An Efficient Method of License Plate Location in Natural-Scene Image

License plate recognition (LPR) plays an important role in the application of intelligent transportation system (ITS), while the license plate (LP) location is the most crucial step in it. In this paper, a new and efficient algorithm for vehicle license plate location is proposed. The purpose of this approach is to locate license plate efficiently regardless of the limitation of LP distance, angle of view, illumination conditions as well as background complexity. The contribution of this method is that we combine sliding concentric windows (SCWs) method and mathematical morphology method so as to gain a more fast and robust one. Moreover color information of LP is also employed to locate LP accurately. Compared with other LP location methods, our method is not restricted by many preconditions and can locate more than one LP in an image. Moreover, the processing time is acceptable in real time (only 0.1 second). The algorithm was tested with 200 natural-scene vehicle images of different backgrounds and ambient illumination. Experimental results lend strong support for the robustness and efficiency of the method presented in this paper.