Application Research On Color Information In License Plate Recognition

With the rapid development of our country's road transportation, the intelligent transportation system has become a hot research topic. As an important part of the intelligent transportation system, the license plate recognition system plays an important role in many fields such as intelligent transportation control system, parking lot monitor system and automatic charging system, and etc.As an integrated real-time computer vision system, the license plate recognition system mainly consists of three parts: license plate location, character segmentation and character recognition. Color information, one of the important features of the license plates, is less considered in the existing methods.Color prior knowledge-based license plate recognition method is studied in this paper. The main works are listed as follows:This paper studies how to makes full use of the color information in the license plate recognition.The license plate location algorithm based on the DOG model and color clustering is proposed. Firstly, according to the GC receptive field model, the DOG model is structured, which is used to detect the edge, secondly license plate geometrical and structural characteristics are used in the coarse location, and finally after using the gray-scale information, the color feature is fully used in the precise location.A new method based on the color clustering and the neural network to identify the license plate type is proposed. Firstly, the confidence areas are extracted by the results of the K-means algorithm, secondly color feature are obtained, and finally the license plate type is identified by the BP neural network.The special character classification algorithm is proposed, which is based on YCbCr color space to increase the recognition accuracy of Chinese character.The experiment results show that the proposed methods of license plate location algorithm and license plate type identification algorithm are robust to noises and illumination variation; the special Chinese character classification algorithm based on YCbCr color space is beneficial to improve the character recognition accuracy.