Preparation of original facial material.

Ten subjects were instructed by a trained FACS coder to voluntarily produce the combination of AUs specified for each emotion. They were then photographed while posing these facial expressions as well as when showing a neutral, relaxed face. All subjects were photographed in front of a black backdrop, wearing a black turtle-neck shirt, unter the same lighting conditions. They were photographed frontally, full-face, with their head being held straight. The printed photographs were all of the same format (17 x 12). Each photograph was then digitalized and stored. In this way 70 facial images (10 subjects x 7 expressions were produced.