Hamid Sadeghi - Department of Electrical Engineering, Amirkabir University of Technology, Tehran. Iran
Abolghasem Asadollah Raie - Department of Electrical Engineering, Amirkabir University of Technology, Tehran. Iran
Mohammad-Reza Mohammadi - Department of Electrical Engineering, Sharif University of Technology, Tehran. Iran

In recent years, facial expression recognition, as an interesting problem in computer vision has been performed by means of static and dynamic methods. Dynamic information plays an important role in recognizing facial expression in the image sequences. However, using the entire dynamic information in the expression image sequences is of higher computational cost compared to the static methods. To reduce the computational cost, instead of entire image sequence, only neutral and emotional faces can be employed. In the previous research, this idea was used by means of Difference of Local Binary Pattern Histogram Sequences (DLBPHS) method in which facial important small displacements were vanished by subtracting Local Binary Pattern (LBP) features of neutral and emotional face images. In this paper, a novel approach is proposed to utilize two face images. In the proposed method, the face component displacements are highlighted by subtracting neutral image from emotional image; then, LBP features are extracted from the difference image as well as the emotional one. Then, the feature vector is created by concatenating two LBP histograms. Finally, a Support Vector Machine (SVM) is used to classify the extracted feature vectors. The proposed method is evaluated on standard databases and the results show a significant accuracy improvement compared to DLBPHS.

Facial Expression Recognition; Difference Image; Displacement Image; Local Binary Patterns; Support Vector Machine