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We propose a PDE-constrained optimization approach for the determination of noise distribution in total variation (TV) image denoising. An optimization problem for the determination of the weights correspondent to different types of noise…

Optimization and Control · Mathematics 2012-07-17 Juan-Carlos De los Reyes , Carola-Bibiane Schönlieb

We consider a bilevel optimisation approach for parameter learning in higher-order total variation image reconstruction models. Apart from the least squares cost functional, naturally used in bilevel learning, we propose and analyse an…

Optimization and Control · Mathematics 2020-02-13 J. C. De los Reyes , C. -B. Schönlieb , T. Valkonen

In this article, we present a method for increasing adaptivity of an existing robust estimation algorithm by learning two parameters to better fit the residual distribution. The analyzed method uses these two parameters to calculate weights…

Robotics · Computer Science 2023-06-27 Shounak Das , Jason Gross

We propose two new variational models aimed to outperform the popular total variation (TV) model for image restoration with L$_2$ and L$_1$ fidelity terms. In particular, we introduce a space-variant generalization of the TV regularizer,…

Image and Video Processing · Electrical Eng. & Systems 2019-06-28 Alessandro Lanza , Serena Morigi , Monica Pragliola , Fiorella Sgallari

The non-stationary nature of image characteristics calls for adaptive processing, based on the local image content. We propose a simple and flexible method to learn local tuning of parameters in adaptive image processing: we extract simple…

Computer Vision and Pattern Recognition · Computer Science 2017-12-29 Jingming Dong , Iuri Frosio , Jan Kautz

This review discusses methods for learning parameters for image reconstruction problems using bilevel formulations. Image reconstruction typically involves optimizing a cost function to recover a vector of unknown variables that agrees with…

Optimization and Control · Mathematics 2022-06-16 Caroline Crockett , Jeffrey A. Fessler

We consider a bilevel optimisation strategy based on normalised residual whiteness loss for estimating the weighted total variation parameter maps for denoising images corrupted by additive white Gaussian noise. Compared to supervised and…

Optimization and Control · Mathematics 2025-03-12 Monica Pragliola , Luca Calatroni , Alessandro Lanza

This paper derives a new class of adaptive regularization parameter choice strategies that can be effectively and efficiently applied when regularizing large-scale linear inverse problems by combining standard Tikhonov regularization and…

Numerical Analysis · Mathematics 2019-07-15 Silvia Gazzola , Malena Sabate Landman

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

In this paper, we propose a regularization technique for noisy-image super-resolution and image denoising. Total variation (TV) regularization is adopted in many image processing applications to preserve the local smoothness. However, TV…

Image and Video Processing · Electrical Eng. & Systems 2022-02-23 Kaicong Sun , Sven Simon

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) regularization is popular in image restoration and reconstruction due to its ability to preserve image edges. To date, most research activities on TV models concentrate on image restoration from blurry and noisy…

Optimization and Control · Mathematics 2010-01-13 Yunhai Xiao , Junfeng Yang

Many imaging problems require solving an inverse problem that is ill-conditioned or ill-posed. Imaging methods typically address this difficulty by regularising the estimation problem to make it well-posed. This often requires setting the…

Methodology · Statistics 2020-08-17 Ana F. Vidal , Valentin De Bortoli , Marcelo Pereyra , Alain Durmus

Locally adapted parameterizations of a model (such as locally weighted regression) are expressive but often suffer from high variance. We describe an approach for reducing the variance, based on the idea of estimating simultaneously a…

Machine Learning · Computer Science 2012-07-03 Doina Precup , Philip Bachman

The choice of the parameter value for regularized inverse problems is critical to the results and remains a topic of interest. This article explores a criterion for selecting a good parameter value by maximizing the probability of the data,…

Numerical Analysis · Mathematics 2020-02-11 Toby Sanders , Rodrigo B. Platte , Robert D. Skeel

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

Popular methods for finding regularized solutions to inverse problems include sparsity promoting $\ell_1$ regularization techniques, one in particular which is the well known total variation (TV) regularization. More recently, several…

Numerical Analysis · Mathematics 2017-03-22 Toby Sanders

In this paper, we propose a novel approach to hyperspectral image super-resolution by modeling the global spatial-and-spectral correlation and local smoothness properties over hyperspectral images. Specifically, we utilize the tensor…

Computer Vision and Pattern Recognition · Computer Science 2016-01-26 Shiying He , Haiwei Zhou , Yao Wang , Wenfei Cao , Zhi Han

A number of image-processing problems can be formulated as optimization problems. The objective function typically contains several terms specifically designed for different purposes. Parameters in front of these terms are used to control…

Medical Physics · Physics 2017-11-02 Chenyang Shen , Yesenia Gonzalez , Liyuan Chen , Steve B. Jiang , Xun Jia

In the last decades, unsupervised deep learning based methods have caught researchers attention, since in many real applications, such as medical imaging, collecting a great amount of training examples is not always feasible. Moreover, the…

Image and Video Processing · Electrical Eng. & Systems 2022-05-24 Pasquale Cascarano , Andrea Sebastiani , Maria Colomba Comes , Giorgia Franchini , Federica Porta