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We propose an unrolled algorithm approach for learning spatially adaptive parameter maps in the framework of convolutional synthesis-based $\ell_1$ regularization. More precisely, we consider a family of pre-trained convolutional filters…

Machine Learning · Computer Science 2025-10-23 Andreas Kofler , Luca Calatroni , Christoph Kolbitsch , Kostas Papafitsoros

Numerous practical medical problems often involve data that possess a combination of both sparse and non-sparse structures. Traditional penalized regularizations techniques, primarily designed for promoting sparsity, are inadequate to…

Methodology · Statistics 2023-11-10 Shun Yu , Yuehan Yang

There exist many scenarios where pixel information is available only on a non-regular subset of pixel positions. For further processing, however, it is required to reconstruct such images on a regular grid. Besides many other algorithms,…

Image and Video Processing · Electrical Eng. & Systems 2022-04-08 Markus Jonscher , Jürgen Seiler , André Kaup

This paper presents a novel Block Iterative Bayesian Algorithm (Block-IBA) for reconstructing block-sparse signals with unknown block structures. Unlike the existing algorithms for block sparse signal recovery which assume the cluster…

Machine Learning · Statistics 2014-12-09 Mehdi Korki , Jingxin Zhang , Cishen Zhang , Hadi Zayyani

Diffusion Probabilistic Models (DPMs) have achieved great success in image generation but suffer from high inference latency due to their iterative denoising nature. Motivated by the evolving feature dynamics across the denoising…

Computer Vision and Pattern Recognition · Computer Science 2026-03-23 Haodong He , Yuan Gao , Weizhong Zhang , Gui-Song Xia

We introduce a novel optimization algorithm for image recovery under learned sparse and low-rank constraints, which we parameterize as weighted extensions of the $\ell_p^p$-vector and $\mathcal S_p^p$ Schatten-matrix quasi-norms for…

Computer Vision and Pattern Recognition · Computer Science 2023-04-21 Stamatios Lefkimmiatis , Iaroslav Koshelev

Image restoration is typically addressed through non-convex inverse problems, which are often solved using first-order block-wise splitting methods. In this paper, we consider a general type of non-convex optimisation model that captures…

Sparse reconstruction approaches using the re-weighted l1-penalty have been shown, both empirically and theoretically, to provide a significant improvement in recovering sparse signals in comparison to the l1-relaxation. However, numerical…

Machine Learning · Statistics 2013-12-06 Dmitry Malioutov , Aleksandr Aravkin

Although remarkable progress has been made on single image super-resolution due to the revival of deep convolutional neural networks, deep learning methods are confronted with the challenges of computation and memory consumption in…

Computer Vision and Pattern Recognition · Computer Science 2020-01-01 Dehua Song , Chang Xu , Xu Jia , Yiyi Chen , Chunjing Xu , Yunhe Wang

Model-based learned iterative reconstruction methods have recently been shown to outperform classical reconstruction algorithms. Applicability of these methods to large scale inverse problems is however limited by the available memory for…

Image and Video Processing · Electrical Eng. & Systems 2020-04-21 Andreas Hauptmann , Jonas Adler , Simon Arridge , Ozan Öktem

In this paper, we consider an LQR design problem for distributed control systems. For large-scale distributed systems, finding a solution might be computationally demanding due to communications among agents. To this aim, we deal with LQR…

Distributed, Parallel, and Cluster Computing · Computer Science 2024-09-02 Myung Cho

Variational regularization of ill-posed inverse problems is based on minimizing the sum of a data fidelity term and a regularization term. The balance between them is tuned using a positive regularization parameter, whose automatic choice…

Numerical Analysis · Mathematics 2025-11-12 Markus Juvonen , Bjørn Jensen , Ilmari Pohjola , Yiqiu Dong , Samuli Siltanen

Applying standard algorithms to sparse data problems in photoacoustic tomography (PAT) yields low-quality images containing severe under-sampling artifacts. To some extent, these artifacts can be reduced by iterative image reconstruction…

Numerical Analysis · Mathematics 2024-12-20 Stephan Antholzer , Johannes Schwab , Robert Nuster , Markus Haltmeier

Two critical steps in fingerprint recognition are binarization and thinning of the image. The need for real time processing motivates us to select local adaptive thresholding approach for the binarization step. We introduce a new hardware…

Computer Vision and Pattern Recognition · Computer Science 2017-10-17 Farshad Kheiri , Shadrokh Samavi , Nader Karimi

The problem of restoration of digital images from their degraded measurements plays a central role in a multitude of practically important applications. A particularly challenging instance of this problem occurs in the case when the…

Computer Vision and Pattern Recognition · Computer Science 2016-11-17 Oleg Michailovich

We present a new inner-outer iterative algorithm for edge enhancement in imaging problems. At each outer iteration, we formulate a Tikhonov-regularized problem where the penalization is expressed in the 2-norm and involves a regularization…

Numerical Analysis · Mathematics 2020-12-30 Silvia Gazzola , Misha E. Kilmer , James G. Nagy , Oguz Semerici , Eric L. Miller

In numerous practical applications, especially in medical image reconstruction, it is often infeasible to obtain a large ensemble of ground-truth/measurement pairs for supervised learning. Therefore, it is imperative to develop unsupervised…

Image and Video Processing · Electrical Eng. & Systems 2021-03-31 Subhadip Mukherjee , Ozan Öktem , Carola-Bibiane Schönlieb

We present an adaptive regularization algorithm that can be effectively applied to the optimization problem in deep learning framework. Our regularization algorithm aims to take into account the fitness of data to the current state of model…

Machine Learning · Computer Science 2019-09-02 Junghee Cho , Junseok Kwon , Byung-Woo Hong

We present an algorithm that enables one to perform locally adaptive block thresholding, while maintaining image continuity. Images are divided into sub-images based some standard image attributes and thresholding technique is employed over…

Computer Vision and Pattern Recognition · Computer Science 2007-05-23 S. Hemachander , Amit Verma , Siddharth Arora , Prasanta K. Panigrahi

In sparse coding, we attempt to extract features of input vectors, assuming that the data is inherently structured as a sparse superposition of basic building blocks. Similarly, neural networks perform a given task by learning features of…

Machine Learning · Computer Science 2022-02-16 Deborah Pereg , Israel Cohen , Anthony A. Vassiliou