安装cv2报错：
Collecting cv2 Could not find a version that satisfies the requirement cv2 (from versions: ) No matching distribution found for cv2
Pycharm/Python OpenCV and CV2 install error
原因：
知道原因是真的是哭笑不得，因为原因是CV2在的软件包不叫从cv2而是叫opencv-python
pip install opencv-python对于python3：
pip3 install opencv-python也可以在pycharm里直接找opencv-python，安装。