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arXiv 2602.20549cs.LGcs.CVstat.ME
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基于扩散先验的模型选择中高效证据估计

Sample-efficient evidence estimation of score based priors for model selection

Department of Computing and Mathematical Sciences(计算与数学科学系)

Frederic Wang, Katherine L. Bouman

AI总结:

本文提出DiME方法,通过整合后验采样方法的时间边际,利用逆扩散采样过程中的大量中间样本,高效估计扩散先验的模型证据,用于模型选择和先验误拟诊断。

摘要:

在解决病态成像反问题中,选择先验至关重要,需选择与测量y一致的先验以避免严重偏差。在贝叶斯反问题中,可通过评估不同模型M下的模型证据p(y| M)来选择最优模型。扩散模型是解决反问题的最先进方法,但直接计算扩散先验的模型证据不可行。本文提出DiME,通过整合后验采样方法的时间边际估计扩散先验的模型证据。方法利用逆扩散采样过程中自然获得的大量中间样本,仅需少量后验样本(如20个)即可获得准确估计。本文还展示了如何与最近的扩散后验采样方法结合实现该估计器。实验表明,当模型证据可解析计算时,该估计器表现良好,并能正确选择扩散模型先验并在不同高度病态、非线性反问题中诊断先验误拟,包括现实中的黑洞成像问题。

英文摘要:

The choice of prior is central to solving ill-posed imaging inverse problems, making it essential to select one consistent with the measurements $y$ to avoid severe bias. In Bayesian inverse problems, this could be achieved by evaluating the model evidence $p(y \mid M)$ under different models $M$ that specify the prior and then selecting the one with the highest value. Diffusion models are the state-of-the-art approach to solving inverse problems with a data-driven prior; however, directly computing the model evidence with respect to a diffusion prior is intractable. Furthermore, most existing model evidence estimators require either many pointwise evaluations of the unnormalized prior density or an accurate clean prior score. We propose DiME, an estimator of the model evidence of a diffusion prior by integrating over the time-marginals of posterior sampling methods. Our method leverages the large amount of intermediate samples naturally obtained during the reverse diffusion sampling process to obtain an accurate estimation of the model evidence using only a handful of posterior samples (e.g., 20). We also demonstrate how to implement our estimator in tandem with recent diffusion posterior sampling methods. Empirically, our estimator matches the model evidence when it can be computed analytically, and it is able to both select the correct diffusion model prior and diagnose prior misfit under different highly ill-conditioned, non-linear inverse problems, including a real-world black hole imaging problem.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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