Packt Publishing offers a big selection of OpenCV books, and many of them focus on the library's C++ interface. Here are some fine examples:
OpenCV Essentials, by multiple authors: This is a concise introduction to OpenCV with C++.
Learning Image Processing with OpenCV, by multiple authors: This book emphasizes photo and video enhancement techniques, from beginning to advanced levels.
OpenCV Computer Vision Application Programming Cookbook, by Robert Laganière: This is a book of recipes showing how to efficiently solve common computer vision problems with OpenCV.
Mastering OpenCV with Practical Computer Vision Projects, by multiple authors: This is a set of advanced projects. Each combines multiple features of OpenCV to solve a problem.
OpenCV Blueprints (forthcoming), by multiple authors: This is a collection of advanced tutorials and articles, which is intended to clear up mysteries about building robust applications with OpenCV. A combination of theory...