Research Of License Plate Location And Character Segmentation

Automatic vehicles'license plate detection and recognition system can be broadly used in bridge intersection's automatic charge and park's entrance management. The automatic detection of license plate is one of the key technologies in LPR system. Because a license image is taken outdoors, the image background is complicated, and there is serious disturbance in the image so that the image quality is bad. The location of plate is not good enough. Therefore, the study on the algorithm of license plate location is always the hotspot problem.In this thesis, I have collected large numbers of interrelated data, and then summarized the latest research achievements and development of license plate location and segmentation. Then I analyze some image disposal measures, and then choose some measures to deal with the images, so we can get good images to locate the license plate. I analyze the characteristic of license images, especially in license plate area, and then defined the most change in pixel value as the most important parameter. Considering the lean of vehicle license plate, I adopt Hough transform to detect the lean angle and rotate the images to made some compensation. Then I enhance and proportion the grayness value of the license plate, and then rectify the color of the license plate. Finally, I locate and segment the vehicle license plate exactly.This paper presents methods for location and segmentation of licenses based on most change in pixel value at license area, and methods of segmentation of characters, and adjustment of the lean vehicle license plate based on Hough transform in details. At the end of the paper, we analyze the result of the experiment and introduce the prospect of the future work.It is proved by the experiment, the arithmetic adopted in this thesis is useful. The system can locate the license plate exactly and segment the license plate characters accurately. The real-time quality and the percent of accuracy can reach the aim. So this system has a good practicality.