Homebrew is struggling with the older python 2.7 version that is missing ssl support. Python 3.8 did not recognize cv2 but this finally worked
brew install python3 brew postinstall python3 pip3 install virtualenv virtualenvwrapper virtualenv env_name --python="python3" /Users/wjst/env_name/bin/pip3 install opencv-python /Users/wjst/env_name/bin/pip3 install pandas scipy matplotlib Pillow tqdm sklearn imageio /Users/wjst/env_name/bin/python3 -c "import cv2"
then I could finally run the image forgery detection from Github.
cd /Users/wjst/Desktop/image-copy-move-detection-master /Users/wjst/env_name/bin/python3 > from copy_move_detection import detect > ...