arXiv:2605.06376cs.CVcs.AI2026-05被引 2

将扩散模型蒸馏从离散时间拓展到连续时间,提升少步生成图像质量。

Continuous-Time Distribution Matching for Few-Step Diffusion Distillation

论文配图:Continuous-Time Distribution Matching for Few-Step Diffusion Distillation
图 1 · 摘自论文原文
  • 用动态连续时间调度替代固定离散时间点,实现任意点分布匹配。
  • 通过学生模型速度场外推隐空间进行连续对齐,保留细节并减少失真。
  • 无需对抗网络或奖励模型,在少步生成中保持高视觉保真度。

步骤蒸馏已成为加速扩散模型的主流技术,其中分布匹配蒸馏(DMD)和一致性蒸馏是代表性方法。尽管一致性方法通过全路径自一致性引导采样轨迹至干净数据流形,但原始DMD仅在少数预设离散时间点施加稀疏监督,其离散时间设定与反向KL散度的模式聚焦特性常导致视觉伪影和过平滑输出,往往需依赖复杂辅助模块(如GAN或奖励模型)恢复视觉保真度。本文首次将DMD框架从离散锚定迁移至连续优化,提出连续时间分布匹配(CDM)。CDM通过两项连续时间设计实现:首先,以随机长度的动态连续调度取代固定离散调度,使分布匹配作用于采样轨迹任意位置而非仅少数固定锚点;其次,提出连续时间对齐目标,通过学生模型速度场外推隐空间进行主动非轨迹匹配,提升泛化能力并保留精细视觉细节。在多种架构(包括SD3-Medium和Longcat-Image)上的大量实验表明,CDM在不依赖复杂辅助目标的前提下,实现了少步图像生成的高视觉保真度。代码已开源:https://github.com/byliutao/cdm。

原文摘要 · Abstract (English)

Step distillation has become a leading technique for accelerating diffusion models, among which Distribution Matching Distillation (DMD) and Consistency Distillation are two representative paradigms. While consistency methods enforce self-consistency along the full PF-ODE trajectory to steer it toward the clean data manifold, vanilla DMD relies on sparse supervision at a few predefined discrete timesteps. This restricted discrete-time formulation and mode-seeking nature of the reverse KL divergence tends to exhibit visual artifacts and over-smoothed outputs, often necessitating complex auxiliary modules -- such as GANs or reward models -- to restore visual fidelity. In this work, we introduce Continuous-Time Distribution Matching (CDM), migrating the DMD framework from discrete anchoring to continuous optimization for the first time. CDM achieves this through two continuous-time designs. First, we replace the fixed discrete schedule with a dynamic continuous schedule of random length, so that distribution matching is enforced at arbitrary points along sampling trajectories rather than only at a few fixed anchors. Second, we propose a continuous-time alignment objective that performs active off-trajectory matching on latents extrapolated via the student's velocity field, improving generalization and preserving fine visual details. Extensive experiments on different architectures, including SD3-Medium and Longcat-Image, demonstrate that CDM provides highly competitive visual fidelity for few-step image generation without relying on complex auxiliary objectives. Code is available at https://github.com/byliutao/cdm.

扩散模型少步生成连续时间蒸馏

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