Enhancing the accuracy of License Plate Recognition Systems with the Angle Recovery Method

The motor vehicle is an important way of transportation for modern people, and its license plate is just like our identi ̄cation cards which can be used for e®ective management of motor vehicles. Hence, the development of a recognition system for license plates can reduce the workload of managing motor vehicles. A license plate recognition system based on computer vision often causes recognition errors due to the plate's angle problem and thus needs to be assisted by manual recognition. In this study, a recovery method for license plate images with large angles is proposed based on perspective projection to increase the recognition accuracy. The experimental results show that applying the angle recovery method to a license plate recognition system can reduce its errors, especially for license plate images with large angles. For the case of small angles, a recognition rate of 89% can be achieved by the angle recovery method, slightly higher than that of the plane rotation method (86%). For the case of a wide range of di®erent angles, the average recognition rate achieved by the angle recovery method is 87.5%, much higher than that of the plane rotation method (57.5%). Thus, the angle recovery method is e®ective for enhancing the accuracy of license plate recognition systems.