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A nonlinear optimization method is proposed for the solution of inverse medium problems with spatially varying properties. To avoid the prohibitively large number of unknown control variables resulting from standard grid-based…

Numerical Analysis · Mathematics 2023-07-28 Yannik G. Gleichmann , Marcus J. Grote

We present a novel inverse rendering-based framework to estimate the 3D shape (per-pixel surface normals and depth) of objects and scenes from single-view polarization images, the problem popularly known as Shape from Polarization (SfP).…

Computer Vision and Pattern Recognition · Computer Science 2024-07-15 Ashish Tiwari , Shanmuganathan Raman

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

It was shown by E. Gluskin and V.D. Milman in [GAFA Lecture Notes in Math. 1807, 2003] that the classical arithmetic-geometric mean inequality can be reversed (up to a multiplicative constant) with high probability, when applied to…

Classical Analysis and ODEs · Mathematics 2018-10-16 Zakhar Kabluchko , Joscha Prochno , Vladislav Vysotsky

We consider the inverse problem of the broken ray transform (sometimes also referred to as the V-line transform). Explicit image reconstruction formulas are derived and tested numerically. The obtained formulas are generalizations of the…

Mathematical Physics · Physics 2011-01-07 Lucia Florescu , Vadim A. Markel , John C. Schotland

We propose iterative inversion algorithms for weighted Radon transforms $R_W$ along hyperplanes in $R^3$. More precisely, expandingthe weight $W = W (x, \theta), x \in R^3 , \theta \in S^2$ , into the series of spherical harmonics in…

Mathematical Physics · Physics 2017-11-22 F Goncharov

As the continuation of the contour mean calculation - designed for averaging the manual delineations of 3D layer stack images - in this paper, the most important equations: a) the reparameterization equations to determine the minimizing…

Metric Geometry · Mathematics 2019-08-01 Jozsef Molnar , Peter Horvath

Let $\mathcal R$ denote the generalized Radon transform (GRT), which integrates over a family of $N$-dimensional smooth submanifolds $\mathcal S_{\tilde y}\subset\mathcal U$, $1\le N\le n-1$, where an open set $\mathcal U\subset\mathbb R^n$…

Numerical Analysis · Mathematics 2021-02-19 Alexander Katsevich

We propose fast, exact and efficient algorithms for the convolution of two arbitrary functions on the sphere which speed up computations by a factor \order{\sqrt{N}} compared to present methods where $N$ is the number of pixels. No…

Astrophysics · Physics 2009-10-31 Benjamin D. Wandelt , Krzysztof M. Gorski

The spherical Radon transform (SRT) is an integral transform that maps a function to its integrals over concentric spherical shells centered at specified sensor locations. It has several imaging applications, including synthetic aperture…

Image and Video Processing · Electrical Eng. & Systems 2024-02-27 Luke Lozenski , Refik Mert Cam , Mark A. Anastasio , Umberto Villa

This work explores the behaviour of demagnetizing tensors for general ellipsoids under arbitrary rotations in homogeneous magnetic fields. The work is motivated by the concerns in magnetic resonance imaging safety and their practical…

Medical Physics · Physics 2025-09-04 Tomppa Pakarinen

We propose an inverse scattering scheme of recovering a polyhedral obstacle in $\mathbb{R}^n$, $n=2,3$, by only a few high-frequency acoustic backscattering measurements. The obstacle could be sound-soft or sound-hard. It is shown that the…

Analysis of PDEs · Mathematics 2015-02-05 Jingzhi Li , Hongyu Liu

We introduce a new method for the reconstruction of a function from linear measurements by means of oblique projections. The space spanned by the measurement vectors may be different from the subspace in which the function is reconstructed.…

Numerical Analysis · Mathematics 2013-12-09 Peter Berger , Karlheinz Gröchenig

Single photon emission computed tomography (SPECT) is a well established clinical tool for functional imaging. A limitation of current SPECT systems is the use of mechanical collimation, where only a small fraction of the emitted photons is…

Numerical Analysis · Mathematics 2016-07-05 Sunghwan Moon , Markus Haltmeier

From the optimization point of view, a difficulty with parallel MRI with simultaneous coil sensitivity estimation is the multiplicative nature of the non-linear forward operator: the image being reconstructed and the coil sensitivities…

Numerical Analysis · Mathematics 2018-02-06 Yonggui Zhu , Tuomo Valkonen

The light field reconstruction from the focal stack can be mathematically formulated as an ill-posed integral equation inversion problem. Although the previous research about this problem has made progress both in practice and theory, its…

Functional Analysis · Mathematics 2025-02-06 Duo Liu , Gangrong Qu , Shan Gao

Super-resolution (SR) refers to a combination of optical design and signal processing techniques jointly employed to obtain reconstructed wave-fronts at a higher-resolution from multiple low-resolution samples, overcoming the intrinsic…

Instrumentation and Methods for Astrophysics · Physics 2025-12-22 Carlos M. Correia , Charlotte Z. Bond , João Aveiro , François Leroux , Cédric Taïssir Heritier , Christophe Vérinaud

In many applications of tomography, the acquired projections are either limited in number or contain a significant amount of noise. In these cases, standard reconstruction methods tend to produce artifacts that can make further analysis…

Numerical Analysis · Mathematics 2016-04-11 D. M. Pelt , K. J. Batenburg

This thesis is concerned with problems related to Synthetic Aperture Radar (SAR). The thesis is structured as follows: The first chapter explains what SAR is, and the physical and mathematical background is illuminated. The following…

Classical Analysis and ODEs · Mathematics 2010-10-26 Jens Klein

Reconstruction of a 3D shape from a single 2D image is a classical computer vision problem, whose difficulty stems from the inherent ambiguity of recovering occluded or only partially observed surfaces. Recent methods address this challenge…

Computer Vision and Pattern Recognition · Computer Science 2020-02-04 Yuan Yao , Nico Schertler , Enrique Rosales , Helge Rhodin , Leonid Sigal , Alla Sheffer