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We study the qualitative properties of optimal regularisation parameters in variational models for image restoration. The parameters are solutions of bilevel optimisation problems with the image restoration problem as constraint. A general…

Optimization and Control · Mathematics 2020-02-13 Juan Carlos De Los Reyes , Carola-Bibiane Schönlieb , Tuomo Valkonen

In this paper, we propose a decomposition approach for eigenvalue problems with spatial symmetries, including the formulation, discretization as well as implementation. This approach can handle eigenvalue problems with either Abelian or…

Numerical Analysis · Mathematics 2012-11-16 Jun Fang , Xingyu Gao , Aihui Zhou

Estimating the values of unknown parameters from corrupted measured data faces a lot of challenges in ill-posed problems. In such problems, many fundamental estimation methods fail to provide a meaningful stabilized solution. In this work,…

Information Theory · Computer Science 2017-01-11 Mohamed Suliman , Tarig Ballal , Tareq Y. Al-Naffouri

This review provides an introduction to - and overview of - the current state of the art in neural-network based regularization methods for inverse problems in imaging. It aims to introduce readers with a solid knowledge in applied…

Optimization and Control · Mathematics 2023-12-25 Andreas Habring , Martin Holler

The truncated singular value decomposition may be used to find the solution of linear discrete ill-posed problems in conjunction with Tikhonov regularization and requires the estimation of a regularization parameter that balances between…

Numerical Analysis · Mathematics 2022-08-16 Rosemary A. Renaut , Anthony W. Helmstetter , Saeed Vatankhah

We present a fast algorithm for the total variation regularization of the $3$-D gravity inverse problem. Through imposition of the total variation regularization, subsurface structures presenting with sharp discontinuities are preserved…

Numerical Analysis · Mathematics 2022-08-16 Saeed Vatankhah , Rosemary A. Renaut , Vahid E. Ardestani

Overdetermined systems of first kind integral equations appear in many applications. When the right-hand side is discretized, the resulting finite-data problem is ill-posed and admits infinitely many solutions. We propose a numerical method…

Numerical Analysis · Mathematics 2023-07-26 Patricia Díaz de Alba , Luisa Fermo , Federica Pes , Giuseppe Rodriguez

We investigate regularizations of distributional sections of vector bundles by means of nets of smooth sections that preserve the main regularity properties of the original distributions (singular support, wavefront set, Sobolev…

Functional Analysis · Mathematics 2014-04-07 Shantanu Dave , Guenther Hoermann , Michael Kunzinger

We present a Hilbert space perspective to homogenization of standard linear evolutionary boundary value problems in mathematical physics and provide a unified treatment for (non-)periodic homogenization problems in thermodynamics,…

Analysis of PDEs · Mathematics 2016-03-08 Marcus Waurick

We consider the reconstruction of a diffusion coefficient in a quasilinear elliptic problem from a single measurement of overspecified Neumann and Dirichlet data. The uniqueness for this parameter identification problem has been established…

Numerical Analysis · Mathematics 2015-06-17 Herbert Egger , Jan-Frederik Pietschmann , Matthias Schlottbom

Ill-posed linear inverse problems (ILIP), such as restoration and reconstruction, are a core topic of signal/image processing. A standard approach to deal with ILIP uses a constrained optimization problem, where a regularization function is…

Optimization and Control · Mathematics 2016-11-15 Manya V. Afonso , Jose M. Bioucas-Dias , Mario A. T. Figueiredo

In this paper, we investigate regularization of linear inverse problems with irregular noise. In particular, we consider the case that the noise can be preprocessed by certain adjoint embedding operators. By introducing the consequent…

Numerical Analysis · Mathematics 2024-01-30 Xinyan Li , Simon Hubmer , Shuai Lu , Ronny Ramlau

Algebraic convergences rates of (iterated) Tikhonov regularization for linear inverse problems in Hilbert spaces are characterized by the membership of the exact solution to intermediate spaces produced by the K-method of real…

Numerical Analysis · Mathematics 2015-09-30 Roman Andreev

Traveltime tomography is a very effective tool to reconstruct acoustic, seismic or electromagnetic wave speed distribution. To infer the velocity image of the medium from the measurements of first arrivals is a typical example of ill-posed…

Geophysics · Physics 2007-05-23 G. Vignoli , L. Zanzi

Regularization by denoising (RED) is a broadly applicable framework for solving inverse problems by using priors specified as denoisers. While RED has been shown to provide state-of-the-art performance in a number of applications, existing…

Image and Video Processing · Electrical Eng. & Systems 2020-11-30 Mingyang Xie , Yu Sun , Jiaming Liu , Brendt Wohlberg , Ulugbek S. Kamilov

We introduce a unified framework based on bi-level optimization schemes to deal with parameter learning in the context of image processing. The goal is to identify the optimal regularizer within a family depending on a parameter in a…

Analysis of PDEs · Mathematics 2022-09-15 Elisa Davoli , Rita Ferreira , Carolin Kreisbeck , Hidde Schönberger

Recovering a function from integrals over conical surfaces recently got significant interest. It is relevant for emission tomography with Compton cameras and other imaging applications. In this paper, we consider the weighted conical Radon…

Numerical Analysis · Mathematics 2018-12-05 Markus Haltmeier , Daniela Schiefeneder

Accurate determination of the regularization parameter in inverse problems still represents an analytical challenge, owing mainly to the considerable difficulty to separate the unknown noise from the signal. We present a new approach for…

Numerical Analysis · Mathematics 2019-07-24 Eitan Levin , Alexander Y. Meltzer

In this work, we consider ill-posed inverse problems in which the forward operator is continuous and weakly closed, and the sought solution belongs to a weakly closed constraint set. We propose a regularization method based on minimizing…

Numerical Analysis · Mathematics 2025-05-27 Barbara Palumbo , Paolo Massa , Federico Benvenuto

Tensor decomposition methods allow us to learn the parameters of latent variable models through decomposition of low-order moments of data. A significant limitation of these algorithms is that there exists no general method to regularize…

Machine Learning · Statistics 2019-05-28 Omer Gottesman , Weiwei Pan , Finale Doshi-Velez
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