DivAug: Plug-in Automated Data Augmentation with Explicit Diversity Maximization

TL;DR

DivAug introduces an explicit diversity measure called Variance Diversity, theoretically links it to regularization benefits, and employs an unsupervised framework to enhance data augmentation, improving semi-supervised learning performance efficiently.

Contribution

Proposes Variance Diversity as a measurable and theoretically justified diversity metric, and develops DivAug, an unsupervised method to maximize it without search, boosting augmentation regularization effects.

Findings

Variance Diversity correlates with test accuracy gains.

DivAug achieves comparable performance to state-of-the-art methods.

Enhances semi-supervised learning with better efficiency.

Abstract

Human-designed data augmentation strategies have been replaced by automatically learned augmentation policy in the past two years. Specifically, recent work has empirically shown that the superior performance of the automated data augmentation methods stems from increasing the diversity of augmented data \cite{autoaug, randaug}. However, two factors regarding the diversity of augmented data are still missing: 1) the explicit definition (and thus measurement) of diversity and 2) the quantifiable relationship between diversity and its regularization effects. To bridge this gap, we propose a diversity measure called Variance Diversity and theoretically show that the regularization effect of data augmentation is promised by Variance Diversity. We validate in experiments that the relative gain from automated data augmentation in test accuracy is highly correlated to Variance Diversity. An unsupervised sampling-based framework, \textbf{DivAug}, is designed to directly maximize Variance Diversity and hence strengthen the regularization effect. Without requiring a separate search process, the performance gain from DivAug is comparable with the state-of-the-art method with better efficiency. Moreover, under the semi-supervised setting, our framework can further improve the performance of semi-supervised learning algorithms compared to RandAugment, making it highly applicable to real-world problems, where labeled data is scarce. The code is available at \texttt{\url{https://github.com/warai-0toko/DivAug}}.