Research And Application Of License Plate Recognition Technique In Embedded System

LPR(Lincense Plate Recognition) is one of most important parts of ITS(Intelligent Transportation System), which has been widely applied in modern transportation management and supervision. This thesis carries out in-depth research upon the LPR's key techniques -- license plate location and character segmentation, on the basis of which, the realization technique of LPR in embedded system is also analized, transplanted and developed.This thesis firstly introduces the constitution of LPR system, which can be mainly devided into vehicle image capture, license plate location, character segmentation and character recognition. For license plate location and character segmentation, the thesis, on the basis of the analyzation of license plate image's characteristics, takes advantage of the characteristic information -- the sharp contrast of the colors of the license plate characters and the background, to propose a viable algorithm. Utilizing both the universal alternation of the pixel colors and the distribution traits of character pixels in the region of license plate of the bi-value image, the location algorithm locates the license plate in the given image. The algorithm of the character segmentation carried out block-sorting on the basis of some rules for the bi-value image of license plate, followed by that, it introduces the desciplines of both fake character blocks judgement and invariable distance between centers of neighbor characters, with the aid of which, the segmentation of license plate characters has been realized.This thesis takes the Sumsong S3C2410 ARM as the hardware platform, adopts arm-linux embedded system, gives detailed analyzation for both the transplantation of arm-linux kernel and the foundation of embedded development enrionment, and introduces the GNU open source development tools(arm-linux-gcc) to carry out developing and debugging works for system.On the basis of analyzation of both the fundamentals of embedded GUI(Graphics User Interface) and the programming mechanism of Qt/Embedded, the thesis discusses the transplantation process of Qt/Embedded in operation system, introduces in detail the realization process of algorithms of both license plate location and character segmentation in Qt/Embedded, and analyzes the embedded realization of vehicle image capture and character recognition.