Facial expression recognition based on Local Sign Directional Pattern

In this paper, we propose a novel local feature descriptor, Local Sign Directional Pattern (LSDP), for face expression recognition. LSDP encodes the directional information of the face´s textures-i.e., the texture´s structure-in a compact way, producing a more discriminating code than other state-of-the-art methods. The structure of each micro-pattern is encoded by using its prominent directions and sign-which allows it to distinguish among similar structural patterns that have different intensity transitions. We divide the face into several regions, from which we extract the distributions of the LSDP features. These features are concatenated into a feature vector, and used as a face descriptor, and the expression recognition is obtained with the aid of Support Vector Machine classifiers.