Abstract:

According to the problem that the traditional license plate algorithms have low location rate when the images are collected in the changing weather or insufficient light, an adaptive license plate location algorithm is proposed. The algorithm determines the different weather and the image contrast by the color characteristics and image definition. The wavelet transform coefficients are used to reduce noise and stretch the contrast, achieving the effect of image enhancement. At last, it combines vertical protection and template matching algorithms to locate the license plate. The tests show that the use of the algorithm can effectively remove the noise, and solve the differentcontrast license plate location in the sun, rain, fog and dusk conditions. The average rate of license plate location is 93.4%.

Key words: image contrast;color characteristics;enhancement of wavelet coefficients;license plate location