Facial action point based emotion recognition by principal component analysis

Abstract

This paper proposes an alternative approach to emotion recognition of a subject from selected 36 facial action points marked at specific locations on their faces. Facial expressions obtained by the subjects enacting them are recorded, and the corresponding changes in marked action points are measured. The measurements reveal that the action points have wider variations in facial expressions containing diverse emotions. Considering 10 instances for each facial expression, and carrying the same emotion, experimented over 10 subjects, we obtain a set of 100 distance matrices, representing the distance between any two selected action points. The 100 matrices for each individual emotion are averaged, and the first principal component, representing the most prominent features of the average distance matrix is evaluated. During the recognition phase, the first Principal component obtained from the distance matrix of an unknown facial expression is evaluated, and its Euclidean distance with the first Principal component of each emotion is determined. The unknown facial expression is classified into emotion class j, if the Euclidean distance between the obtained principal component and that of j-th emotion class is minimum. Classification of 120 facial images, containing equal number of samples for six emotion classes, reveals an average classification accuracy of 92.5%, the highest being in relax and disgust and the least in fear and anger. © 2012 Springer India Pvt. Ltd.