An efficient thresholding algorithm for license plate recognition based on intelligent block detection

License plate recognition system (LPR) plays an important role in many applications such as access control, traffic control, and the detection of stolen vehicles. A LPR system can be classified into the detection and recognition parts. Improvement of the detection part will be discussed in this paper. Binarization of plate images is one of the major tasks of detection which consumes huge processing time and impacts on the recognition rate. This paper proposes an efficient binarization algorithm with intelligent block size detection. Based on image characteristics, the plate image is automatically divided into several blocks with various sizes. Then, a threshold surface is constructed to derive the binary image. Experimental results show that the proposed method not only provides promising binarization result, but also low computation cost.