A Gradient Flow Approach to Solving Inverse Problems with Latent Diffusion Models

arXiv:2509.19276 · stat.ML, cs.LG, stat.CO · Submitted 2025-09-23 · Read on arXiv

stat.ML, cs.LG, stat.CO

Submitted: 2025-09-23

Updated: 2026-09-16

Comments: Accepted at the 2nd Workshop on Frontiers in Probabilistic Inference: Sampling Meets Learning, 39th Conference on Neural Information Processing Systems (NeurIPS 2025). Revision (v2): fixed likelihood objective $\mathcal{F}[μ]$ and its derivation; the algorithm and reported results are unchanged

License: http://creativecommons.org/licenses/by/4.0/

The gist: Solving ill-posed inverse problems requires powerful and flexible priors.

Terminology

Abstract

Solving ill-posed inverse problems requires powerful and flexible priors. We propose leveraging pretrained latent diffusion models for this task through a new training-free approach, termed Diffusion-regularized Wasserstein Gradient Flow (DWGF). Specifically, we formulate the posterior sampling problem as a Wasserstein gradient flow in the latent space of an expected negative log posterior objective, regularized by a Kullback-Leibler divergence to the diffusion prior. We demonstrate the performance of our method on standard benchmarks using StableDiffusion (Rombach et al., 2022) as the prior.

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