This is a tutorial on OpenCV initially written for the HCC Summer School in Bremen: [http://hcc.uni-bremen.de/school2016/]
The target audience is broad and includes
- People who have done computer science (maybe to graduate level) but who have not looked at OpenCV before
- People who are studying other subjects and want to play with computer vision
For those with computing experience, you can view this as a set of examples and code snippets to take and modify; it probably doesn't really matter what order you do things in.
For those without computing expertise, try following the notebooks sequentially. This should take you through the basics of opening images, modifying images, and doing some straightforward image operations.