Replace PATH_TO_FOLDER_WITH_CODE_AND_IMAGE_FOLDERS and IMAGE_FOLDER with appropriate folder path and name below:
docker run -v PATH_TO_FOLDER_WITH_CODE_AND_IMAGE_FOLDERS:/root/demo/opendock -e DISPLAY=$DISPLAY:0 -p 5000:5000 -it spmallick/opencv-docker:opencv /bin/bash
workon OpenCV-master-py3
ipython
import cv2
cv2.version
exit()
cd /root/demo/opendock
source activate OpenCV-master-py3
cd PATH_TO_FOLDER_WITH_CODE_AND_IMAGE_FOLDERS
python ./face_features/extract_features.py /root/demo/opendock/IMAGE_FOLDER