Fig 1.
General flow diagram for a typical facial expression recognition (FER) system.
Fig 2.
(a) shows the dependency graph of HMM, while (b) presents the dependency graph of MEMM.
Fig 3.
MEMM based on expression state model for FER system.
Table 1.
Recognition rate of the proposed FER system using CK+ dataset of facial expressions (Unit: %).
Table 2.
Recognition rate of the proposed FER system using JAFFE dataset of facial expressions (Unit: %).
Table 3.
Recognition rate of the proposed FER system using MUG dataset of facial expressions (Unit: %).
Table 4.
Recognition rate of the proposed FER system using USTC-NVIE dataset of facial expressions (Unit: %).
Table 5.
Recognition rate of the proposed FER system using IMFDB dataset of facial expressions (Unit: %).
Table 6.
Recognition rate of the proposed FER system using AFEW dataset of facial expressions (Unit: %).
Fig 4.
3D-feature plot of the proposed FER system for the six facial expressions using CK+ dataset.
It can be seen that the system clearly classified the expressions classes.
Fig 5.
3D-feature plot of the proposed FER system for the six facial expressions using JAFFE dataset.
It can be seen that the system clearly classified the expressions classes.
Fig 6.
3D-feature plot of the proposed FER system for the six facial expressions using MUG dataset.
It can be seen that the system clearly classified the expressions classes.
Fig 7.
3D-feature plot of the proposed FER system for the six facial expressions using USTC-NVIE dataset.
It can be seen that the system clearly classified the expressions classes.
Fig 8.
3D-feature plot of the proposed FER system for the six facial expressions using IMFDB dataset.
It can be seen that the system clearly classified the expressions classes.
Fig 9.
3D-feature plot of the proposed FER system for the six facial expressions using AFEW dataset.
It can be seen that the system clearly classified the expressions classes.
Table 7.
Confusion matrix of the proposed FER system that is trained on CK+ dataset and tested on JAFFE, MUG, USTC-NVIE, IMFDB, and AFEW datasets of facial expressions (Unit: %).
Table 8.
Confusion matrix of the proposed FER system that is trained on JAFFE dataset and tested on CK+, MUG, USTC-NVIE, IMFDB, and AFEW datasets of facial expressions (Unit: %).
Table 9.
Confusion matrix of the proposed FER system that is trained on MUG dataset and tested on CK+, JAFFE, USTC-NVIE, IMFDB, and AFEW datasets of facial expressions (Unit: %).
Table 10.
Confusion matrix of the proposed FER system that is trained on USTC-NVIE dataset and tested on CK+, JAFFE, MUG, IMFDB, and AFEW datasets of facial expressions (Unit: %).
Table 11.
Confusion matrix of the proposed FER system that is trained on IMFDB dataset and tested on CK+, JAFFE, MUG, USTC-NVIE, and AFEW datasets of facial expressions (Unit: %).
Table 12.
Confusion matrix of the proposed FER system that is trained on AFEW dataset and tested on CK+, JAFFE, MUG, USTC-NVIE, and IMFDB datasets of facial expressions (Unit: %).
Table 13.
Confusion matrix of the proposed FER system with HMM (as a recognition model), instead of using the proposed recognition model (that is MEMM model) using CK+ dataset of facial expressions (Unit: %).
Table 14.
Confusion matrix of the proposed FER system with HMM (as a recognition model), instead of using the proposed recognition model (that is MEMM model) using JAFFE dataset of facial expressions (Unit: %).
Table 15.
Confusion matrix of the proposed FER system with HMM (as a recognition model), instead of using the proposed recognition model (that is MEMM model) using MUG dataset of facial expressions (Unit: %).
Table 16.
Confusion matrix of the proposed FER system with HMM (as a recognition model), instead of using the proposed recognition model (that is MEMM model) using USTC-NVIE dataset of facial expressions (Unit: %).
Table 17.
Confusion matrix of the proposed FER system with HMM (as a recognition model), instead of using the proposed recognition model (that is MEMM model) using IMFDB dataset of facial expressions (Unit: %).
Table 18.
Confusion matrix of the proposed FER system with HMM (as a recognition model), instead of using the proposed recognition model (that is MEMM model) using AFEW dataset of facial expressions (Unit: %).
Table 19.
Comparison results of the proposed FER system with the proposed MEMM model against some stat-of-the-art works (Unit: %).