[1] LU Sheng-lin，ZHANG Xian-min，KUANG Yong-cong. Neural network-based inspecting method of PCB solder joint [J]. Journal of South China University of Technology，2008，36(5)：135-139.

[2] WU Fu-pei，ZHANG Xian-min，KUAN Yong-cong，et al. An AOI algorithm for PCB based on feature extraction [C]//Proceedings of the 7th World Congress on Intelligent Control and Automation，Chongqing，China，June 25-27，2008：240-247.

[3] Assen H C V，Egmont Petersen M，Reiber J H C. Accurate object localization in gray level images using the center of gravity measure: Accuracy versus precision [J]. IEEE Transactions on Image Processing(S1057-7149)，2002，11(12)：1379-1384.

[4] BAI Chang-bing，QI Chun，SONG Fu-min，et al. Fast detection of circular pcb mark using Hough transform [J]. Opto-Electronic Engineering，2005，32(9)：75-78.

[5] YUAN Wei-qi，QIAO Yi-qin. Detection of eyelash occlusions method for the iris recognition [J]. Opto-Electronic Engineering，2008，35(6)：124-129.

[6] Lyvers Edward P，Mitchell Owen Robert. Subpixel measurements using a momen-based edge operator [J]. IEEE Transactions on Pattern Analysis and Machine Intelligence(S0162-8828)，1989，11(12)：1296-1307.

[7] Moura L. A direct method for least-squares circle fitting [J]. Computer Physics Communications(S0010-4655)，1991，64： 57-63.