The following references will help you dive deeper into contours and other image processing techniques: Python 3.x for Computer Vision by Saurabh Kapur (2017) (https://www.packtpub.com/application-development/python-3x-computer-vision-video-0) OpenCV: Computer Vision Projects with Python (2016) (https://www.packtpub.com/application-development/opencv-computer-vision-projects-python)