Introduction - If you have any usage issues, please Google them yourself
Do a small thing, some time ago in the OPENCV in sub-images used to extract and copy, for a time did not find a good way, either direct access to the assignment of pixels, either through the array to convert, and always feel awkward, and later got to know the a relatively simple method, you need to use the OPENCV in the ROI method, the method for grayscale or color images of any format