In this chapter, we first learned about different feature extraction algorithms that are useful in different situations. We started with looking at one of the first face detection algorithms that uses Haar Cascades. The concepts used in Haar Cascades, such as integral images and Haar wavelets, are fundamental concepts that are used in many other algorithms such as SURF. Going forward, we understood how SIFT and SURF work and looked at their OpenCV implementations.
In the next chapter, we will expand our OpenCV skills and look at how we can do video processing in real time.