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The Gridding algorithm has shown great utility for reconstructing images from non-uniformly spaced samples in the Fourier domain in several imaging modalities. Due to the non-uniform spacing, some correction for the variable density of the…

Image and Video Processing · Electrical Eng. & Systems 2021-06-17 Nicholas Dwork , Daniel O'Connor , Ethan M. I. Johnson , Corey A. Baron , Jeremy W. Gordon , John M. Pauly , Peder E. Z. Larson

Variational regularization techniques are dominant in the field of mathematical imaging. A drawback of these techniques is that they are dependent on a number of parameters which have to be set by the user. A by now common strategy to…

Optimization and Control · Mathematics 2020-12-10 Matthias J. Ehrhardt , Lindon Roberts

For medical image analysis, segmentation models trained on one or several domains lack generalization ability to unseen domains due to discrepancies between different data acquisition policies. We argue that the degeneration in segmentation…

Computer Vision and Pattern Recognition · Computer Science 2022-08-09 Ziqi Zhou , Lei Qi , Yinghuan Shi

We tackle the problem of reflectance estimation from a set of multi-view images, assuming known geometry. The approach we put forward turns the input images into reflectance maps, through a robust variational method. The variational model…

Computer Vision and Pattern Recognition · Computer Science 2018-01-24 Jean Mélou , Yvain Quéau , Jean-Denis Durou , Fabien Castan , Daniel Cremers

The recovery of images from the observations that are degraded by a linear operator and further corrupted by Poisson noise is an important task in modern imaging applications such as astronomical and biomedical ones. Gradient-based…

Computer Vision and Pattern Recognition · Computer Science 2015-03-17 Dai-Qiang Chen

The importance of regularization has been well established in image reconstruction -- which is the computational inversion of imaging forward model -- with applications including deconvolution for microscopy, tomographic reconstruction,…

Image and Video Processing · Electrical Eng. & Systems 2021-06-29 Sanjay Viswanath , Manu Ghulyani , Muthuvel Arigovindan

In many imaging applications where segmented features (e.g. blood vessels) are further used for other numerical simulations (e.g. finite element analysis), the obtained surfaces do not have fine resolutions suitable for the task. Increasing…

Analysis of PDEs · Mathematics 2023-09-19 Yiyao Zhang , Ke Chen , Shang-Hua Yang

The reconstruction of images from measured data is an increasing field of research. For highly under-determined problems, template-based image reconstruction provides a way of compensating for the lack of sufficient data. A caveat of this…

Optimization and Control · Mathematics 2023-05-29 Sebastian Neumayer , Antonia Topalovic

This paper focuses on solving the multiplicative gamma denoising problem via a variation model. Variation-based regularization models have been extensively employed in a variety of inverse problem tasks in image processing. However,…

Computer Vision and Pattern Recognition · Computer Science 2024-12-24 Shengkun Yang , Zhichang Guo , Jia Li , Fanghui Song , Wenjuan Yao

We present a method for dimensionality reduction of an affine variational inequality (AVI) defined over a compact feasible region. Centered around the Johnson Lindenstrauss lemma, our method is a randomized algorithm that produces with high…

Optimization and Control · Mathematics 2014-11-11 Bharat Prabhakar , Ankur A. Kulkarni

We present a new vectorial total variation method that addresses the problem of color consistent image filtering. Our approach is inspired from the double-opponent cell representation in the human visual cortex. Existing methods of…

Computer Vision and Pattern Recognition · Computer Science 2016-05-20 Freddie Åström , Christoph Schnörr

It was recently shown that the phase retrieval imaging of a sample can be modeled as a simple convolution process. Sometimes, such a convolution depends on physical parameters of the sample which are difficult to estimate a priori. In this…

Numerical Analysis · Mathematics 2017-02-20 Eduardo X. Miqueles , Nathaly L. Archilha , Marcelo R. Dos Anjos , Harry Westfahl , Elias S. Helou

Stochastic optimisation algorithms are the de facto standard for machine learning with large amounts of data. Handling only a subset of available data in each optimisation step dramatically reduces the per-iteration computational costs,…

Numerical Analysis · Mathematics 2024-12-19 Matthias J. Ehrhardt , Zeljko Kereta , Jingwei Liang , Junqi Tang

In the context of image processing, given a $k$-th order, homogeneous and linear differential operator with constant coefficients, we study a class of variational problems whose regularizing terms depend on the operator. Precisely, the…

Numerical Analysis · Mathematics 2022-11-15 Valerio Pagliari , Kostas Papafitsoros , Bogdan Raiţă , Andreas Vikelis

We consider the iterative reconstruction of both the internal geometry and the values of an inhomogeneous acoustic refraction index through a piecewise constant approximation. In this context, we propose two enhancements intended to reduce…

Numerical Analysis · Mathematics 2015-06-15 Yann Grisel , Jean-Pierre Raymond , Pierre-Alain Mazet , Vincent Mouysset

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

We propose a globally convergent alternating minimization (AM) algorithm for image reconstruction in transmission tomography, which extends automatic relevance determination (ARD) to Poisson noise models with Beer's law. The algorithm…

A wide array of image recovery problems can be abstracted into the problem of minimizing a sum of composite convex functions in a Hilbert space. To solve such problems, primal-dual proximal approaches have been developed which provide…

Optimization and Control · Mathematics 2014-06-23 Patrick L. Combettes , Laurent Condat , Jean-Christophe Pesquet , Bang Cong Vu

Dynamic inverse problems are challenging to solve due to the need to identify and incorporate appropriate regularization in both space and time. Moreover, the very large scale nature of such problems in practice presents an enormous…

Numerical Analysis · Mathematics 2025-01-23 Toluwani Okunola , Mirjeta Pasha , Misha Kilmer , Melina Freitag

Several important classes of images such as text, barcode and pattern images have the property that pixels can only take a distinct subset of values. This knowledge can benefit the restoration of such images, but it has not been widely…

Computer Vision and Pattern Recognition · Computer Science 2015-08-21 Xing Mei , Honggang Qi , Bao-Gang Hu , Siwei Lyu