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Three-phase Pupil Localization Method in Non-ideal Eye Images

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Journal of Donghua University(English Edition) 2008年第1期25卷 101-105页

作者：袁晓燕施鹏飞 Institute of Image Processing and pattern recognition Shanghai Jiaotong University

Pupil localization is a very important preprocessing step in many reel applications. Accurate and robust pupil localization in non-ideal eye images is a challenging task. A detailed method of pupil localization in non-ideal eye images is proposed. This method is implemented in three main phases： first, segment the rough pupil region based on Gaussian Mixture Model： then modify the rough segmentation result using morphological method to minimize the influence of some disturbing factors; last estimate the pupil parameters based on minimizing the least square error. The proposed method is first tested on CASIA iris image dataset, and then on our self-captured iris dataset which contains a wider variety of iris images. Experiments show that the proposed method can perform well for nonideal eye images of various qualities.

关键词： biometrics pupillocalization

Segment Based Camera Calibration

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Journal of Computer Science & Technology 1993年第1期8卷 11-16页

作者：马颂德魏国庆黄金风 National Lab of pattern recognition Institute of AutomationChinese Academy of SciencesBeijing 100080

The basic idea of calibrating a camera system in previous approaches is to determine camera parameters by using a set of known 3D points as calibration *** this paper,we present a method of camera calibration in which camera parameters are determined by a set of 3D lines.A set of constraints is derived on camera parameters in terms of perspective line *** these con- straints,the same perspective transformation matrix as that for point mapping can be computed *** minimum number of calibration lines is *** result generalizes that of Lin,Huang and Faugeras for camera location determination in which at least 8 line correspondences are re- quired for linear computation of camera *** line segments in an image can be located easi- ly and more accurately than points,the use of lines as calibration reference tends to ease the compu- tation in image preprocessing and to improve calibration *** results on the calibration along with stereo reconstruction are reported.

关键词： Camera calibration line correspondences perspective transformation matrix 3D reconstruction

Joint specular highlight detection and removal in single images via Unet-Transformer

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computational Visual Media 2023年第1期9卷 141-154页

作者： Zhongqi Wu Jianwei Guo Chuanqing Zhuang Jun Xiao Dong-Ming Yan Xiaopeng Zhang National laboratory of pattern recognition Institute of AutomationChinese Academy of SciencesBeijing 100190China The School of Artificial Intelligence University of Chinese Academy of SciencesBeijingChina

Specular highlight detection and removal is a fundamental problem in computer vision and image *** this paper,we present an efficient endto-end deep learning model for automatically detecting and removing specular highlights in a single *** particular,an encoder–decoder network is utilized to detect specular highlights,and then a novel Unet-Transformer network performs highlight removal;we append transformer modules instead of feature maps in the Unet *** also introduce a highlight detection module as a mask to guide the removal ***,these two networks can be jointly trained in an effective *** to the hierarchical and global properties of the transformer mechanism,our framework is able to establish relationships between continuous self-attention layers,making it possible to directly model the mapping between the diffuse area and the specular highlight area,and reduce indeterminacy within areas containing strong specular highlight *** on public benchmark and real-world images demonstrate that our approach outperforms state-of-the-art methods for both highlight detection and removal tasks.

关键词： specular highlight detection specular highlight removal Unet-Transformer

Practical Fast computation of Zernike Moments

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Journal of Computer Science & Technology 2002年第2期17卷 181-188页

作者： Al-Rawi Mohammed 杨杰 Image Processing and pattern recognition Institute Shanghai Jiaotong University Shanghai 200030 P.R. China

The fast computation of Zernike moments from normalized geometric moments has been developed in this paper. The computation is multiplication free and only additions are needed to generate Zernike moments. Geometric moments are generated using Hatamian's filter up to high orders by a very simple and straightforward computation scheme. Other kinds of moments (e.g., Legendre, pseudo Zernike) can be computed using the same algorithm after giving the proper transformations that state their relations to geometric moments. Proper normalizations of geometric moments are necessary so that the method can be used in the efficient computation of Zernike moments. To ensure fair comparisons, recursive algorithms are used to generate Zernike polynomials and other coefficients. The computational complexity model and test programs show that the speed-up factor of the proposed algorithm is superior with respect to other fast and/or direct computations. It perhaps is the first time that Zernike moments can be computed in real time rates, which encourages the use of Zernike momentfeatures in different image retrieval systems that support huge databases such as the XM experimental model stated for the MPEG-7 experimental core. It is concluded that choosing direct computation would be impractical.

关键词： Zernike moment fast algorithm digital filter invariant patternrecognition

Face recognition using improved-LDA with facial combined feature

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Chinese Optics Letters 2005年第6期3卷 330-332页

作者：周大可杨新彭宁嵩 Institute of Image Processing & pattern recognition Shanghai Jiao Tong University Shanghai 200030

Pace recognition subjected to various conditions is a challenging task. This paper presents a combined feature improved Fisher classifier method for face recognition. Both of the facial holistic information and local information are used for face representation. In addition, the improved linear discriminant analysis (I-LDA) is employed for good generalization capability. Experiments show that the method is not only robust to moderate changes of illumination, pose and facial expression but also superior to the traditional methods, such as eigenfaces and Fisherfaces.

关键词： Lighting Robustness (control systems)

Yield enhancement of elliptical high harmonics driven by bicircular laser pulses

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Chinese Physics B 2022年第11期31卷 358-363页

作者： Xiaofan Zhang Xiaosong Zhu Hubei Key laboratory of Optical Information and pattern recognition Wuhan Institute of TechnologyWuhan 430205China Wuhan National laboratory for Optoelectronics and School of Physics Huazhong University of Science and TechnologyWuhan 430074China

We theoretically investigate the yield enhancement of elliptical high harmonics in the interaction of molecules with bicircular laser pulses by solving the time-dependent Schrodinger *** is shown that by adjusting the relative intensity ratio of the two bicircular field components in specific ranges the yield of the molecular high harmonics for the plateau and cutoff regions can be respectively *** analyze this enhancement phenomenon,we calculate the weights of the electron classical ***,we also study the ellipticity distribution of harmonics for different intensity *** find that these enhanced harmonics are elliptically polarized,which we mainly attribute to the recombination dipole moment of the major weighted *** enhanced elliptical extreme ultraviolet and soft x-ray radiations may serve as essential tools for exploring the ultrafast dynamics in magnetic materials and chiral media.

关键词： high harmonics extreme ultraviolet and soft x-ray bicircular laser pulses

Probing time delay of strong-field resonant above-threshold ionization

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Chinese Physics B 2021年第1期30卷 215-220页

作者： Shengliang Xu Qingbin Zhang Cheng Ran Xiang Huang Wei Cao Peixiang Lu School of Physics and Wuhan National laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key laboratory of Optical Information and pattern recognition Wuhan Institute of TechnologyWuhan 430205China

The high-resolution three-dimensional photoelectron momentum distributions via above-threshold ionization(ATI)of Xe atoms are measured in an intense near circularly polarized laser field using velocity map imaging and tomography reconstruction. Compared to the linearly polarized laser field, the employed near circularly polarized laser field imposes a more strict selection rule for the transition via resonant excitation, and therefore we can selectively enhance the resonant ATI through certain atomic Rydberg states. Our results show the self-reference ionization delay, which is determined from the difference between the measured streaking angles for nonadiabatic ATI via the 4 f and 5 f Rydberg states, is 45.6 as. Our method provides an accessible route to highlight the role of resonant transition between selected states, which will pave the way for fully understanding the ionization dynamics toward manipulating electron motion as well as reaction in an ultrafast time scale.

关键词： above threshold ionization resonant ionization delay transition selection rule

Unsupervised Domain Adaptation on Sentence Matching Through Self-Supervision

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Journal of Computer Science & Technology 2023年第6期38卷 1237-1249页

作者：白桂荣刘庆斌何世柱刘康赵军 National laboratory of pattern recognition Institute of AutomationChinese Academy of SciencesBeijing 100190China School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049China

Although neural approaches have yielded state-of-the-art results in the sentence matching task,their perfor-mance inevitably drops dramatically when applied to unseen *** tackle this cross-domain challenge,we address unsupervised domain adaptation on sentence matching,in which the goal is to have good performance on a target domain with only unlabeled target domain data as well as labeled source domain ***,we propose to perform self-su-pervised tasks to achieve *** from previous unsupervised domain adaptation methods,self-supervision can not on-ly flexibly suit the characteristics of sentence matching with a special design,but also be much easier to *** training,each self-supervised task is performed on both domains simultaneously in an easy-to-hard curriculum,which gradually brings the two domains closer together along the direction relevant to the *** a result,the classifier trained on the source domain is able to generalize to the unlabeled target *** total,we present three types of self-super-vised tasks and the results demonstrate their *** addition,we further study the performance of different usages of self-supervised tasks,which would inspire how to effectively utilize self-supervision for cross-domain scenarios.

关键词： unsupervised domain adaptation sentence matching self-supervision

Spectroscopic Features of Quantum Many-Body Scar States

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Chinese Physics Letters 2025年第2期 24-28页

作者： Wenjie Wei Long Zhang Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum computation University of Chinese Academy of Sciences Hefei National laboratory

We studied the dynamic correlations of non-integrable systems with quantum many-body scar(QMBS) states generated by a ladder operator. The ladder operator's spectral function has an exact δ-function peak induced by the QMBS states. As a concrete example, we show that in the one-dimensional(1D) spin-1 Affleck–Kennedy–Lieb–Tasaki model, the spectral function of two-magnon excitations exhibits a characteristic bowtie shape composed of a δ-function resonance peak at momentum k = π and a continuum spectrum elsewhere.

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