Block-coordinate Plug-And-Play Methods with Armijo-like line-search for Image Restoration

Fuente: arXiv
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Hauptverfasser: Porta, Federica, Rebegoldi, Simone, Sebastiani, Andrea
Format: Preprint
Veröffentlicht: 2026
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author Porta, Federica
Rebegoldi, Simone
Sebastiani, Andrea
author_facet Porta, Federica
Rebegoldi, Simone
Sebastiani, Andrea
contents In this paper, we develop a class of block-coordinate Plug-and-Play (PnP) methods to address imaging inverse problems. The block-coordinate strategy is designed to reduce the high memory consumption arising in PnP methods that rely on Gradient Step denoisers, whose implementation typically requires storing large computational graphs. The proposed methods are based on a block-coordinate forward-backward framework for solving non-convex and non-separable composite optimization problems. Furthermore, such methods allow for the joint use of inertial acceleration, variable metric strategies, inexact proximal computations, and adaptive steplength selection via an appropriate line-search procedure. Under mild assumptions on the objective function, we establish a sublinear convergence rate and the stationarity of the limit points. Moreover, convergence of the entire sequence of the iterates is guaranteed under a Kurdyka-Łojasiewicz assumption. Numerical experiments on ill-posed imaging problems, including deblurring and super-resolution, demonstrate that the proposed PnP approach achieves state-of-the-art reconstruction quality while substantially reducing GPU memory requirements, making it particularly suitable for large-scale and resource-constrained imaging applications.
format Preprint
id arxiv_https___arxiv_org_abs_2603_01734
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Block-coordinate Plug-And-Play Methods with Armijo-like line-search for Image Restoration
Porta, Federica
Rebegoldi, Simone
Sebastiani, Andrea
Optimization and Control
In this paper, we develop a class of block-coordinate Plug-and-Play (PnP) methods to address imaging inverse problems. The block-coordinate strategy is designed to reduce the high memory consumption arising in PnP methods that rely on Gradient Step denoisers, whose implementation typically requires storing large computational graphs. The proposed methods are based on a block-coordinate forward-backward framework for solving non-convex and non-separable composite optimization problems. Furthermore, such methods allow for the joint use of inertial acceleration, variable metric strategies, inexact proximal computations, and adaptive steplength selection via an appropriate line-search procedure. Under mild assumptions on the objective function, we establish a sublinear convergence rate and the stationarity of the limit points. Moreover, convergence of the entire sequence of the iterates is guaranteed under a Kurdyka-Łojasiewicz assumption. Numerical experiments on ill-posed imaging problems, including deblurring and super-resolution, demonstrate that the proposed PnP approach achieves state-of-the-art reconstruction quality while substantially reducing GPU memory requirements, making it particularly suitable for large-scale and resource-constrained imaging applications.
title Block-coordinate Plug-And-Play Methods with Armijo-like line-search for Image Restoration
topic Optimization and Control
url https://arxiv.org/abs/2603.01734