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INSTANTANEOUS VELOCITY-FIELD MEASUREMENTS IN UNSTEADY GAS-FLOW BY SPECKLE VELOCIMETRY

APPLIED OPTICS 1983年第4期22卷 535-540页

作者： MEYNART, R []The author is with Universite Libre de Bruxelles Service des Milieux Continus 1050 Bruxelles Belgium.

An application of speckle photography techniques to unsteady gas flow measurements is presented. The instrumentation developed for the analysis of double-exposure photographs by digital signal processing is described. It is shown that 2-D velocity fields can be measured even when the flow is not perfectly 2-D. Accuracy and limitations of these techniques are discussed.

关键词： Digital image processing Fringe analysis image processing image processing algorithms Signal processing Speckle photography

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AUTOMATED-METHOD FOR FUNDUS image REGISTRATION AND ANALYSIS

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APPLIED OPTICS 1988年第6期27卷 1107-1112页

作者： MITRA, S NUTTER, BS KRILE, TF BROWN, RH UNIV TEXAS HLTH SCI CTR DALLAS TX 75235 USA

Automated detection of subtle changes in sequential images requires development of procedures that ensure true subtraction of two images by proper registration and normalization of illumination. The difference image can then be further processed to analyze the spectral components and the gray level variations. An innovative and generalized approach to accurate image subtraction incorporating illumination normalization and correction for translation, rotation, and scale difference in two sequential images is considered. The entire procedure yielding true image subtraction has been implemented in a PC-based image processing system and can be executed by menu-driven operations. The effectiveness of this approach is illustrated through subtraction of registered sequential fundus images and analysis of the spectral and gray-level variations of the difference images.

关键词： Digital imaging image analysis image processing image processing algorithms Retinal nerve fiber layer Spectral imaging

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DOUBLE PHASE-CONJUGATE MIRROR - ANALYSIS, DEMONSTRATION, AND APPLICATIONS

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OPTICS LETTERS 1987年第2期12卷 114-116页

作者： WEISS, S STERNKLAR, S FISCHER, B []Department of Electrical Engineering Technion-Israel Institute of Technology Haifa 32000 Israel

We report on the operation of the double phase-conjugate mirror (DPCM). Two inputs to opposite sides of a photorefractive barium titanate crystal, which may carry different spatial images, are shown to pump the same four-wave mixing process mutually and are self-refracted without any external or internal crystal surface. This results in the phase-conjugate reproduction of the two images simultaneously. This device is analyzed theoretically, and applications in image processing, interferometry, and rotation sensing are discussed. We also demonstrate the operation of a ring laser, using the DPCM, as well as a photorefractive resonator with two facing DPCM’s that can support spatial information in its oscillations.

关键词： Barium titanate Crosstalk Four wave mixing image processing image processing algorithms Sagnac interferometry

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Generative adversarial networks and faster-region convolutional neural networks based object detection in X-ray baggage security imagery

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OSA CONTINUUM 2020年第12期3卷 3604-3614页

作者： Kim, Jongchol Kim, Jiyong Ri, Jinmyong Univ Sci Dept Control Sci Pyongyang 999093 South Korea

X-ray images have now been widely used in public transportation security. However, the ever-increasing number of dangerous object types, along with the complexity of the baggage's contents, makes it unsuitable for clearly displaying various baggages and hazards on X-ray images obtained directly from the inspection system. This article aims to improve the detection of dangerous objects by proposing a data augmentation method for enriching the X-ray prohibited item images using a Generative Adversarial Networks(GANs) based approach. Using the improved GANs model, a new X-ray images were generated with better quality and diversity, and the performance of the proposed method was evaluated using FID(Frechet Inception Distance) score and Faster R-CNN (Region-based Convolutional Neural Network). Experimental results show that the new augmented X-ray security inspection image dataset can improve the detector performance. If other representative training datasets are utilized, we believe that our methodology could aid in the detection of other kinds of threat objects. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： image processing algorithms image quality Neural networks Object detection Vision modeling X ray imaging

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228 x 304 200-mW lidar based on a single-point global-depth d-ToF sensor and RGB-guided super-resolution neural network

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OPTICS LETTERS 2023年第13期48卷 3415-3418页

作者： Sun, Miao Wu, Yifan Cui, Lebei Yu, Hengwei Li, Jie Qian, Jian Wang, Jier Qiu, Lei Chiang, Patrick Yin Zhuo, Shenglong Fudan Univ State Key Lab ASIC & Syst Shanghai 201203 Peoples R China Tongji Univ Coll Elect Informat & Engn Shanghai Peoples R China

The cutting-edge imaging system exhibits low output resolution and high power consumption, presenting challenges for the RGB-D fusion algorithm. In practical scenarios, aligning the depth map resolution with the RGB image sensor is a crucial requirement. In this Letter, the software and hardware co-design is considered to implement a lidar system based on the monocular RGB 3D imaging algorithm. A 6.4x6.4-mm(2) deep-learning accelerator (DLA) system-on-chip (SoC) manufactured in a 40-nm CMOS is incorporated with a 3.6-mm(2) TX-RX integrated chip fabricated in a 180-nm CMOS to employ the customized single-pixel imaging neural network. In comparison to the RGB-only monocular depth estimation technique, the root mean square error is reduced from 0.48 m to 0.3 m on the evaluated dataset, and the output depth map resolution matches the RGB input. (c) 2023 Optica Publishing Group

关键词： Diode lasers image processing algorithms image sensors Neural networks Superresolution Three dimensional imaging

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Exoscope-based videocapillaroscopy system for in vivo skin microcirculation imaging of various body areas

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BIOMEDICAL OPTICS EXPRESS 2021年第8期12卷 4627-4636页

作者： Machikhin, Alexander S. Volkov, Mikhail V. Khokhlov, Demid D. Lovchikova, Ekaterina D. Potemkin, Andrey, V Danilycheva, Inna, V Dorofeeva, Irina, V Shulzhenko, Andrey E. Russian Acad Sci Sci & Technol Ctr Unique Instrumentat Lab Acoustoopt Spect 15 Butlerova Moscow 117342 Russia ITMO Univ Fac Appl Opt 49 Kronverksky St Petersburg 197101 Russia Fed Med Biol Agcy Dept Allergol & Immunotherapy Inst Immunol 24 Kashirskoe Moscow 115522 Russia

The capillary system immediately responds to many pathologies and environmental conditions. Accurate monitoring of its functioning often enables early detection of various diseases related to disorders in skin microcirculation. To expand the scope of capillaroscopy application, it is reasonable to visualize and assess blood microcirculation exactly in the areas of inflamed skin. Body vibrations, breathing, non-flat skin surface and other factors hamper the application of conventional capillaroscopes outside the nailfold area. In this paper, we propose an exoscope-based optical system for high-quality non-invasive computational imaging of capillary network in various areas of the body. Accurate image matching and tracking temporal intensity variations allow detecting the presence of blood pulsations, precise mapping of capillaries and photoplethysmogram acquisition. We have demonstrated the efficiency of the proposed approach experimentally by in vivo mapping and analysis of microvessels in wrist, forearm, upper-arm, breast and hip areas. We believe that the developed system will increase the diagnostic value of video capillaroscopy in clinical practice. (c) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Computational imaging image processing image processing algorithms image quality Optical coherence tomography Speckle imaging

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Transmission and fluorescence angular domain optical projection tomography of turbid media

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APPLIED OPTICS 2009年第33期48卷 6448-6457页

作者： Vasefi, Fartash Ng, Eldon Kaminska, Bozena Chapman, Glenn H. Jordan, Kevin Carson, Jeffery J. L. Lawson Hlth Res Inst Imaging Program London ON Canada Univ Western Ontario London ON Canada London Hlth Sci Ctr London Reg Canc Program London ON Canada Simon Fraser Univ Sch Engn Sci Burnaby BC V5A 1S6 Canada

When imaging through turbid media, objects are often blurred by scattered light. An optical collimator (i.e., an angular filter array) improves images by accepting only photons propagating within a narrow solid angle about the direction of the incident light. These photons are expected to participate in a limited number of small-angle scattering events, maintaining their original propagation direction and, finally, contributing to the development of a faithful image of an object within a turbid medium. The collimation method, also referred to as angular domain imaging (ADI), applies to a see-through configuration where the incident collimated light beam can be aligned with the collimator in a transillumination mode of operation. In this paper, we present angular domain optical projection tomography (ADOPT), a method that can extract depth information of optical contrast in turbid media with high longitudinal resolution based on ADI technology. The resolution of the ADI system has been tested over various depths in a 5 cm optical cuvette using a resolution target suspended in a homogeneous turbid medium. The ADOPT system reconstructed images from a series of angular domain projections collected at angular intervals. The system was used to measure the attenuation of an absorbing target in transmission mode (t-ADOPT) and to measure the light emitting from a fluorescent target (f-ADOPT). Tissue-mimicking phantoms were used to validate the performance of the method. In the t-ADOPT configuration, a background scattered light estimation and subtraction methodology was introduced to improve the imaging contrast. A target consisting of two graphite rods (0.9 mm diameter) was suspended in the cuvette by a rotation stage. An Indocyanine Green-filled glass rod was used as an imaging target in the f-ADOPT arrangement. The target was placed in a manner such that the line of laser light was perpendicular to the longitudinal axis of the rods. Several projections were collected at i

关键词： Attenuation Biological imaging image processing algorithms Laser light Scattering measurement Turbid media imaging

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image fusion using a multi-level image decomposition and fusion method

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APPLIED OPTICS 2021年第24期60卷 7466-7479页

作者： Tian, Yu Yang, Wenjing Wang, Ji Natl Univ Def Technol Coll Comp Inst Quantum Informat Changsha 410073 Peoples R China Natl Univ Def Technol Coll Comp State Key Lab High Performance Comp Changsha 410073 Peoples R China

In recent years, image fusion has emerged as an important research field due to its various applications. images acquired by different sensors have significant differences in feature representation due to the different imaging principles. Taking visible and infrared image fusion as an example, visible images contain abundant texture details with high spatial resolution. In contrast, infrared images can obtain dear target contour information according to the principle of thermal radiation, and work well in all day/night and all weather conditions. Most existing methods employ the same feature extraction algorithm to get the feature information from visible and infrared images, ignoring the differences among these images. Thus, this paper proposes what we believe to be a novel fusion method based on a multi-level image decomposition method and deep learning fusion strategy for multi-type images. In image decomposition, we not only utilize a multi-level extended approximate low-rank projection matrix learning decomposition method to extract salient feature information from both visible and infrared images, but also apply a multi-level guide filter decomposition method to obtain texture information in visible images. In image fusion, a novel fusion strategy based on a pretrained ResNet50 network is presented to fuse multi-level feature information from both visible and infrared images into corresponding multi-level fused feature information, so as to improve the quality of the final fused image. The proposed method is evaluated subjectively and objectively in a large number of experiments. The experimental results demonstrate that the proposed method exhibits better fusion performance than other existing methods. (C) 2021 Optical Society of America

关键词： Feature extraction image fusion image processing image processing algorithms image quality Spatial resolution

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Characterization of fibrillar collagen isoforms in infarcted mouse hearts using second harmonic generation imaging

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BIOMEDICAL OPTICS EXPRESS 2021年第1期12卷 604-618页

作者： Sahu, Sushant P. Liu, Qianglin Prasad, Alisha Hasan, Sped Mohammad Abid Liu, Qun Rodriguez, Maria Ximena Bastidas Mukhopadhyay, Orna Burk, David Francis, Joseph Mukhopadhyay, Supratik Fu, Xing Gartia, Manas Ranjan Univ Louisiana Lafayette Dept Chem Lafayette LA 70504 USA Louisiana State Univ LSU AgCtr Sch Anim Sci Baton Rouge LA 70803 USA Louisiana State Univ Dept Mech & Ind Engn Baton Rouge LA 70803 USA Louisiana State Univ Dept Comp Sci Baton Rouge LA 70803 USA Baton Rouge Magnet High Sch Baton Rouge LA 70806 USA Shared Instrumentat Facil & Pennington Biomed Res Baton Rouge LA 70808 USA Louisiana State Univ Sch Vet Med Comparat Biomed Sci Baton Rouge LA 70803 USA

We utilized collagen specific second harmonic generation (SHG) signatures coupled with correlative immunofluorescence imaging techniques to characterize collagen structural isoforms (type I and type III) in a murine model of myocardial infarction (MI). Tissue samples were imaged over a four week period using SHG, transmitted light microscopy and immunofluorescence imaging using fluorescently-labeled collagen antibodies. The post-mortem cardiac tissue imaging using SHG demonstrated a progressive increase in collagen deposition in the left ventricle (LV) post-MI. We were able to monitor structural morphology and LV remodeling parameters in terms of extent of LV dilation, stiffness and fiber dimensions in the infarcted myocardium. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： High speed imaging image processing algorithms Imaging techniques Light scattering Magnetic resonance imaging Medical imaging

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Continuous digital zooming using local self-similarity-based super-resolution for an asymmetric dual camera system

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS image SCIENCE AND VISION 2017年第6期34卷 991-1003页

作者： Moon, Byeongho Yu, Soohwan Ko, Seungyong Park, Seonhee Paik, Joonki Chung Ang Univ Dept Image 84 Heukseok Ro Seoul 06975 South Korea

This paper presents a digital zooming method using a super-resolution (SR) algorithm based on the local self-similarity between the wide-and tele-view images acquired by an asymmetric dual camera system. The proposed SR algorithm consists of four steps: (i) registration of an optically zoomed image to the wide-view image, (ii) restoration of the central region of the zoomed wide-view image, (iii) restoration of the boundary region of the zoomed wideview image, and (iv) fusion of the results from steps (ii) and (iii). Since an asymmetric dual camera system acquires different-resolution images on the same scene due to the different optical specifications, the proposed method can restore the low-resolution wide-view image using the ideal high-frequency component estimated from the optically zoomed image. Experimental results demonstrate that the proposed method can provide significantly improved high-resolution wide-view images compared to existing single-image- based SR methods. (C) 2017 Optical Society of America

关键词： Digital image processing image processing image processing algorithms image quality image restoration Point spread function

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