arXiv:2504.16667cs.LGcs.AI2025-04被引 7

提出一种无需对比的互信息学习方法,提升图像表征质量。

Representation Learning via Non-Contrastive Mutual Information

  • 将谱对比损失转化为非对比形式,避免成对比较
  • 在ImageNet上优于谱对比基线,且防止表示坍塌
  • 适合追求高效、稳定自监督训练的研究者

标注数据通常耗时且昂贵,导致大量未标注数据存在。自监督表征学习方法如SimCLR或BYOL已成功从无标签图像中学习有意义的潜在表示,显著提升下游任务的通用性和可迁移性。自监督方法大致分为两类:1)对比方法(如SimCLR),通过最大化相关数据点间的互信息来学习表征,但需进行成对比较,方差高,需大批次才能有效;2)非对比方法(如BYOL),方差低,无需成对比较,但易陷入常数向量坍塌。本文旨在结合两者优势,从谱对比损失(Spectral Contrastive Loss)出发,将其转换为更通用的非对比形式,消除成对比较带来的高方差,同时保留对比方法的互信息建模机制,防止坍塌。提出的新型目标函数称为互信息非对比(MINC)损失。在ImageNet上进行图像表征学习实验,结果表明MINC持续优于谱对比损失基线。

原文摘要 · Abstract (English)

Labeling data is often very time consuming and expensive, leaving us with a majority of unlabeled data. Self-supervised representation learning methods such as SimCLR (Chen et al., 2020) or BYOL (Grill et al., 2020) have been very successful at learning meaningful latent representations from unlabeled image data, resulting in much more general and transferable representations for downstream tasks. Broadly, self-supervised methods fall into two types: 1) Contrastive methods, such as SimCLR; and 2) Non-Contrastive methods, such as BYOL. Contrastive methods are generally trying to maximize mutual information between related data points, so they need to compare every data point to every other data point, resulting in high variance, and thus requiring large batch sizes to work well. Non-contrastive methods like BYOL have much lower variance as they do not need to make pairwise comparisons, but are much trickier to implement as they have the possibility of collapsing to a constant vector. In this paper, we aim to develop a self-supervised objective that combines the strength of both types. We start with a particular contrastive method called the Spectral Contrastive Loss (HaoChen et al., 2021; Lu et al., 2024), and we convert it into a more general non-contrastive form; this removes the pairwise comparisons resulting in lower variance, but keeps the mutual information formulation of the contrastive method preventing collapse. We call our new objective the Mutual Information Non-Contrastive (MINC) loss. We test MINC by learning image representations on ImageNet (similar to SimCLR and BYOL) and show that it consistently improves upon the Spectral Contrastive loss baseline.

自监督学习表征学习互信息非对比

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