Lately I was given an opportunity to read a book about OpenCV called (very accurately) Instant OpenCV Starter. The book does exactly what the says - it's a short introduction to everyone's favorite Computer Vision library.
The book itself contains a few sections worth mentioning. First part about installation contains great explanation how to install OpenCV (2.4.2) on Ubuntu (12.04 LTS) and configure it within Code::Blocks. There is also a part about Windows installation, but it falls a little short. Mainly because it is, well...short in comparison to Linux counterpart.
The most interesting part is one called "Top 5 features you need to know about" and it covers things like pixel manipulation, image resizing or edge detection. The features are nicely organized into tasks, which states a problem (e.g. reading and displaying an image) and shows the solution. All code has very detailed explanations, but there is very little theory. For example in task regarding edge detection the Canny Edge Detector is used but there is no mention about morphological operations or even what Canny exactly does. It just states a problem and gives you a straightforward solution without going into theoretical reflections, which sometimes is good but it isn't very helpful in understanding the topic.
There was one part that I didn't like. I am an amateur cryptologist - I treat cryptography and cryptoanalysis as a hobby and I don't know enough to be writing about it, so I don't (if you want to read a good blog about cryptography and security look here). The authors in one of the tasks describe a steganography as a "very interesting technology that is being used for the wrong reasons in the world today" and that's all about it. Not only this sentence is a very negative description of a technique that is quite neutral but doesn't explain what exactlysteganography is. After saying that it is used for illegal purposes, there is, of course, an example how to use it :)
Also there is a short part with links to useful OpenCV sites. It isn't anything what you wouldn't find without a very short Google query, and probably you already been there because you are reading a book about OpenCV, but it is nice to have it organized. I would add some other links like Damiles blog (BTW Damiles is a reviewer of this book).
All in all it is a great book if you are an OpenCV beginner or want to have a quick look at OpenCV features. The book is written in very accessible way with clearly organized tasks. It covers the basics like pixel manipulations, color space transformations and video processing, but doesn't trouble you with excessive theory. It is a good read before some more serious lecture like "Learning OpenCV". The book can be purchased from PacktPub.