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Effective method for low-light image enhancement based on the JND and OCTM models

OPTICS EXPRESS 2023年第9期31卷 14008-14026页

作者： Lang, Yi-Zheng Wang, Yi-Lun Qian, Yun-Sheng Kong, Xiang-Yu Cao, Yang Nanjing Univ Sci & Technol Sch Elect & Opt Engn Nanjing 210094 Jiangsu Peoples R China

Low-light images always suffer from dim overall brightness, low contrast, and low dynamic ranges, thus result in image degradation. In this paper, we propose an effective method for low-light image enhancement based on the just-noticeable-difference (JND) and the optimal contrast-tone mapping (OCTM) models. First, the guided filter decomposes the original images into base and detail images. After this filtering, detail images are processed based on the visual masking model to enhance details effectively. At the same time, the brightness of base images is adjusted based on the JND and OCTM models. Finally, we propose a new method to generate a sequence of artificial images to adjust the brightness of the output, which has a better performance in image detail preservation compared with other single-input algorithms. Experiments have demonstrated that the proposed method not only achieves low-light image enhancement, but also outperforms state-of-the-art methods qualitatively and quantitatively.(c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

关键词： image enhancement image fusion image processing image processing algorithms image quality Vision modeling

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Adaptive exposure control for image-based visual-servo systems using local gradient information

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS image SCIENCE AND VISION 2020年第1期37卷 56-62页

作者： Ding, Zhushun Chen, Xin Jiang, Zhe Tan, Cheng Natl Univ Def Technol Dept Aerospace & Engn Changsha 410073 Peoples R China Beijing Inst Aerosp Control Devices Beijing 100039 Peoples R China

We present anew method for automatic adjustment of camera exposure time for visual-servo systems. The proposed method can improve the robustness of image processing in a high-dynamic-range environment. In this paper, we evaluate an appropriate exposure time by computing the local gradient information of a target area, allowing a camera to capture images without losing target features under artificially adjusted illumination conditions. To validate the advantage of the proposed method, an evaluation is made using an off-the-shelf visual-servo system with a machine vision camera. The experimental results demonstrate the effectiveness of our method, which improves the performance of the target recognition algorithm. (C) 2019 Optical Society of America

关键词： image metrics image processing image processing algorithms image quality Liquid crystals Machine vision

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Gradient-based interpolation method for division-of-focal-plane polarimeters

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OPTICS EXPRESS 2013年第1期21卷 1137-1151页

作者： Gao, Shengkui Gruev, Viktor Washington Univ Dept Comp Sci & Engn St Louis MO 63130 USA

Recent advancements in nanotechnology and nanofabrication have allowed for the emergence of the division-of-focal-plane (DoFP) polarization imaging sensors. These sensors capture polarization properties of the optical field at every imaging frame. However, the DoFP polarization imaging sensors suffer from large registration error as well as reduced spatial-resolution output. These drawbacks can be improved by applying proper image interpolation methods for the reconstruction of the polarization results. In this paper, we present a new gradient-based interpolation method for DoFP polarimeters. The performance of the proposed interpolation method is evaluated against several previously published interpolation methods by using visual examples and root mean square error (RMSE) comparison. We found that the proposed gradient-based interpolation method can achieve better visual results while maintaining a lower RMSE than other interpolation methods under various dynamic ranges of a scene ranging from dim to bright conditions. (C) 2013 Optical Society of America

关键词： Charge coupled devices image processing algorithms Light intensity Polarimetric imaging Underwater imaging Visible light

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Smart three-dimensional imaging ladar using two Geiger-mode avalanche photodiodes

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OPTICS EXPRESS 2011年第20期19卷 19323-19329页

作者： Kong, Hong Jin Kim, Tae Hoon Jo, Sung Eun Oh, Min Seok Korea Adv Inst Sci & Technol Dept Phys Taejon 305701 South Korea

In this paper, we propose a new method that is capable of obtaining a clear 3D image by the reduction of false alarms caused by noise in the stage of acquisition of raw time of flight (TOF) data. This method is implemented by intensity dividing a laser-return pulse into two Geiger-mode avalanche photodiodes (GmAPDs);an AND gate compares the arrival time of the electrical signals from the GmAPDs. Despite the fact that the energy of a laser-return pulse is decreased by half, the false alarm probability is drastically decreased because the noise distributed randomly in the time domain is filtered out. The experimental measurement is in agreement with the theoretical analysis. As a result, we can obtain a clear 3D image despite the high noise. (C) 2011 Optical Society of America

关键词： Avalanche photodiodes image processing image processing algorithms Laser sources Q switched lasers Three dimensional imaging

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High-efficiency single-photon compressed sensing imaging based on the best choice scheme

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OPTICS EXPRESS 2023年第5期31卷 7589-7598页

作者： Fan, Yanshan Bai, Miaoqing Wu, Shuxiao Qiao, Zhixing Hu, Jianyong Shanxi Univ Sch Modern Educ Technol Taiyuan 030006 Peoples R China Shanxi Univ Coll Automat & Software Engn Taiyuan 030006 Peoples R China Shanxi Univ Inst Laser Spect State Key Lab Quantum Opt & Quantum Devices Taiyuan 030006 Peoples R China Shanxi Univ Collaborat Innovat Ctr Extreme Opt Taiyuan 030006 Peoples R China Shanxi Med Univ Coll Med Imaging Taiyuan 030001 Peoples R China

With single-photon sensitivity and picosecond resolution, single-photon imaging technology is an ideal solution for extreme conditions and ultra-long distance imaging. However, the current single-photon imaging technology has the problem of slow imaging speed and poor quality caused by the quantum shot noise and the fluctuation of background noise. In this work, an efficient single-photon compressed sensing imaging scheme is proposed, in which a new mask is designed by the Principal Component Analysis algorithm and the Bit-plane Decomposition algorithm. By considering the effects of quantum shot noise, dark count on imaging, the number of masks is optimized to ensure high-quality single-photon compressed sensing imaging with different average photon counts. The imaging speed and quality are greatly improved compared with the commonly used Hadamard scheme. In the experiment, a 64 x 64 pixels' image is obtained with only 50 masks, the sampling compression rate reaches 1.22%, and the sampling speed increases by 81 times. The simulation and experimental results demonstrated that the proposed scheme will effectively promote the application of single-photon imaging in practical scenarios.

关键词： Fourier transforms Hadamard transform image processing algorithms image quality image restoration Speckle interferometry

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250 kHz, 1.5 μm resolution SD-OCT for in-vivo cellular imaging of the human cornea

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BIOMEDICAL OPTICS EXPRESS 2018年第12期9卷 6569-6583页

作者： Tan, Bingyao Hosseinaee, Zohreh Han, Le Kralj, Olivera Sorbara, Luigina Bizheva, Kostadinka Univ Waterloo Dept Phys & Astron Waterloo ON N2L 3G1 Canada Singapore Natl Eye Ctr Singapore Eve Res Inst Singapore Singapore Univ Waterloo Dept Syst Design Engn Waterloo ON N2L 3G1 Canada Univ Waterloo Sch Optometry & Vis Sci Waterloo ON N2L 3G1 Canada

We present the first spectral domain optical coherence tomography (SD-OCT) system that combines an isotropic imaging resolution of similar to 1.5 mu m in biological tissue with a 250 kHz image acquisition rate, for in vivo non-contact, volumetric imaging of the cellular structure of the human cornea. OCT images of the healthy human cornea acquired with this system reveal the cellular structure of the corneal epithelium, cellular debris and mucin clusters in the tear film, the shape, size and spatial distribution of the sub-basal corneal nerves and keratocytes in the corneal stroma, as well as reflections from endothelial nuclei. The corneal images presented here demonstrate the potential clinical value of the new high speed. high resolution OCT system for non-invasive diagnostics and monitoring the treatment of corneal diseases. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Full field optical coherence tomography High speed photography image processing image processing algorithms Optical imaging Three dimensional imaging

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Edge detection methods applied to the analysis of spherical raindrop images

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APPLIED OPTICS 2007年第22期46卷 5352-5367页

作者： Saylor, J. R. Sivasubramanian, N. A. Clemson Univ Dept Mech Engn Clemson SC 29634 USA

Optical imaging of raindrops provides important information on the statistical distribution of raindrop size and raindrop shape. These distributions are critical for extracting rainfall rates from both dual- and single-polarization radar signals. A large number of raindrop images are required to obtain these statistics, necessitating automatic processing of the imagery. The accuracy of the measured drop size depends critically on the characteristics of the digital image processing algorithm used to identify and size the drop. Additionally, the algorithm partially determines the effective depth of field of the camera/image processing system. Because a large number of drop images are required to obtain accurate statistics, a large depth of field is needed, which tends to increase errors in drop size measurement. This trade-off between accuracy and depth of field (dof) is also affected by the algorithm used to identify the drop outline. In this paper, eight edge detection algorithms are investigated and compared to determine which is best suited for accurately extracting the drop outline and measuring the diameter of an imaged raindrop while maintaining a relatively large depth of field. The algorithm which overall gave the largest dof along with the most accurate estimate of the size of the drop was the Hueekel algorithm.

关键词： Analytical techniques Digital image processing Edge detection image processing algorithms Line scan cameras Optical imaging

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Fundamental uncertainty limit for speckle displacement measurements

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APPLIED OPTICS 2017年第25期56卷 7013-7019页

作者： Fischer, Andreas Univ Bremen Bremen Inst Metrol Automat & Qual Sci Linzer Str 13 D-28359 Bremen Germany

The basic metrological task in speckle photography is to quantify displacements of speckle patterns, allowing for instance the investigation of the mechanical load and modification of objects with rough surfaces. However, the fundamental limit of the measurement uncertainty due to photon shot noise is unknown. For this reason, the Cramer-Rao bound (CRB) is derived for speckle displacement measurements, representing the squared minimal achievable measurement uncertainty. As result, the CRB for speckle patterns is only two times the CRB for an ideal point light source. Hence, speckle photography is an optimal measurement approach for contactless displacement measurements on rough surfaces. In agreement with a derivation from Heisenberg's uncertainty principle, the CRB depends on the number of detected photons and the diffraction limit of the imaging system described by the speckle size. The theoretical results are verified and validated, demonstrating the capability for displacement measurements with nanometer resolution. (C) 2017 Optical Society of America

关键词： Diffraction limit image processing algorithms Laser triangulation Speckle noise Speckle patterns Speckle photography

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Real-time identification of the singleness of a trapped bead in optical tweezers

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APPLIED OPTICS 2018年第5期57卷 1241-1246页

作者： Hu, Chunguang Su, Chenguang Yun, Zelin Wang, Sirong He, Chengzhi Gao, Xiaoqing Li, Shuai Li, Hongbin Hu, Xiaodong Hu, Xiaotang Tianjin Univ State Key Lab Precis Measuring Technol & Instrume Tianjin 300072 Peoples R China Univ British Columbia Dept Chem Vancouver BC V6T 1Z1 Canada

Beads trapped in optical tweezers are aligned along the optical propagation direction, which makes it difficult to determine the number of beads with bright-field microscopy. This problem also dramatically influences the measurement of the optical trapping based single-molecule force spectroscopy. Here, we propose a video processing approach to count the number of trapped micro-objects in real time. The approach uses a normalized cross-correlation algorithm and image enhancement techniques to amplify a slight change of the image induced by the entry of an exotic object. As tested, this method introduces a similar to 10% change per bead to the image similarity, and up to four beads, one-by-one falling into the trap, are identified. Moreover, the feasibility of the above analysis in a moving trap is investigated. A movement of the trap leads to a fluctuation of less than 2% for the similarity signal and can be ignored in most cases. The experimental results prove that image similarity measurement is a sensitive way to monitor the interruption, which is very useful, especially during experiments. In addition, the approach is easy to apply to an existing optical tweezers system. (c) 2018 Optical Society of America

关键词： Coherence imaging image processing algorithms image quality Low coherence interferometry Optical measurement Optical tweezers

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Classification of maize leaf diseases based on hyperspectral imaging technology

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JOURNAL OF OPTICAL TECHNOLOGY 2020年第4期87卷 212-217页

作者： Xu, Jing Miao, Teng Zhou, Yuncheng Xiao, Yang Deng, Hanbing Song, Ping Song, Kai Shenyang Agr Univ Coll Informat & Elect Engn Shenyang 110866 Peoples R China Shenyang Ligong Univ Shenyang 110159 Peoples R China

Curvularia lunata and Aureobasidium zeae are the main leaf diseases of maize in Northeast China. These two diseases are similar and difficult to distinguish. In order to diagnose diseases correctly, a diagnostic method based on hyperspectral imaging technology for Curvularia lunata and Aureobasidium zeae was proposed. The experimental leaves were inoculated in vivo, and a hyperspectral imaging system was used to collect hyperspectral image data of leaves with Curvularia lunata, leaves with Aureobasidium zeae, and normal leaves in the near-infrared band. By analyzing the spectral characteristics of chlorotic spots and normal leaves, it is found that there is a significant difference in the spectral information between chlorotic spots and normal leaves. Then, by means of confidence interval estimation and significance testing, the characteristic bands of Curvularia lunata and Aureobasidium zeae can be distinguished. Finally, the classification model of the support vector machine is established based on the characteristic bands. The results show that the 10 characteristic bands of 412.7, 416.3, 421.2, 465.1, 484.8, 580.9, 615, 640.5, 676.2, and 880.8 nm can be used to distinguish between the spectral characteristics of Curvularia lunata and Aureobasidiurn zeae , and the support vector machine classification model established by the above band is used for 288 samples. The accuracy rate was 96.7%. These results provide a theoretical basis and technical method for rapid and nondestructive diagnosis of Curvularia lunata and Aureobasidiurn zeae. (C) 2020 Optical Society of America

关键词： Absorption spectroscopy Hyperspectral imaging image processing algorithms Multispectral imaging Spectral imaging Spectroscopy

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