基于Sobel算子和Radon变换的车牌倾斜校正方法

Tilt correction method of license plate based on Sobel operator and Radon transform

倾斜的车牌不利于车牌字符的分割。基于Sobel算子和Radon变换,提出了一种新的车牌倾斜校正方法。利用Sobel算子对二值化后的车牌进行水平和垂直两个方向的边缘检测,在边缘检测结果的基础上用Radon变换测出车牌在水平和垂直两个方向上的倾斜角,结合倾斜角用剪切变换对二值化后的车牌进行校正。实验结果表明,该方法简单易行,对污迹、光照不敏感。

The tilt license plate is bad for license plate characters segmentation. A new approach for license plate tilt correction based on Sobel operator and Radon transform was presented. The horizontal edge and vertical edge of the binary image were detected by Sobel operator. On the basis of the results of edge detection, the horizontal tilt angle and vertical tilt angle were detected by Radon transform. Combined with tilt angle, the binary image was corrected by shear transformation. Experimental results show that the method offers robustness when dealing with dirty plates and license plates in variant lighting conditions.