用流生成模型提升图像修复,支持多种噪声类型。
Image Restoration via Primal Dual Hybrid Gradient and Flow Generative Model
- 将流生成模型作为先验嵌入原对偶混合梯度框架
- 在泊松和脉冲噪声下,ℓ₁与ℓ₂损失优于传统ℓ₂损失
- 适用于去噪、超分、去模糊等任务,计算高效
正则化优化是求解成像逆问题的经典方法,其中正则项用于约束未知图像的期望特性。近年来,流匹配生成模型因其强大的先验建模能力,被引入图像修复任务中。本文将此类生成先验集成到基于邻近分裂的即插即用(PnP)框架中,用时间依赖的去噪器替代正则项对应的邻近算子。尽管现有PnP方法在平方ℓ₂数据保真度(通常对应高斯噪声)的逆问题中表现优异,但其在更一般保真项下的适用性仍待探索。为此,我们提出一种受原对偶混合梯度(PDHG)启发的通用且高效的PnP算法。该方法计算高效、内存友好,可适配多种保真项,尤其支持ℓ₁与ℓ₂范数损失,从而对泊松噪声和脉冲噪声等非高斯噪声具有鲁棒性。我们在去噪、超分辨率、去模糊和补全等多个图像修复任务上验证了该方法,结果表明,在非高斯噪声环境下,ℓ₁与ℓ₂保真项优于传统的平方ℓ₂损失。
原文摘要 · Abstract (English)
Regularized optimization has been a classical approach to solving imaging inverse problems, where the regularization term enforces desirable properties of the unknown image. Recently, the integration of flow matching generative models into image restoration has garnered significant attention, owing to their powerful prior modeling capabilities. In this work, we incorporate such generative priors into a Plug-and-Play (PnP) framework based on proximal splitting, where the proximal operator associated with the regularizer is replaced by a time-dependent denoiser derived from the generative model. While existing PnP methods have achieved notable success in inverse problems with smooth squared $\ell_2$ data fidelity--typically associated with Gaussian noise--their applicability to more general data fidelity terms remains underexplored. To address this, we propose a general and efficient PnP algorithm inspired by the primal-dual hybrid gradient (PDHG) method. Our approach is computationally efficient, memory-friendly, and accommodates a wide range of fidelity terms. In particular, it supports both $\ell_1$ and $\ell_2$ norm-based losses, enabling robustness to non-Gaussian noise types such as Poisson and impulse noise. We validate our method on several image restoration tasks, including denoising, super-resolution, deblurring, and inpainting, and demonstrate that $\ell_1$ and $\ell_2$ fidelity terms outperform the conventional squared $\ell_2$ loss in the presence of non-Gaussian noise.
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