In this book, various state-of-art techniques about face recognition has been studied. The main portion of the book discuss about the face recognition system based on the probability distribution functions (PDF) of pixels in colour channels. This book studies into two main issues of face recognition, one of which is facial image illumination enhancement and the other one is classification stage where the face images are being recognized. In the pre-processing stage a novel facial image equalization method is studied and discussed. Further more PDF based face recognition is analytically is studied.