分类识别，可以选择很多方法，一般步骤：找特征点，训练，比对，找出方法

或者你的那种更容易，可以根据灰度值不同来查找具体位置-Classification, can choose to many methods and general steps: feature points, find training, comparison, find a way

Or the kind of easier, you can according to different gray values to find the location