OPENCV学习笔记1-7_定义感兴趣区域

　　Sometimes, a processing function(处理函数) needs to be applied only to a portion(部分) of an image. OpenCV incorporates (内嵌)an elegant(精致) and simple mechanism(机制) to define a subregion(子区域) in an image and manipulate(操作) it as a regular image(普通图像).　　Sometimes, a processing function(处理函数) needs