OpenCV C++圖像操作常用API

cv::Resize(): https://stackoverflow.com/questions/23984191/resize-image-opencv

cv::flip(): https://docs.opencv.org/3.4/d2/de8/group__core__array.html#gaca7be533e3dac7feb70fc60635adf441

根據cv::Rect來crop圖像patch: https://stackoverflow.com/questions/8267191/how-to-crop-a-cvmat-in-opencv

cv::cvtColor

reshape操作：https://www.cnblogs.com/denny402/p/5035535.html