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New luminescence lifetime macro-imager based on a Tpx3Cam optical camera

BIOMEDICAL OPTICS EXPRESS 2020年第1期11卷 77-88页

作者： Sen, Rajannya Hirvonen, Liisa M. Zhdanov, Alexander Svihra, Peter Andersson-Engels, Stefan Nomerotski, Andrei Papkovsky, Dmitri Univ Coll Cork Sch Biochem & Cell Biol Cork Ireland Univ Western Australia CMCA Crawley WA 6009 Australia Czech Tech Univ Fac Nucl Sci & Phys Engn Dept Phys Prague 11519 Czech Republic Univ Manchester Sch Nat Sci Dept Phys & Astron Manchester M13 9PL Lancs England Tyndall Natl Inst Irish Photon Integrat Ctr Cork Ireland Brookhaven Natl Lab Phys Dept Upton NY 11973 USA

The properties of a novel ultra-fast optical imager, Tpx3Cam, were investigated for macroscopic wide-field phosphorescent lifetime imaging (PLIM) applications. The camera is based on a novel optical sensor and Timepix3 readout chip with a time resolution of 1.6 ns, recording of photon arrival time and time over threshold for each pixel, and readout rate of 80 megapixels per second. In this study, we coupled the camera to an image intensifier, a 760 nm emission filter and a 50 mm lens, and with a super-bright 627nm LED providing pulsed excitation of a 18 x 18 mm sample area. The resulting macro-imager with compact and rigid optical alignment of its main components was characterised using planar phosphorescent 02 sensors and a resolution plate mask. Several acquisition and image processing algorithms were evaluated to optimise the system resolution and performance for the wide-field PLIM, followed by imaging a variety of phosphorescent samples. The new PLIM system looks promising, particularly for phosphorescence lifetime-based imaging of O-2 in various chemical and biological samples. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： CCD cameras CMOS cameras image intensifiers image processing algorithms Optical testing Quantum imaging

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TG Vascutrack: A User-Friendly and Open-Source Software for Automated Extraction of Arterial Diameter and Velocity Profile Data From Vascular Ultrasound Videos

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JOURNAL OF ULTRASOUND IN MEDICINE 2024年第11期43卷 2203-2211页

作者： Tecchio, Paolo Gentilin, Alessandro Ruhr Univ Bochum Fac Sport Sci Human Movement Sci Bochum Germany

Existing automated software for vascular ultrasound data extraction lacks free, open-source options suitable for professionals without coding experience. These programs typically include signal-cleaning algorithms, resulting in processed output without access to raw data. To address these needs, we developed TG Vascutrack, an open-source and user-friendly software tailored for non-coder professionals. It features a graphical interface, multiple functionalities, and provides access to raw data. Comparative analysis against validated software and manual extraction revealed minimal biases and standard deviations in diameter and velocity measurements. TG Vascutrack offers a free, promising solution for non-coders needing automated vascular ultrasound data extraction.

关键词： automated software coding image processing algorithms open-source technology vascular research

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Speckle noise reduction in optical coherence tomography images based on edge-sensitive cGAN

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BIOMEDICAL OPTICS EXPRESS 2018年第11期9卷 5129-5146页

作者： Ma, Yuhui Chen, Xinjian Zhu, Weifang Cheng, Xuena Xiang, Dehui Shi, Fei Soochow Univ Sch Elect & Informat Engn Suzhou 215006 Peoples R China Soochow Univ State Key Lab Radiat Med & Protect Suzhou 215123 Peoples R China Minjiang Univ Collaborat Innovat Ctr IoT Technol & Intelligent Fuzhou 350108 Fujian Peoples R China

Speckle noise in optical coherence tomography (OCT) impairs both the visual quality and the performance of automatic analysis. Edge preservation is an important issue for speckle reduction. In this paper, we propose an end-to-end framework for simultaneous speckle reduction and contrast enhancement for retinal OCT images based on the conditional generative adversarial network (cGAN). The edge loss function is added to the final objective so that the model is sensitive to the edge-related details. We also propose a novel method for obtaining clean images for training from outputs of commercial OCT scanners. The results show that the overall denoising performance of the proposed method is better than other traditional methods and deep learning methods. The proposed model also has good generalization ability and is capable of despeckling different types of retinal OCT images. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

关键词： Anisotropic diffusion image analysis image processing algorithms image quality Speckle noise Speckle reduction

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Analysis and application of multiframe superresolution processing for conventional imaging systems and lenslet arrays

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APPLIED OPTICS 2007年第20期46卷 4320-4328页

作者： Kanaev, A. V. Scribner, D. A. Ackerman, J. R. Fleet, E. F. SFA Inc Crofton MD 21114 USA Northrop Grumman Mission Syst Reston VA 20190 USA USN Res Lab Washington DC 20375 USA

Low-cost compact sensors for ultrasmall systems are a pressing need in many new applications. One potential solution is a shallow aspect ratio system using a lenslet array to form multiple undersampled subimages of a scene on a single focal plane array, where processing techniques then produce an upsampled restored image. We have investigated the optimization and theoretical limits of the performance of such arrays. We have built a hardware simulator and developed algorithms to process imagery similar to that of a full lenslet imaging sensor, which allowed us to quickly test optical components, algorithms, and complete system designs for future lenslet imaging systems. (C) 2007 Optical Society of America.

关键词： image processing image processing algorithms Imaging systems Optical components Optical testing Systems design

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Industrial x-ray image enhancement network based on a ray scattering model

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APPLIED OPTICS 2023年第20期62卷 5526-5537页

作者： Ding, Xiaxu Liu, Yi Yan, Hongxu Zhang, Pengcheng Guo, Niu Gui, Zhiguo North Univ China Sch Informat & Commun Engn Taiyuan 030051 Peoples R China North Univ China State Key Lab Dynam Testing Technol Taiyuan 030051 Peoples R China

X-ray images frequently have low contrast and lost edge features because of the complexity of objects, attenuation of reflected light, and scattering superposition of rays. image features are frequently lost in traditional enhancement methods. In this paper, we use a ray scattering model to estimate coarsely clear images and an encoder-decoder network and multi-scale feature extraction module to add multi-scale and detail information to the images. To selectively emphasize useful features, a dual attention module and UnsharpMasking with learnable correction factors are used. The results of the experiments demonstrate that the method may significantly enhance the quality of x-ray images. & COPY;2023 Optica Publishing Group

关键词： image enhancement image processing image processing algorithms image quality Light scattering X ray imaging

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Lattice algebra approach to multispectral analysis of ancient documents

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APPLIED OPTICS 2013年第4期52卷 674-682页

作者： Valdiviezo-N, Juan C. Urcid, Gonzalo Univ Politecn Tulancingo Div Ingn Tulancingo 43629 Hidalgo Mexico Inst Nacl Astrofis Opt & Electr Puebla 72000 Mexico

This paper introduces a lattice algebra procedure that can be used for the multispectral analysis of historical documents and artworks. Assuming the presence of linearly mixed spectral pixels captured in a multispectral scene, the proposed method computes the scaled min- and max-lattice associative memories to determine the purest pixels that best represent the spectra of single pigments. The estimation of fractional proportions of pure spectra at each image pixel is used to build pigment abundance maps that can be used for subsequent restoration of damaged parts. Application examples include multispectral images acquired from the Archimedes Palimpsest and a Mexican pre-Hispanic codex. (C) 2013 Optical Society of America

关键词： Digital image processing image processing image processing algorithms Multispectral imaging Reflectance spectroscopy Spectral imaging

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General Bayesian estimation for speckle noise reduction in optical coherence tomography retinal imagery

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OPTICS EXPRESS 2010年第8期18卷 8338-8352页

作者： Wong, Alexander Mishra, Akshaya Bizheva, Kostadinka Clausi, David A. Univ Waterloo Dept Syst Design Engn Waterloo ON N2L 3G1 Canada Univ Waterloo Dept Phys & Astron Waterloo ON N2L 3G1 Canada

An important image post-processing step for optical coherence tomography (OCT) images is speckle noise reduction. Noise in OCT images is multiplicative in nature and is difficult to suppress due to the fact that in addition the noise component, OCT speckle also carries structural information about the imaged object. To address this issue, a novel speckle noise reduction algorithm was developed. The algorithm projects the imaging data into the logarithmic space and a general Bayesian least squares estimate of the noise-free data is found using a conditional posterior sampling approach. The proposed algorithm was tested on a number of rodent (rat) retina images acquired in-vivo with an ultrahigh resolution OCT system. The performance of the algorithm was compared to that of the state-of-the-art algorithms currently available for speckle denoising, such as the adaptive median, maximum a posteriori (MAP) estimation, linear least squares estimation, anisotropic diffusion and wavelet-domain filtering methods. Experimental results show that the proposed approach is capable of achieving state-of-the-art performance when compared to the other tested methods in terms of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), edge preservation, and equivalent number of looks (ENL) measures. Visual comparisons also show that the proposed approach provides effective speckle noise suppression while preserving the sharpness and improving the visibility of morphological details, such as tiny capillaries and thin layers in the rat retina OCT images. (C) 2010 Optical Society of America

关键词： image processing algorithms image quality Speckle noise Speckle patterns Speckle reduction Synthetic aperture radar

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Optical fiber probe based on spherical coupling of light energy for inner-dimension measurement of microstructures with high aspect ratios

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OPTICS LETTERS 2011年第23期36卷 4689-4691页

作者： Cui, Jiwen Li, Lei Tan, Jiubin Harbin Inst Technol Ctr Ultra Precis Optoelect Instrument Harbin 150080 Peoples R China

An optical fiber probe, based on spherical coupling of light energy, is proposed to transform the lateral displacement of a spherical coupler into the deflection of a light energy center, while the light energy is transmitted in the reverse direction. Therefore, the shadowing effect of a microcavity can be eliminated. The probe has a high displacement sensitivity, allowing precision inner-dimension measurements of microstructures with high aspect ratios. Measurements of microholes and fuel injection nozzles indicate that, for a microstructure with an aspect ratio of up to 15: 1, a probing force <1 mu N, a resolution of up to 0.05 mu m can be achieved using the proposed probe, which is easy to exchange and low cost. (C) 2011 Optical Society of America

关键词： image processing algorithms Microcavities Microstructures Nanopositioning equipment Optical fibers Precision metrology

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Adaptive coded-aperture imaging with subpixel superresolution

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OPTICS LETTERS 2012年第5期37卷 854-856页

作者： Slinger, Chris Bennett, Helen Dyer, Gavin Gordon, Neil Huckridge, David McNie, Mark Penney, Richard Proudler, Ian Rice, Kevin Ridley, Kevin Russell, Lee de Villiers, Geoffrey Watson, Philip Malvern Innovat The Elms Courtyard HR8 1RZ Bromesberrow England QinetiQ Ltd Great Malvern WR14 3PS Worcs England Goodrich ISR Syst Westford MA 01886 USA Cooke Opt Ltd Leicester LE4 8P Leics England

We describe an adaptive coded-aperture imager operating in the midwave IR. This consists of a coded-aperture mask, a set of optics, and a 4k x 4k focal plane array (FPA). This system can produce images with a resolution better than the detector pixel limit by combining multiple frames of data recorded with different coding. This superresolution capability has been demonstrated both in the laboratory and with targets placed outside, the highest resolution being one-half of the FPA pixel pitch. (C) 2012 Optical Society of America

关键词： Adaptive imaging image processing algorithms Modulation transfer function Optical design Optical systems Spatial frequency

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Nanoscale topography of dynamic surfaces with ultrafast time resolution

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APPLIED OPTICS 2008年第28期47卷 5082-5086页

作者： Valenzuela, Anthony R. Clarke, Steven A. Rodriguez, George Los Alamos Natl Lab Mat Phys & Applicat Div Los Alamos NM 87545 USA Los Alamos Natl Lab Weap Syst Engn Div Los Alamos NM 87545 USA

We describe an optical system for detecting the movement of a surface with subnanosecond temporal and nanometer vertical displacement resolution. The system is fielded on an experiment to determine the distortion of a laser-ablated metal layer and compare the results with hydrodynamic simulations. We also discuss errors that can arise and potential means to mitigate them. The resultant data show one can examine dynamic changes to a reflective surface with accuracy down to tens of nanometers at hundreds of picoseconds time resolution. (C) 2008 Optical Society of America

关键词： Distortion image processing algorithms Laser beams Optical surfaces Temporal resolution Ultrafast lasers

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