Facial expression recognition based on LLENet

Facial expression recognition plays an important role in lie detection, and computer-aided diagnosis. Many deep learning facial expression feature extraction methods have a great improvement in recognition accuracy and robutness than traditional feature extraction methods. However, most of current deep learning methods need special parameter tuning and ad hoc fine-tuning tricks. This paper proposes a novel feature extraction model called Locally Linear Embedding Network (LLENet) for facial expression recognition. The proposed LLENet first reconstructs image sets for the cropped images. Unlike previous deep convolutional neural networks that initialized convolutional kernels randomly, we learn multi-stage kernels from reconstructed image sets directly in a supervised way. Also, we create an improved LLE to select kernels, from which we can obtain the most representative feature maps. Furthermore, to better measure the contribution of these kernels, a new distance based on kernel Euclidean is proposed. After the procedure of multi-scale feature analysis, feature representations are finally sent into a linear classifier. Experimental results on facial expression datasets (CK+) show that the proposed model can capture most representative features and thus improves previous results.