用熵值重排采样时间点,提升生成模型质量。
Entropic Time Schedulers for Generative Diffusion Models
- 基于信息熵选择采样点,确保每步贡献相等信息量。
- 在ImageNet上使用少量采样步数时,FID和FD-DINO得分显著提升。
- 无需增加计算量,适合资源受限场景下的高效生成。
生成扩散模型的实际性能依赖于噪声调度函数的选择,该函数可等价地表示为时间重参数化。本文提出一种基于熵的时序调度方法,根据熵值而非均匀时间间隔选择采样点,确保每一步对最终生成结果的信息贡献相等。我们证明该时间重参数化不依赖初始时间选择,并提供一个可解析计算的精确公式,仅通过训练损失即可估算训练好的模型的“熵时”且开销极小。此外,受最优性结果启发,我们引入缩放后的熵时。在高斯混合分布与ImageNet上的实验表明,使用(缩放)熵时能显著提升模型推理性能。尤其在低函数评估次数(NFE)情况下,预训练EDM2模型的图像质量(以FID和FD-DINO评分衡量)得到明显改善,且无需增加计算量。代码已开源。
原文摘要 · Abstract (English)
The practical performance of generative diffusion models depends on the appropriate choice of the noise scheduling function, which can also be equivalently expressed as a time reparameterization. In this paper, we present a time scheduler that selects sampling points based on entropy rather than uniform time spacing, ensuring that each point contributes an equal amount of information to the final generation. We prove that this time reparameterization does not depend on the initial choice of time. Furthermore, we provide a tractable exact formula to estimate this \emph{entropic time} for a trained model using the training loss without substantial overhead. Alongside the entropic time, inspired by the optimality results, we introduce a rescaled entropic time. In our experiments with mixtures of Gaussian distributions and ImageNet, we show that using the (rescaled) entropic times greatly improves the inference performance of trained models. In particular, we found that the image quality in pretrained EDM2 models, as evaluated by FID and FD-DINO scores, can be substantially increased by the rescaled entropic time reparameterization without increasing the number of function evaluations, with greater improvements in the few NFEs regime. Code is available at https://github.com/DejanStancevic/Entropic-Time-Schedulers-for-Generative-Diffusion-Models.
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