提出新型泊松反问题去噪器,提升图像恢复效果。
Learning Cocoercive Conservative Denoisers via Helmholtz Decomposition for Poisson Inverse Problems
- 基于赫尔姆霍兹分解设计可扩展的保守去噪器
- 在多个数据集上实现更优的视觉质量与定量指标
- 适合图像重建、医学成像等弱凸优化场景
基于深度去噪器的插件式(PnP)方法在图像恢复中表现优异,但通常要求保真项具有强凸性或光滑性,且去噪器为非扩张。这些假设在泊松反问题中不成立,且非扩张性会限制去噪性能。为此,本文提出一种共强制保守(CoCo)去噪器,允许残差扩张,从而提升去噪能力。通过广义赫尔姆霍兹分解,引入哈密顿正则化以保证保守性,以及谱正则化以确保共强制。我们证明,CoCo去噪器是弱凸函数的近端算子,支持隐式弱凸先验的重建模型。该模型的PnP方法全局收敛至驻点。大量实验表明,本方法在视觉质量和定量指标上均优于现有方法。
原文摘要 · Abstract (English)
Plug-and-play (PnP) methods with deep denoisers have shown impressive results in imaging problems. They typically require strong convexity or smoothness of the fidelity term and a (residual) non-expansive denoiser for convergence. These assumptions, however, are violated in Poisson inverse problems, and non-expansiveness can hinder denoising performance. To address these challenges, we propose a cocoercive conservative (CoCo) denoiser, which may be (residual) expansive, leading to improved denoising. By leveraging the generalized Helmholtz decomposition, we introduce a novel training strategy that combines Hamiltonian regularization to promote conservativeness and spectral regularization to ensure cocoerciveness. We prove that CoCo denoiser is a proximal operator of a weakly convex function, enabling a restoration model with an implicit weakly convex prior. The global convergence of PnP methods to a stationary point of this restoration model is established. Extensive experimental results demonstrate that our approach outperforms closely related methods in both visual quality and quantitative metrics.
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