This is one of my master's degree works and was presented on the Encontro Nacional de Engenharia Biomecânica 2011. The following image is taken from this results section of this publication:
Figure caption: Results for the face detection using limits. a) original, b) ground truth, c) RGB and d) LUV
Publication (portuguese): Dropbox link (pdf)
OpenGL and OpenCV
Just run make to use the Makefile building