arXiv:2607.04276cs.CV2026-07

解决扩散模型蒸馏后图像质量下降问题,无需训练即可提升多样性。

EMPURPLE: A Free Lunch for Diffusion Distillation based on the Information Bottleneck

论文配图:EMPURPLE: A Free Lunch for Diffusion Distillation based on the Information Bottleneck
图 1 · 摘自论文原文
  • 通过信息瓶颈分析发现早期步骤速度场重定向导致分布失配。
  • 提出EMPURPLE方法,复用原模型中间潜变量,提升生成多样性。
  • 适用于各类蒸馏模型,不依赖训练,显著改善FID得分。

扩散模型虽生成质量优异,但推理成本高昂。扩散蒸馏可减少采样步骤,但包括SDXL-Lightning和分布匹配蒸馏在内的许多方法存在弗雷切特起始距离(FID)下降问题。我们通过类似PAC的泛化界分析指出:激进的早期步骤速度场重定向使蒸馏目标更难学习,扩大了训练与测试间的差距,导致中间噪声潜变量在训练与推理时分布不一致。我们通过实验证明中间特征和最终输出多样性降低。为此,提出EMPURPLE——一种无需训练的通用方法,复用原始模型采样的中间潜变量。该方法在DMD2、Hyper-SD、FlashSD和SDXL-Lightning上均提升FID 7%至20%。项目地址:https://github.com/TheLovesOfLadyPurple/Empurple-Training-Free-Algorithm-To-enhance-Diversity-of-The-Diffusion-Distillation-Model

原文摘要 · Abstract (English)

Diffusion models achieve impressive image-generation quality but remain expensive at inference time. Diffusion distillation reduces sampling steps, yet many distilled models, including SDXL-Lightning and distribution matching distillation methods, suffer from degraded Fréchet Inception Distance (FID). We analyze this phenomenon through a PAC-style generalization bound. Our analysis suggests that aggressive early-step redirection of the velocity field makes the distillation target harder to learn, enlarging the train-test gap. As a result, early-step output distributions differ between training and inference, causing distribution mismatch in the intermediate noisy latent used as next-step inputs. We empirically validate this mechanism by showing reduced diversity in both intermediate features and final outputs. To address this issue, we propose EMPURPLE, a simple training-free method that recycles intermediate latents sampled from the original model. EMPURPLE is model-agnostic and improves FID by 7\% to 20\% across DMD2, Hyper-SD, FlashSD, and SDXL-Lightning. The repo is: https://github.com/TheLovesOfLadyPurple/Empurple-Training-Free-Algorithm-To-enhance-Diversity-of-The-Diffusion-Distillation-Model

扩散模型蒸馏FID优化无训练

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