Confidence-based Local Feature Selection for Material Classification
Sixiang Xu, Damien Muselet, Alain Trémeau, Robert Laganière · 2020
With the rise of Convolutional Neural Network (CNN) in the recent years, image classification has shown outstanding performances in the computer vision field. Many wellknown state of the art's CNN architectures such as the ResNet family are applying a Global Average Pooling (GAP) to reduce the number of parameters of the fully connected layers. Most of the time, this pooling operation helps to prevent overfitting but we claim that it has a serious weakness for specific images where small details are crucial to predict their category, such as material images. In this case, the details are lost in the global average, providing non accurate global features. In this paper, we propose to select the most important local features before applying the GAP. In this aim, we add a branch in the classification network that predicts the confidence the network should have in each local feature vector. The less confident features are filtered out before applying the GAP. Experimental results on three datasets show that our approach outperforms recent alternatives in terms of classification accuracy and output probability calibration.