Multi-license Plate Localization Algorithm Based on Dyadic Wavelet Transform

SHANG Zhao-wei1,GUO Qing1,MA Shang-jun2,YUAN Bo1,YANG Jian-wei3 (1.College of Computer Science,Chongqing University,Chongqing 400030,China;2.School of Mechatronic,Northwestern Polytechnical University,Xi'an 710072,China;3.College of Mathematics and Physics,Nanjing University of Information Engineering,Nanjing 210044,China)  

An algorithm which can improve the accuracy of vehicle license plate location using dyadic wavelet transform is presented.Based on texture feature of license plates and the characteristic of dyadic wavelet transform,the wavelet coefficients in vertical direction are retained.The proposed algorithm is suitable for the single-license and multi-license plate detection in the various illumination conditions with high accuracy.The performance of the proposed algorithm is tested on monitoring images obtained from the practical application.Experimental results show that the algorithm has better performance than Mallat's on location precision,misdetection rate,and misjudgment rate.

【Key Words】： dyadic wavelet license plate localization morphology
【Fund】： 国家自然科学基金资助重点项目(90820306);国家自然科学基金资助面上项目(60973157)
【CateGory Index】： TP391.41
【DOI】： CNKI:SUN:JSJC.0.2011-03-007