Local MAP Sampling for Diffusion Models

Fuente: arXiv
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Main Authors: Zhang, Shaorong, Brekelmans, Rob, Steeg, Greg Ver
Format: Preprint
Published: 2025
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author Zhang, Shaorong
Brekelmans, Rob
Steeg, Greg Ver
author_facet Zhang, Shaorong
Brekelmans, Rob
Steeg, Greg Ver
contents Diffusion Posterior Sampling (DPS) provides a principled Bayesian approach to inverse problems by sampling from $p(x_0 \mid y)$. While posterior sampling is valuable for capturing uncertainty and multi-modality, many classical and practical inverse problem settings ultimately prioritize accurate point estimation -- most notably the MAP estimator, which has long served as a standard reconstruction objective in imaging and scientific applications. We introduce Local MAP Sampling (LMAPS), a new inference framework that iteratively solves local MAP subproblems along the diffusion trajectory. This perspective clarifies their connection to global MAP and DPS, offering a unified probabilistic interpretation for optimization-based methods. Building on this foundation, we develop practical algorithms with a covariance approximation motivated by a Gaussian prior assumption, and a reformulated objective for stability and interpretability. Across a broad set of image restoration and scientific tasks, LMAPS achieves state-of-the-art performance.
format Preprint
id arxiv_https___arxiv_org_abs_2510_07343
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Local MAP Sampling for Diffusion Models
Zhang, Shaorong
Brekelmans, Rob
Steeg, Greg Ver
Graphics
Artificial Intelligence
Image and Video Processing
Diffusion Posterior Sampling (DPS) provides a principled Bayesian approach to inverse problems by sampling from $p(x_0 \mid y)$. While posterior sampling is valuable for capturing uncertainty and multi-modality, many classical and practical inverse problem settings ultimately prioritize accurate point estimation -- most notably the MAP estimator, which has long served as a standard reconstruction objective in imaging and scientific applications. We introduce Local MAP Sampling (LMAPS), a new inference framework that iteratively solves local MAP subproblems along the diffusion trajectory. This perspective clarifies their connection to global MAP and DPS, offering a unified probabilistic interpretation for optimization-based methods. Building on this foundation, we develop practical algorithms with a covariance approximation motivated by a Gaussian prior assumption, and a reformulated objective for stability and interpretability. Across a broad set of image restoration and scientific tasks, LMAPS achieves state-of-the-art performance.
title Local MAP Sampling for Diffusion Models
topic Graphics
Artificial Intelligence
Image and Video Processing
url https://arxiv.org/abs/2510.07343