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Low-cost, readily available 3D microscopy imaging system with variable focus spinner

OPTICS EXPRESS 2018年第23期26卷 30576-30587页

作者： Wang, Lihui Cui, Jianjiang Tabata, Satoshi Ishikawa, Masatoshi Univ Tokyo Grad Sch Informat Sci & Technol Dept Creat Informat Bunkyo Ku 7-3-1 Hongo Tokyo 1138656 Japan Northeastern Univ Coll Informat Sci & Engn Inst Intelligent Syst 11 Lane 3Wenhua Rd Shenyang 110819 Liaoning Peoples R China Univ Tokyo Grad Sch Informat Sci & Technol Dept Informat Phys & Comp Bunkyo Ku 7-3-1 Hongo Tokyo 1138656 Japan

A large open aperture in an optical system can capture high-resolution images but yields a shallow depth of field. To overcome this issue, we investigated a low-cost, readily available method for retrofitting microscopy imaging systems to achieve 3D focus scanning in this study. Specifically, a procedure for fabricating variable focus spinners with dissimilar plates was introduced, and a sequence of 12 images was captured in different focal planes. The image scale and phase were corrected, and the in-focus pixels were abstracted by employing the Laplacian operator. Finally, an all-in-focus sharp image was generated, and a depth map was obtained. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Fast Fourier transforms image processing image processing algorithms Imaging systems Laser sensors Medical imaging

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Deep learning provides high accuracy in automated chondrocyte viability assessment in articular cartilage using nonlinear optical microscopy

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BIOMEDICAL OPTICS EXPRESS 2021年第5期12卷 2759-2772页

作者： Chen, Xun Li, Yang Wyman, Nicole Zhang, Zheng Fan, Hongming Le, Michael Gannon, Steven Rose, Chelsea Zhang, Zhao Mercuri, Jeremy Yao, Hai Gao, Bruce Woolf, Shane Pecot, Thierry Ye, Tong Clemson Univ Dept Bioengn Clemson SC 29634 USA Beihang Univ Inst Med Photon Beijing Adv Innovat Ctr Biomed Engn Sch Biol Sci & Med Engn Beijing 100083 Peoples R China Med Univ South Carolina Dept Orthoped Charleston SC 29425 USA Med Univ South Carolina Hollings Canc Ctr Charleston SC 29425 USA Med Univ South Carolina Dept Regenerat Med & Cell Biol Charleston SC 29425 USA

Chondrocyte viability is a crucial factor in evaluating cartilage health. Most cell viability assays rely on dyes and are not applicable for in vivo or longitudinal studies. We previously demonstrated that two-photon excited autofluorescence and second harmonic generation microscopy provided high-resolution images of cells and collagen structure;those images allowed us to distinguish live from dead chondrocytes by visual assessment or by the normalized autofluorescence ratio. However, both methods require human involvement and have low throughputs. Methods for automated cell-based image processing can improve throughput. Conventional image processing algorithms do not perform well on autofluorescence images acquired by nonlinear microscopes due to low image contrast. In this study, we compared conventional, machine learning, and deep learning methods in chondrocyte segmentation and classification. We demonstrated that deep learning significantly improved the outcome of the chondrocyte segmentation and classification. With appropriate training, the deep learning method can achieve 90% accuracy in chondrocyte viability measurement. The significance of this work is that automated imaging analysis is possible and should not become a major hurdle for the use of nonlinear optical imaging methods in biological or clinical studies.& nbsp;(c) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： image analysis image processing image processing algorithms Medical image processing Nonlinear microscopy Optical imaging

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Automated surface inspection for steel products using computer vision approach

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APPLIED OPTICS 2017年第2期56卷 184-192页

作者： Xi, Jiaqi Shentu, Lifeng Hu, Jikang Li, Mian Baosteel Res Inst Dept Automat 885 Fu Jin Rd Shanghai 201900 Peoples R China Shanghai Jiao Tong Univ Univ Michigan Shanghai Jiao Tong Univ Joint Inst Shanghai 200240 Peoples R China

Surface inspection is a critical step in ensuring product quality in the steel-making industry. In order to relieve inspectors of laborious work and improve the consistency of inspection, much effort has been dedicated to the automated inspection using computer vision approaches over the past decades. However, due to non-uniform illumination conditions and similarity between the surface textures and defects, the present methods are usually applicable to very specific cases. In this paper a new framework for surface inspection has been proposed to overcome these limitations. By investigating the image formation process, a quantitative model characterizing the impact of illumination on the image quality is developed, based on which the non-uniform brightness in the image can be effectively removed. Then a simple classifier is designed to identify the defects among the surface textures. The significance of this approach lies in its robustness to illumination changes and wide applicability to different inspection scenarios. The proposed approach has been successfully applied to the real-time surface inspection of round billets in real manufacturing. Implemented on a conventional industrial PC, the algorithm can proceed at 12.5 frames per second with the successful detection rate being over 90% for turned and skinned billets. (C) 2017 Optical Society of America

关键词： Fourier transforms image processing image processing algorithms image quality Machine vision Real time implementation

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Broadening the detection view of 2D photoacoustic tomography using two linear array transducers

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OPTICS EXPRESS 2016年第12期24卷 12755-12768页

作者： Shu, Weihang Ai, Min Salcudean, Tim Rohling, Robert Abolmaesumi, Purang Tang, Shuo Univ British Columbia Dept Elect & Comp Engn 2332 Main Mall Vancouver BC V6T 1Z4 Canada

Although commercial linear array transducers are widely used in clinical ultrasound, their application in photoacoustic tomography (PAT) is still limited due to the limited-view problem that restricts the image quality. In this paper, we propose a simple approach to address the limited-view problem in 2D by using two linear array transducers to receive PAT signal from different orientations. The positions of the two transducers can be adjusted to fit the specific geometry of an imaging site. This approach is made possible by using a new calibration method, where the relative position between the two transducers can be calibrated using ultrasound by transmitting ultrasound wave with one transducer while receiving with the other. The calibration results are then applied in the subsequent PAT imaging to incorporate the detected acoustic signals from both transducers and thereby increase the detection view. In this calibration method, no calibration phantom is required which largely simplifies and shortens the process. The efficacy of the calibration and improvement on the PAT image quality are demonstrated through phantom studies and in vivo imaging. (C) 2016 Optical Society of America

关键词： image processing algorithms image quality In vivo imaging Medical imaging Phantom studies Three dimensional imaging

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Characterization and quantification of necrotic tissues and morphology in multicellular ovarian cancer tumor spheroids using optical coherence tomography

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BIOMEDICAL OPTICS EXPRESS 2021年第6期12卷 3352-3371页

作者： Yan, Feng Gunay, Gokhan Valerio, Trisha, I Wang, Chen Wilson, Jayla A. Haddad, Majood S. Watson, Maegan Connell, Michael O. Davidson, Noah Fung, Kar-Ming Acar, Handan Tang, Qinggong Univ Oklahoma Stephenson Sch Biomed Engn Norman OK 73019 USA Univ Oklahoma Dept Pathol Hlth Sci Ctr Oklahoma City OK 73104 USA Univ Oklahoma Stephenson Canc Ctr Hlth Sci Ctr Oklahoma City OK 73104 USA

The three-dimensional (3D) tumor spheroid model is a critical tool for high-throughput ovarian cancer research and anticancer drug development in vitro. However, the 3D structure prevents high-resolution imaging of the inner side of the spheroids. We aim to visualize and characterize 3D morphological and physiological information of the contact multicellular ovarian tumor spheroids growing over time. We intend to further evaluate the distinctive evolutions of the tumor spheroid and necrotic tissue volumes in different cell numbers and determine the most appropriate mathematical model for fitting the growth of tumor spheroids and necrotic tissues. A label-free and noninvasive swept-source optical coherence tomography (SS-OCT) imaging platform was applied to obtain two-dimensional (2D) and 3D morphologies of ovarian tumor spheroids over 18 days. Ovarian tumor spheroids of two different initial cell numbers (5,000-and 50,000-cells) were cultured and imaged (each day) over the time of growth in 18 days. Four mathematical models (Exponential-Linear, Gompertz, logistic, and Boltzmann) were employed to describe the growth kinetics of the tumor spheroids volume and necrotic tissues. Ovarian tumor spheroids have different growth curves with different initial cell numbers and their growths contain different stages with various growth rates over 18 days. The volumes of 50,000-cells spheroids and the corresponding necrotic tissues are larger than that of the 5,000-cells spheroids. The formation of necrotic tissue in 5,000-cells numbers is slower than that in the 50,000-cells ones. Moreover, the Boltzmann model exhibits the best fitting performance for the growth of tumor spheroids and necrotic tissues. Optical coherence tomography (OCT) can serve as a promising imaging modality to visualize and characterize morphological and physiological features of multicellular ovarian tumor spheroids. The Boltzmann model integrating with 3D OCT data of ovarian tumor spheroids provides great

关键词： image processing image processing algorithms Imaging techniques Optical coherence tomography Optical imaging Three dimensional imaging

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Automated calibration of multi-camera-projector structured light systems for volumetric high-speed 3D surface reconstructions

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OPTICS EXPRESS 2018年第25期26卷 33278-33304页

作者： Deetjen, Marc E. Lentink, David Stanford Univ Dept Mech Engn Stanford CA 94305 USA

It is challenging to calibrate multiple camera-projector pairs for multi-view 3D surface reconstruction based on structured light. Here, we present a new automated calibration method for high-speed multi-camera-projector systems. The method uses printed and projected dot patterns on a planar calibration target, which is moved by hand in the calibration volume. Calibration is enabled by automated image processing and bundle-adjusted parameter optimization. We determined the performance of our method by 3D reconstructing a sphere. The accuracy is -0.03 +/- 0.09 % as a percentage of the diameter of the calibration volume. Applications include quality control, autonomous systems, engineering measurements, and motion capture, such as the preliminary 3D reconstruction of a bird in flight we present here. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Camera calibration image processing image processing algorithms Reconstruction algorithms Stray light Three dimensional image processing

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Back propagation neutral network based signal acquisition for Brillouin distributed optical fiber sensors

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OPTICS EXPRESS 2019年第4期27卷 4549-4561页

作者： Cao, Zhiyuan Guo, Nan Li, Meihong Yu, Kuanglu Gao, Kaiqiang Beijing Jiaotong Univ Sch Comp & Informat Technol Beijing 100044 Peoples R China Hong Kong Polytech Univ Dept Elect & Informat Engn Kowloon Hong Kong Peoples R China China Elect Power Res Inst Dept Informat & Commun Beijing 100085 Peoples R China

This manuscript proposes a method based on back propagation (BP) neural network and the spectral subtraction method to quickly obtain sensing information in Brillouin fiber optics sensors. BP neural network's characteristics which can realize any complex nonlinear mapping help to determine the frequency shift section(s) information. The training function, transfer function and number of hidden layer nodes of BP neural network are determined with experimental data. The experimental results show that comparing with traditional Lorentz fitting algorithm and edge detection with Sobel operator, the BP neural network is about 1/12 in terms of time complexity with the Lorentz algorithm, about 1/9 with the edge detection based on Sobel operator;while the respective accuracy on determine the frequency shifted section(s) has improved by 79.4% and 27.9%. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Digital image processing Edge detection image processing image processing algorithms Neural networks Pattern recognition

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Generic camera model and its calibration for computational integral imaging and 3D reconstruction

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS image SCIENCE AND VISION 2011年第3期28卷 318-326页

作者： Li, Weiming Li, Youfu City Univ Hong Kong Dept Mfg Engn & Engn Management Kowloon Hong Kong Peoples R China

Integral imaging (II) is an important 3D imaging technology. To reconstruct 3D information of the viewed objects, modeling and calibrating the optical pickup process of II are necessary. This work focuses on the modeling and calibration of an II system consisting of a lenslet array, an imaging lens, and a charge-coupled device camera. Most existing work on such systems assumes a pinhole array model (PAM). In this work, we explore a generic camera model that accommodates more generality. This model is an empirical model based on measurements, and we constructed a setup for its calibration. Experimental results show a significant difference between the generic camera model and the PAM. images of planar patterns and 3D objects were computationally reconstructed with the generic camera model. Compared with the images reconstructed using the PAM, the images present higher fidelity and preserve more high spatial frequency components. To the best of our knowledge, this is the first attempt in applying a generic camera model to an II system. (C) 2011 Optical Society of America

关键词： Camera calibration CCD cameras image processing algorithms image quality Imaging systems Optical components

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Approach for recognizing and tracking beacon in inter-satellite optical communication based on optical flow method

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OPTICS EXPRESS 2018年第21期26卷 28080-28090页

作者： Wang, Qiang Yu, Siyuan Tan, Liying Ma, Sing Harbin Inst Technol Natl Key Lab Tunable Laser Technol Harbin 150001 Heilongjiang Peoples R China

In inter-satellite laser communication systems, accurate positioning of the beacon is essential for establishing a steady laser communication link. For inter-satellite optical communication, the main factor affecting the acquisition and tracking of the beacon is the background noise, such as stellar background light. In this study, we considered the effect of the background noise on a beacon in inter-satellite optical communication and proposed a new recognition algorithm for the beacon, which uses the optical flow vector obtained from the image data. We verified the feasibility of this method by performing simulation analysis and experiments. Both simulation and experiments showed that the new algorithm could accurately obtain the position of the centroid of the beacon under the effect of the background light. Furthermore, considering the identification probability of a light spot through the background light, the locating accuracy of the new algorithm was higher than that of the conventional gray centroid algorithm. Therefore, this new approach would be beneficial for the design of satellite-to-ground optical communication systems. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： image processing image processing algorithms Laser beams Laser communications Optical flow Systems design

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Design and investigation of a digital photocolorimeter

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JOURNAL OF OPTICAL TECHNOLOGY 2020年第9期87卷 521-526页

作者： Zhbanova, V. L. Branch Natl Res Univ Moscow Power Engn Inst Smolensk Russia

In this study, a digital photocolorimeter was developed based on a detector matched with an intrinsic operational color space and a set of optical filters. The color space M-2'N-2'P-2' with properties similar to the curves of the CIE XYZ 1931 system was used. Software was developed for processing of black-and-white images to operate the digital colorimeter. The image processing algorithm in the CIE LAB system is explained and the experimental procedure for determining the color coordinates of samples in the M-2'N-2'P-2' color space using X1X2Y1Z1 detectors is described herein. The color difference between green, yellow-green, and yellow optical filters was determined for an objective assessment of the quality of the developed system. Subsequently, an analysis of the experimental values was performed, and our system exhibited satisfactory results. The possible applications of the developed photocolorimeter are also proposed. (C) 2020 Optical Society of America

关键词： Color difference Color reproduction Color spaces image processing image processing algorithms Optical devices

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