Understanding Adversarial Robustness from Feature Maps of Convolutional Layers
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The adversarial robustness of a neural network mainly relies on two factors, one is the feature representation capacity of the network, and the other is its resistance ability to perturbations. In this paper, we study the anti-perturbation ability of the network from the feature maps of convolutional layers. Our theoretical analysis discovers that larger convolutional features before average pooling can contribute to better resistance to perturbations, but the conclusion is not true for max pooling. Based on the theoretical findings, we present two feasible ways to improve the robustness of existing neural networks. The proposed approaches are very simple and only require upsampling the inputs or modifying the stride configuration of convolution operators. We test our approaches on several benchmark neural network architectures, including AlexNet, VGG16, RestNet18 and PreActResNet18, and achieve non-trivial improvements on both natural accuracy and robustness under various attacks. Our study brings new insights into the design of robust neural networks. The code is available at <https://github.com/MTandHJ/rcm>.
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