Viola Jones object detection framework

The Viola–Jones object detection framework is the first object detection framework to provide competitive object detection rates in real-time proposed in 2001 by Paul Viola and Michael Jones. Although it can be trained to detect a variety of object classes, it was motivated primarily by the problem of face detection. This algorithm is implemented in OpenCV as cvHaarDetectObjects().

YouTube video explaining Viola Jones face detection:

https://www.youtube.com/watch?v=WfdYYNamHZ8

This is a slide deck explaining Viola Jones face detection:

http://www.slideshare.net/wolf/avihu-efrats-viola-and-jones-face-detection-slides/


Haar features are not an AI or ML algorithm themselves, but instead are often a useful tool for transforming data into a format that an AI or ML algorithm can use.

The Wikipedia article only talks about them with respect to object recognition in visible light images.  However, they can be used with images from any spectrum or even any type of data that can be represented as X,Y,Z such as a digital elevation map of terrain.

http://en.wikipedia.org/wiki/Haar-like_features

This pdf has a good explanation of how to use Haar features:

http://nichol.as/papers/Wilson/Facial%20feature%20detection%20using%20Haar.pdf