Browsing by Author "Zhang, Yaping"
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- Editorial on Special Issue “Holography, 3-D Imaging and 3-D Display”Poon, Ting-Chung; Zhang, Yaping; Cao, Liangcai; Yoshikawa, Hiroshi (MDPI, 2020-10-11)Modern holographic techniques have been successfully applied in many important areas, such as 3D inspection, 3D microscopy, metrology and profilometry, augmented reality, and industrial informatics [...]
- Fast 3D Analytical Affine Transformation for Polygon-Based Computer-Generated HologramsFan, Houxin; Zhang, Bing; Zhang, Yaping; Wang, Fan; Qin, Wenlong; Fu, Qingyang; Poon, Ting-Chung (MDPI, 2022-07-07)We present a fast 3D analytical affine transformation (F3DAAT) method to obtain polygon-based computer-generated holograms (CGHs). CGHs consisting of tens of thousands of triangles from 3D objects are obtained by this method. We have attempted a revised method based on previous 3D affine transformation methods. In order to improve computational efficiency, we have derived and analyzed our proposed affine transformation matrix. We show that we have further increased the computational efficiency compared with previous affine methods. We also have added flat shading to improve the reconstructed image quality. A 3D object from a 3D camera is reconstructed holographically by numerical and optical experiments.
- Isotropic Two-Dimensional Differentiation Based on Dual Dynamic Volume HologramsWang, Pin; Fan, Houxin; Zhang, Yaping; Yao, Yongwei; Zhang, Bing; Qin, Wenlong; Poon, Ting-Chung (MDPI, 2023-07-17)We study the use of two dynamic thick holograms to realize isotropic two-dimensional (2D) differentiation under Bragg diffraction. Acousto-optic modulators (AOMs) are used as dynamic volume holograms. Using a single volume hologram, we can accomplish a first-order derivative operation, corresponding to selective edge extraction of an image. Since the AOM is a 1D spatial light modulator, filtering of the image only occurs along the direction of the sound propagation. To achieve 2D image processing, two AOMs are used within a Mach–Zehnder interferometer (MZI). By aligning one AOM along the x-direction on the upper arm of the interferometer and another AOM along the y-direction on the lower arm, we accomplish the sum of two first-derivative operations, leading to isotropic edge extraction. We have performed both computer simulations and optical experiments to verify the proposed idea. The system provides additional operations in optical computing using AOMs as dynamic holograms.
- Off-axis optical scanning holography [Invited]Zhang, Yaping; Yao, Yongwei; Zhang, Jingyuan; Liu, Jung-Ping; Poon, Ting-Chung (Optical Society of America, 2022-02-01)Optical scanning holography (OSH) involves the principles of optical scanning and heterodyning. The use of heterodyning leads to phase-preserving, which is the basic idea of holography. While heterodyning has numerous advantages, it requires complicated and expensive electronic processing. We investigate an off-axis approach to OSH, thereby eliminating the use of heterodyning for phase retrieval.We develop optical scanning theory for holographic imaging and show that by properly designing the scanning beam, we can performcoherent and incoherent holographic recording. Simulation results are provided to verify the proposed idea.
- Polygon-based computer-generated holography: a review of fundamentals and recent progress [Invited]Zhang, Yaping; Fan, Houxin; Wang, Fan; Gu, Xianfeng; Qian, Xiaofan; Poon, Ting-Chung (2022-01-31)In this review paper, we first provide comprehensive tutorials on two classical methods of polygon-based computer generated holography: the traditional method (also called the fast-Fourier-transform-based method) and the analytical method. Indeed, other modern polygon-based methods build on the idea of the two methods. We will then present some selective methods with recent developments and progress and compare their computational reconstructions in terms of calculation speed and image quality, among other things. Finally, we discuss and propose a fast analytical method called the fast 3D affine transformation method, and based on the method,we present a numerical reconstruction of a computer-generated hologram (CGH) of a 3D surface consisting of 49,272 processed polygons of the face of a real person without the use of graphic processing units; to the best of our knowledge, this represents a state-of-the-art numerical result in polygon-based computed-generated holography. Finally, we also show optical reconstructions of such a CGH and another CGH of the Stanford bunny of 59,996 polygons with 31,724 processed polygons after back-face culling. We hope that this paper will bring out some of the essence of polygon-based computer-generated holography and provide some insights for future research.
- Sectioning with edge extraction in optical incoherent imaging processingZhang, Yaping; Wang, Rende; Tsang, Peter; Poon, Ting-Chung (2020-04-15)Employing a single-pixel digital holographic recording technique called optical scanning holography (OSH), we accomplish the formidable task of sectioning with edge extraction in three-dimensional (3D) optical incoherent imaging. OSH is a special variant of generalized two-pupil heterodyning image processing, where one of the pupils used is a delta function with the other being a uniform function. In this study, we investigate the use of an annular pupil and a random-phase pupil for edge extraction during sectioning of a 3-D object. Novel simulation results indicate excellent edge extraction of a multi-section object with good sectioning capability, i.e., with each focused edge-extracted section out-of-focused haze has been eliminated. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
- Study of Image Classification Accuracy with Fourier PtychographyZhang, Hongbo; Zhang, Yaping; Wang, Lin; Hu, Zhijuan; Zhou, Wenjing; Tsang, Peter W. M.; Cao, Deng; Poon, Ting-Chung (MDPI, 2021-05-14)In this research, the accuracy of image classification with Fourier Ptychography Microscopy (FPM) has been systematically investigated. Multiple linear regression shows a strong linear relationship between the results of image classification accuracy and image visual appearance quality based on PSNR and SSIM with multiple training datasets including MINST, Fashion MNIST, Cifar, Caltech 101, and customized training datasets. It is, therefore, feasible to predict the image classification accuracy only based on PSNR and SSIM. It is also found that the image classification accuracy of FPM reconstructed with higher resolution images is significantly different from using the lower resolution images under the lower numerical aperture (NA) condition. The difference is yet less pronounced under the higher NA condition.