Reservation of High-frequency Characteristics Based License Plate Detection

The vehicle license plate detection is challenging first step in license plate recognition system. The license plate region is in the characteristics of gradient and frequent changes. This paper proposes High-pass filter to extract the gradient and frequent changes regions. Then merge adjacent regions as license plate candidates. Combined with the geometric features of license plates and the ratio of regional objectives in the background to find the license plate location, adopted the projection methods to remove the license plate frame, to achieve the exact position of license plate. Computer simulation results show that the proposed method of location has high accuracy.