基于子区域投影分析的车牌倾斜校正

摘要

A license plate slant correction method based on analysing the projection profiles of sub-regions is proposed. First the horizontal slant is corrected, the license plate image is divided into sub-regions along horizontal direction, and the centre point coordinates with regard to the character areas in the sub-regions are determined based on project analysis. Then all the centre points are fit to a line, the line inclination is the horizontal inclination. To detect the vertical inclination, this method divides the license plate image into sub-regions along vertical direction. The projections on sub-regions are used to compute the sheer transform and vertical projection of license plate image to determine the vertical inclination. Experimental results show that, compared to common rotation and projection-based method, the proposed one requires less computation and is robust.%提出一种基于子区域投影分析的车牌倾斜校正方法.首先进行水平倾斜校正,将车牌图像划分为水平方向上的子区域,进行投影分析后确定子区域内字符区域中心点坐标,然后将各中心点拟合为一条直线,直线的倾角即为水平倾角.对于检测垂直倾角,该方法将车牌图像划分为垂直方向上的子区域,利用子区域的投影来快速计算车牌图像的错切变换和垂直投影,确定垂直倾角.实验结果表明,与常用的旋转投影法相比,该方法运算时间少且鲁棒性好.