A Study On Location Of License Plate In The Intelligent Transport System

With the development of the world economy,traffic jam,pollution and traffic accident are more and more serious. Thus Intelligent Transport System (ITS) comes out and now many countries focus their attention on the study and constitution of ITS.As the mark of vehicle,license plate is unique,if we recognize all the vehicles in the path network in real time and gather the information,the most detailed information for ITS can be obtained. So license plate recognition system (LPRS) has important application in many places. At present,LPRS has become a research hotspot in ITS.The accurate degree of license plate location is an important parameter of LPRS. It is difficult to recognize the character directly in original image because the original image has big dimensions,which need big memory,and at the same time,there are many disturbed areas in the image. However,if we can locate license plate and segment character precisely,thus the capacity of storage can be reduced and the disturbance can also be avoided,and so the character will be recognized accurately,which can ultimately improve the efficiency and precision of the recognition system. Therefore,the study on the algorithm of license plate location is always the hotspot problem.In this paper we have summarized the latest research achievements and development of license plate location and discussed the intrinsic characteristic of license plate. On the basis of previous work,firstly,we studied the representation of shape characteristic in Hough space,put forward the algorithm based on shape characteristic and Inverse Hough Transform (IHT) to locate and reconstruct license plate. We elaborated the principle and application of IHT,and on this basis we got rid of the disturbance in Hough space and reconstructed license plate in image space in the end. Moreover,aiming at the location of inclined license plate,we have proposed the algorithm based on gray changing characteristic and Orientation Field. In this section,we discussed in detail the application of Mathematical Morphology operator in rough locating objective region and introduced the theory and realization method of Orientation Field. Then we used it to detect inclined angel of objective region,finally we can precisely locate and emendate the inclined license plate based on detection result,and so we provided the favorable foundation for segmenting character.