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In this paper we study the reconstruction of moving object densities from undersampled dynamic X-ray tomography in two dimensions. A particular motivation of this study is to use realistic measurement protocols for practical applications,…

Numerical Analysis · Mathematics 2018-03-28 Martin Burger , Hendrik Dirks , Lena Frerking , Andreas Hauptmann , Tapio Helin , Samuli Siltanen

In this paper, a new tool for Doppler tomography, Tomo-V (https://tomo-v.inasan.ru) that is developed based on the algebraic reconstruction technique (ART) has been presented. Previously, the ART method has not been widely used in…

Instrumentation and Methods for Astrophysics · Physics 2026-03-30 P. V. Kaygorodov

A Rotating Modulator (RM) is one of a class of techniques for indirect imaging of an object scene by modulation and detection of incident photons. Comparison of the RM to more common imaging techniques, the Rotating Modulation Collimator…

Instrumentation and Methods for Astrophysics · Physics 2010-10-14 B. Budden , G. L. Case , M. L. Cherry

This study presents the development of a spatially adaptive weighting strategy for Total Variation regularization, aimed at addressing under-determined linear inverse problems. The method leverages the rapid computation of an accurate…

Numerical Analysis · Mathematics 2025-01-20 Elena Morotti , Davide Evangelista , Andrea Sebastiani , Elena Loli Piccolomini

We consider the problem of optimizing the sum of a smooth convex function and a non-smooth convex function using proximal-gradient methods, where an error is present in the calculation of the gradient of the smooth term or in the proximity…

Machine Learning · Computer Science 2011-12-02 Mark Schmidt , Nicolas Le Roux , Francis Bach

We generalize Newton-type methods for minimizing smooth functions to handle a sum of two convex functions: a smooth function and a nonsmooth function with a simple proximal mapping. We show that the resulting proximal Newton-type methods…

Machine Learning · Statistics 2014-03-19 Jason D. Lee , Yuekai Sun , Michael A. Saunders

We propose a supervised machine learning approach for boosting existing signal and image recovery methods and demonstrate its efficacy on example of image reconstruction in computed tomography. Our technique is based on a local nonlinear…

Computer Vision and Pattern Recognition · Computer Science 2013-12-02 Joseph Shtok , Michael Zibulevsky , Michael Elad

Tomographic investigations are a central tool in medical applications, allowing doctors to image the interior of patients. The corresponding measurement process is commonly modeled by the Radon transform. In practice, the solution of the…

Numerical Analysis · Mathematics 2025-10-17 Richard Huber

In this paper we study a variational problem in the space of functions of bounded Hessian. Our model constitutes a straightforward higher-order extension of the well known ROF functional (total variation minimisation) to which we add a…

Numerical Analysis · Mathematics 2013-08-09 Konstantinos Papafitsoros , Carola-Bibiane Schönlieb

Low-dose tomography is highly preferred in medical procedures for its reduced radiation risk when compared to standard-dose Computed Tomography (CT). However, the lower the intensity of X-rays, the higher the acquisition noise and hence the…

Image and Video Processing · Electrical Eng. & Systems 2019-12-24 Preeti Gopal , Sharat Chandran , Imants Svalbe , Ajit Rajwade

Nowadays, the field computed tomography (CT) encompasses a large variety of settings, ranging from nanoscale to meter-sized objects imaged by different kinds of radiation in various acquisition modes. This experimental diversity challenges…

Numerical Analysis · Mathematics 2019-01-11 Simon Maretzke

Near-field multiple-input multiple-output (MIMO) radar imaging suffers from high computational load inherently due to irregular spatial sampling with distributed antennas. Existing acceleration methods for near-field MIMO imaging typically…

Signal Processing · Electrical Eng. & Systems 2025-09-03 Okyanus Oral

We propose a novel study of the stochastic proximal gradient method for minimizing the sum of two convex functions, one of which is smooth. Under suitable assumptions and without requiring any boundedness or control of the variance of the…

Optimization and Control · Mathematics 2026-04-16 Javier I. Madariaga

Computational imaging methods that can exploit multiple modalities have the potential to enhance the capabilities of traditional sensing systems. In this paper, we propose a new method that reconstructs multimodal images from their linear…

Computer Vision and Pattern Recognition · Computer Science 2017-06-15 Kevin Degraux , Ulugbek S. Kamilov , Petros T. Boufounos , Dehong Liu

In this paper, we consider gradient methods for minimizing smooth convex functions, which employ the information obtained at the previous iterations in order to accelerate the convergence towards the optimal solution. This information is…

Optimization and Control · Mathematics 2021-06-02 Yurii Nesterov , Mihai I. Florea

We consider the problem of minimizing the sum of two convex functions: one is smooth and given by a gradient oracle, and the other is separable over blocks of coordinates and has a simple known structure over each block. We develop an…

Optimization and Control · Mathematics 2014-07-07 Qihang Lin , Zhaosong Lu , Lin Xiao

Riemannian accelerated gradient methods have been well studied for smooth optimization, typically treating geodesically convex and geodesically strongly convex cases separately. However, their extension to nonsmooth problems on manifolds…

Optimization and Control · Mathematics 2025-09-29 Shuailing Feng , Yuhang Jiang , Wen Huang , Shihui Ying

The ability of widely distributed radar systems to capture diverse spatial scattering properties substantially improves radar imaging performance. Traditional imaging methods leverage regularized optimization techniques to reconstruct…

Signal Processing · Electrical Eng. & Systems 2023-07-18 Ahmed Murtada , Bhavani Shankar Mysore Rama Rao , Udo Schroeder

Tomography is a central tool in medical applications, allowing doctors to investigate patients' interior features. The Radon transform (in two dimensions) is commonly used to model the measurement process in parallel-beam CT. Suitable…

Numerical Analysis · Mathematics 2026-02-27 Richard Huber

In this paper, we propose new accelerated methods for smooth convex optimization, called contracting proximal methods. At every step of these methods, we need to minimize a contracted version of the objective function augmented by a…

Optimization and Control · Mathematics 2021-05-21 Nikita Doikov , Yurii Nesterov