to date. Digital image correlation (DIC) provides full field strain maps, making it possible to calculate the J-integral value. The aim of this study was to measure the J-integral value for CAD/CAM restorative materials. Four types of materials (sintered IPS E-MAX CAD, non-sintered IPS E-MAX CAD, Vita Mark II and Paradigm MZ100) were used to prepare beam samples for three-point bending tests. J-integrals were calculated for different integral path size and locations with respect to the crack tip. J-integral at path 1 for each material was 1.26±0.31×10(-4)MPam for MZ 100, 0.59±0.28×10(-4)MPam for sintered E-MAX, 0.19±0.07×10(-4)MPam for VM II, and 0.21±0.05×10(-4)MPam for non-sintered E-MAX. There were no significant differences between different integral path size, except for the non-sintered E-MAX group. J-integral paths of non-sintered E-MAX located within 42% of the height of the sample provided consistent values whereas outside this range resulted in lower J-integral values. Moreover, no significant difference was found among different integral path locations. The critical SIF was calculated from J-integral (KJ) along with geometry derived SIF values (KI). KI values were comparable with KJ and geometry based SIF values obtained from literature. Therefore, DIC derived J-integral is a reliable way to assess the fracture toughness of small sized specimens for dental CAD/CAM restorative materials; however, with caution applied to the selection of J-integral path.

  13. Color stabilizes textbook visual processing

    Paeglis, Roberts; Orlovska, Madara; Bluss, Kristaps


    We report that pages with color illustrations elicit more homogeneous duration of fixations in 12 elementary school children. For six first graders, we compared the reading of the color cover and a greyscale illustrated text page of an abcbook. For six second grade pupils, we demonstrated a color and a greyscale fairytale book page. The fixations we recorded are concordant with the duration for preschoolers reported elsewhere. Average duration of fixations on a page with color elements are shorter than on greyscale ones, 425 (SE=13.4) and 461 (18.3) ms, respectively. The correlation analysis lends support that a color page is processed differently than its greyscale version. Fixation duration for color and greyscale condition was correlated neither for text (r=.567, p=.241) nor for images (r=.517, p=.294) for the second graders. Our research suggests that color elements on textbook pages encourage emergent readers to perform better in acquisition.

  14. Genetic Determinants of Skin Color, Aging, and Cancer

    L.C. Jacobs (Leonie)


    markdownabstractChapter 1 gives a general introduction to this thesis. In Chapter 2 we validated perceived skin color as skin color measurement. In Chapter 3 we investigated whether digitally quantified skin color was a suitable measure to discover new skin color genes. In Chapter 4 we investi

  15. Color Categories and Color Appearance

    Webster, Michael A.; Kay, Paul


    We examined categorical effects in color appearance in two tasks, which in part differed in the extent to which color naming was explicitly required for the response. In one, we measured the effects of color differences on perceptual grouping for hues that spanned the blue-green boundary, to test whether chromatic differences across the boundary…

  16. Color Categories and Color Appearance

    Webster, Michael A.; Kay, Paul


    We examined categorical effects in color appearance in two tasks, which in part differed in the extent to which color naming was explicitly required for the response. In one, we measured the effects of color differences on perceptual grouping for hues that spanned the blue-green boundary, to test whether chromatic differences across the boundary…

  17. [Correlation between basic imaging properties and subjective evaluations of two digital radiographic X-ray systems based on direct-conversion flat panel detector].

    Sakaguchi, Taro; Katayama, Reiji; Morishita, Junji; Sakai, Shinji; Kuroki, Hidefumi; Ohkubo, Seiji; Maeda, Takashi; Hayabuchi, Naofumi


    The purpose of this study was to examine the correlation between the basic imaging properties of two digital radiographic X-ray systems with a direct conversion flat-panel detector and their image qualities, which were evaluated by the observer in hard copy and soft copy studies. The subjective image quality was evaluated and compared in terms of the low-contrast detectability and image sharpness in the two digital radiographic X-ray systems. We applied the radiographs of a contrast detail phantom to the evaluation of low-contrast detectability and analyzed the contrast detail diagrams. Finally, low-contrast detectability was evaluated by the image quality figure (IQF) calculated from the contrast detail diagrams. Also, the subjective image sharpness of human dry bones of two systems was examined and evaluated by the normalized-rank method. The results indicated that System A tended to provide superior subjective image quality compared to System B in both observer studies. We also found high correlations between IQFs and basic imaging properties, such as the noise power spectrum (NPS) and the noise equivalent quantum (NEQ). In conclusion, the low-contrast detectability of the two digital radiographic X-ray systems with a direct conversion flat-panel detector corresponded to the NPS and the NEQ in both outputs (soft copy and hard copy). On the other hand, the subjective image sharpness of human dry bones was affected by their noise properties.

  18. 2016 - Color & Infrared - Rutland and Windsor (0.3m)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata record describes the acquisition and production of natural color and color infrared digital ground orthoimagery covering a portion...

  19. 2014 - Color & Infrared - Northeastern Vermont (0.5m)

    Vermont Center for Geographic Information — (Link to Metadata) This metadata record describes the acquisition and production of natural color and color infrared digital ground orthoimagery covering a portion...

  20. Real color captures attention and overrides spatial cues in grapheme-color synesthetes but not in controls

    Leeuwen, T.M. van; Hagoort, Peter; Händel, B.F.


    Grapheme-color synesthetes perceive color when reading letters or digits. We investigated oscillatory brain signals of synesthetes vs. controls using magnetoencephalography. Brain oscillations specifically in the alpha band ( approximately 10Hz) have two interesting features: alpha has been linked