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The problem of establishing out-of-sample bounds for the values of an unkonwn ground-truth function is considered. Kernels and their associated Hilbert spaces are the main formalism employed herein along with an observational model where…

Machine Learning · Computer Science 2022-09-13 Paul Scharnhorst , Emilio T. Maddalena , Yuning Jiang , Colin N. Jones

We give properties of strict pseudocontractions and demicontractions defined on a Hilbert space, which constitute wide classes of operators that arise in iterative methods for solving fixed point problems. In particular, we give necessary…

Optimization and Control · Mathematics 2023-07-17 Andrzej Cegielski

Undersampling the k-space during MR acquisitions saves time, however results in an ill-posed inversion problem, leading to an infinite set of images as possible solutions. Traditionally, this is tackled as a reconstruction problem by…

Image and Video Processing · Electrical Eng. & Systems 2022-02-10 Kerem C. Tezcan , Neerav Karani , Christian F. Baumgartner , Ender Konukoglu

We address in this paper the following two closely related problems: 1. How to represent functions with singularities (up to a prescribed accuracy) in a compact way? 2. How to reconstruct such functions from a small number of measurements?…

Classical Analysis and ODEs · Mathematics 2007-11-01 Boris Ettinger , Niv Sarig , Yosef Yomdin

Compressed sensing is an image reconstruction technique to achieve high-quality results from limited amount of data. In order to achieve this, it utilizes prior knowledge about the samples that shall be reconstructed. Focusing on image…

In approximation of functions based on point values, least-squares methods provide more stability than interpolation, at the expense of increasing the sampling budget. We show that near-optimal approximation error can nevertheless be…

Numerical Analysis · Mathematics 2024-02-14 Abdellah Chkifa , Matthieu Dolbeault

We study combinatorial group testing schemes for learning $d$-sparse Boolean vectors using highly unreliable disjunctive measurements. We consider an adversarial noise model that only limits the number of false observations, and show that…

Discrete Mathematics · Computer Science 2015-05-13 Mahdi Cheraghchi

We use compressed sensing to demonstrate theoretically the reconstruction of sub-wavelength features from measured far-field, and provide experimental proof-of-concept. The methods can be applied to non-optical microscopes, provided the…

Optics · Physics 2015-05-14 Snir Gazit , Alexander Szameit , Yonina C. Eldar , Mordechai Segev

Solving inverse problems requires the knowledge of the forward operator, but accurate models can be computationally expensive and hence cheaper variants that do not compromise the reconstruction quality are desired. This chapter reviews…

Numerical Analysis · Mathematics 2024-03-19 Simon Arridge , Andreas Hauptmann , Yury Korolev

Diffractive lenses have recently been applied to the domain of multispectral imaging in the X-ray and UV regimes where they can achieve very high resolution as compared to reflective and refractive optics. Conventionally, spectral…

Image and Video Processing · Electrical Eng. & Systems 2020-05-26 Evan Widloski , Ulas Kamaci , Farzad Kamalabadi

Finite-rate-of-innovation (FRI) signals are ubiquitous in applications such as radar, ultrasound, and time of flight imaging. Due to their finite degrees of freedom, FRI signals can be sampled at sub-Nyquist rates using appropriate sampling…

Signal Processing · Electrical Eng. & Systems 2021-07-02 Satish Mulleti , Haiyang Zhang , Yonina C. Eldar

Signal reconstruction from a sample using an orthogonal projector onto a guiding subspace is theoretically well justified, but may be difficult to practically implement. We propose more general guiding operators, which increase signal…

Computer Vision and Pattern Recognition · Computer Science 2017-09-08 Andrew Knyazev , Alexander Malyshev

We want to exactly reconstruct a sparse signal f (a vector in R^n of small support) from few linear measurements of f (inner products with some fixed vectors). A nice and intuitive reconstruction by Linear Programming has been advocated…

Numerical Analysis · Mathematics 2016-12-23 Mark Rudelson , Roman Vershynin

Recently it has been established that asymptotic incoherence can be used to facilitate subsampling, in order to optimize reconstruction quality, in a variety of continuous compressed sensing problems, and the coherence structure of certain…

Information Theory · Computer Science 2016-10-25 Alex Jones , Ben Adcock , Anders Hansen

This work introduces a novel method to generate snapshot data for operator inference that guarantees the exact reconstruction of intrusive projection-based reduced-order models (ROMs). To ensure exact reconstruction, the operator inference…

Numerical Analysis · Mathematics 2026-02-18 Henrik Rosenberger , Benjamin Sanderse , Giovanni Stabile

We consider $L^2$-approximation on weighted reproducing kernel Hilbert spaces of functions depending on infinitely many variables. We focus on unrestricted linear information, admitting evaluations of arbitrary continuous linear…

Numerical Analysis · Mathematics 2026-01-13 Kumar Harsha , Michael Gnewuch , Marcin Wnuk

This paper addresses the problem of regression to reconstruct functions, which are observed with superimposed errors at random locations. We address the problem in reproducing kernel Hilbert spaces. It is demonstrated that the estimator,…

Statistics Theory · Mathematics 2021-08-17 Paul Dommel , Alois Pichler

We study the space spanned by the integer shifts of a bivariate Gaussian function and the problem of reconstructing any function in that space from samples scattered across the plane. We identify a large class of lattices, or more generally…

Functional Analysis · Mathematics 2024-08-07 José Luis Romero , Alexander Ulanovskii , Ilya Zlotnikov

In tomographic reconstruction, the goal is to reconstruct an unknown object from a collection of line integrals. Given a complete sampling of such line integrals for various angles and directions, explicit inverse formulas exist to…

Numerical Analysis · Mathematics 2018-01-18 Tristan van Leeuwen , Simon Maretzke , K. Joost Batenburg

We propose a novel method to accurately reconstruct a set of images representing a single scene from few linear multi-view measurements. Each observed image is modeled as the sum of a background image and a foreground one. The background…

Computer Vision and Pattern Recognition · Computer Science 2013-09-19 Gilles Puy , Pierre Vandergheynst