Constructing an Interpretable Deep Denoiser by Unrolling Graph Laplacian Regularizer

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Hauptverfasser: Hosseini, Seyed Alireza, Do, Tam Thuc, Cheung, Gene, Tanaka, Yuichi
Format: Preprint
Veröffentlicht: 2024
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author Hosseini, Seyed Alireza
Do, Tam Thuc
Cheung, Gene
Tanaka, Yuichi
author_facet Hosseini, Seyed Alireza
Do, Tam Thuc
Cheung, Gene
Tanaka, Yuichi
contents An image denoiser can be used for a wide range of restoration problems via the Plug-and-Play (PnP) architecture. In this paper, we propose a general framework to build an interpretable graph-based deep denoiser (GDD) by unrolling a solution to a maximum a posteriori (MAP) problem equipped with a graph Laplacian regularizer (GLR) as signal prior. Leveraging a recent theorem showing that any (pseudo-)linear denoiser $\boldsymbol Ψ$, under mild conditions, can be mapped to a solution of a MAP denoising problem regularized using GLR, we first initialize a graph Laplacian matrix $\mathbf L$ via truncated Taylor Series Expansion (TSE) of $\boldsymbol Ψ^{-1}$. Then, we compute the MAP linear system solution by unrolling iterations of the conjugate gradient (CG) algorithm into a sequence of neural layers as a feed-forward network -- one that is amenable to parameter tuning. The resulting GDD network is "graph-interpretable", low in parameter count, and easy to initialize thanks to $\mathbf L$ derived from a known well-performing denoiser $\boldsymbol Ψ$. Experimental results show that GDD achieves competitive image denoising performance compared to competitors, but employing far fewer parameters, and is more robust to covariate shift.
format Preprint
id arxiv_https___arxiv_org_abs_2409_06676
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Constructing an Interpretable Deep Denoiser by Unrolling Graph Laplacian Regularizer
Hosseini, Seyed Alireza
Do, Tam Thuc
Cheung, Gene
Tanaka, Yuichi
Image and Video Processing
Computer Vision and Pattern Recognition
Signal Processing
An image denoiser can be used for a wide range of restoration problems via the Plug-and-Play (PnP) architecture. In this paper, we propose a general framework to build an interpretable graph-based deep denoiser (GDD) by unrolling a solution to a maximum a posteriori (MAP) problem equipped with a graph Laplacian regularizer (GLR) as signal prior. Leveraging a recent theorem showing that any (pseudo-)linear denoiser $\boldsymbol Ψ$, under mild conditions, can be mapped to a solution of a MAP denoising problem regularized using GLR, we first initialize a graph Laplacian matrix $\mathbf L$ via truncated Taylor Series Expansion (TSE) of $\boldsymbol Ψ^{-1}$. Then, we compute the MAP linear system solution by unrolling iterations of the conjugate gradient (CG) algorithm into a sequence of neural layers as a feed-forward network -- one that is amenable to parameter tuning. The resulting GDD network is "graph-interpretable", low in parameter count, and easy to initialize thanks to $\mathbf L$ derived from a known well-performing denoiser $\boldsymbol Ψ$. Experimental results show that GDD achieves competitive image denoising performance compared to competitors, but employing far fewer parameters, and is more robust to covariate shift.
title Constructing an Interpretable Deep Denoiser by Unrolling Graph Laplacian Regularizer
topic Image and Video Processing
Computer Vision and Pattern Recognition
Signal Processing
url https://arxiv.org/abs/2409.06676