Sampler Scheduler for Diffusion Models

Abstract

Diffusion modeling (DM) has high-quality generative performance, and the sampling problem is an important part of the DM performance. Thanks to efficient differential equation solvers, the sampling speed can be reduced while higher sampling quality is guaranteed. However, currently, there is a contradiction in samplers for diffusion-based generative models: the mainstream sampler choices are diverse, each with its own characteristics in terms of performance. However, only a single sampler algorithm can be specified on all sampling steps in the generative process. This often makes one torn between sampler choices; in other words, it makes it difficult to fully utilize the advantages of each sampler. In this paper, we propose the feasibility of using different samplers (ODE/SDE) on different sampling steps of the same sampling process based on analyzing and generalizing the updating formulas of each mainstream sampler, and experimentally demonstrate that such a multi-sampler scheduling improves the sampling results to some extent. In particular, we also verify that the combination of using SDE in the early sampling steps and ODE in the later sampling steps solves the inherent problems previously caused by using both singly. We show that our design changes improve the sampling efficiency and quality in previous work. For instance, when Number of Function Evaluations (NFE) = 24, the ODE Sampler Scheduler achieves a FID score of 1.91 on the CIFAR-10 dataset, compared to 2.02 for DPM++ 2M, 1.97 for DPM2, and 11.90 for Heun for the same NFE. Meanwhile the Sampler Scheduler with the combined scheduling of SDE and ODE reaches 1.899, compared to 18.63 for Euler a, 3.14 for DPM2 a and 23.14 for DPM++ SDE.