Feedback-guided Data Synthesis for Imbalanced Classification
Reyhane Askari Hemmat Mohammad Pezeshki Florian Bordes Michal Drozdzal Adriana Romero-Soriano
Current status quo in machine learning is to use static datasets of real
images for training, which often come from long-tailed distributions. With the
recent advances in generative models, researchers have started augmenting these
static datasets with synthetic data, reporting moderate performance
improvements on classification tasks. We hypothesize that these performance
gains are limited by the lack of feedback from the classifier to the generative
model, which would promote the usefulness of the generated samples to improve
the classifier's performance. In this work, we introduce a framework for
augmenting static datasets with useful synthetic samples, which leverages
one-shot feedback from the classifier to drive the sampling of the generative
model. In order for the framework to be effective, we find that the samples
must be close to the support of the real data of the task at hand, and be
sufficiently diverse. We validate three feedback criteria on a long-tailed
dataset (ImageNet-LT) as well as a group-imbalanced dataset (NICO++). On
ImageNet-LT, we achieve state-of-the-art results, with over 4 percent
improvement on underrepresented classes while being twice efficient in terms of
the number of generated synthetic samples. NICO++ also enjoys marked boosts of
over 5 percent in worst group accuracy. With these results, our framework paves
the path towards effectively leveraging state-of-the-art text-to-image models
as data sources that can be queried to improve downstream applications.