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In the field of quantitative imaging, the image information at a pixel or voxel in an underlying domain entails crucial information about the imaged matter. This is particularly important in medical imaging applications, such as…

Optimization and Control · Mathematics 2024-04-12 Guozhi Dong , Moritz Flaschel , Michael Hintermüller , Kostas Papafitsoros , Clemens Sirotenko , Karsten Tabelow

Proper regularization is crucial in inverse problems to achieve high-quality reconstruction, even with an ill-conditioned measurement system. This is particularly true for three-dimensional photoacoustic tomography, which is computationally…

Optimization and Control · Mathematics 2024-09-26 Chao Wang , Alexandre H. Thiery

We consider the problem of supervised learning with convex loss functions and propose a new form of iterative regularization based on the subgradient method. Unlike other regularization approaches, in iterative regularization no constraint…

Machine Learning · Statistics 2015-04-02 Junhong Lin , Lorenzo Rosasco , Ding-Xuan Zhou

This work addresses a central topic in Magnetic Resonance Imaging (MRI) which is the motion-correction problem in a joint reconstruction and registration framework. From a set of multiple MR acquisitions corrupted by motion, we aim at -…

While recent model-free Reinforcement Learning (RL) methods have demonstrated human-level effectiveness in gaming environments, their success in everyday tasks like visual navigation has been limited, particularly under significant…

Machine Learning · Computer Science 2024-04-04 Rudra P. K. Poudel , Harit Pandya , Stephan Liwicki , Roberto Cipolla

A regularization algorithm allowing random noise in derivatives and inexact function values is proposed for computing approximate local critical points of any order for smooth unconstrained optimization problems. For an objective function…

Optimization and Control · Mathematics 2021-04-07 S. Bellavia , G. Gurioli , B. Morini , Ph. L. Toint

Large-scale dynamic inverse problems are often ill-posed due to model complexity and the high dimensionality of the unknown parameters. Regularization is commonly employed to mitigate ill-posedness by incorporating prior information and…

Numerical Analysis · Mathematics 2026-01-21 Aryeh Keating , Mirjeta Pasha

Generating multi-contrasts/modal MRI of the same anatomy enriches diagnostic information but is limited in practice due to excessive data acquisition time. In this paper, we propose a novel deep-learning model for joint reconstruction and…

Image and Video Processing · Electrical Eng. & Systems 2022-06-30 Wanyu Bian , Qingchao Zhang , Xiaojing Ye , Yunmei Chen

This paper proposes a novel self-supervised learning method, RELAX-MORE, for quantitative MRI (qMRI) reconstruction. The proposed method uses an optimization algorithm to unroll a model-based qMRI reconstruction into a deep learning…

Biological Physics · Physics 2023-07-26 Wanyu Bian , Albert Jang , Fang Liu

Sparsity-based models and techniques have been exploited in many signal processing and imaging applications. Data-driven methods based on dictionary and sparsifying transform learning enable learning rich image features from data, and can…

Machine Learning · Computer Science 2019-09-25 Saiprasad Ravishankar , Anna Ma , Deanna Needell

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

A regularization algorithm using inexact function values and inexact derivatives is proposed and its evaluation complexity analyzed. This algorithm is applicable to unconstrained problems and to problems with inexpensive constraints (that…

Optimization and Control · Mathematics 2019-04-22 S. Bellavia , G. Gurioli , B. Morini , Ph. L. Toint

We present a general variational framework for the training of freeform nonlinearities in layered computational architectures subject to some slope constraints. The regularization that we add to the traditional training loss penalizes the…

Machine Learning · Statistics 2025-03-31 Michael Unser , Alexis Goujon , Stanislas Ducotterd

This work addresses the recovery and demixing problem of signals that are sparse in some general dictionary. Involved applications include source separation, image inpainting, super-resolution, and restoration of signals corrupted by…

Information Theory · Computer Science 2017-03-24 Fei Wen , Lasith Adhikari , Ling Pei , Roummel F. Marcia , Peilin Liu , Robert C. Qiu

Semantic search is an important task which objective is to find the relevant index from a database for query. It requires a retrieval model that can properly learn the semantics of sentences. Transformer-based models are widely used as…

Machine Learning · Computer Science 2022-09-28 Mingxi Tan , Alexis Rolland , Andong Tian

Inverse problems for accelerated MRI typically incorporate domain-specific knowledge about the forward encoding operator in a regularized reconstruction framework. Recently physics-driven deep learning (DL) methods have been proposed to use…

Image and Video Processing · Electrical Eng. & Systems 2020-07-09 Seyed Amir Hossein Hosseini , Burhaneddin Yaman , Steen Moeller , Mingyi Hong , Mehmet Akçakaya

We use convex relaxation techniques to provide a sequence of solutions to the matrix completion problem. Using the nuclear norm as a regularizer, we provide simple and very efficient algorithms for minimizing the reconstruction error…

Machine Learning · Statistics 2009-06-12 Rahul Mazumder , Trevor Hastie , Rob Tibshirani

Machine learning techniques for the solution of inverse problems have become an attractive approach in the last decade, while their theoretical foundations are still in their infancy. In this chapter we want to pursue the study of…

Numerical Analysis · Mathematics 2025-12-10 Martin Burger , Samira Kabri , Gitta Kutyniok , Yunseok Lee , Lukas Weigand

We propose a regularization method to solve a nonlinear ill-posed problem connected to inversion of data gathered by a ground conductivity meter.

Numerical Analysis · Mathematics 2021-09-21 Gian Piero Deidda , Caterina Fenu , Giuseppe Rodriguez

Iterative regularization exploits the implicit bias of an optimization algorithm to regularize ill-posed problems. Constructing algorithms with such built-in regularization mechanisms is a classic challenge in inverse problems but also in…

Optimization and Control · Mathematics 2022-02-02 Cesare Molinari , Mathurin Massias , Lorenzo Rosasco , Silvia Villa