在图像数字和字符识别过程中，定位是实现智能化的关键一步，同时也是最难的一步，本方法实现了几种常用的定位方法 并做了比较 可以在matlab直接运行-In the digital image and character recognition process, the positioning is a key step to achieve intelligent, but also the most difficult step, this method several commonly use