A Novel Graph-TCN with a Graph Structured Representation for Micro-expression Recognition

Facial micro-expressions (MEs) recognition has attracted much attention recently. However, because MEs are spontaneous, subtle and transient, recognizing MEs is a challenge task. In this paper, first, we use transfer learning to apply learning-based video motion magnification to magnify MEs and extract the shape information, aiming to solve the problem of the low muscle movement intensity of MEs. Then, we design a novel graph-temporal convolutional network (Graph-TCN) to extract the features of the local muscle movements of MEs. First, we define a graph structure based on the facial landmarks. Second, the Graph-TCN deals with the graph structure in dual channels with a TCN block. One channel is for node feature extraction, and the other one is for edge feature extraction. Last, the edges and nodes are fused for classification. The Graph-TCN can automatically train the graph representation to distinguish MEs while not using a hand-crafted graph representation. To the best of our knowledge, we are the first to use the learning-based video motion magnification method to extract the features of shape representations from the intermediate layer while magnifying MEs. Furthermore, we are also the first to use deep learning to automatically train the graph representation for MEs.