Facial Expression Recognition: A Cross-Database Evaluation of Features and Classifiers
Francisco Edvan Chaves, Thelmo Pontes de Araujo, José Everardo Bessa Maia · Journal of Intelligent Computing · 2019
Many approaches in both feature extraction and classification have been proposed in order to build a robust automatic facial expression recognition system.The chosen features and classifiers are usually compared in limited scenarios.In this paper, 5 feature extractors (3 variations of Gabor filters, Local Binary Patterns, and Discrete Cosine Transform) and 4 classifiers (K-Nearest Neighbors, Support Vector Machine, Radial Basis Function Neural Network, and Naive Bayes) were combined and applied to three different datasets: JAFFE, Yale, and CK+.The combinations of feature extractors and classifiers were compared in more robust settings, being evaluated in each dataset separately and in 3 cross-database settings, to verify the technique's generalization power.All experiments were performed in two validation scenarios: in the first one, the system tries to recognize the facial expression of a person already known to it in the training phase, using an image not present in the training set (leave-one-out); in the other scenario, all images of a certain individual are in the testing set, so the system tries to recognize the facial expression of a person unknown to it in the training phase (leave-one-subject-out). Accuracy results, as well as computational times, are presented, suggesting the combination of feature extractors and classifiers more suited for generalization.