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In a number of tomographic applications, data cannot be fully acquired, resulting in a severely underdetermined image reconstruction. In such cases, conventional methods lead to reconstructions with significant artifacts. To overcome these…

Numerical Analysis · Mathematics 2023-06-21 Simon Göppel , Jürgen Frikel , Markus Haltmeier

Non-smooth regularization is widely used in image reconstruction to eliminate the noise while preserving subtle image structures. In this work, we investigate the use of proximal Newton (PN) method to solve an optimization problem with a…

Signal Processing · Electrical Eng. & Systems 2019-12-05 Tao Ge , Umberto Villa , Ulugbek S. Kamilov , Joseph A. O'Sullivan

Natural images tend to mostly consist of smooth regions with individual pixels having highly correlated spectra. This information can be exploited to recover hyperspectral images of natural scenes from their incomplete and noisy…

Computer Vision and Pattern Recognition · Computer Science 2016-11-03 Reza Arablouei , Frank de Hoog

We propose an efficient estimation technique for the automatic selection of locally-adaptive Total Variation regularisation parameters based on an hybrid strategy which combines a local maximum-likelihood approach estimating space-variant…

Optimization and Control · Mathematics 2020-05-20 Luca Calatroni , Alessandro Lanza , Monica Pragliola , Fiorella Sgallari

In this work, we propose Regularization-by-Equivariance (REV), a novel structure-adaptive regularization scheme for solving imaging inverse problems under incomplete measurements. This regularization scheme utilizes the equivariant…

Optimization and Control · Mathematics 2022-02-15 Junqi Tang

The L1-norm of the gradient-magnitude images (GMI), which is the well-known total variation (TV) model, is widely used as regularization in the few views CT reconstruction. As the L1-norm TV regularization is tending to uniformly penalize…

Information Theory · Computer Science 2019-05-01 Yuli Sun , Jinxu Tao

Due to the COVID-19 pandemic, there is an increasing demand for portable CT machines worldwide in order to diagnose patients in a variety of settings. This has led to a need for CT image reconstruction algorithms that can produce high…

Numerical Analysis · Mathematics 2025-12-10 Mai Phuong Pham Huynh , Manuel Santana , Ana Castillo

The parameter selection is crucial to regularization based image restoration methods. Generally speaking, a spatially fixed parameter for regularization item in the whole image does not perform well for both edge and smooth areas. A larger…

Image and Video Processing · Electrical Eng. & Systems 2021-04-07 Tingting Zhang , Jie Chen , Caiying Wu , Zhifei He , Tieyong Zeng , Qiyu Jin

While Computerized Tomography (CT) images can help detect disease such as Covid-19, regular CT machines are large and expensive. Cheaper and more portable machines suffer from errors in geometry acquisition that downgrades CT image quality.…

Image and Video Processing · Electrical Eng. & Systems 2021-08-03 Peijian Ding

We consider total variation minimization for manifold valued data. We propose a cyclic proximal point algorithm and a parallel proximal point algorithm to minimize TV functionals with $\ell^p$-type data terms in the manifold case. These…

Optimization and Control · Mathematics 2014-12-12 Andreas Weinmann , Laurent Demaret , Martin Storath

We study the problem of one-dimensional regression of data points with total-variation (TV) regularization (in the sense of measures) on the second derivative, which is known to promote piecewise-linear solutions with few knots. While there…

Optimization and Control · Mathematics 2021-12-22 Thomas Debarre , Quentin Denoyelle , Michael Unser , Julien Fageot

Hyperspectral analysis has gained popularity over recent years as a way to infer what materials are displayed on a picture whose pixels consist of a mixture of spectral signatures. Computing both signatures and mixture coefficients is known…

Optimization and Control · Mathematics 2017-06-29 Adrien Faivre , Clément Dombry

We consider the problem of finding a sparse solution for an underdetermined linear system of equations when the known parameters on both sides of the system are subject to perturbation. This problem is particularly relevant to…

Systems and Control · Computer Science 2016-06-16 Reza Arablouei

Total-variation (TV)-based Computed Tomography (CT) image reconstruction has shown experimentally to be capable of producing accurate reconstructions from sparse-view data. In particular TV-based reconstruction is very well suited for…

This work is concerned with applying iterative image reconstruction, based on constrained total-variation minimization, to low-intensity X-ray CT systems that have a high sampling rate. Such systems pose a challenge for iterative image…

Medical Physics · Physics 2016-11-17 Emil Y. Sidky , Rick Chartrand , Yuval Duchin , Christer Ullberg , Xiaochuan Pan

We show how total variation regularization of images in arbitrary dimensions can be approximately performed by applying appropriate shrinkage to some Haar wavelets coefficients. The approach works directly on the wavelet coefficients and is…

Numerical Analysis · Mathematics 2024-11-04 Tomas Sauer , A. Michael Stock

In this paper we present a new regularization term for variational image restoration which can be regarded as a space-variant anisotropic extension of the classical isotropic Total Variation (TV) regularizer. The proposed regularizer comes…

Image and Video Processing · Electrical Eng. & Systems 2019-08-05 Luca Calatroni , Alessandro Lanza , Monica Pragliola , Fiorella Sgallari

Total variation (TV) is a powerful regularization method that has been widely applied in different imaging applications, but is difficult to apply to diffuse optical tomography (DOT) image reconstruction (inverse problem) due to complex and…

Computer Vision and Pattern Recognition · Computer Science 2019-04-08 Wenqi Lu , Jinming Duan , David Orive-Miguel , Lionel Herve , Iain B Styles

In the past decade, sparsity-driven regularization has led to significant improvements in image reconstruction. Traditional regularizers, such as total variation (TV), rely on analytical models of sparsity. However, increasingly the field…

Computer Vision and Pattern Recognition · Computer Science 2018-10-31 Jiaming Liu , Yu Sun , Xiaojian Xu , Ulugbek S. Kamilov

In this work we present a novel optimization strategy for image reconstruction tasks under analysis-based image regularization, which promotes sparse and/or low-rank solutions in some learned transform domain. We parameterize such…

Computer Vision and Pattern Recognition · Computer Science 2023-08-11 Iaroslav Koshelev , Stamatios Lefkimmiatis