Background derivation and image flattening: getimages

被引：16

作者：

Men'shchikov, A. ^{[1
]}

机构：

[1] Univ Paris Diderot, Lab AIM Paris Saclay, Ctr Etud Saclay, CEA,DSM,CNRS,IRFU,Serv Astrophys, F-91191 Gif Sur Yvette, France

来源：

ASTRONOMY & ASTROPHYSICS | 2017年 / 607卷

关键词：

stars: formation; infrared: ISM; submillimeter: ISM; methods: data analysis; techniques: image processing; techniques: photometric;

D O I：

10.1051/0004-6361/201730925

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Modern high-resolution images obtained with space observatories display extremely strong intensity variations across images on all spatial scales. Source extraction in such images with methods based on global thresholding may bring unacceptably large numbers of spurious sources in bright areas while failing to detect sources in low-background or low-noise areas. It would be highly beneficial to subtract background and equalize the levels of small-scale fluctuations in the images before extracting sources or filaments. This paper describes getimages, a new method of background derivation and image flattening. It is based on median filtering with sliding windows that correspond to a range of spatial scales from the observational beam size up to a maximum structure width X-lambda. The latter is a single free parameter of getimages that can be evaluated manually from the observed image I-lambda. The median filtering algorithm provides a background image (B) over tilde (lambda) for structures of all widths below X-lambda. The same median filtering procedure applied to an image of standard deviations D-lambda derived from a background-subtracted image (S) over tilde (lambda) results in a flattening image (F) over tilde (lambda). Finally, a flattened detection image I-lambda D=(S) over tilde (lambda)/(F) over tilde (lambda) is computed, whose standard deviations are uniform outside sources and filaments. Detecting sources in such greatly simplified images results in much cleaner extractions that are more complete and reliable. As a bonus, getimages reduces various observational and map-making artifacts and equalizes noise levels between independent tiles of mosaicked images.

引用

页数：14

共 12 条

[1]

Andre P., 2014, PROTOSTARS PLANETS, P27, DOI [DOI 10.2458/AZUUAPRESS9780816531240-CH002, DOI 10.2458/AZU_UAPRESS_9780816531240-CH002]

[2] From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt Survey [J].

Andre, Ph. ;

Men'shchikov, A. ;

Bontemps, S. ;

Koenyves, V. ;

Motte, F. ;

Schneider, N. ;

Didelon, P. ;

Minier, V. ;

Saraceno, P. ;

Ward-Thompson, D. ;

Di Francesco, J. ;

White, G. ;

Molinari, S. ;

Testi, L. ;

Abergel, A. ;

Griffin, M. ;

Henning, Th. ;

Royer, P. ;

Merin, B. ;

Vavrek, R. ;

Attard, M. ;

Arzoumanian, D. ;

Wilson, C. D. ;

Ade, P. ;

Aussel, H. ;

Baluteau, J. -P. ;

Benedettini, M. ;

Bernard, J. -Ph. ;

Blommaert, J. A. D. L. ;

Cambresy, L. ;

Cox, P. ;

Di Giorgio, A. ;

Hargrave, P. ;

Hennemann, M. ;

Huang, M. ;

Kirk, J. ;

Krause, O. ;

Launhardt, R. ;

Leeks, S. ;

Le Pennec, J. ;

Li, J. Z. ;

Martin, P. G. ;

Maury, A. ;

Olofsson, G. ;

Omont, A. ;

Peretto, N. ;

Pezzuto, S. ;

Prusti, T. ;

Roussel, H. ;

Russeil, D. .

ASTRONOMY & ASTROPHYSICS, 2010, 518

[3] SExtractor: Software for source extraction [J].

Bertin, E ;

Arnouts, S .

ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES, 1996, 117 (02) :393-404

[4] BOYLES LAW AND GRAVITATIONAL INSTABILITY [J].

BONNOR, WB .

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1956, 116 (03) :351-359

[5] A multi-scale filament extraction method: getfilaments [J].

Men'shchikov, A. .

ASTRONOMY & ASTROPHYSICS, 2013, 560

[6] A multi-scale, multi-wavelength source extraction method: getsources [J].

Men'shchikov, A. ;

Andre, Ph ;

Didelon, P. ;

Motte, F. ;

Hennemann, M. ;

Schneider, N. .

ASTRONOMY & ASTROPHYSICS, 2012, 542

[7] Filamentary structures and compact objects in the Aquila and Polaris clouds observed by Herschel [J].

Men'shchikov, A. ;

Andre, Ph. ;

Didelon, P. ;

Koenyves, V. ;

Schneider, N. ;

Motte, F. ;

Bontemps, S. ;

Arzoumanian, D. ;

Attard, M. ;

Abergel, A. ;

Baluteau, J. -P. ;

Bernard, J. -Ph. ;

Cambresy, L. ;

Cox, P. ;

Di Francesco, J. ;

Di Giorgio, A. M. ;

Griffin, M. ;

Hargrave, P. ;

Huang, M. ;

Kirk, J. ;

Li, J. Z. ;

Martin, P. ;

Minier, V. ;

Miville-Deschenes, M. -A. ;

Molinari, S. ;

Olofsson, G. ;

Pezzuto, S. ;

Roussel, H. ;

Russeil, D. ;

Saraceno, P. ;

Sauvage, M. ;

Sibthorpe, B. ;

Spinoglio, L. ;

Testi, L. ;

Ward-Thompson, D. ;

White, G. ;

Wilson, C. D. ;

Woodcraft, A. ;

Zavagno, A. .

ASTRONOMY & ASTROPHYSICS, 2010, 518

[8]

MENSHCHIKOV A, 2016, A A, V593

[9] Source extraction and photometry for the far-infrared and sub-millimeter continuum in the presence of complex backgrounds [J].

Molinari, S. ;

Schisano, E. ;

Faustini, F. ;

Pestalozzi, M. ;

Di Giorgio, A. M. ;

Liu, S. .

ASTRONOMY & ASTROPHYSICS, 2011, 530

[10] Initial highlights of the HOBYS key program, the Herschel imaging survey of OB young stellar objects [J].

Motte, F. ;

Zavagno, A. ;

Bontemps, S. ;

Schneider, N. ;

Hennemann, M. ;

Di Francesco, J. ;

Andre, Ph. ;

Saraceno, P. ;

Griffin, M. ;

Marston, A. ;

Ward-Thompson, D. ;

White, G. ;

Minier, V. ;

Men'shchikov, A. ;

Hill, T. ;

Abergel, A. ;

Anderson, L. D. ;

Aussel, H. ;

Balog, Z. ;

Baluteau, J. -P. ;

Bernard, J. -Ph. ;

Cox, P. ;

Csengeri, T. ;

Deharveng, L. ;

Didelon, P. ;

di Giorgio, A. -M. ;

Hargrave, P. ;

Huang, M. ;

Kirk, J. ;

Leeks, S. ;

Li, J. Z. ;

Martin, P. ;

Molinari, S. ;

Nguyen-Luong, Q. ;

Olofsson, G. ;

Persi, P. ;

Peretto, N. ;

Pezzuto, S. ;

Roussel, H. ;

Russeil, D. ;

Sadavoy, S. ;

Sauvage, M. ;

Sibthorpe, B. ;

Spinoglio, L. ;

Testi, L. ;

Teyssier, D. ;

Vavrek, R. ;

Wilson, C. D. ;

Woodcraft, A. .

ASTRONOMY & ASTROPHYSICS, 2010, 518

← 1 2 →