问题：在windows命令窗口输入pip install cv2后出现： Could not find a version that satisfies the requirement cv (from versions: ) No matching distribution found for cv
解决办法：换成以下命令：
pip3 install opencv-python
问题：在windows命令窗口输入pip install cv2后出现： Could not find a version that satisfies the requirement cv (from versions: ) No matching distribution found for cv
解决办法：换成以下命令：
pip3 install opencv-python