Prototype-Oriented Clean Subset Extraction for Noisy Long-Tailed Classification

Real-world datasets usually suffer from class imbalance and label noise. To solve the joint challenge of long-tailed distribution and label noise, most previous works usually aim to design a noise detector to distinguish the noisy from clean samples. While effective, they may be limited in handling the joint issue in a unified way. In this work, we bridge this gap by effectively extracting a clean training subset from the noisy and long-tailed dataset, where we develop a novel re-labeling method using class prototypes from the perspective of distribution matching that can be solved with optimal transport. By using the learned transport plan to re-label training samples and setting a class-specific probability measure, our method can simultaneously reduce the side-effects of label noise and data imbalance during label refinement. Then we introduce a simple yet effective filter by combining the observed and refined labels to obtain a clean subset for robust model training. Comprehensive experiments show that our method can effectively extract clean subsets and bring significant performance gains in noisy long-tailed classification. Code is available at https://github.com/BIRlz/NLT_prototype_clean_subset_extraction