arXiv:2511.06848cs.CV2025-11中稿 · AAAI被引 2

发现视觉变压器压缩中特征蒸馏失效原因,提出新分析框架

Distillation Dynamics: Towards Understanding Feature-Based Distillation in Vision Transformers

  • 构建蒸馏动力学框架,结合频谱与信息熵分析
  • 揭示视觉变压器具先压缩后扩展的特殊信息处理模式
  • 指出师生模型表征不匹配是性能下降主因,适合模型压缩研究者

尽管基于特征的知识蒸馏在压缩卷积神经网络方面表现优异,但将其应用于视觉变压器(ViTs)时却意外失效,常不如简单的输出层蒸馏。本文首次通过名为“蒸馏动力学”的新型分析框架系统探究此现象,该框架融合频谱分析、信息熵度量与激活幅值追踪。研究发现,视觉变压器具有独特的倒U型信息处理模式:早期压缩,后期扩张。根源在于师生模型间存在根本性的表征范式差异。频域分析表明,教师模型在深层采用分布式、高维编码策略,而学生模型因通道容量有限无法复现,导致后期特征对齐反而损害性能。因此,成功的视觉变压器蒸馏需超越简单特征模仿,尊重其表征约束,为有效压缩提供理论指导。所有代码与实验日志见 https://github.com/thy960112/Distillation-Dynamics。

原文摘要 · Abstract (English)

While feature-based knowledge distillation has proven highly effective for compressing CNNs, these techniques unexpectedly fail when applied to Vision Transformers (ViTs), often performing worse than simple logit-based distillation. We provide the first comprehensive analysis of this phenomenon through a novel analytical framework termed as "distillation dynamics", combining frequency spectrum analysis, information entropy metrics, and activation magnitude tracking. Our investigation reveals that ViTs exhibit a distinctive U-shaped information processing pattern: initial compression followed by expansion. We identify the root cause of negative transfer in feature distillation: a fundamental representational paradigm mismatch between teacher and student models. Through frequency-domain analysis, we show that teacher models employ distributed, high-dimensional encoding strategies in later layers that smaller student models cannot replicate due to limited channel capacity. This mismatch causes late-layer feature alignment to actively harm student performance. Our findings reveal that successful knowledge transfer in ViTs requires moving beyond naive feature mimicry to methods that respect these fundamental representational constraints, providing essential theoretical guidance for designing effective ViTs compression strategies. All source code and experimental logs are provided at https://github.com/thy960112/Distillation-Dynamics.

知识蒸馏视觉变压器模型压缩表征学习

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