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Noise and Bias In Square-Root Compression Schemes

Bernstein, Gary M. and Bebek, Chris and Rhodes, Jason and Stoughton, Chris and Vanderveld, R. Ali and Yeh, Penshu (2010) Noise and Bias In Square-Root Compression Schemes. Publications of the Astronomical Society of the Pacific, 122 (889). pp. 336-346. ISSN 0004-6280.

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We investigate data compression schemes for proposed all-sky diffraction-limited visible/NIR sky surveys aimed at the dark-energy problem. We show that lossy square-root compression to 1 bit pixel^(-1) of noise, followed by standard lossless compression algorithms, reduces the images to 2.5–4 bits pixel^(-1), depending primarily upon the level of cosmic-ray contamination of the images. Compression to this level adds noise equivalent to ≤ 10% penalty in observing time. We derive an analytic correction to flux biases inherent to the square-root compression scheme. Numerical tests on simple galaxy models confirm that galaxy fluxes and shapes are measured with systematic biases ≾ 10^-4 induced by the compression scheme, well below the requirements of supernova and weak gravitational lensing dark-energy experiments. In a related investigation, Vanderveld and coworkers bound the shape biases using realistic simulated images of the high-Galactic–latitude sky. The square-root preprocessing step has advantages over simple (linear) decimation when there are many bright objects or cosmic rays in the field, or when the background level will vary.

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Additional Information:© 2010. The Astronomical Society of the Pacific. Received 2009 October 23; accepted 2010 January 13; published 2010 February 18. The work of J. R. and R. A. V. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA, and was funded by JPL’s Research and Technology Development Funds. G. B. is supported by grant AST-0607667 from the NSF and the US Department of Energy (DOE) grant DE-FG02-95ER40893. C. B. is supported by the Director, Office of Science, Office of High Energy Physics, of the DOE under grant DE-AC02-05CH11231. Fermilab is operated by Fermi Research Alliance, LLC under DOE grant DE-AC02-07CH11359.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-95ER40893
Department of Energy (DOE)DE-AC02-05CH11231
Department of Energy (DOE)DE-AC02-07CH11359
Issue or Number:889
Record Number:CaltechAUTHORS:20100331-093310360
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Official Citation:Noise and Bias In Square-Root Compression Schemes Gary M. Bernstein, Chris Bebek, Jason Rhodes, Chris Stoughton, R. Ali Vanderveld, and Penshu Yeh Publications of the Astronomical Society of the Pacific 2010 122:889, 336-346
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17825
Deposited By: Ruth Sustaita
Deposited On:31 Mar 2010 21:21
Last Modified:03 Oct 2019 01:34

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