OpenCV is a must when talking about computer vision, rapid prototyping, and open source solutions. Many people is interested in learning OpenCV, but sometimes it is a little bit tricky to find the correct way to use the primitives that OpenCV offers.
A great help can be found in the OpenCV documentation and tutorials, but it is more difficult to find good larger examples on the many features OpenCV provides.
An excellent way is to take a look to Mastering OpenCV with Practical Computer Vision Projects by Daniel Lélis. I’ve found this book really amazing. It does not only cover the hot topics around OpenCV (Android, iOS, structure from motion, face modeling, etc.) but it also comes with the source code available, which you can use and see all this cool stuff running in your own PC or smartphone. I really recommend to read this book. The authors and reviewers of the book are first class computer vision and OpenCV experts, not mentioning the high quality of the coding itself, which can be used as a guide on how to fully exploit C++ with OpenCV.
In summary: if you are learning OpenCV, you have tried some of the examples and you want to give the next step building your own large projects (especially in Android or iOS), you need this book!
Hope you enjoy it!