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We propose three fast algorithms for solving the inverse problem of the thermoacoustic tomography corresponding to certain acquisition geometries. Two of these methods are designed to process the measurements done with point-like detectors…

Analysis of PDEs · Mathematics 2011-02-08 Leonid Kunyansky

Understanding the mechanisms underlying deep neural networks remains a fundamental challenge in machine learning and computer vision. One promising, yet only preliminarily explored approach, is feature inversion, which attempts to…

Computer Vision and Pattern Recognition · Computer Science 2025-08-15 Jan Rathjens , Shirin Reyhanian , David Kappel , Laurenz Wiskott

The article presents an efficient image reconstruction algorithm for single scattering optical tomography (SSOT) in circular geometry of data acquisition. This novel medical imaging modality uses photons of light that scatter once in the…

Numerical Analysis · Mathematics 2016-03-08 Gaik Ambartsoumian , Souvik Roy

This paper considers the inversion of ill-posed linear operators. To regularise the problem the solution is enforced to lie in a non-convex subset. Theoretical properties for the stable inversion are derived and an iterative algorithm akin…

Numerical Analysis · Mathematics 2009-11-30 Thomas Blumensath

We introduce a technique for recovering a sufficiently smooth function from its ray transform over a wide class of curves in a general region of Euclidean space. The method is based on a complexification of the underlying vector fields…

Complex Variables · Mathematics 2010-11-17 Nicholas Hoell , Guillaume Bal

We first give a constructive answer to the attenuated tensor tomography problem on simple surfaces. We then use this result to propose two approaches to produce vector-valued integral transforms which are fully injective over tensor fields.…

Differential Geometry · Mathematics 2018-11-30 Venkateswaran P. Krishnan , Rohit Kumar Mishra , François Monard

We characterize discrete (anti-)unitary symmetries and their non-invertible generalizations in $2+1$d topological quantum field theories (TQFTs) through their actions on line operators and fusion spaces. We explain all possible sources of…

High Energy Physics - Theory · Physics 2023-09-28 Matthew Buican , Rajath Radhakrishnan

In this paper, we study multi-dimensional image recovery. Recently, transform-based tensor nuclear norm minimization methods are considered to capture low-rank tensor structures to recover third-order tensors in multi-dimensional image…

Image and Video Processing · Electrical Eng. & Systems 2022-06-15 Yi-Si Luo , Xi-Le Zhao , Tai-Xiang Jiang , Yi Chang , Michael K. Ng , Chao Li

We consider the inverse scattering problem for sparse scatterers. An image reconstruction algorithm is proposed that is based on a nonlinear generalization of iterative hard thresholding. The convergence and error of the method was analyzed…

Numerical Analysis · Mathematics 2019-03-27 Anna C. Gilbert , Howard W. Levinson , John C. Schotland

We present an algorithm for solving inverse problems on graphs analogous to those arising in diffuse optical tomography for continuous media. In particular, we formulate and analyze a discrete version of the inverse Born series, proving…

Combinatorics · Mathematics 2017-04-26 Francis J. Chung , Anna C. Gilbert , Jeremy G. Hoskins , John C. Schotland

Multi-energy computed tomography (ME-CT) is an x-ray transmission imaging technique that uses the energy dependence of x-ray photon attenuation to determine the elemental composition of an object of interest. Mathematically, forward ME-CT…

Medical Physics · Physics 2022-02-16 Guillaume Bal , Ruoming Gong , Fatma Terzioglu

Many authors studied numeric algorithms for solving the linear systems of the pentadiagonal type. The well-known Fast Pentadiagonal System Solver algorithm is an example of such algorithms. The current article are described new numeric and…

Numerical Analysis · Mathematics 2015-01-05 A. A. Karawia

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

This paper constructs a semi-discrete tight frame of tensor needlets associated with a quadrature rule for tangent vector fields on the unit sphere $\mathbb{S}^2$ of $\mathbb{R}^3$ --- tensor needlets. The proposed tight tensor needlets…

Numerical Analysis · Mathematics 2019-08-01 Ming Li , Philip Broadbridge , Andriy Olenko , Yu Guang Wang

Cosmological perturbation theory is a powerful tool to predict the statistics of large-scale structure in the weakly non-linear regime, but even at 1-loop order it results in computationally expensive mode-coupling integrals. Here we…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-17 Xiao Fang , Jonathan A. Blazek , Joseph E. McEwen , Christopher M. Hirata

We show that symmetrically padded convolution can be analytically inverted via DFT. We comprehensively analyze several different symmetric and anti-symmetric padding modes and show that multiple cases exist where the inversion can be…

Computer Vision and Pattern Recognition · Computer Science 2023-03-31 Bo Li

Image recovery in optical interferometry is an ill-posed nonlinear inverse problem arising from incomplete power spectrum and bispectrum measurements. We reformulate this nonlin- ear problem as a linear problem for the supersymmetric rank-1…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 Anna Auria , Rafael Carrillo , Jean-Philippe Thiran , Yves Wiaux

We present a reconstruction method that stably recovers the real valued, symmetric tensors compactly supported in the Euclidean plane, from knowledge of their attenuated momenta ray transform. The problem is recast as an inverse boundary…

Analysis of PDEs · Mathematics 2024-05-09 Hiroshi Fujiwara , David Omogbhe , Kamran Sadiq , Alexandru Tamasan

We introduce a new numerical method for the computation of the inverse nonlinear Fourier transform and compare its computational complexity and accuracy to those of other methods available in the literature. For a given accuracy, the…

Numerical Analysis · Mathematics 2015-11-26 Stella Civelli , Luigi Barletti , Marco Secondini

Marine Controlled Source Electromagnetic (CSEM) is employed both in large-scale geophysical applications as well as within exploration of hydrocarbons and gas hydrates. Due to the diffusive character of the EM field only very low…

Geophysics · Physics 2022-11-08 Feng-Ping Li , Vemund Stenbekk Thorkildsen , Leiv-J Gelius , Jian-Hua Yue