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Regularization methods are commonly used in X-ray CT image reconstruction. Different regularization methods reflect the characterization of different prior knowledge of images. In a recent work, a new regularization method called a…

Medical Physics · Physics 2017-04-18 Wenxiang Cong , Ge Wang , Qingsong Yang , Jiang Hsieh , Jia Li , Rongjie Lai

Building on the well-known total-variation (TV), this paper develops a general regularization technique based on nonlinear isotropic diffusion (NID) for inverse problems with piecewise smooth solutions. The novelty of our approach is to be…

Numerical Analysis · Mathematics 2021-08-25 Bernadette N. Hahn , Gael Rigaud , Richard Schmähl

Total variation (TV) denoising is a nonparametric smoothing method that has good properties for preserving sharp edges and contours in objects with spatial structures like natural images. The estimate is sparse in the sense that TV…

Methodology · Statistics 2016-05-06 Sylvain Sardy , Hatef Monajemi

Experimentally acquired microscopy images are unavoidably affected by the presence of noise and other unwanted signals, which degrade their quality and might hide relevant features. With the recent increase in image acquisition rate, modern…

Image and Video Processing · Electrical Eng. & Systems 2025-05-15 Marco Corrias , Giada Franceschi , Michele Riva , Alberto Tampieri , Karin Föttinger , Ulrike Diebold , Thomas Pock , Cesare Franchini

Variational methods have become an important kind of methods in signal and image restoration - a typical inverse problem. One important minimization model consists of the squared $\ell_2$ data fidelity (corresponding to Gaussian noise) and…

Numerical Analysis · Mathematics 2018-06-15 Chunlin Wu , Zhifang Liu , Shuang Wen

Hyperspectral image (HSI) denoising aims to restore clean HSI from the noise-contaminated one. Noise contamination can often be caused during data acquisition and conversion. In this paper, we propose a novel spatial-spectral total…

Image and Video Processing · Electrical Eng. & Systems 2021-04-07 Haijin Zeng , Xiaozhen Xie , Jifeng Ning

In this work, we introduce a function space setting for a wide class of structural/weighted total variation (TV) regularization methods motivated by their applications in inverse problems. In particular, we consider a regularizer that is…

Optimization and Control · Mathematics 2018-05-23 Michael Hintermüller , Martin Holler , Kostas Papafitsoros

Non-smooth regularization is widely used in image reconstruction to eliminate the noise while preserving subtle image structures. In this work, we investigate the use of proximal Newton (PN) method to solve an optimization problem with a…

Signal Processing · Electrical Eng. & Systems 2019-12-05 Tao Ge , Umberto Villa , Ulugbek S. Kamilov , Joseph A. O'Sullivan

For electrical impedance tomography (EIT), most practical reconstruction methods are based on linearizing the underlying non-linear inverse problem. Recently, it has been shown that the linearized problem still contains the exact shape…

Numerical Analysis · Mathematics 2018-11-20 Moon Kyung Choi , Bastian Harrach , Jin Keun Seo

In electrical impedance tomography, we aim to solve the conductivity within a target body through electrical measurements made on the surface of the target. This inverse conductivity problem is severely ill-posed, especially in real…

Optimization and Control · Mathematics 2022-05-24 Jyrki Jauhiainen , Aku Seppänen , Tuomo Valkonen

Previous work showed that total variation superiorization (TVS) improves reconstructed image quality in proton computed tomography (pCT). The structure of the TVS algorithm has evolved since then and this work investigated if this new…

Medical Physics · Physics 2019-01-18 Blake Schultze , Yair Censor , Paniz Karbasi , Keith E. Schubert , Reinhard W. Schulte

The aim of this paper is to test and analyze a novel technique for image reconstruction in positron emission tomography, which is based on (total variation) regularization on both the image space and the projection space. We formulate our…

Numerical Analysis · Mathematics 2014-07-24 Martin Burger , Jahn Müller , Evangelos Papoutsellis , Carola-Bibiane Schönlieb

Dielectric tensor tomography reconstructs the three-dimensional dielectric tensors of microscopic objects and provides information about the crystalline structure orientations and principal refractive indices. Because dielectric tensor…

Optics · Physics 2022-10-13 Herve Hugonnet , Seungwoo Shin , Yongkeun Park

In this paper, we propose a variational approach for video denoising, based on a total directional variation (TDV) regulariser proposed in Parisotto et al. (2018), for image denoising and interpolation. In the TDV regulariser, the…

Numerical Analysis · Mathematics 2019-04-01 Simone Parisotto , Carola-Bibiane Schönlieb

In multiband fusion, an image with a high spatial and low spectral resolution is combined with an image with a low spatial but high spectral resolution to produce a single multiband image having high spatial and spectral resolutions. This…

Image and Video Processing · Electrical Eng. & Systems 2022-10-11 Unni V. S. , Pravin Nair , Kunal N. Chaudhury

We propose a new fast algorithm for solving one of the standard formulations of image restoration and reconstruction which consists of an unconstrained optimization problem where the objective includes an $\ell_2$ data-fidelity term and a…

Optimization and Control · Mathematics 2015-05-14 Manya V. Afonso , José M. Bioucas-Dias , Mário A. T. Figueiredo

Tensors serve as a crucial tool in the representation and analysis of complex, multi-dimensional data. As data volumes continue to expand, there is an increasing demand for developing optimization algorithms that can directly operate on…

Optimization and Control · Mathematics 2024-05-15 Katherine Henneberger , Jing Qin

Inverse problems and regularization theory is a central theme in contemporary signal processing, where the goal is to reconstruct an unknown signal from partial indirect, and possibly noisy, measurements of it. A now standard method for…

Optimization and Control · Mathematics 2014-12-09 Samuel Vaiter , Gabriel Peyré , Jalal M. Fadili

We consider $L^1$-TV regularization of univariate signals with values on the real line or on the unit circle. While the real data space leads to a convex optimization problem, the problem is non-convex for circle-valued data. In this paper,…

Numerical Analysis · Mathematics 2017-05-16 Martin Storath , Andreas Weinmann , Michael Unser

Regularization is a critical technique for ensuring well-posedness in solving inverse problems with incomplete measurement data. Traditionally, the regularization term is designed based on prior knowledge of the unknown signal's…

Numerical Analysis · Mathematics 2024-12-16 Bosu Choi , Jihun Han , Yoonsang Lee