Using Diverse ConvNets to Classify Face Action Units in Dataset on Emotions Among Mexicans (DEM)

Abstract

To understand how Convolutional Neural Networks (ConvNets) perceive the muscular movements of the human face, known as Action Units (AUs) in this work, we introduce a new dataset named Dataset on Emotions among Mexicans (DEM), consisting of 1557 images of Mexicans labeled with twentysix AUs and seven emotions. As a benchmark, we used the comparison with DISFA+ labeled with 12 AUs. To address the task of detecting AUs in each image, six ConvNets were employed, and we evaluated their performance using the F1 Score. The two ConvNets with the best performance were VGG19 with 0.8180% (DEM), 0.9106 % (DISFA+), and ShuffleNetV2 with 0.7154% (DEM), 0.9440% (DISFA+). Subsequently, these ConvNets were analyzed using Grad-CAM and Grad-CAM++; this algorithms allows us to observe the areas of the face considered for prediction. In most cases, these areas consider the region of the labeled AU. Considering the F1 score and the visual study, we can conclude that using DEM as a dataset to classify AUs is promising since the experiments achieved performances similar to those of the current literature that only use ConvNets.INDEX TERMS Action Units, ConvNets, CAM analysis.