What preprocessing image techniques should I take in consideration before applying OpenCV's Viola-Jones method for face detection?

Question

I am working for a project at school regarding face detection, based on a technique described by Viola and Jones 2001/2004.

I've read that the OpenCV has an implementation of this algorithm, and it works very good.

I was wondering if you have any advices regarding what techniques (pre-processing) to apply to the images before testing the existence of a face (eg. histogram equalization) ?

Answer 1

I basically used the code from this sample program from the OpenCV page and it worked very well for my masters thesis project. If you get bad results or your lighting is strange you can try a histogram equalization.