Non-Normal Diffusion Models

Published: 19 Jun 2023, Last Modified: 28 Jul 20231st SPIGM @ ICML PosterEveryoneRevisionsBibTeX
Keywords: diffusion models, generative modeling
Abstract: Diffusion models generate samples by incrementally reversing a process that turns data into noise. We show that when the step size goes to zero, the reversed process is invariant to the distribution of these increments. This reveals a previously unconsidered parameter in the design of diffusion models: the distribution of the diffusion step $\boldsymbol \Delta \mathbf{x}_k = \mathbf{x}_k - \mathbf{x}_{k + 1}$. This parameter is implicitly set by default to be normally distributed in most diffusion models. By lifting this assumption, we generalize the framework for designing diffusion models and establish an expanded class of diffusion processes with greater flexibility in the choice of loss function used during training. We demonstrate the effectiveness of these models on density estimation and generative modeling tasks on standard image datasets, and show that different choices of the distribution of $\boldsymbol\Delta \mathbf{x}_k$ result in qualitatively different generated samples.
Submission Number: 107
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