License Plate Detection Based on Expanded Haar Wavelet Transform

This paper presents a fast license plate localization algorithm base on expanded wavelet transform. The system consists of three major stages. First, a wavelet transform based method is used for extracting important contrast features as guides to search for desired license plates. Then, generating candidate regions in LH sub-image. In last stage we locate the license plate accurately in HL sub-image. The 1229 tested images taken from various scenes were employed, including diverse angles, different lightening conditions and the dynamic conditions. The experiments shows that proposed method can quickly and correctly detect the region of license plate and the license plate detecting rate of success is 97.31%. The average processing time of one color image is about 0.016 s.