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We address the denoising of images contaminated with multiplicative noise, e.g. speckle noise. Classical ways to solve such problems are filtering, statistical (Bayesian) methods, variational methods, and methods that convert the…

Optimization and Control · Mathematics 2008-12-10 Sylvain Durand , Jalal Fadili , Mila Nikolova

Over the last decade or so, reconstruction methods using $\ell_1$ regularization, often categorized as compressed sensing (CS) algorithms, have significantly improved the capabilities of high fidelity imaging in electron tomography. The…

Numerical Analysis · Mathematics 2017-03-07 Toby Sanders , Anne Gelb , Rodrigo Platte , Ilke Arslan , Kai Landskron

In this paper, we propose a new variational model for image reconstruction by minimizing the $L^1$ norm of the \emph{Weingarten map} of image surface $(x,y,f(x,y))$ for a given image $f:{\mathrm{\Omega}}\rightarrow \mathbb R$. We…

Numerical Analysis · Mathematics 2022-04-07 Qiuxiang Zhong , Ryan Wen Liu , Yuping Duan

In this paper we present a new regularization term for variational image restoration which can be regarded as a space-variant anisotropic extension of the classical isotropic Total Variation (TV) regularizer. The proposed regularizer comes…

Image and Video Processing · Electrical Eng. & Systems 2019-08-05 Luca Calatroni , Alessandro Lanza , Monica Pragliola , Fiorella Sgallari

In this paper, a new regularization term is proposed to solve mathematical image problems. By using difference operators in the four directions; horizontal, vertical and two diagonal directions, an estimation of derivative amplitude is…

Numerical Analysis · Mathematics 2022-09-14 Alireza Hosseini

We present a note on the implementation and efficacy of a box-constrained $L_1/L_2$ regularization in numerical optimization approaches to performing tomographic reconstruction from a single projection view. The constrained $L_1/L_2$…

Optimization and Control · Mathematics 2023-03-16 Sean Breckling , Malena I. Español , Victoria Uribe , Chrisitan Bobmara , Jordan Pillow , Brandon Baldonado

This paper considers the problem of signal denoising using a sparse tight-frame analysis prior. The L1 norm has been extensively used as a regularizer to promote sparsity; however, it tends to under-estimate non-zero values of the…

Computer Vision and Pattern Recognition · Computer Science 2015-09-11 Ankit Parekh , Ivan W. Selesnick

In this thesis, we offer a thorough investigation of different regularisation terms used in variational imaging problems, together with detailed optimisation processes of these problems. We begin by studying smooth problems and partially…

Computer Vision and Pattern Recognition · Computer Science 2021-10-07 Joseph Bartlett , Jinming Duan

In image processing, Total Variation (TV) regularization models are commonly used to recover blurred images. One of the most efficient and popular methods to solve the convex TV problem is the Alternating Direction Method of Multipliers…

Optimization and Control · Mathematics 2019-10-02 Tao Sun , Roberto Barrio , Marcos Rodriguez , Hao Jiang

We introduce a class of higher-order anisotropic total variation regularisers, which are defined for possibly inhomogeneous, smooth elliptic anisotropies, that extends the Total Generalized Variation (TGV) regulariser and its variants. We…

Numerical Analysis · Mathematics 2020-07-10 Simone Parisotto , Jan Lellmann , Simon Masnou , Carola-Bibiane Schönlieb

Identifying the discontinuous diffusion coefficient in an elliptic equation with observation data of the gradient of the solution is an important nonlinear and ill-posed inverse problem. Models with total variational (TV) regularization…

Numerical Analysis · Mathematics 2021-09-01 Wenyi Tian , Xiaoming Yuan , Hangrui Yue

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

Total Variation (TV) and related extensions have been popular in image restoration due to their robust performance and wide applicability. While the original formulation is still relevant after two decades of extensive research, its…

Image and Video Processing · Electrical Eng. & Systems 2021-06-02 Sanjay Viswanath , Simon de Beco , Maxime Dahan , Muthuvel Arigovindan

Total variation (TV) is a powerful regularization method that has been widely applied in different imaging applications, but is difficult to apply to diffuse optical tomography (DOT) image reconstruction (inverse problem) due to complex and…

Computer Vision and Pattern Recognition · Computer Science 2019-04-08 Wenqi Lu , Jinming Duan , David Orive-Miguel , Lionel Herve , Iain B Styles

We study \emph{TV regularization}, a widely used technique for eliciting structured sparsity. In particular, we propose efficient algorithms for computing prox-operators for $\ell_p$-norm TV. The most important among these is $\ell_1$-norm…

Machine Learning · Statistics 2018-01-03 Álvaro Barbero , Suvrit Sra

This paper focuses on the development of a space-variant regularization model for solving an under-determined linear inverse problem. The case study is a medical image reconstruction from few-view tomographic noisy data. The primary…

Image and Video Processing · Electrical Eng. & Systems 2024-04-29 Elena Morotti , Davide Evangelista , Andrea Sebastiani , Elena Loli Piccolomini

Total variation (TV) is a widely used function for regularizing imaging inverse problems that is particularly appropriate for images whose underlying structure is piecewise constant. TV regularized optimization problems are typically solved…

Image and Video Processing · Electrical Eng. & Systems 2025-08-26 Edward P. Chandler , Shirin Shoushtari , Brendt Wohlberg , Ulugbek S. Kamilov

Electrical capacitance tomography (ECT) has been investigated in many fields due to its advantages of being non-invasive and low cost. Sparse algorithms with l1-norm regularization are used to reduce the smoothing effect and obtain sharp…

Signal Processing · Electrical Eng. & Systems 2017-11-08 Jiaoxuan Chen , Maomao Zhang , Yi Li

We present a novel approach to denoising and inpainting problems for surface meshes. The purpose of these problems is to remove noise or fill in missing parts while preserving important features such as sharp edges. A discrete variant of…

Numerical Analysis · Mathematics 2025-02-03 Lukas Baumgärtner , Ronny Bergmann , Roland Herzog , Stephan Schmidt , José Vidal-Núñez , Manuel Weiß

Total variation (TV) is a widely used regularizer for stabilizing the solution of ill-posed inverse problems. In this paper, we propose a novel proximal-gradient algorithm for minimizing TV regularized least-squares cost functional. Our…

Information Theory · Computer Science 2016-01-05 Ulugbek S. Kamilov