基于灭点的倾斜畸变车牌图像快速校正方法研究*

由于相机与汽车牌照之间的方位关系导致了拍摄图像发生倾斜畸变，极大影响了车牌识别率。针对这一问题，利用畸变图像所蕴涵的灭点信息，提出了一种快速校正方法：首先对图像进行预处理，提取车牌的四条边框来产生灭点；然后根据灭点信息快速标定相机内参数并计算空间平面重建矩阵；最后进行空间坐标变换和灰度插值完成畸变图像的校正。实验表明，该方法对于倾斜畸变车牌有良好的校正效果，并有效提高了识别率。

Rapid skew distortion rectification for vehicle licenses plate images based on vanished points

The skew distortion was the crucial problem that influenced the procession for the vehicle licenses plate image recog-nition.However,as a result of the skew distortion,the vanishing points provided valuable information concerning the camera model used to capture the image.This paper put forward a robust and fast algorithm for skew distortion correction in vehicle licenses plate images based on vanishing points.This method included three steps: detecting vanishing points in an image,calibrating camera model coefficients and correcting skew distortion.Experimental results show this method performs well and increase the recognition rate.