A novel maximum and minimum response-based Gabor (MMRG) feature extraction method for facial expression recognition

In facial expression recognition applications, the images are corrupted with random noise, and this affects the classification accuracy. This article proposes a maximum and Minimum Response-based Gabor (MMRG) that can encode the facial texture more discriminatively and eliminate random noise. Two code images are produced from the available Gabor images. Then, after dividing the code images into grids, feature vectors are formed using histograms. A technique based on the bat algorithm is proposed for the optimization of the Gabor filter banks as Bat Algorithm-based Gabor Optimization (BAGO). The MMRG increases the efficiency of Gabor filter-based features by precisely distinguishing the texture frequencies. It also helps in reducing the dimensions of feature vector which is a major problem in Gabor filter-based feature extraction. Radial Basis Function-Extreme Learning Machine (RBF-ELM) classifier is used for a faster and accurate multi-classification. The proposed approach has been evaluated with six datasets namely, Japanese Female Facial Expression (JAFFE), Cohn Kanade (CK+), Multi-media Understanding Group (MUG), Static Facial Expressions in the Wild (SFEW), Oulu-Chinese Academy of Science, Institute of Automation (Oulu-CASIA) and Man–Machine Interaction (MMI) datasets to meet a classification accuracy of 97.2, 97.4, 95.4, 35.4, 87.4 and 82.3% for seven class emotion detection, which is high when compared to other state-of –the-art methods.