Fast License Plate Localization Using Discrete Wavelet Transform

摘要

Some previous works use discrete wavelet transform (DWT) to extract license plate (LP), however, most of them are not capable of dealing with complex environments such as the low-contrast source images and the dynamic-range problems. In this paper, we propose a license plate localization (LPL) algorithm based on DWT. The LP can be extracted from complex environments and different quality of source images by using two frequency subbands. We first use the HL subband to search the features of LP and then verify the features by checking whether a horizontal line around the feature exists in the LH subband or not. The proposed method can extract both front and back LPs of various vehicles. The experiments show that the proposed method can achieve good LPL results with both short run-time and high accurate detection rate.