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Total variation gradient flows are important in several applied fields, including image analysis and materials science. In this paper, we review a few basic topics including definition of a solution, explicit examples and the notion of…

Analysis of PDEs · Mathematics 2024-01-31 Yoshikazu Giga , Hirotoshi Kuroda , Michał Łasica

Dual gradient descent combined with early stopping represents an efficient alternative to the Tikhonov variational approach when the regularizer is strongly convex. However, for many relevant applications, it is crucial to deal with…

Optimization and Control · Mathematics 2023-05-12 Vassilis Apidopoulos , Cesare Molinari , Lorenzo Rosasco , Silvia Villa

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

We consider curvature depending variational models for image regularization, such as Euler's elastica. These models are known to provide strong priors for the continuity of edges and hence have important applications in shape-and image…

Numerical Analysis · Mathematics 2018-07-31 Antonin Chambolle , Thomas Pock

Based on transformed $\ell_1$ regularization, transformed total variation (TTV) has robust image recovery that is competitive with other nonconvex total variation (TV) regularizers, such as TV$^p$, $0<p<1$. Inspired by its performance, we…

Computer Vision and Pattern Recognition · Computer Science 2024-06-05 Elisha Dayag , Kevin Bui , Fredrick Park , Jack Xin

The goal of this paper is to present a novel approach for total variation regularization and Sobolev minimization, which are prominent tools for variational imaging. Thereby we use derivative free characterizations of the total variation…

Optimization and Control · Mathematics 2009-11-09 Carsten Pontow , Otmar Scherzer

A Bayesian hierarchical model for total variation regularisation is presented in this paper. All the parameters of an inverse problem, including the "regularisation parameter", are estimated simultaneously from the data in the model. The…

Numerical Analysis · Mathematics 2014-12-16 Marko Järvenpää , Robert Piché

In this paper, we consider the variational regularization of manifold-valued data in the inverse problems setting. In particular, we consider TV and TGV regularization for manifold-valued data with indirect measurement operators. We provide…

Numerical Analysis · Mathematics 2018-04-30 Martin Storath , Andreas Weinmann

We present a powerful and easy-to-implement algorithm for solving constrained optimization problems that involve $L_1$/total-variation regularization terms, and both equality and inequality constraints. We discuss the relationship of our…

Optimization and Control · Mathematics 2015-05-22 Musa Maharramov , Stewart A. Levin

Total variation regularization and total variation flows (TVF) have been widely applied for image enhancement and denoising. To include a generic preservation of crossing curvilinear structures in TVF we lift images to the homogeneous space…

Analysis of PDEs · Mathematics 2019-07-02 Remco Duits , Etienne St-Onge , Jim Portegies , Bart Smets

In this work we present a novel approach for single depth map super-resolution. Modern consumer depth sensors, especially Time-of-Flight sensors, produce dense depth measurements, but are affected by noise and have a low lateral resolution.…

Computer Vision and Pattern Recognition · Computer Science 2016-07-28 Gernot Riegler , Matthias Rüther , Horst Bischof

Obtaining high resolution images from low resolution data with clipped noise is algorithmically challenging due to the ill-posed nature of the problem. So far such problems have hardly been tackled, and the few existing approaches use…

Computer Vision and Pattern Recognition · Computer Science 2021-05-03 Kireeti Bodduna , Joachim Weickert , Marcelo Cárdenas

We study a general class of infimal convolution type regularisation functionals suitable for applications in image processing. These functionals incorporate a combination of the total variation ($\mathrm{TV}$) seminorm and $\mathrm{L}^{p}$…

Anisotropic Diffusion is widely used for noise reduction with simultaneous preservation of vascular structures in maximum intensity projected (MIP) angiograms. However, extension to minimum intensity projected (mIP) venograms in…

Computer Vision and Pattern Recognition · Computer Science 2015-01-15 P. K. Akshara , J. S. Paul

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 a class of piecewise-constant image segmentation models, we propose to incorporate a weighted difference of anisotropic and isotropic total variation (AITV) to regularize the partition boundaries in an image. In particular, we replace…

Computer Vision and Pattern Recognition · Computer Science 2021-07-20 Kevin Bui , Fredrick Park , Yifei Lou , Jack Xin

This paper proposes to solve the Total Variation regularized models by finding the residual between the input and the unknown optimal solution. After analyzing a previous method, we developed a new iterative algorithm, named as Residual…

Computer Vision and Pattern Recognition · Computer Science 2020-09-09 Yuanhao Gong

We consider a variational model for single-image super-resolution based on the assumption that the gradient of the target image is sparse. We enforce this assumption by considering both an isotropic and an anisotropic $\ell^0$…

Image and Video Processing · Electrical Eng. & Systems 2020-12-17 Pasquale Cascarano , Luca Calatroni , Elena Loli Piccolomini

We propose a new constrained optimization approach to hyperspectral (HS) image restoration. Most existing methods restore a desirable HS image by solving some optimization problem, which consists of a regularization term(s) and a…

Signal Processing · Electrical Eng. & Systems 2020-09-09 Saori Takeyama , Shunsuke Ono , Itsuo Kumazawa

This paper presents an efficient algorithm to solve total variation (TV) regularizations of images contaminated by a both blur and noise. The unconstrained structure of the problem suggests that one can solve a constrained optimization…

Numerical Analysis · Computer Science 2018-02-13 A. Bentbib , M. El Guide , K. Jbilou