Geometric Feature-Based Face Normalization for Facial Expression Recognition

In this paper, we propose a robust facial expression recognition approach using ASM (Active Shape Model) based face normalization and embedded hidden Markov model (EHMM). Since the face region generally varies as different emotion states, the face alignment procedure is a vital step for successful facial expression recognition. Thus, we first propose ASM-based facial region acquisition method for performance improvement. In addition, we also introduce the EHMM-based recognition method using two-dimensional discrete cosine transform (2D-DCT) feature vector. Here, we apply large window size during feature extraction of 2D-DCT. The reason is that the facial feature of large window size will represent better facial expression characteristic than that of small window size. The performance evaluation of proposed method was performed with the CK facial expression database and the JAFFE database, and the proposed ASM-based method showed average performance improvements of 7.9% and 5.3% compared to eye-based method for CK database and JAFFE database, respectively.