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Báo cáo hóa học: " Robust Face Image Matching under Illumination Variations"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Robust Face Image Matching under Illumination Variations | EURASIP Journal on Applied Signal Processing 2004 16 2533-2543 2004 Hindawi Publishing Corporation Robust Face Image Matching under Illumination Variations Chyuan-Huei Thomas Yang Department of Computer Science National TsingHua University 101 KuangFu Road Section 2 Hsinchu 300 Taiwan Email chyang@cs.nthu.edu.tw Shang-Hong Lai Department of Computer Science National TsingHua University 101 KuangFu Road Section 2 Hsinchu 300 Taiwan Email lai@cs.nthu.edu.tw Long-Wen Chang Department of Computer Science National TsingHua University 101 KuangFu Road Section 2 Hsinchu 300 Taiwan Email lchang@cs.nthu.edu.tw Received 1 September 2003 Revised 21 September 2004 Face image matching is an essential step for face recognition and face verification. It is difficult to achieve robust face matching under various image acquisition conditions. In this paper a novel face image matching algorithm robust against illumination variations is proposed. The proposed image matching algorithm is motivated by the characteristics of high image gradient along the face contours. We define a new consistency measure as the inner product between two normalized gradient vectors at the corresponding locations in two images. The normalized gradient is obtained by dividing the computed gradient vector by the corresponding locally maximal gradient magnitude. Then we compute the average consistency measures for all pairs of the corresponding face contour pixels to be the robust matching measure between two face images. To alleviate the problem due to shadow and intensity saturation we introduce an intensity weighting function for each individual consistency measure to form a weighted average of the consistency measure. This robust consistency measure is further extended to integrate multiple face images of the same person captured under different illumination conditions thus making our robust face matching algorithm. Experimental results of applying the proposed face image matching algorithm on some .