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A new parameter choice rule for inverse problems is introduced. This parameter choice rule was developed for total variation regularization in electron tomography and might in general be useful for $L^1$ regularization of inverse problems…

Numerical Analysis · Mathematics 2008-04-28 Hans Rullgård

1D Total Variation (TV) denoising, considering the data fidelity and the Total Variation (TV) regularization, proposes a good restored signal preserving shape edges. The main issue is how to choose the weight $\lambda$ balancing those two…

Signal Processing · Electrical Eng. & Systems 2020-12-18 Zhanhao Liu , Marion Perrodin , Thomas Chambrion , Radu Stoica

In this paper, we study the problem of image recovery from given partial (corrupted) observations. Recovering an image using a low-rank model has been an active research area in data analysis and machine learning. But often, images are not…

Computer Vision and Pattern Recognition · Computer Science 2020-03-13 Pawan Goyal , Hussam Al Daas , Peter Benner

We propose a new space-variant regularization term for variational image restoration based on the assumption that the gradient magnitudes of the target image distribute locally according to a half-Generalized Gaussian distribution. This…

Image and Video Processing · Electrical Eng. & Systems 2019-06-27 Alessandro Lanza , Serena Morigi , Monica Pragliola , Fiorella Sgallari

Feature selection with specific multivariate performance measures is the key to the success of many applications, such as image retrieval and text classification. The existing feature selection methods are usually designed for…

Machine Learning · Computer Science 2015-03-19 Qi Mao , Ivor W. Tsang

Variational regularization is commonly used to solve linear inverse problems, and involves augmenting a data fidelity by a regularizer. The regularizer is used to promote a priori information and is weighted by a regularization parameter.…

Optimization and Control · Mathematics 2024-01-23 Matthias J. Ehrhardt , Silvia Gazzola , Sebastian J. Scott

Variational methods in imaging are nowadays developing towards a quite universal and flexible tool, allowing for highly successful approaches on tasks like denoising, deblurring, inpainting, segmentation, super-resolution, disparity, and…

Optimization and Control · Mathematics 2014-12-16 Martin Burger , Alex Sawatzky , Gabriele Steidl

The objectives of this chapter are: (i) to introduce a concise overview of regularization; (ii) to define and to explain the role of a particular type of regularization called total variation norm (TV-norm) in computer vision tasks; (iii)…

Computer Vision and Pattern Recognition · Computer Science 2016-04-01 Vania V. Estrela , Hermes Aguiar Magalhaes , Osamu Saotome

We propose a novel automatic parameter selection strategy for variational imaging problems under Poisson noise corruption. The selection of a suitable regularization parameter, whose value is crucial in order to achieve high quality…

Numerical Analysis · Mathematics 2022-07-22 Francesca Bevilacqua , Alessandro Lanza , Monica Pragliola , Fiorella Sgallari

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

In dynamic MRI, sufficient time resolution can often only be obtained using imaging protocols which produce undersampled data for each image in the time series. This has led to the popularity of compressed sensing (CS) based image…

This paper is concerned with the analysis of convergent sequential and parallel overlapping domain decomposition methods for the minimization of functionals formed by a discrepancy term with respect to data and a total variation constraint.…

Numerical Analysis · Mathematics 2009-05-15 Massimo Fornasier , Andreas Langer , Carola-Bibiane Schönlieb

In this paper, we consider a primal-dual domain decomposition method for total variation regularized problems appearing in mathematical image processing. The model problem is transformed into an equivalent constrained minimization problem…

Numerical Analysis · Mathematics 2019-12-10 Chang-Ock Lee , Jongho Park

We study a regularization framework that combines a convex fidelity term with multiple $\ell_1$-based regularizers, each linked to a distinct linear transform. This multi-penalty model enhances flexibility in promoting structured sparsity.…

Numerical Analysis · Mathematics 2026-02-02 Qianru Liu , Rui Wang , Yuesheng Xu

We address the problem of optimal scale-dependent parameter learning in total variation image denoising. Such problems are formulated as bilevel optimization instances with total variation denoising problems as lower-level constraints. For…

Optimization and Control · Mathematics 2021-07-20 Juan Carlos De los Reyes , David Villacís

Image deconvolution is still to be a challenging ill-posed problem for recovering a clear image from a given blurry image, when the point spread function is known. Although competitive deconvolution methods are numerically impressive and…

Computer Vision and Pattern Recognition · Computer Science 2016-09-07 Hang Yang , Zhongbo Zhang , Yujing Guan

We consider a bilevel optimization approach in function space for the choice of spatially dependent regularization parameters in TV image restoration models. First- and second-order optimality conditions for the bilevel problem are studied,…

Optimization and Control · Mathematics 2016-10-18 C. Chung , J. C. De los Reyes , C. B. Schoenlieb

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

Variable selection in cluster analysis is important yet challenging. It can be achieved by regularization methods, which realize a trade-off between the clustering accuracy and the number of selected variables by using a lasso-type penalty.…

Methodology · Statistics 2016-12-23 Marbac Matthieu , Sedki Mohammed

We propose a new fast algorithm for solving one of the standard formulations of frame-based image deconvolution: an unconstrained optimization problem, involving an $\ell_2$ data-fidelity term and a non-smooth regularizer. Our approach is…

Optimization and Control · Mathematics 2016-11-17 Mario A. T. Figueiredo , Jose M. Bioucas-Dias , Manya V. Afonso