一.python3安装opencv
1 pip3 install opencv-python==3.4.6.27
二.python3安装face_recognition
1 pip3 install cmake
如果安装失败提示"Could not find a version that satisfies the requirement openpyxl (from versions: "
是pip版本过低，需要更新pip，然后在安装cmake：
1 python -m pip install --upgrade pip
2 或者
3 python -m pip3 install --upgrade pip3
pip3 install face_recognition