Maximum entropy image reconstruction: general algorithm

Skilling, John; Bryan, R. K.

doi:10.1093/mnras/211.1.111

Cited by 919 publications

(670 citation statements)

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“…The so-called Cambridge algorithm (Skilling and Bryan, 1984;Gull and Skilling, 1999) for MEM analysis is another longed-for-feature, which may be useful in structure refinement from powder diffraction data. To achieve the above improvements, we have recently developed a new generation of MEM-analysis program Dysnomia (Izumi and Momma, 2011;Momma and Izumi, 2011a), which is a successor to PRIMA.…”

Section: Introductionmentioning

confidence: 99%

Dysnomia, a computer program for maximum-entropy method (MEM) analysis and its performance in the MEM-based pattern fitting

et al. 2013

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A computer program, Dysnomia, for the maximum-entropy method (MEM) has been tested for the evaluation and advancement of MEM-based pattern fitting (MPF). Dysnomia is a successor to PRIMA, which was the only program integrated with RIETAN-FP for MPF. Two types of MEM algorithms, i.e., 0th-order single-pixel approximation and a variant of the Cambridge algorithm, were implemented in Dysnomia in combination with a linear combination of the "generalized F constraints" and arbitrary weighting factors for them. Dysnomia excels PRIMA in computation speed, memory efficiency, and scalability owing to parallel processing and automatic switching of discrete Fourier transform and fast Fourier transform depending on sizes of grids and observed reflections. These features of Dysnomia were evaluated for MPF analyses from X-ray powder diffraction data of three different types of compounds: taurine, Cu 2 CO 3 (OH) 2 (malachite), and Sr 9 In(PO 4 ) 7 . Reliability indices in MPF analyses proved to have been improved by using multiple F constraints and weighting factors based on lattice-plane spacings, d, in comparison with those obtained with PRIMA.

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Section: Introductionmentioning

confidence: 99%

Dysnomia, a computer program for maximum-entropy method (MEM) analysis and its performance in the MEM-based pattern fitting

et al. 2013

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“…Because the one-dimensional data light curve cannot fully constrain a two-dimensional map, additional freedom remains to optimise some map property. A maximum entropy (MEM) procedure [56,57] is used to select, among all possible solutions, the one that maximises the entropy of the eclipse map with respect to a smooth default map.…”

Section: Principles and Inner Workingsmentioning

confidence: 99%

Eclipse Mapping: Astrotomography of Accretion Discs

Baptista¹

2016

Astronomy at High Angular Resolution

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The Eclipse Mapping Method is an indirect imaging technique that transforms the shape of the eclipse light curve into a map of the surface brightness distribution of the occulted regions. Three decades of application of this technique to the investigation of the structure, the spectrum and the time evolution of accretion discs around white dwarfs in cataclysmic variables have enriched our understanding of these accretion devices with a wealth of details such as (but not limited to) moving heating/cooling waves during outbursts in dwarf novae, tidally-induced spiral shocks of emitting gas with sub-Keplerian velocities, elliptical precessing discs associated to superhumps, and measurements of the radial run of the disc viscosity through the mapping of the disc flickering sources. This chapter reviews the principles of the method, discusses its performance, limitations, useful error propagation procedures, and highlights a selection of applications aimed at showing the possible scientific problems that have been and may be addresses with it.

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“…In order to choose a unique solution some additional constraint, called regularisation, is usually applied. Our code uses the Skilling & Bryan (1984) maximum entropy optimisation scheme which produces an image with the minimum amount of information required to fit the data.…”

Section: Detecting and Mapping Magnetic Fieldsmentioning

confidence: 99%

Do young Suns undergo magnetic reversals?

et al. 2009

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Abstract.A key part of the modern-day regenerative solar magnetic dynamo is the reversal of the Sun's global magnetic field every eleven years. However, recent theoretical models indicate that young-rapidly rotating Sun-like stars may not always undergo full magnetic reversals, but instead may sometimes undergo "attempted" reversals where the magnetic field declines in strength only to return with the same polarity. Using the technique of Zeeman Doppler imaging we have mapped the magnetic field topology of a small sample of young Sun-like stars at multiple epochs, and present tentative evidence of an "attempted" magnetic field reversal on one of our stars.

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Maximum entropy image reconstruction: general algorithm

Abstract: Maximum entropy is an optimal technique of image reconstruction, widely applicable in astronomy and elsewhere. We present a general-purpose algorithm, capable of generating maximum entropy images from a wide variety of types of data.

Cited by 919 publications

References 0 publications

Dysnomia, a computer program for maximum-entropy method (MEM) analysis and its performance in the MEM-based pattern fitting

Dysnomia, a computer program for maximum-entropy method (MEM) analysis and its performance in the MEM-based pattern fitting

Eclipse Mapping: Astrotomography of Accretion Discs

Do young Suns undergo magnetic reversals?

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