Research On Location Methods For Vehicle License Plate Of Intelligent Transport System

This paper is a part of research of methods of vehicle-license-plate recognition system that is one part of Intelligent Transport System. Automatic vehicle-license-plate recognition system that is an important part of Intelligent Transport System, is an attractive subject. This paper pays attention to the key part—vehicle-license-plate location. It does some deep research and attempts several methods. We hope to find some location methods that have high location accuracy and great computing speed by the research.Firstly, the location method of license-plate based on line scanning is researched. After subtracting between two adjacent pixels in a binarization image, the image become an edge image. Then scanning the edge image with the method of line scanning, we will find the license plate area based on the count of leap and the distance between two characters in the license plate area. The method is implemented with Visual C++ 6.0.Secondly, the location method of license-plate based on neural network is researched. The ability of adaptive learning and Fault-tolerance of neural network is very strong, which is the best characteristic for locating the license plate. After training neural network, the neural network is sensitive with the area of license plate. Then search the image with a glide window and fine the license plate area.Thirdly, mathematical morphology and color characteristics on license plate are combined to locate the license-plate. Mathematical morphology is good at extracting the edge image and analyzing the shape of image. After opening operation and closing operation with mathematical morphology, the area of license plate is connected inside and separated from the other areas. Then filtrating some areas bases on the area of license plate, and locating the license plate bases on color characteristics of license plate. The method is implemented with MATLAB 6.5.Lastly, this paper summarizes the advantage and disadvantage of all above location methods. It also introduces some segmentation and recognition methods of characters in brief.