AdvST: Revisiting Data Augmentations for Single Domain Generalization
Guangtao Zheng, Mengdi Huai, Aidong Zhang
TL;DR
AdvST reframes standard data augmentations as learnable semantics transformations and optimizes a mini-max objective to train models robust to unseen domain shifts from a single source domain. By interpreting the learned augmentations as semantics-induced distributions $Q_{\psi}$ and leveraging a Wasserstein-based DRO formulation, AdvST provides a tractable inner optimization and expands target-domain coverage. Empirically, AdvST and its entropy-regularized variant AdvST-ME achieve state-of-the-art average SDG performance on the Digits, PACS, and DomainNet benchmarks and remain effective with limited source data. This work demonstrates that principled, learnable augmentation semantics can effectively simulate diverse domain shifts using only the source domain, with practical implications for SDG in vision applications.
Abstract
Single domain generalization (SDG) aims to train a robust model against unknown target domain shifts using data from a single source domain. Data augmentation has been proven an effective approach to SDG. However, the utility of standard augmentations, such as translate, or invert, has not been fully exploited in SDG; practically, these augmentations are used as a part of a data preprocessing procedure. Although it is intuitive to use many such augmentations to boost the robustness of a model to out-of-distribution domain shifts, we lack a principled approach to harvest the benefit brought from multiple these augmentations. Here, we conceptualize standard data augmentations with learnable parameters as semantics transformations that can manipulate certain semantics of a sample, such as the geometry or color of an image. Then, we propose Adversarial learning with Semantics Transformations (AdvST) that augments the source domain data with semantics transformations and learns a robust model with the augmented data. We theoretically show that AdvST essentially optimizes a distributionally robust optimization objective defined on a set of semantics distributions induced by the parameters of semantics transformations. We demonstrate that AdvST can produce samples that expand the coverage on target domain data. Compared with the state-of-the-art methods, AdvST, despite being a simple method, is surprisingly competitive and achieves the best average SDG performance on the Digits, PACS, and DomainNet datasets. Our code is available at https://github.com/gtzheng/AdvST.
