opencv for python
pip install scikit-image
brew install opencv
echo /usr/local/opt/opencv/lib/python3.7/site-packages >> /usr/local/lib/python3.6/site-packages/opencv3.pth
pip install numpy scipy scikit-image matplotlib scikit-learn
cd ~/.virtualenvs/cv-py3/lib/python3.7/site-packages/
ln -s /usr/local/opt/opencv@3/lib/python3.7/site-packages/cv2.cpython-37m-darwin.so cv2.so