基于改进Sobel算子的车牌定位方法

Research on Calculation Method to do with Locating License Plate based on Improved Sobel Arithmetic Operators

车牌定位作为车牌识别系统中的一个重要环节,定位算法的好坏直接影响到识别的效果。本文针对不同背景和光照条件下的车辆图像,提出一种改进Sobel算子的车牌定位算法,首先对已经过预处理的车牌图像进行改进的Sobel运算,然后使用迭代求图像最佳分割阈值的算法二值化出前景,根据车牌区域纹理丰富的特点,采用水平梯度算子求得图像的水平投影图,再运用数学形态学的开闭运算进行车牌垂直定位,最终定位车牌位置。经过大量试验证明,该算法准确率高、定位速度快,具有较好的实用价值。

With license plate location as a key part of license plate identification system, locating calculation method has a big influence on the effect of identification.Considering the vehicle images under different backgrounds and illumination conditions, this paper brings forward the calculation method of locating license plate with improved Sobel arithmetic operators. It involves initial processing of pre-treated license plate images by applying improved Sobel, specifying the foreground with threshold, using the horizontal gradient algorithm to get the horizontal projection image according as the characteristic of rich license plate regional veins, then using the opening and closing operations of the mathematical morphology to do vertical location of the license plate and locating the license plate finally. It is proved by experiments that the calculation method is of high accuracy, quick location and great value.