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Objective speckle velocimetry for autonomous vehicle odometry

APPLIED OPTICS 2012年第16期51卷 3478-3490页

作者： Francis, D. Charrett, T. O. H. Waugh, L. Tatam, R. P. Cranfield Univ Sch Engn Dept Engn Photon Bedford MK43 0AL England EADS Astrium Stevenage SG1 2AS Herts England

Speckle velocimetry is investigated as a means of determining odometry data with potential for application on autonomous robotic vehicles. The technique described here relies on the integration of translation measurements made by normalized cross-correlation of speckle patterns to determine the change in position over time. The use of objective (non-imaged) speckle offers a number of advantages over subjective (imaged) speckle, such as a reduction in the number of optical components, reduced modulation of speckles at the edges of the image, and improved light efficiency. The influence of the source/ detector configuration on the speckle translation to vehicle translation scaling factor for objective speckle is investigated using a computer model and verified experimentally. Experimental measurements are presented at velocities up to 80 mm s(-1) which show accuracy better than 0.4%. (C) 2012 Optical Society of America

关键词： Digital image correlation image processing algorithms Laser light Laser speckle Optical components Speckle patterns

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Hyperspectral database of fruits and vegetables

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS image SCIENCE AND VISION 2018年第4期35卷 B256-B266页

作者： Ennis, Robert Schiller, Florian Toscani, Matteo Gegenfurtner, Karl R. Univ Giessen Dept Psychol Otto Behaghel Str 10 D-35394 Giessen Germany

We have built a hyperspectral database of 42 fruits and vegetables. Both the outside (skin) and inside of the objects were imaged. We used a Specim VNIR HS-CL-30-V8E-OEM mirror-scanning hyperspectral camera and took pictures at a spatial resolution of similar to 57 px/deg by 800 pixels at a wavelength resolution of similar to 1.12 nm. A stable, broadband illuminant was used. images and software are freely available on our webserver (http://***/GHIFVD;pronounced "gift"). We performed two kinds of analyses on these images. First, when comparing the insides and outsides of the objects, we observed that the insides were lighter than the skins, and that the hues of the insides and skins were significantly correlated (circular correlation = 0.638). Second, we compared the color distribution within each object to corresponding human color discrimination thresholds. We found a significant correlation (0.75) between the orientation of ellipses fit to the chromaticity distributions of our fruits and vegetables with the orientations of interpolated MacAdam discrimination ellipses. This indicates a close relationship between sensory processing and the characteristics of environmental objects. (c) 2018 Optical Society of America

关键词： Color spaces Color vision Hyperspectral imaging image processing algorithms Spectral imaging Visual system

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Robust laser stripe extraction for three-dimensional reconstruction based on a cross-structured light sensor

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APPLIED OPTICS 2017年第4期56卷 823-832页

作者： He, Leiying Wu, Shanshan Wu, Chuanyu Zhejiang Sci Tech Univ Fac Mech Engn & Automat Hangzhou 310018 Zhejiang Peoples R China

Cross-structured light sensor architecture for 3D reconstruction was established. An improved center of mass method was proposed for laser stripe extraction. For each initial laser stripe center point, the center of mass method was performed along the normal direction that was calculated using the Hessian matrix. The normal directions can be used to divide the laser stripe center points into two categories. Laser stripe extraction experiments showed that the proposed method is fast and robust. 3D reconstruction of a cylinder was used to analyze reconstruction accuracy, with relative accuracy of less than 0.15 mm. 3D reconstruction of a shoe last showed that cross-structured light sensors can obtain more abundant information than single-structured light sensors. (C) 2017 Optical Society of America

关键词： image processing algorithms Laser beams Laser light Laser materials processing Structured light Three dimensional reconstruction

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Method of space object detection by wide field of view telescope based on its following error

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OPTICS EXPRESS 2021年第22期29卷 35348-35365页

作者： Yang, Wenbo Zhao, Yan Liu, Ming Liu, Delong Jilin Univ Coll Commun Engn Changchun 130012 Peoples R China Natl Astron Observ CAS Changchun Observ Changchun 130117 Peoples R China

Space objects and stars appear similar in images acquired by the wide field of view (FOV) survey telescope. This work investigates a unique property of the telescope observing a space object in satellite tracking mode, namely that the azimuth and altitude angles of the object and those of the optical axis of the telescope vary, in theory, in the same way. Based on this property we derive that the movement distance of the object between the two adjacent frames is minimal compared to the distance of the star. With this conclusion, it is possible to detect the object from a large number of background stars. To improve the robustness of the detection, the set of candidate objects is created. Finally, a clustering algorithm is employed to successfully extract the motion trajectory of the object. Unlike traditional detection methods or techniques based on image processing and analysis, our proposed detection is closely related to the parameters of the trajectory-following performance, which provides a more reliable basis for improving the detection rate. The feasibility and accuracy of the algorithm was verified by the 1.2-meter wide FOV survey telescope at the Jilin base of the Changchun observatory, with a detection rate of over 98%. The test results indicate that the method can satisfy the demand for detecting the object in an open-loop tracking. If the detection method is implemented in hardware, it can detect the object in a closed-loop tracking. As a result, it will have a wider scope for applications. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： image deconvolution image processing algorithms Optical flow Optical telescopes Point spread function Space telescopes

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image registration method for mobile-device-based multispectral optical diagnostics for buildings

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APPLIED OPTICS 2019年第26期58卷 7165-7173页

作者： Sahin, Cem Dogan Menguc, M. Pinar Ozyegin Univ CEEE ECEM TR-34394 Istanbul Turkey Ozyegin Univ Mech Engn TR-34394 Istanbul Turkey

The recent advances in mobile device hardware and software introduced new opportunities to perform more advanced computation and measurements for buildings. Multispectral optical imaging is a widely recognized technique for building diagnostics, as it is non-destructive, quick, and provides rich spatial-spectral information about the different surfaces for decisions related to building energy performance. However, such implementations require an accurate image fission. The purpose of this study is to introduce a practical and robust image registration method for mobile-device-based multispectral imaging analysis for building diagnostics. Considering the complicated building geometries including walls, floors, ceilings, roofs, windows, and doors, a new approach based on planar homography is chosen for determining the feature points that are required to perform image fusion between different images. The results obtained are compared against the other available methods, which show that the current method provides multispectral images enhanced with accurate qualitative information, as long as the constraints are satisfied. The results are compared with the state-of-the-art methods. The possible impact of the multispectral imaging to the future of building diagnostics is also discussed. (C) 2019 Optical Society of America

关键词： image enhancement image fusion image processing image processing algorithms Multispectral imaging Optical imaging

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Gas detection using absorption properties of liquid crystals

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OPTICS EXPRESS 2017年第26期25卷 32532-32538页

作者： Wolowelsky, K. Gil, A. Elkabets, M. Rotschild, C. Technion Israel Inst Technol Fac Mech Engn Haifa Israel CI Syst Ltd Migdal Haemeq Israel

Optical gas imaging is critical for many applications, but its use is currently limited by complexity and cost. Here we experimentally demonstrate a low cost solution based on an alternating bispectral IR filter. This filter is based on liquid crystal having absorption lines, which overlap those of hydrocarbon gases, and depend on the orientation of the liquid crystal molecules. An alternating voltage modulates the orientation and thus the transmittance in the absorption bands, giving rise to different on-to-off intensity ratios for gases, and any clutter emission. Our demonstration of refrigerant gas R134a detection shows a high gas to clutter contrast and opens the way for using this method in many low cost applications. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Fourier transform infrared spectroscopy image processing algorithms Multispectral imaging Optical properties Refractive index Wire grid polarizers

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Selective polarization imager for contrast enhancements in remote scattering media

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APPLIED OPTICS 2012年第18期51卷 4092-4102页

作者： Miller, Darren A. Dereniak, Eustace L. Univ Arizona Coll Opt Sci Tucson AZ 85721 USA

Conventional intensity imaging through turbid media suffers from rapid loss of image contrast due to light scattering from particles or random variations of refractive index. This paper features the development of an active imaging, snapshot, system design and postprocessing algorithms that differentiate between radiation that scatters or reflects from remote, obscured objects and the radiation from the scattering media itself through a combination of polarization difference imaging, channel blurring, and Fourier spatial filtering. The produced sensor acquires and processes image data in real time, yielding improved image contrasts by factors of 10 or greater for dense water vapor obscurants. (C) 2012 Optical Society of America

关键词： image processing image processing algorithms image quality Light scattering Refractive index Turbid media imaging

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Divide and conquer: real-time maximum likelihood fitting of multiple emitters for super-resolution localization microscopy

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OPTICS EXPRESS 2019年第15期27卷 21029-21049页

作者： Li, Luchang Xin, Bo Kuang, Weibing Zhou, Zhiwei Huang, Zhen-Li Huazhong Univ Sci & Technol Wuhan Natl Lab Optoelect Britton Chance Ctr Biomed Photon Wuhan 430074 Hubei Peoples R China Huazhong Univ Sci & Technol Sch Engn Sci Collaborat Innovat Ctr Biomed Engn MoE Key Lab Biomed Photon Wuhan 430074 Hubei Peoples R China

Multi-emitter localization has great potential for maximizing the imaging speed of super-resolution localization microscopy. However, the slow image analysis speed of reported multi-emitter localization algorithms limits their usage in mostly off-line image processing with small image size. Here we adopt the well-known divide and conquer strategy in computer science and present a fitting-based method called QC-STORM for fast multi-emitter localization. Using simulated and experimental data, we verify that QC-STORM is capable of providing real-time full image processing on raw images with 100 mu m x 100 mu m field of view and 10 ms exposure time, with comparable spatial resolution as the popular fitting-based ThunderSTORM and the up-to-date non-iterative WindSTORM. This study pushes the development and practical use of super-resolution localization microscopy in high-throughput or high-content imaging of cell-to-cell differences or discovering rare events in a large cell population. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： image analysis image processing image processing algorithms image reconstruction Three dimensional image processing Three dimensional imaging

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An improved PRNU noise extraction model for highly compressed image blocks with low resolutions

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MULTIMEDIA TOOLS AND APPLICATIONS 2024年第25期83卷 66657-66690页

作者： Tian, Nili Qiu, Xian Pan, Qing Guangdong Univ Technol Sch Informat Engn Guangzhou 510006 Peoples R China

Detecting sources in digital images and videos is crucial to multimedia forensics research. The inherent physical properties of imaging sensors result in the presence of Photo Response Non-Uniformity Noise (PRNU) within the captured multimedia content. This particular noise, often called the "fingerprint," is a unique and stable feature for identifying the source camera. However, the compression of images by platform codecs on social network media introduces varying degrees of quantization noise, making to address this issue, a noise extractor based on variance stabilizing transform and adaptive block clustering principal component analysis (PCA) is proposed, along with an enhanced processing model that incorporates cyclic residual recycling. Firstly, the GAT and adaptive block clustering PCA filtering are applied to extract noises from the images. The obtained noises are then subjected to zero-mean and diagonal artifact elimination processing. Next, the real and imaginary parts of the noise spectrum are individually subjected to real-time iterative least squares smoothing based on half-quadratic optimization. Due to the presence of PRNU information in the residual between the pre-smoothed and post-smoothed signals, additional cyclic smoothing is applied to refine the signal further. Finally, the smoothed signals are accumulated to obtain the enhanced PRNU noise. Experimental comparisons conducted on the public dataset Dresden demonstrate that the proposed model significantly outperforms existing methods in terms of source camera identification for low-resolution and strong JPEG compression images.

关键词： image forensics Source camera identification Photo response non-uniformity image processing algorithms Compressed image identification

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Logic-operated mathematical morphology and its optical implementation

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APPLIED OPTICS 1999年第26期38卷 5605-5612页

作者： Jing, HM Liu, LR Wang, C Zhou, CH Acad Sinica Shanghai Inst Opt & Fine Mech Shanghai 201800 Peoples R China

A more powerful tool for binary image processing, i.e., logic-operated mathematical morphology (LOMM), is proposed. With LOMM the image and the structuring element (SE) are treated as binary logical variables, and the MULTIPLY between the image and the SE in correlation is replaced with 16 logical operations. A total of 12 LOMM operations are obtained. The optical implementation of LOMM is described. The application of LOMM and its experimental results are also presented. (C) 1999 Optical Society of America.

关键词： image analysis image processing image processing algorithms Optical computing Optical devices Parallel processing

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