Face recognition has been actively studied recently, and continues to be a big research challenge. Just recently, researchers have begun to investigate face recognition under unconstrained conditions. This is a comprehensive review of the facial biometric, especially face recognition from video. The underlying basis of these approaches is that, unlike conventional face recognition algorithms, they exploit the inherent characteristics of the unconstrained situation and thus improve the recognition performance when compared with conventional algorithms. Unconstrained Face Recognition is structured to meet the needs of a professional audience of researchers and practitioners in industry. This volume is also suitable for advanced-level students in computer science.