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Manifold-valued signal- and image processing has received attention due to modern image acquisition techniques. Recently, a convex relaxation of the otherwise nonconvex Tikhonov-regularization for denoising circle-valued data has been…

Numerical Analysis · Mathematics 2024-05-17 Robert Beinert , Jonas Bresch , Gabriele Steidl

The handling of manifold-valued data, for instance, plays a central role in color restoration tasks relying on circle- or sphere-valued color models, in the study of rotational or directional information related to the special orthogonal…

Optimization and Control · Mathematics 2025-07-01 Robert Beinert , Jonas Bresch

We introduce a novel relaxation strategy for denoising hyperbolic-valued data. The main challenge is here the non-convexity of the hyperbolic sheet. Instead of considering the denoising problem directly on the hyperbolic space, we exploit…

Numerical Analysis · Mathematics 2024-10-22 Robert Beinert , Jonas Bresch

We consider the deconvolution problem for densities supported on a $(d-1)$-dimensional sphere with unknown center and unknown radius, in the situation where the distribution of the noise is unknown and without any other observations. We…

Statistics Theory · Mathematics 2022-03-08 Jérémie Capitao-Miniconi , Elisabeth Gassiat

It is common to have to process signals, whose values are points on the 3-D sphere. We consider a Tikhonov-type regularization model to smoothen or interpolate sphere-valued signals defined on arbitrary graphs. We propose a convex…

Optimization and Control · Mathematics 2022-07-26 Laurent Condat

We focus on the maximum regularization parameter for anisotropic total-variation denoising. It corresponds to the minimum value of the regularization parameter above which the solution remains constant. While this value is well know for the…

Machine Learning · Statistics 2016-12-12 Charles-Alban Deledalle , Nicolas Papadakis , Joseph Salmon , Samuel Vaiter

This work concerns noise reduction for one-dimensional spectra in the case that the signal is corrupted by an additive white noise. The proposed method starts with mapping the noisy spectrum to a partial circulant matrix. In virtue of…

Data Analysis, Statistics and Probability · Physics 2020-10-29 X. C. Chen , Yu. A. Litvinov , M. Wang , Q. Wang , Y. H. Zhang

Various problems in computer vision and medical imaging can be cast as inverse problems. A frequent method for solving inverse problems is the variational approach, which amounts to minimizing an energy composed of a data fidelity term and…

Computer Vision and Pattern Recognition · Computer Science 2020-06-17 Erich Kobler , Alexander Effland , Karl Kunisch , Thomas Pock

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 a recent paper by A. Chambolle et al. [Geometric properties of solutions to the total variation denoising problem. Inverse Problems 33, 2017] it was proven that if the subgradient of the total variation at the noise free data is not…

Optimization and Control · Mathematics 2021-06-09 José A. Iglesias , Gwenael Mercier , Otmar Scherzer

We consider the problem of robust deconvolution, and particularly the recovery of an unknown deterministic signal convolved with a known filter and corrupted by additive noise. We present a novel, non-iterative data-driven approach.…

Signal Processing · Electrical Eng. & Systems 2021-11-04 Amir Weiss , Boaz Nadler

We present a rotation-equivariant unsupervised learning framework for the sparse deconvolution of non-negative scalar fields defined on the unit sphere. Spherical signals with multiple peaks naturally arise in Diffusion MRI (dMRI), where…

Image and Video Processing · Electrical Eng. & Systems 2021-02-19 Axel Elaldi , Neel Dey , Heejong Kim , Guido Gerig

This work studies the denoising of piecewise smooth graph signals that exhibit inhomogeneous levels of smoothness over a graph, where the value at each node can be vector-valued. We extend the graph trend filtering framework to denoising…

Signal Processing · Electrical Eng. & Systems 2020-01-16 Rohan Varma , Harlin Lee , Jelena Kovačević , Yuejie Chi

Non-stationary blind super-resolution is an extension of the traditional super-resolution problem, which deals with the problem of recovering fine details from coarse measurements. The non-stationary blind super-resolution problem appears…

Information Theory · Computer Science 2019-10-09 Shuang Li , Michael B. Wakin , Gongguo Tang

We consider one-dimensional variants of the classical first order total variation denoising model introduced by Rudin, Osher and Fatemi. This study is based on our previous work on various denoising and inpainting problems in image…

Analysis of PDEs · Mathematics 2018-03-29 Martin Fuchs , Jan Mueller , Christian Tietz

In this paper, we are interested in the classical problem of restoring data degraded by a convolution and the addition of a white Gaussian noise. The originality of the proposed approach is two-fold. Firstly, we formulate the restoration…

Methodology · Statistics 2015-05-13 Jean-Christophe Pesquet , Amel Benazza-Benyahia , Caroline Chaux

We consider the inverse problem of recovering a continuous-domain function from a finite number of noisy linear measurements. The unknown signal is modeled as the sum of a slowly varying trend and a periodic or quasi-periodic seasonal…

Functional Analysis · Mathematics 2025-05-16 Julien Fageot

It is common to have to process signals or images whose values are cyclic and can be represented as points on the complex circle, like wrapped phases, angles, orientations, or color hues. We consider a Tikhonov-type regularization model to…

Optimization and Control · Mathematics 2022-06-08 Laurent Condat

Regularization by denoising (RED) is a widely-used framework for solving inverse problems by leveraging image denoisers as image priors. Recent work has reported the state-of-the-art performance of RED in a number of imaging applications…

Image and Video Processing · Electrical Eng. & Systems 2022-02-11 Yuyang Hu , Jiaming Liu , Xiaojian Xu , Ulugbek S. Kamilov

We propose a new space-variant anisotropic regularisation term for variational image restoration, based on the statistical assumption that the gradients of the target image distribute locally according to a bivariate generalised Gaussian…

Numerical Analysis · Mathematics 2019-04-04 Luca Calatroni , Alessandro Lanza , Monica Pragliola , Fiorella Sgallari
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