pip3.exe install opencv-python
报错：
Fatal error in launcher: Unable to create process using '"c:\python37\python3.exe" "C:\Python37\Scripts\pip3.exe" install opencv-python'
原因：
安装了多个版本python
解决方法：
python37 -m pip install opencv-python
pip3.exe install opencv-python
报错：
Fatal error in launcher: Unable to create process using '"c:\python37\python3.exe" "C:\Python37\Scripts\pip3.exe" install opencv-python'
原因：
安装了多个版本python
解决方法：
python37 -m pip install opencv-python