License Plate Recognition: A Literature Survey

The license plate of the vehicle is the most appropriate method of authentication. Uncontrolled growth of the vehicle causes problems in different fields including traffic control systems, highway management systems, electronic payment issues, parking management strategies and the like. Automatic car plate recognition is defined as an automatic extraction of information from consecutive images of license plates. In most analyzing systems, license plate recognition cameras capture images by recording black and white colors, and in some cases, infrared cameras are utilized. It is worth mentioning that one of the main factors in the success of license plate recognition systems is the high quality of the input images. In other words, the quality of images, attained in either outdoor or indoor environmental conditions during daytime, is considerable. Nonetheless, to get a better result regarding recognizing license plate, a vast range of methods has differently been presented and employed in various countries, cities, and even in states. Features of car plates for different areas have usually distinctive background color, language characters, sizes and fonts. In spite of this fact, the license plate images may be occluded with poor light conditions, soil, and blurring. License plate recognition systems usually come in three basic steps: 1) car plate extraction; 2) characters segmentation; 3) characters recognition. In this paper, due to the limited number of review articles in this field, a comprehensive review of the recent methods and techniques used in segmentation and recognition steps for license plate recognition are presented. Herein, different articles have presented the latest approaches and according to the used techniques used as well as based on segmentation and recognition steps in car plate recognition system, these investigations are set to be classified. Additionally, comparison between different methods in terms of advantages, disadvantages, and recognition rate of output is done, and finally, the current issues in this area are discussed so as to propose new challenges for future researches.

کلیدواژه ها:

Automatic license plate recognition ، characters segmentation ، feature extraction ، classification