- 标题
- 摘要
- 关键词
- 实验方案
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Virtual Image Points Based Geometrical Parameters’ Calibration for Focused Light Field Camera
摘要： In the light field imaging, the geometrical parameters' calibration of the light field camera is the foundation of computational imaging techniques, such as the calibration of the light field data, digital refocusing, depth reconstruction, all-in-focus imaging, and so on. In this paper, we propose a virtual image points based geometrical parameters' calibration for focused light field camera. In the forward model, the mapping from the object points to the virtual image points with respect to the main lens as well as the mapping from the virtual image points to the image points on the detector with respect to the microlens array are established. While calibrating geometrical parameters, the inverse problem of calculating the virtual image points from the corner on the detector is established and the model of calculating the geometrical parameters of the focused light field camera is established. Levenberg–Marquardt algorithm is used to solve the geometrical parameters iteratively. We use the checkerboard for the calibration experiment and validate the calculation via the reprojection of the checkerboard corners.
关键词： computational imaging,virtual image point,light field camera,Camera calibration
更新于2025-09-23 15:23:52
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Experimental analysis and designing strategies of lens-less microscopy with partially coherent illumination
摘要： Lens-less microscopy can achieve a wide field of view imaging (FOV) through a simple configuration compared to conventional microscopy, and it’s very attractive in resource-limited areas because of its cost-effectiveness and portability. Featuring a small package and cheapness, LEDs and LDs both show the potential to act as a reasonable illumination source for lens-less microscopes, especially for portable ones. However, based on holographic theorem, the complex light-field reconstruction algorithms consider the light source as a highly coherent one, while both LEDs and LDs can only provide partially coherent illumination. In this manuscript, we would systematically and experimentally analyze the imaging performances of lens-less microscopy with partially coherent illumination. The analysis covers autofocusing under LED/LD illumination, imaging performances under different LED spatial coherence and imaging performances under LED/LD illumination. Furthermore, based on the analysis, some conclusions about designing a lens-less microscope are presented. We think that the experiments and conclusions can provide effective guidance to construct a low-cost lens-less microscope with trade-off hardware parameters in practices.
关键词： Computational imaging,Digital holography,Microscopy,Portable imaging device,Phase retrieval
更新于2025-09-23 15:21:01
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[IEEE 2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting - Boston, MA, USA (2018.7.8-2018.7.13)] 2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting - Phase Retrieval in Frequency-Diverse Imaging
摘要： We demonstrate a phaseless computational frequency-diverse imaging system at K-band frequencies. The integration of the phase retrieval concept with computational frequency-diverse imaging is achieved by leveraging a gradient-descent based Wirtinger Flow algorithm. Using the developed phaseless imaging system, imaging of complex-shaped targets, such as the letters of the word “DUKE”, is shown, and it is observed that the phaseless reconstructed images are on par with the complex-based reconstructions.
关键词： computational imaging,phase retrieval,microwaves,imaging,phaseless
更新于2025-09-19 17:15:36
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Improving image reconstruction quality of compressed ultrafast photography via augmented lagrangian algorithm
摘要： Compressed ultrafast photography (CUP) has shown to be a powerful tool to measure ultrafast dynamic scenes. In previous studies, CUP used a two-step iterative shrinkage/thresholding (TwIST) algorithm to reconstruct three-dimensional image information. However, the image reconstruction quality greatly depended on the selection of the penalty parameter, which caused the reconstructed images to be unable to be correctly determined if the ultrafast dynamic scenes are unknown in advance. Here, we develop an augmented lagrangian (AL) algorithm for the image reconstruction of CUP to overcome the limitation of TwIST algorithm. Our numerical simulations and experimental results show that, compared to the TwIST algorithm, the AL algorithm is less dependent on the selection of the penalty parameter, and can obtain the higher image reconstruction quality and stability, which may further promote the practical applications of CUP.
关键词： Augmented lagrangian,Computational imaging,Compressed sensing,Compressed ultrafast photography.
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Conference on Automation/XXIII Congress of the Chilean Association of Automatic Control (ICA-ACCA) - Concepcion, Chile (2018.10.17-2018.10.19)] 2018 IEEE International Conference on Automation/XXIII Congress of the Chilean Association of Automatic Control (ICA-ACCA) - Low-Cost High Resolution Microscopy based on Fourier Ptychography
摘要： We present an advanced low-cost computational microscope based on simple components such as a cheap objective lens, a LED illumination matrix and 3D-printed parts. By implementing the Fourier Ptychographic Microscopy (FPM) technique onto a raspberry PI, we are able to acquire and synthetically produce images with wide field of view and high resolution. We present preliminary results, with the aim that at the end of this project, a low-cost kit will be presented to the community with assembly diagrams, 3D models and the FPM algorithms developed as a fully integrated system, so that it can be used and configured with relative simplicity such as in schools.
关键词： computational imaging,phase retrieval,microscopy,Fourier ptychography
更新于2025-09-19 17:15:36
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Plasmonic ommatidia for lensless compound-eye vision
摘要： The vision system of arthropods such as insects and crustaceans is based on the compound-eye architecture, consisting of a dense array of individual imaging elements (ommatidia) pointing along different directions. This arrangement is particularly attractive for imaging applications requiring extreme size miniaturization, wide-angle fields of view, and high sensitivity to motion. However, the implementation of cameras directly mimicking the eyes of common arthropods is complicated by their curved geometry. Here, we describe a lensless planar architecture, where each pixel of a standard image-sensor array is coated with an ensemble of metallic plasmonic nanostructures that only transmits light incident along a small geometrically-tunable distribution of angles. A set of near-infrared devices providing directional photodetection peaked at different angles is designed, fabricated, and tested. Computational imaging techniques are then employed to demonstrate the ability of these devices to reconstruct high-quality images of relatively complex objects.
关键词： metasurface,computational imaging,lensless compound-eye vision,Plasmonic ommatidia,directional photodetection
更新于2025-09-19 17:13:59
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Multi-height phase recovery combined with Fast Iterative Shrinkage-Thresholding Algorithm to handle phase microspheres from complex diffracted field in inline holography
摘要： We describe in this work an approach that individually combines constant initialization, free-space backpropagation, transport of intensity equation (TIE) and multi-height phase recovery with Fast Iterative Shrinkage-Thresholding Algorithm (FISTA) to predict reconstruction of the phase microspheres from diffracted field measurements. We incorporate appropriate initialization and regularization to reconstruct unknown phase microspheres (transparent objects).
关键词： phase recovery,diffraction,object bounds,phase microsphere,computational imaging,Inline holography
更新于2025-09-11 14:15:04
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Million-Pixel Computational Imaging Model
摘要： The limited sensor size in the cameras on mobile devices leads to a low signal-to-noise ratio (SNR) during imaging. Traditionally, denoising methods are used to improve the image quality after interpolation-based demosaicking. Recently, deep learning has been employed to combine the demosaicking and denoising processes. The dual camera is designed to enhance the SNR directly by increasing the number of sensors. All of these methods have achieved success at some stage. In this study, we recast traditional imaging as independent of sampling, demosaicking, and denoising. We propose a million-pixel model to merge these three processes together in the theory of computational imaging. Our experiments demonstrated the successful application of the proposed model.
关键词： demosaicking,compressed sensing,color filter array,denoising,computational imaging
更新于2025-09-11 14:15:04
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Principles and prospects for single-pixel imaging
摘要： Modern digital cameras employ silicon focal plane array (FPA) image sensors featuring millions of pixels. However, it is possible to make a camera that only needs one pixel. In these cameras a spatial light modulator, placed before or after the object to be imaged, applies a time-varying pattern and synchronized intensity measurements are made with a single-pixel detector. The principle of compressed sensing then allows an image to be generated. As the approach suits a wide a variety of detector technologies, images can be collected at wavelengths outside the reach of FPA technology or at high frame rates or in three dimensions. Promising applications include the visualization of hazardous gas leaks and 3D situation awareness for autonomous vehicles.
关键词： 3D imaging,computational imaging,spatial light modulator,compressed sensing,infrared imaging,single-pixel imaging,terahertz imaging
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - The Accurate Estimation of Disparity Maps from Cross-Scale Reference-Based Light Field
摘要： This paper addresses the problem of disparity map accurate estimation in the cross-scale reference-based light ?eld, which consists several low-quality images arranged around one central high-resolution (HR) image. In the framework, we use a HR image-guidance CNN (HRIG-CNN) for estimating the disparity map in the HR level. Speci?cally, we ?rst calculate the coarse disparity map using our cross-pattern strategy, which can blend the multiple disparity maps. And then, we re?ne this coarse disparity map using HRIG-CNN for obtaining high-quality disparity map, which contains detail information and preserve edge information. With the HR image guidance, our HRIG-CNN achieves state-of-the-art for obtaining disparity map in such hybrid light ?eld condition. In the end, we provide both quantitative and qualitative evaluations on different methods, and demonstrate the high performance and robustness of the proposed framework compared with the state-of-the-arts algorithms.
关键词： super-resolution,computational imaging,light field,disparity map,cross-scale resolution
更新于2025-09-09 09:28:46