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Robustmix: Improving Robustness by Regularizing the Frequency Bias of Deep Nets

Jonas Ngnawe, Marianne Abemgnigni Njifon, Jonathan Heek, Yann Dauphin

TL;DR

This work proposes a novel extension of Mixup called Robustmix that regularizes networks to classify based on lower-frequency spatial features and shows that this type of regularization improves robustness on a range of benchmarks such as Imagenet-C and Stylized Imagenets.

Abstract

Deep networks have achieved impressive results on a range of well-curated benchmark datasets. Surprisingly, their performance remains sensitive to perturbations that have little effect on human performance. In this work, we propose a novel extension of Mixup called Robustmix that regularizes networks to classify based on lower-frequency spatial features. We show that this type of regularization improves robustness on a range of benchmarks such as Imagenet-C and Stylized Imagenet. It adds little computational overhead and, furthermore, does not require a priori knowledge of a large set of image transformations. We find that this approach further complements recent advances in model architecture and data augmentation, attaining a state-of-the-art mCE of 44.8 with an EfficientNet-B8 model and RandAugment, which is a reduction of 16 mCE compared to the baseline.

Robustmix: Improving Robustness by Regularizing the Frequency Bias of Deep Nets

TL;DR

This work proposes a novel extension of Mixup called Robustmix that regularizes networks to classify based on lower-frequency spatial features and shows that this type of regularization improves robustness on a range of benchmarks such as Imagenet-C and Stylized Imagenets.

Abstract

Deep networks have achieved impressive results on a range of well-curated benchmark datasets. Surprisingly, their performance remains sensitive to perturbations that have little effect on human performance. In this work, we propose a novel extension of Mixup called Robustmix that regularizes networks to classify based on lower-frequency spatial features. We show that this type of regularization improves robustness on a range of benchmarks such as Imagenet-C and Stylized Imagenet. It adds little computational overhead and, furthermore, does not require a priori knowledge of a large set of image transformations. We find that this approach further complements recent advances in model architecture and data augmentation, attaining a state-of-the-art mCE of 44.8 with an EfficientNet-B8 model and RandAugment, which is a reduction of 16 mCE compared to the baseline.
Paper Structure (10 sections, 7 equations, 4 figures, 3 tables, 1 algorithm)

This paper contains 10 sections, 7 equations, 4 figures, 3 tables, 1 algorithm.

Figures (4)

  • Figure 1: Illustration of the method. To better illustrate the method, we display the Fourier spectrum of the images next to them. We can see that even though 90% of the higher frequencies belong to the image of a dog, Robustmix assigns more weight to the boathouse label because it assigns more weight to the lower frequencies.
  • Figure 2: Plot of the cumulative energy in ImageNet images as a function of the frequency cutoff.
  • Figure 3: Highlighting the tradeoff between mCE and Clean Error for various models.
  • Figure 4: Test accuracy on ImageNet samples passed through a low-pass filter with increasing cut-off. As expected, we observe that Robustmix is more robust to the removal of high frequencies than Mixup. The comparison is done here on ResNet-50 models.