Recently, technology became available to allow verification of "true" individual identity. This
technology is based in a field called "biometrics". Biometric access control are automated
methods of verifying or recognizing the identity of a living person on the basis of some
physiological characteristics, such as fingerprints or facial features, or some aspects of the
person's behavior, like his/her handwriting style or keystroke patterns. Since biometric systems
identify a person by biological characteristics, they are difficult to forge. Among the various
biometric ID methods, the physiological methods (fingerprint, face, DNA) are more stable than
methods in behavioral category (keystroke, voice print). The reason is that physiological
features are often non-alterable except by severe injury. The behavioral patterns, on the other
hand, may fluctuate due to stress, fatigue, or illness. However, behavioral IDs have the
advantage of being no intrusiveness. People are more comfortable signing their names or
speaking to a microphone than placing their eyes before a scanner or giving a drop of blood for
DNA sequencing. Face recognition is one of the few biometric methods that possess the merits
of both high accuracy and low intrusiveness. Also, it provides information about Age, gender,
personal identity (physical structure), Mood and emotional state (facial expression) and Interest
/ attentional focus (direction of gaze). However, even after decades of research, face is still an
active topic because of the variability observed in face due to illumination[11], pose, expression
and occlusion[12]. A new challenge to face recognition is facial plastic surgery[8]. These
surgeries alters the facial features to such an extent that human being often struggle to identify
a person face after surgery. The Fig. 1 shows an example of the effect of plastic surgery on facial
appearances.