Facial Expression Recognition Using Fusion Features Based on Center-Symmetric Local Octonary Pattern

A local feature descriptor has gained a lot of interest in many applications, such as image retrieval, texture classification, and face recognition. This paper proposes a novel local feature descriptor: center-symmetric local octonary pattern (CS-LOP) for facial expression recognition. A CS-LOP operator not only considers the difference of the gray value between central pixels and neighboring pixels in all eight directions but also compares the gray value of four pairs of center-symmetric pixels. Besides, this paper used the CS-LOP to extract diverse features from the preprocessed facial image, the feature map of gradient magnitude, and the feature map of Gabor, and also to make extracted features more abundant and detailed. To evaluate the performance of the proposed method, experiments on JAFFE and CK facial expression datasets demonstrate that the proposed method outperforms the method using the individual descriptor. Compared with other state-of-the-art methods, our approach improves the overall recognition accuracy.