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Combining undersampled dithered images. (1999)

by T R Lauer
Venue:PASP,
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Multisource data fusion and super-resolution from astronomical images

by A Jalobeanu , J A Gutiérrez , E Slezak , ( A Jalobeanu , J A Gutiérrez - Statistical Methodology , 2008
"... Abstract Virtual Observatories give us access to huge amounts of image data that are often redundant. Our goal is to take advantage of this redundancy by combining images of the same field of view into a single model. To achieve this goal, we propose to develop a multi-source data fusion method tha ..."
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Abstract Virtual Observatories give us access to huge amounts of image data that are often redundant. Our goal is to take advantage of this redundancy by combining images of the same field of view into a single model. To achieve this goal, we propose to develop a multi-source data fusion method that relies on probability and band-limited signal theory. The target object is an image to be inferred from a number of blurred and noisy sources, possibly from different sensors under various conditions (i.e. resolution, shift, orientation, blur, noise...). We aim at the recovery of a compound model "image+uncertainties" that best relates to the observations and contains a maximum of useful information from the initial data set. Thus, in some cases, spatial super-resolution may be required in order to preserve the information. We propose to use a Bayesian inference scheme to invert a forward model, which describes the image formation process for each observation and takes into account some a priori knowledge (e.g. stars as point sources). This involves both automatic registration and spatial resampling, which are ill-posed inverse problems that are addressed within a rigorous Bayesian framework. The originality of the work is in devising a new technique of multi-image data fusion that provides us with super-resolution, self-calibration and possibly model selection capabilities. This approach should outperform existing methods such as resample-and-add or drizzling since it can handle different instrument characteristics for each input image and compute uncertainty estimates as well. Moreover, it is designed to also work in a recursive way, so that the model can be updated when new data become available. Key words: Model-based data fusion, uncertainties, generative models, inverse problems, signal reconstruction, super-resolution, spatial resampling, resolution-limited, B-Splines Email addresses: jalobeanu@lsiit.u-strasbg.fr (A. Jalobeanu, J.A. Gutiérrez), slezak@obs-nice.fr (E. Slezak). URLs: lsiit-miv.u-strasbg.fr/paseo (A. Jalobeanu, J.A. Gutiérrez), www.obs-nice.fr/cassiopee (E. Slezak).
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... from aliasing due to inappropriate spatial discretization, which impedes any accurate measurement of physical quantities. We aim at solving this problem by reconstructing an image through a probabilistic framework, with Nyquist-Shannon sampling theory [10], geometry and noise modeling as basic ingredients. Our research area is closely related to super-resolution from blurred or undersampled images, a popular topic in computer vision [5]. Examples of algorithms applied to astronomical data can be found in [6] where a fast resampling and co-addition is performed using an arbitrary geometry, in [13] where images are combined in the Fourier domain, assuming pure translational motion between the frames, or in [21] where wavelet-based priors help constrain the super-resolved solution. Super-resolution has also been applied to planetary imaging or remote sensing [3]. However, in order to minimize information loss, it is necessary to build the fused model as a multivariate probability distribution, rather than a conventional (image-like) solution. As observations are realizations of random variables, restricting the result to a deterministic object would mean a loss of uncertainties as well a...

Observational probes of cosmic . . .

by David H. Weinberg, Michael J. Mortonson, Daniel J. Eisenstein, Christopher Hirata, Adam G. Riess, Eduardo Rozo , 2013
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VISTA Data Flow System: Pipeline Processing for WFCAM and VISTA

by Mike Irwina, Jim Lewisa, Simon Hodgkina, Peter Bunclarka, Dafydd Evansa, Mcmahona Jim Emersonb, Malcolm Stewartc, Steven Beardc
"... The UKIRT Wide Field Camera (WFCAM) on Mauna Kea and the VISTA IR mosaic camera at ESO, Paranal, with respectively 4 Rockwell 2kx2k and 16 Raytheon 2kx2k IR arrays on 4m-class telescopes, represent an enormous leap in deep IR survey capability. With combined nightly data-rates of typically 1TB, auto ..."
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The UKIRT Wide Field Camera (WFCAM) on Mauna Kea and the VISTA IR mosaic camera at ESO, Paranal, with respectively 4 Rockwell 2kx2k and 16 Raytheon 2kx2k IR arrays on 4m-class telescopes, represent an enormous leap in deep IR survey capability. With combined nightly data-rates of typically 1TB, automated pipeline processing and data management requirements are paramount. Pipeline processing of IR data is far more technically challenging than for optical data. IR detectors are inherently more unstable, while the sky emission is over 100 times brighter than most objects of interest, and varies in a complex spatial and temporal manner. In this presentation we describe the pipeline architecture being developed to deal with the IR imaging data from WFCAM and VISTA, and discuss the primary issues involved in an end-to-end system capable of: robustly removing instrument and night sky signatures; monitoring data quality and system integrity; providing astro-metric and photometric calibration; and generating photon noise-limited images and astronomical catalogues. Accompanying papers by Emerson et al. and Hambly et al. provide an overview of the project and a detailed description of the science archive aspects.
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