通过灰度化、分段灰度拉伸、中值滤波、边缘检测和二值化等方式对车牌图像进行预处理，然后基于灰阶跳变定位车牌。-By gray, fractional gray stretch, median filtering, edge detection and binarization, etc. on the license plate image is preprocessed, and then jump on gray positioning plate.