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Weighted V-line transforms map a symmetric tensor field of order $m\ge0$ to a linear combination of certain integrals of those fields along two rays emanating from the same vertex. A significant focus of current research in integral…

Classical Analysis and ODEs · Mathematics 2025-11-05 Gaik Ambartsoumian , Rohit Kumar Mishra , Indrani Zamindar

We give an exact inversion formula for the approximate discrete Radon transform introduced in [Brady, SIAM J. Comput., 27(1), 107--119] that is of cost $O(N \log N)$ for a square 2D image with $N$ pixels and requires only partial data.

Numerical Analysis · Mathematics 2020-05-19 Donsub Rim

A new version of the convexification method is developed analytically and tested numerically for a 1-D coefficient inverse problem in the frequency domain. Unlike the previous version, this one does not use the so-called "tail function",…

Numerical Analysis · Mathematics 2018-10-17 Michael V. Klibanov , Aleksandr E. Kolesov , Anders Sullivan , Lam Nguyen

A Radon-type transform called a cone transform that assigns to a given function its integral over various sets of cones has arisen in the last decade in the context of the study of Compton cameras used in Single Photon Emission Computed…

Functional Analysis · Mathematics 2015-03-27 Sunghwan Moon

Vector tomography methods intend to reconstruct and visualize vector fields in restricted domains by measuring line integrals of projections of these vector fields. Here, we deal with the reconstruction of irrotational vector functions from…

Quantitative Methods · Quantitative Biology 2017-05-03 Alexandra Koulouri

Computed Tomography (CT) reconstruction is a fundamental component to a wide variety of applications ranging from security, to healthcare. The classical techniques require measuring projections, called sinograms, from a full 180$^\circ$…

Computer Vision and Pattern Recognition · Computer Science 2018-07-12 Rushil Anirudh , Hyojin Kim , Jayaraman J. Thiagarajan , K. Aditya Mohan , Kyle Champley , Timo Bremer

The paper discusses numerical implementations of various inversion schemes for generalized V-line transforms on vector fields introduced in [6]. It demonstrates the possibility of efficient recovery of an unknown vector field from five…

Numerical Analysis · Mathematics 2023-11-20 Gaik Ambartsoumian , Mohammad Javad Latifi Jebelli , Rohit Kumar Mishra

Learned iterative reconstruction algorithms for inverse problems offer the flexibility to combine analytical knowledge about the problem with modules learned from data. This way, they achieve high reconstruction performance while ensuring…

Image and Video Processing · Electrical Eng. & Systems 2022-10-24 Mareike Thies , Fabian Wagner , Mingxuan Gu , Lukas Folle , Lina Felsner , Andreas Maier

Inverse transformation optics is introduced, and used to calculate the reflection at the boundary of a transformation medium under consideration. The transformation medium for a practical device is obtained from a two-dimensional (2D)…

Optics · Physics 2014-03-31 Pu Zhang , Yi Jin , Sailing He

The significance of the broken ray transform (BRT) is due to its occurrence in a number of modalities spanning optical, x-ray, and nuclear imaging. When data are indexed by the scatter location, the BRT is both linear and shift invariant.…

Signal Processing · Electrical Eng. & Systems 2019-08-07 Michael R. Walker , Joseph A. O'Sullivan

In this article, we study the problem of recovering symmetric $m$-tensor fields (including vector fields) supported in a unit disk $\mathbb{D}$ from a set of generalized V-line transforms, namely longitudinal, transverse, and mixed V-line…

Numerical Analysis · Mathematics 2024-11-08 Rohit Kumar Mishra , Anamika Purohit , Indrani Zamindar

Direct contour regression for instance segmentation is a challenging task. Previous works usually achieve it by learning to progressively refine the contour prediction or adopting a shape representation with limited expressiveness. In this…

Computer Vision and Pattern Recognition · Computer Science 2021-06-08 Tutian Tang , Wenqiang Xu , Ruolin Ye , Yan-Feng Wang , Cewu Lu

The present article proposes a partial answer to the explicit inversion of the tensor tomography problem in two dimensions, by proving injectivity over certain kinds of tensors and providing reconstruction formulas for them. These tensors…

Analysis of PDEs · Mathematics 2015-06-18 François Monard

In this paper, we consider the conical Radon transform on all cones with horizontal central axis whose vertices are on a straight line. We derive an explicit inversion formula for such transform. The inversion makes use of the vertical…

Classical Analysis and ODEs · Mathematics 2019-08-23 Duy N. Nguyen , Linh V. Nguyen

The article suggests a new approach what is called a consistency method for the inversion of the spherical Radon transform in 2D with detectors on a line. It is known that there is not an exact inversion formula in 2D. By means of the…

Numerical Analysis · Mathematics 2017-05-31 Rafik Aramyan

The inverse problem of electrical impedance tomography is severely ill-posed. In particular, the resolution of images produced by impedance tomography deteriorates as the distance from the measurement boundary increases. Such depth…

Analysis of PDEs · Mathematics 2020-04-21 Henrik Garde , Nuutti Hyvönen

We present a computational method for reconstructing a vector field on a convex polytope $\mathcal{P} \subset \mathbb{R}^d$ of arbitrary dimension from discrete samples. We specifically address the scenario where the vector field is subject…

Dynamical Systems · Mathematics 2026-02-03 Junyan Chu , Shizuo Kaji

Spectropolarimetric inversions are routinely used in the field of Solar Physics for the extraction of physical information from observations. The application to two-dimensional fields of view often requires the use of supercomputers with…

Solar and Stellar Astrophysics · Physics 2019-06-26 A. Asensio Ramos , C. Diaz Baso

In spherical surface wave tomography, one measures the integrals of a function defined on the sphere along great circle arcs. This forms a generalization of the Funk--Radon transform, which assigns to a function its integrals along full…

Numerical Analysis · Mathematics 2018-08-13 Ralf Hielscher , Daniel Potts , Michael Quellmalz

X-ray Bragg coherent diffraction imaging has been demonstrated as a powerful three-dimensional (3D) microscopy approach for the investigation of sub-micrometer-scale crystalline particles. It is based on the measurement of a series of…