基于图像矩的车牌号码倾斜校正  

Vehicle License Plate Tilt Correction Based on Image Moments

作　　者：潘梅森[1] 郭国强[1] 

机构地区：[1]湖南文理学院计算机科学与技术系,常德415000

出　　处：《计算机辅助设计与图形学学报》2007年第8期1041-1045,共5页Journal of Computer-Aided Design & Computer Graphics

基　　金：湖南省自然科学基金(05JJ40098);湖南省教育厅科研基金(05C720)

摘　　要：根据矩的旋转不变性计算倾斜车牌号码图像的质心和归一化的中心矩,得到使二阶中心矩变得最小时的旋转角α,把整个图像绕质心旋转α进行水平倾斜校正;在垂直倾斜校正中,提出了坐标相关系数法和最小二乘拟合直线法等2种校正方法,分别计算出垂直倾斜角θ,并对水平倾斜校正后的图像进行错切变换,得到最终的校正图像.实验结果表明,该方法简单实用,能快速、准确地检测出图像的倾斜角,为图像倾斜校正提供了一种有效方法.The centroid and the normalized central moments of a vehicle license plate image are calculated, and the rotation angle a is obtained by minimizing the second order central moment based on its rotational invariance. Then whole image is rotated around the centroid by a to correct the image horizontal tilt. For the vertical tilt correction, two approaches, the one is based on the coordinate correlation coefficient, the other is based on line fitting with the least squares method, are proposed to compute the vertical tilt angle O, and with which a shear transform is clone on the previously rotated image for the final correction. The experimental results show that the proposed method is fairly reliable and accurate for the determination of tilt angles, and is a practical and effective tilt correction technique.

关 键 词：倾斜校正 中心矩 坐标相关系数 最小二乘法 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]