English
Related papers

Related papers: Faraday Tomography with Sparse Modeling

200 papers

We present the experimental reconstruction of sub-wavelength features from the far-field of sparse optical objects. We show that it is sufficient to know that the object is sparse, and only that, and recover 100 nm features with the…

(arXiv abridged abstract) The current years are seeing huge developments of radio telescopes and a tremendous increase of their capabilities. Such systems make mandatory the design of more sophisticated techniques not only for transporting,…

Instrumentation and Methods for Astrophysics · Physics 2015-03-18 Arwa Dabbech , Chiara Ferrari , David Mary , Eric Slezak , Oleg Smirnov , Jonathan S. Kenyon

Optical interferometers provide multiple wavelength measurements. In order to fully exploit the spectral and spatial resolution of these instruments, new algorithms for image reconstruction have to be developed. Early attempts to deal with…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Éric Thiébaut , Ferréol Soulez , Loïc Denis

This paper extends the sample complexity theory for ill-posed inverse problems developed in a recent work by the authors [`Compressed sensing for inverse problems and the sample complexity of the sparse Radon transform', J. Eur. Math. Soc.,…

Functional Analysis · Mathematics 2025-01-06 Giovanni S. Alberti , Alessandro Felisi , Matteo Santacesaria , S. Ivan Trapasso

This paper provides a general introduction to the problem of image reconstruction from interferometric data. A simple model of the interferometric observables is given and the issues arising from sparse Fourier data are discussed. The…

Instrumentation and Methods for Astrophysics · Physics 2017-08-29 Éric Thiébaut , John Young

Faraday rotation describes the change of the linear polarization angle of radiation passing through a magnetized plasma and it is quantified by the rotation measure (RM), which is related to the line-of-sight (LOS) magnetic field component…

Magnetic Particle Imaging (MPI) is a preclinical imaging technique capable of visualizing the spatio-temporal distribution of magnetic nanoparticles. The image reconstruction of this fast and dynamic process relies on efficiently solving an…

Numerical Analysis · Mathematics 2021-09-15 Florian Lieb , Tobias Knopp

This paper addresses the problem of expressing a signal as a sum of frequency components (sinusoids) wherein each sinusoid may exhibit abrupt changes in its amplitude and/or phase. The Fourier transform of a narrow-band signal, with a…

Machine Learning · Computer Science 2013-02-27 Yin Ding , Ivan W. Selesnick

In this paper, we describe the principle of a multi-aperture interferometer that uses a phase-shifting technique and is suitable for quick, snapshot imaging of astrophysical objects at extreme angular resolution through Fourier inversion. A…

Optics · Physics 2015-05-28 Francois Henault

Coherent X-ray photons with energies higher than 50 keV offer new possibilities for imaging nanoscale lattice distortions in bulk crystalline materials using Bragg peak phase retrieval methods. However, the compression of reciprocal space…

Signal Processing · Electrical Eng. & Systems 2018-08-14 Siddharth Maddali , Irene Calvo-Almazan , Jonathan Almer , Peter Kenesei , Jun-Sang Park , Ross Harder , Youssef Nashed , Stephan Hruszkewycz

The FFT algorithm that implements the discrete Fourier transform is considered one of the top ten algorithms of the $20$th century. Its main strengths are the low computational cost of $\mathcal{O}(n \log n$) and its stability. It is one of…

Numerical Analysis · Mathematics 2017-06-15 Matteo Briani , Annie Cuyt , Wen-shin Lee

The reconstruction of Faraday depth structure from incomplete spectral polarization radio measurements using the RM Synthesis technique is an under-constrained problem requiring additional regularisation. In this paper we present cs-romer:…

Instrumentation and Methods for Astrophysics · Physics 2022-10-27 Miguel Cárcamo , Anna M. M. Scaife , Emma L. Alexander , J. Patrick Leahy

Image super-resolution (SR) is one of the long-standing and active topics in image processing community. A large body of works for image super resolution formulate the problem with Bayesian modeling techniques and then obtain its…

Computer Vision and Pattern Recognition · Computer Science 2012-09-20 Haichao Zhang , David Wipf , Yanning Zhang

Polarimetric imaging is one of the most effective techniques for high-contrast imaging and characterization of circumstellar environments. These environments can be characterized through direct-imaging polarimetry at near-infrared…

Instrumentation and Methods for Astrophysics · Physics 2021-09-29 Laurence Denneulin , Maud Langlois , Éric Thiébaut , Nelly Pustelnik

In this paper we propose a new approach for tomographic reconstruction with spatially varying regularization parameter. Our work is based on the SA-TV image restoration model proposed in [3] where an automated parameter selection rule for…

Numerical Analysis · Mathematics 2018-11-27 Yiqiu Dong , Carola-Bibiane Schönlieb

Ptychography is a popular imaging technique that combines diffractive imaging with scanning microscopy. The technique consists of a coherent beam that is scanned across an object in a series of overlapping positions, leading to reliable and…

Numerical Analysis · Mathematics 2024-08-08 Ricardo Parada , Samy Wu Fung , Stanley Osher

We present a novel algorithm, named the 2D-FFAST, to compute a sparse 2D-Discrete Fourier Transform (2D-DFT) featuring both low sample complexity and low computational complexity. The proposed algorithm is based on mixed concepts from…

Information Theory · Computer Science 2015-09-22 Frank Ong , Sameer Pawar , Kannan Ramchandran

In this paper, we propose a novel sparse recovery method based on the generalized error function. The penalty function introduced involves both the shape and the scale parameters, making it very flexible. The theoretical analysis results in…

Numerical Analysis · Mathematics 2021-06-04 Zhiyong Zhou

The phenomenon of Faraday rotation of linearly polarized synchrotron emission in a magneto-ionized medium has been understood and studied for decades. But since the sense of the rotation itself is irrelevant in most contexts, some…

Astrophysics of Galaxies · Physics 2021-07-14 K. Ferrière , J. L. West , T. R. Jaffe

We present a principled Bayesian framework for signal reconstruction, in which the signal is modelled by basis functions whose number (and form, if required) is determined by the data themselves. This approach is based on a Bayesian…

Instrumentation and Methods for Astrophysics · Physics 2019-01-23 Edward Higson , Will Handley , Michael Hobson , Anthony Lasenby