| As one of the very important techniques in modern intelligent transportation system, the automatic vehicle license plate recognizing technique is the hot spot of recent years' research. Intelligent transportation system plays an important role in vehicle tracking and locating,high way toll collecting,automatic parking fee charging and transportation statistic. Because license plate is the only identity of each vehicle, the technique of automatic license plate recognizing stands at a key position in the modern transportation system. Researchers at home and overseas have done extensive works on license plate recognizing, and proposed many algorithms and proposals. Many products were put into practical use, but they never achieved the performance as people had expected. There are many works need to be done to improve the accuracy of plate locating and recognizing, robustness and real-time ability.On the basis of other people's research, this paper accomplished research and design of vehicle LPR system. This paper's theory foundation is the new theory——wavelet analysis. The system consists of three main modules: (1) Vehicle license plate extraction; (2) Character segmentation; (3) Character recognition.In plate extraction module, this paper employs wavelet analysis to extract the number plate from the complicated background image. The algorithm locates the plate correctly based on wavelet analysis. According to the experiment, the algorithm achieves the goal and the rate of plate location of this system is over 98%.In the character segmentation module, area growth algorithm is adopted, and plate image vertical projection is combined to segment the character. The algorithm is much better than the traditional methods based on projection. In the character recognition module, the traditional character recognition method based on neural network is adopted in this paper. But the BP neural network has been modified a little and the performance of the BP neural network is improved. |
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