基于边缘跳变和投影法的车牌定位方法

提出了一种基于边缘跳变和投影法的多级车牌定位方法。该方法首先利用边缘跳变特征对车牌区域进行水平定位,得到一组水平区域;然后,通过垂直投影,利用车牌区域波峰—波谷—波峰密集特点定位车牌左右边界,得到候选车牌区域;最后,对多个候选车牌区域进行分析,剔除错误区域,得到粗定位的车牌区域。并对粗定位车牌区域做进一步修正,获得最终的车牌区域。本文提出的车牌定位方法在车牌倾斜角度较小(小于5度),图像拍摄距离为1.5m到2.5m条件下,能够较为准确的定位出车牌区域,对复杂背景、光照、车牌种类等条件不敏感。

Location Method of License Plate Based on Edge Changes and Projection Method

A Multi-level Location Method of License Plate is proposed based on edge changes and projection method. Firstly, it localizes the horizontal borderlines of LP by setting a threshold of the features of edge changes. Secondly, through the vertical projection, we realize vertical localization, by using license plate peak-trough-peak-intensive features, to get the candidate plate region. At last, we get the Coarse Location by analyzing candidate regions and excluding the error areas. And then we modify the coarse region further. The proposed method in this paper can accurately position the plate region when the tilt is small （less than 5 degrees）and the image shooting distance of 1.5m to 2.5m, and is not sensitive to comnlex background, light and car card tvne.