Pycharm，Python 安装OpenCV and CV2 时，报错，教你如何正确安装。

Collecting cv2
  Could not find a version that satisfies the requirement cv2 (from versions: )
No matching distribution found for cv2

初学Python，在安装cv2框架的时候，报以上错误，试了很多次  pip install cv2  依然无效，后来查阅了好多资料，总结下面的方法，安装了opencv后，里面包含了cv2框架。

If you are using python 2 you can install with pip:

pip install opencv-python

Or use the equivilent for python 3:

pip3 install opencv-python