Face detection using classifier.
#Interesting sources
- https://en.wikipedia.org/wiki/Kernel_(image_processing)
- http://mccormickml.com/2013/05/07/gradient-vectors/ (gradient vector calculus and explaination )
- http://mccormickml.com/2013/05/09/hog-person-detector-tutorial/ (hog descriptor explaination)
- http://mccormickml.com/2013/02/26/image-derivative/
- https://en.wikipedia.org/wiki/Prewitt_operator