An approach for automatically measuring facial activity in depressed subjects

This paper is motivated by Ellgring´s work in non-verbal communication in depression to measure and compare the levels of facial activity, before and after treatment, of endogenous and neurotic depressives. Similar to that work, we loosely associate the measurements with action units (AU) groups from the facial action coding system (FACS). However, we use the neologism region units (RU) to describe regions of the face that encapsulate AUs. In contrast to Ell-gring´s approach, we automatically generate the measurements and provide both prototypical expression recognition and RU-specific activity measurements. Latency between expressions is also measured and the system is conducive to comparison across groups and individual subjects. By using active appearance models (AAM) to locate the fiduciary facial points, and multiboost to classify prototypical expressions and the RUs, we can provide a simple, objective, flexible and cost-effective means of automatically measuring facial activity.