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arXiv 2606.21358cs.CV

LEViL: 通过VLM生成的伪标签空间上的零样本蒸馏实现标签高效视频学习

LEViL: Label-Efficient Video Learning via Zero-Shot Distillation over VLM-Generated Pseudo-Label Spaces

Kocaeli University(科贾埃利大学)

Aslı Çelik

AI总结:

提出一种无需标注的视频预训练与目标标签集感知微调结合的标签高效视频学习框架,利用VLM生成伪标签空间进行零样本蒸馏,在有限标签下优于半监督方法。

摘要:

监督视频预训练是提高下游动作识别性能的常见迁移学习实践。然而,它需要大规模标注的源数据集,且学习到的初始化的有效性受源域和目标域之间相似性的影响。为不同目标域构建这样的标注预训练数据集成本高昂且难以扩展。为了解决这些限制,本研究提出了一种标签高效的视频学习框架,结合了无标注视频预训练与目标标签集感知微调。在预训练期间,视觉语言模型(VLM)生成未标注视频的文本描述,这些描述被处理以构建可解释的语义伪标签空间。然后,一个冻结的视频语言模型在该空间上产生零样本软目标分布,使得学生视频编码器能够在没有人工源标注的情况下学习语义丰富的表示。在下游适应期间,目标标签集感知微调结合了来自标注目标视频的监督学习与在真实目标标签集上的零样本蒸馏,有助于在将预训练编码器适应目标任务的同时保留VLM派生的语义指导。在UCF101和HMDB51上的实验表明,所提出的框架在所有评估的有限标签设置下优于比较的半监督视频动作识别方法。此外,尽管依赖于相对适度的未标注预训练池,但无标注预训练阶段学习了可迁移的表示,为全数据微调提供了有效的初始化。

英文摘要:

Supervised video pretraining is a common transfer learning practice for improving downstream action recognition performance. However, it requires large-scale labeled source datasets, and the effectiveness of the learned initialization is influenced by the similarity between the source and target domains. Constructing such labeled pretraining datasets for different target domains is costly and difficult to scale. To address these limitations, this study proposes a label-efficient video learning framework that combines annotation-free video pretraining with target-label-set-aware fine-tuning. During pretraining, a vision-language model (VLM) generates textual descriptions of unlabeled videos, which are processed to construct an interpretable semantic pseudo-label space. A frozen video-language model then produces zero-shot soft target distributions over this space, allowing a student video encoder to learn semantically rich representations without manual source annotations. During downstream adaptation, target-label-set-aware fine-tuning combines supervised learning from labeled target videos with zero-shot distillation over the actual target label set, helping preserve VLM-derived semantic guidance while adapting the pretrained encoder to the target task. Experiments on UCF101 and HMDB51 show that the proposed framework outperforms the compared semi-supervised video action recognition methods across all evaluated limited-label regimes. Moreover, the annotation-free pretraining stage learns transferable representations that provide an effective initialization for full-data fine-tuning, despite relying on a comparatively modest unlabeled pretraining pool.

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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