An approach to vehicle license plate location based on SIFT

In order to overcome the drawbacks such as high demands for image quality,poor robustness and low accuracy in traditional vehicle license plate location algorithms,this paper presents a new license plate location method based on scale invariant feature transform(SIFT) algorithm.By using the local features of the Chinese characters in the license plate,the approach extracts SIFT features of the license plate in the sample template database,matches the SIFT features of the license plate image to be identified with them,and then eliminates the error matching points with RANSAC algorithm and calculates the affine transformation matrix of the template,thus the approach achieves accurate initial license plate location and initial tilt correction,then transforms the extracted license plate region to binary image,obtains the incline angle with the Radon transform to calculate the accurate affine transformation matrix,finally achieves the precise vehicle license plate location and tilt correction.Experiment shows that compared with traditional algorithms,the proposed method not only achieves accurate license plate location and tilt correction,but also has good adaptability to the image brightness,defilement,tilt,scale change and so on,so it has a good performance of robustness.