I. Introduction
Emotion recognition via facial expressions has attracted much interest with recent advances in pattern recognition and artificial intelligence due to its various applications e.g. in video games, intelligent human-computer interactions, educational software for special need children, medical related software for treating PTSD. A human face has superior expressive ability and provides one of the most powerful and natural ways of communicating motivational and affective states [1]. Facial expressions are used not only to express our emotions but also to provide important communicative cues during social interaction such as our level of interest, signaling understanding of conveyed information.