License Plate Location And Character Segmentation Research And Realization

As coming along with the development of the highway traffic enterprise in the new century, the requirement of the Intelligent Traffic System (ITS) gets into a new level. The information about vehicle's manufacturer, the owner, and the road maintenance cost and so on are the objects of the auto management of vehicle information, and one of the useful method to get these information is by Vehicle License Recognition System. Thus, Vehicle License Recognition system play a vital role in ITS.A Vehicle License Recognition system usually comprises three parts, vehicle license locating, character segmentation and character recognition. Vehicle license locating and character segmentation play the crucial role, which influence the precision of the whole system directly. Thus, this thesis mainly studies the vehicle license location and the character division.In this thesis, two vehicle licenses locating methods are studied. The first one is based on the analysis of region connectivity, which transforms image into binary images in continuous thresholds, getting all contours by tracing algorithm, and all the licenses plate liked regions are selected to compute the center position of the license plate. The second one is based on edge detection, by through extracting vertical edges to generate the density of edge points in a rectangle region, and the region with the most density can be considered as the position of license plate.In this thesis, area projection and fixed space gap are adapted to character segmentation, and experiments shows a good result.In this thesis, one method that uses the Hough Transform to correct the license plate is discussed also. By using the Hough Transform to compute incline angles of the plate in horizontal and vertical directions. The distort license plate can be corrected well.