Unsupervised Contrastive Learning Using Out-Of-Distribution Data for Long-Tailed Dataset

Fuente: arXiv
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Main Authors: Hoang, Cuong Manh, Lee, Yeejin, Kang, Byeongkeun
Format: Preprint
Published: 2025
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author Hoang, Cuong Manh
Lee, Yeejin
Kang, Byeongkeun
author_facet Hoang, Cuong Manh
Lee, Yeejin
Kang, Byeongkeun
contents This work addresses the task of self-supervised learning (SSL) on a long-tailed dataset that aims to learn balanced and well-separated representations for downstream tasks such as image classification. This task is crucial because the real world contains numerous object categories, and their distributions are inherently imbalanced. Towards robust SSL on a class-imbalanced dataset, we investigate leveraging a network trained using unlabeled out-of-distribution (OOD) data that are prevalently available online. We first train a network using both in-domain (ID) and sampled OOD data by back-propagating the proposed pseudo semantic discrimination loss alongside a domain discrimination loss. The OOD data sampling and loss functions are designed to learn a balanced and well-separated embedding space. Subsequently, we further optimize the network on ID data by unsupervised contrastive learning while using the previously trained network as a guiding network. The guiding network is utilized to select positive/negative samples and to control the strengths of attractive/repulsive forces in contrastive learning. We also distil and transfer its embedding space to the training network to maintain balancedness and separability. Through experiments on four publicly available long-tailed datasets, we demonstrate that the proposed method outperforms previous state-of-the-art methods.
format Preprint
id arxiv_https___arxiv_org_abs_2506_12698
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unsupervised Contrastive Learning Using Out-Of-Distribution Data for Long-Tailed Dataset
Hoang, Cuong Manh
Lee, Yeejin
Kang, Byeongkeun
Computer Vision and Pattern Recognition
Artificial Intelligence
Machine Learning
This work addresses the task of self-supervised learning (SSL) on a long-tailed dataset that aims to learn balanced and well-separated representations for downstream tasks such as image classification. This task is crucial because the real world contains numerous object categories, and their distributions are inherently imbalanced. Towards robust SSL on a class-imbalanced dataset, we investigate leveraging a network trained using unlabeled out-of-distribution (OOD) data that are prevalently available online. We first train a network using both in-domain (ID) and sampled OOD data by back-propagating the proposed pseudo semantic discrimination loss alongside a domain discrimination loss. The OOD data sampling and loss functions are designed to learn a balanced and well-separated embedding space. Subsequently, we further optimize the network on ID data by unsupervised contrastive learning while using the previously trained network as a guiding network. The guiding network is utilized to select positive/negative samples and to control the strengths of attractive/repulsive forces in contrastive learning. We also distil and transfer its embedding space to the training network to maintain balancedness and separability. Through experiments on four publicly available long-tailed datasets, we demonstrate that the proposed method outperforms previous state-of-the-art methods.
title Unsupervised Contrastive Learning Using Out-Of-Distribution Data for Long-Tailed Dataset
topic Computer Vision and Pattern Recognition
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2506.12698