Identification of Thai characters and numbers on plate number

This paper proposes a method of Thai characters and numeral identification on plate number. The proposed method consists of license plate detection and identification of characters and numbers. In the license plate detection, the vertical edges, the vertical projection, and some operations of morphology are used to searching for license plate location. Once plate location is known, the identification of characters and numbers starts from inversion of binary image, character and number segmentation, normalization, computation of the horizontal and vertical DCT coefficients. Finally, the impulse response of FIR system of character and number are determined using the horizontal and vertical DCT coefficients as input and output of FIR system. The unknown characters or numbers on the plate number can be identified by comparison of their impulse response with the impulse responses of known characters and numbers in database, if the sum square error of them is smallest. On experiments, it found that the correct detection of license plate is about 95.52% and the accuracy of characters and numeral identification is about 81.25%.