arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2512.10244cs.CVcs.LG

从自动标注视角解决半监督少样本学习

Solving Semi-Supervised Few-Shot Learning from an Auto-Annotation Perspective

Texas A\&M University(德克萨斯A&M大学);University of Macau(澳门大学);Institute of Collaborative Innovation(协同创新研究院)

Tian Liu, Anwesha Basu, James Caverlee, Shu Kong

AI总结:

提出SWIFT方法,通过温度锐化softmax输出和分阶段训练,利用视觉语言模型和开放数据,在半监督少样本学习中显著提升性能,接近监督学习水平。

摘要:

半监督少样本学习(SSFSL)类似于自动标注等现实应用,旨在从少量标注和大量未标注的任务特定示例中学习模型以标注未标注示例。尽管存在强大的开源视觉语言模型(VLM)和开放世界数据,现有SSFSL文献在很大程度上忽略了这些资源。相比之下,相关领域少样本学习(FSL)已经利用它们来提升性能。可以说,为了解决现实世界的自动标注,SSFSL应该利用此类开放资源。为弥补这一差距,我们探索了利用已有的SSL方法微调VLM。出乎意料的是,它们的性能显著低于不使用未标注数据的FSL基线。我们的深入分析揭示了失败的根本原因:VLM产生softmax概率的平坦分布,导致未标注数据利用率为零且监督信号弱。为解决这一挑战,我们提出一个极其简单的解决方案,即使用温度锐化softmax输出,这不仅提高了伪标签的置信度分数以改善未标注数据的利用率,还增强了训练监督以实现有效微调。此外,我们利用任务相关的开放数据,例如从VLM公开可用的预训练集中检索的数据。为缓解检索数据中的不平衡和领域差距,我们采用分阶段训练策略。基于VLM的成功微调和开放数据的利用,我们提出一种简单而有效的SSFSL方法,即带温度的分阶段微调(SWIFT)。在五个基准测试中,SWIFT比最近的FSL和SSL方法高出约5个准确率点。SWIFT甚至与监督学习相媲美,后者假设未标注数据具有真实标签来微调VLM。

英文摘要:

Semi-supervised few-shot learning (SSFSL) resembles real-world applications such as auto-annotation, as it aims to learn a model from a few labeled and abundant unlabeled task-specific examples to annotate the unlabeled ones. Despite the availability of powerful open-source Vision-Language Models (VLMs) and open-world data, existing SSFSL literature largely neglects these resources. In contrast, the related area few-shot learning (FSL) has already exploited them to boost performance. Arguably, to solve real-world auto-annotation, SSFSL should leverage such open resources. To bridge this gap, we explore established SSL methods to finetune a VLM. Unexpectedly, they significantly underperform FSL baselines that do not use unlabeled data. Our in-depth analysis reveals the root cause of failure: VLMs produce flat distributions of softmax probabilities, resulting in zero utilization of unlabeled data and weak supervision signals. To address this challenge, we propose an embarrassingly simple solution that uses temperatures to sharpen the softmax output, which not only increases the confidence scores of pseudo-labels to improve the utilization of unlabeled data, but also strengthens training supervision for effective finetuning. Furthermore, we exploit task-relevant open data, e.g., those retrieved from VLMs' publicly available pretraining set. To mitigate the imbalance and domain gaps in retrieved data, we employ a stage-wise training strategy. Building on the successful finetuning of VLMs and the exploitation of open data, we present a simple yet effective SSFSL method, Stage-Wise Finetuning with Temperatures (SWIFT). Across five benchmarks, SWIFT outperforms recent FSL and SSL methods by $\sim$5 accuracy points. SWIFT even rivals supervised learning, which finetunes a VLM assuming unlabeled data having ground-truth labels!

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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