A Smile Detection Method Based on Improved LeNet-5 and Support Vector Machine

Abstract

Conventional facial expression recognition methods usually deal with frontal face images via only one or several features, which are easy to loss useful information and sensitive to face poses, scales and noise. As an interesting application of facial expression, this paper proposes an effective smile detection method under unconstrained scenarios, employing convolution neural network to learn and automatically extract discriminative features from a large number of human face images. Specifically, our method firstly converts the original color images to grayscale images, and due to the important role of mouth in expression analysis, we then localizes the mouth region according to 5 key points on the face. After the brightness adjustment and size normalization, the mouth images are input as training images of an improved LeNet-5 model to learn and automatically extract the discriminative features of the mouth regions. Finally, a SVM classifier is trained to distinguish smiling or non-smiling. Experimental results of the public MTFL database and GENKI-4K database show that the accuracy rates of our method are up to 87.81% and 86.80%, respectively.