Fourier-basis Functions to Bridge Augmentation Gap: Rethinking Frequency Augmentation in Image Classification

TL;DR

This paper introduces Auxiliary Fourier-basis Augmentation (AFA), a frequency domain technique that enhances model robustness against corruptions and out-of-distribution data without sacrificing standard accuracy.

Contribution

AFA is a novel augmentation method in the frequency domain that complements visual augmentations, improving robustness and OOD generalization in image classification.

Findings

AFA improves robustness against common corruptions.

AFA enhances out-of-distribution generalization.

AFA maintains standard performance with negligible loss.

Abstract

Computer vision models normally witness degraded performance when deployed in real-world scenarios, due to unexpected changes in inputs that were not accounted for during training. Data augmentation is commonly used to address this issue, as it aims to increase data variety and reduce the distribution gap between training and test data. However, common visual augmentations might not guarantee extensive robustness of computer vision models. In this paper, we propose Auxiliary Fourier-basis Augmentation (AFA), a complementary technique targeting augmentation in the frequency domain and filling the augmentation gap left by visual augmentations. We demonstrate the utility of augmentation via Fourier-basis additive noise in a straightforward and efficient adversarial setting. Our results show that AFA benefits the robustness of models against common corruptions, OOD generalization, and consistency of performance of models against increasing perturbations, with negligible deficit to the standard performance of models. It can be seamlessly integrated with other augmentation techniques to further boost performance. Code and models can be found at: https://github.com/nis-research/afa-augment