Linear Subspace Learning for Facial Expression Analysis

Facial expression, resulting from movements of the facial muscles, is one of the most powerful, natural, and immediate means for human beings to communicate their emotions and intentions. Some examples of facial expressions are shown in Fig. 1. Darwin (1872) was the first to describe in detail the specific facial expressions associated with emotions in animals and humans; he argued that all mammals show emotions reliably in their faces. Psychological studies (Mehrabian, 1968; Ambady & Rosenthal, 1992) indicate that facial expressions, with other non-verbal cues, play a major and fundamental role in face-to-face communication.