用于从一个IplImage对象或者BYTE型数组中取出一幅图像的子图像，类似于OpenCV中的SetImageROI，但是该函数提供的功能是原图像子图像的一个拷贝，而非在原图像中设置ROI。-For the IplImage from a BYTE array object or remove an image of the sub-image, similar to OpenCV' s SetImageROI, but the function is the function of the original image to provide the child a copy of the image, rather than set in the original image ROI.