Learning to Amend Facial Expression Representation via De-albino and Affinity.

Facial Expression Recognition (FER) is a classification task that points to face variants. Hence, there are certain intimate relationships between facial expressions. We call them affinity features, which are barely taken into account by current FER algorithms. Besides, to capture the edge information of the image, Convolutional Neural Networks (CNNs) generally utilize a host of edge paddings. Although they are desirable, the feature map is deeply eroded after multi-layer convolution. We name what has formed in this process the albino features, which definitely weaken the representation of the expression. To tackle these challenges, we propose a novel architecture named Amend Representation Module (ARM). ARM is a substitute for the pooling layer. Theoretically, it could be embedded in any CNN with a pooling layer. ARM efficiently enhances facial expression representation from two different directions: 1) reducing the weight of eroded features to offset the side effect of padding, and 2) sharing affinity features over mini-batch to strengthen the representation learning. In terms of data imbalance, we designed a minimal random resampling (MRR) scheme to suppress network overfitting. Experiments on public benchmarks prove that our ARM boosts the performance of FER remarkably. The validation accuracies are respectively 90.55% on RAF-DB, 64.49% on Affect-Net, and 71.38% on FER2013, exceeding current state-of-the-art methods.