Automatic License Plate Location And Character Segmentation

The intelligent transportation is the main direction of the development of transportation management. License plate recognition (LPR) technology is a key of intelligent transportation systems. It is important in the project management of urban road management, ports, airports, expressway and parking area, etc. Usually, the LPR system consists of three main parts: license plate localization, character segmentation, and character recognition. The license plate localization and character segmentation are the most crucial stage. It result has an important impact on the accuracy and speed for the LPR system. The propose algorithm with research to the license plate location and character segmentation.Firstly, the vehicle license plate image is preprocessed with image processing technology to get better quality vehicle image. It has built a good foundation for license plate localization and character segmentation. Secondly, the license plate upper and lower borders are parallel each other. There are rich edge and texture information. We present an algorithm based on orientation field and edge information for location of license plates. Furthermore, we present a new algorithm based on orientation field for horizontal skew correction and an algorithm based on single-character projection for vertical distortion correction. Finally, character feature is analyzed with statistic method, and license plate character is segmented by vertical projection method.Based on the above algorithm, we develop practical experimental system with Visual C++ and it is tested with 200 various vehicle images. Experimental results show that proposed method can accurately localization and character segmentation various license plate of different size and illumination. The research is an important foundation for next character recognition and LPR system completing, and it has both better the theoretical research significance and applied value.