Flexible Image Transport System (FITS) is an open standard defining a digital file format useful for storage, transmission and processing of data: formatted as multi-dimensional arrays (for example a 2D image), or tables.[3] FITS is the most commonly used digital file format in astronomy. The FITS standard was designed specifically for astronomical data, and includes provisions such as describing photometric and spatial calibration information, together with image origin metadata.
The FITS format was first standardized in 1981;[4] it has evolved gradually since then, and the most recent version (4.0) was standardized in 2016. FITS was designed with an eye towards long-term archival storage, and the maxim once FITS, always FITS represents the requirement that developments to the format must be backward compatible.
Image metadata is stored in a human-readable ASCII header. The information in this header is designed to calculate the byte offset of some information in the subsequent data unit to support direct access to the data cells. Each FITS file consists of one or more headers containing ASCII card images[a] that carry keyword/value pairs, interleaved between data blocks. The keyword/value pairs provide information such as size, origin, coordinates, binary data format, free-form comments, history of the data, and anything else the creator desires: while many keywords are reserved for FITS use, the standard allows arbitrary use of the rest of the name-space.
FITS is also often used to store non-image data, such as spectra, photon lists, data cubes, or structured data such as multi-table databases. A FITS file may contain several extensions, and each of these may contain a data object. For example, it is possible to store x-ray and infrared exposures in the same file.
The earliest and still most commonly used type of FITS data is an image header/data block.[citation needed] The term 'image' is somewhat loosely applied, as the format supports data arrays of arbitrary dimension—normal image data are usually 2-D or 3-D, with the third dimension representing for example time or the color plane. The data themselves may be in one of several integer and floating-point formats, specified in the header.
FITS image headers can contain information about one or more scientific coordinate systems that are overlaid on the image itself. Images contain an implicit Cartesian coordinate system that describes the location of each pixel in the image, but scientific uses usually require working in 'world' coordinates, for example the celestial coordinate system. As FITS has been generalized from its original form, the world coordinate system (WCS) specifications have become more and more sophisticated: early FITS images allowed a simple scaling factor to represent the size of the pixels; but recent versions of the standard permit multiple nonlinear coordinate systems, representing arbitrary distortions of the image. The WCS standard includes many different spherical projections, including, for example, the HEALPix spherical projection widely used in observing the cosmic microwave background radiation.[5]
Tables
FITS also supports tabular data with named columns and multidimensional rows. Both binary and ASCII table formats have been specified. The data in each column of the table can be in a different format from the others. Together with the ability to string multiple header/data blocks together, this allows FITS files to represent entire relational databases.
Image processing programs such as ImageJ, GIMP, Photoshop, Chasys Draw IES, XnView and IrfanView can generally read simple FITS images, but frequently cannot interpret more complex tables and databases. Scientific teams frequently write their own code to interact with their FITS data, using the tools available in their language of choice. The FITS Liberator software is used by imaging scientists at the European Space Agency, the European Southern Observatory and NASA.[9] The SAOImage DS9 Astronomical Data Visualization Application[10] is available for many OSs, and handles images and headers.[11]
Many scientific computing environments make use of the coordinate system data in the FITS header to display, compare, rectify, or otherwise manipulate FITS images. Examples are the coordinate transform library included with PDL, the PLOT MAP library in the Solarsoft solar-physics-related software tree, the Starlink Project AST library in C, and the PyFITS package in Python, now merged into the Astropy library.[12]
Current status
The FITS standard version 4.0 was officially approved by the IAU FITS Working Group in July 2016.[13][14]
^"Flexible Image Transport System: a new standard file format for long-term preservation projects?" (PDF). Vatican City. 2012-07-05. Retrieved 2013-03-06.
^Wells, D. C.; Greisen, E. W.; Harten, R. H. (June 1981). "FITS: A Flexible Image Transport System". Astronomy and Astrophysics Supplement Series. 44: 363–370. Bibcode:1981A&AS...44..363W.
^Greisen, E. W.; Calabretta, M. R. (December 2002). "Representations of world coordinates in FITS". Astronomy and Astrophysics. 395 (3): 1061–1075. arXiv:astro-ph/0207407. Bibcode:2002A&A...395.1061G. doi:10.1051/0004-6361:20021326. S2CID 3248582.
^FITS Working Group (2016-07-22). "Definition of the Flexible Image Transport System (FITS)" (PDF). Retrieved 2018-03-05.
^"Recent FITS Activities and Issues". 2016-07-22. Retrieved 2018-03-05.
^ abcdeFITS Standard Document, FITS Documentation Page, High Energy Astrophysics Science Archive Research Center
External links
Official website, Goddard Support Office
FITS Birthday Announcement - Historical note from Don Wells on the events leading up to the 'birth' of the FITS format in 1979.
FITS I/O Libraries, a list of software for reading and writing FITS files for various languages
SAOImage DS9
March 04, 2023
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For other uses see FITS disambiguation Flexible Image Transport System FITS is an open standard defining a digital file format useful for storage transmission and processing of data formatted as multi dimensional arrays for example a 2D image or tables 3 FITS is the most commonly used digital file format in astronomy The FITS standard was designed specifically for astronomical data and includes provisions such as describing photometric and spatial calibration information together with image origin metadata FITSFilename extension fits fit ftsInternet media typeimage fitsapplication fits 1 Developed byIAU FITS Working Group 2 Initial release1981 42 years ago 1981 Latest release4 0July 2016 6 years ago 2016 07 Type of formatimage format structured dataWebsitefits wbr gsfc wbr nasa wbr govThe FITS format was first standardized in 1981 4 it has evolved gradually since then and the most recent version 4 0 was standardized in 2016 FITS was designed with an eye towards long term archival storage and the maxim once FITS always FITS represents the requirement that developments to the format must be backward compatible Image metadata is stored in a human readable ASCII header The information in this header is designed to calculate the byte offset of some information in the subsequent data unit to support direct access to the data cells Each FITS file consists of one or more headers containing ASCII card images a that carry keyword value pairs interleaved between data blocks The keyword value pairs provide information such as size origin coordinates binary data format free form comments history of the data and anything else the creator desires while many keywords are reserved for FITS use the standard allows arbitrary use of the rest of the name space FITS is also often used to store non image data such as spectra photon lists data cubes or structured data such as multi table databases A FITS file may contain several extensions and each of these may contain a data object For example it is possible to store x ray and infrared exposures in the same file Contents 1 Images 2 Tables 3 Using FITS files 4 Current status 5 See also 6 Notes 7 References 8 External linksImages EditThe earliest and still most commonly used type of FITS data is an image header data block citation needed The term image is somewhat loosely applied as the format supports data arrays of arbitrary dimension normal image data are usually 2 D or 3 D with the third dimension representing for example time or the color plane The data themselves may be in one of several integer and floating point formats specified in the header FITS image headers can contain information about one or more scientific coordinate systems that are overlaid on the image itself Images contain an implicit Cartesian coordinate system that describes the location of each pixel in the image but scientific uses usually require working in world coordinates for example the celestial coordinate system As FITS has been generalized from its original form the world coordinate system WCS specifications have become more and more sophisticated early FITS images allowed a simple scaling factor to represent the size of the pixels but recent versions of the standard permit multiple nonlinear coordinate systems representing arbitrary distortions of the image The WCS standard includes many different spherical projections including for example the HEALPix spherical projection widely used in observing the cosmic microwave background radiation 5 Tables EditFITS also supports tabular data with named columns and multidimensional rows Both binary and ASCII table formats have been specified The data in each column of the table can be in a different format from the others Together with the ability to string multiple header data blocks together this allows FITS files to represent entire relational databases Using FITS files EditFITS support is available in a variety of programming languages that are used for scientific work including C 6 C C Fortran 6 IGOR Pro IDL Java Julia 7 LabVIEW Mathematica MATLAB Perl Perl Data Language PDL Python R and Tcl The FITS Support Office at NASA GSFC maintains a list of libraries and platforms that currently support FITS 8 SAOImage DS9 in FVWM2 Image processing programs such as ImageJ GIMP Photoshop Chasys Draw IES XnView and IrfanView can generally read simple FITS images but frequently cannot interpret more complex tables and databases Scientific teams frequently write their own code to interact with their FITS data using the tools available in their language of choice The FITS Liberator software is used by imaging scientists at the European Space Agency the European Southern Observatory and NASA 9 The SAOImage DS9 Astronomical Data Visualization Application 10 is available for many OSs and handles images and headers 11 Many scientific computing environments make use of the coordinate system data in the FITS header to display compare rectify or otherwise manipulate FITS images Examples are the coordinate transform library included with PDL the PLOT MAP library in the Solarsoft solar physics related software tree the Starlink Project AST library in C and the PyFITS package in Python now merged into the Astropy library 12 Current status EditThe FITS standard version 4 0 was officially approved by the IAU FITS Working Group in July 2016 13 14 Release history FITS version b Release date Notes4 0 July 2016 15 3 0 July 2008 15 2 1b December 2005 15 Added support for 64 bit integer primary arrays and image extensionsNOST 100 2 0 March 1999 15 NOST 100 1 0 June 1993 15 See also EditAdvanced Scientific Data Format ASDF FITS Liberator Hierarchical Data Format HDF Common Data Format CDF NetCDF Aperture Photometry Tool APT Notes Edit 80 character fixed length strings MeaningRed Old Standard Draft not supportedYellow Old Standard still supportedGreen Current StandardBlue Future DraftReferences Edit MIME Sub type Registrations for Flexible Image Transport System FITS rfc4047 txt IAU FITS Working Group NASA Flexible Image Transport System a new standard file format for long term preservation projects PDF Vatican City 2012 07 05 Retrieved 2013 03 06 Wells D C Greisen E W Harten R H June 1981 FITS A Flexible Image Transport System Astronomy and Astrophysics Supplement Series 44 363 370 Bibcode 1981A amp AS 44 363W Greisen E W Calabretta M R December 2002 Representations of world coordinates in FITS Astronomy and Astrophysics 395 3 1061 1075 arXiv astro ph 0207407 Bibcode 2002A amp A 395 1061G doi 10 1051 0004 6361 20021326 S2CID 3248582 a b HEASARC Software NASA Goddard Space Flight Center FITSIO jl GitHub 15 February 2022 FITS I O Libraries NASA Goddard Space Flight Center Retrieved 2011 09 29 The ESA ESO NASA FITS Liberator 3 ESA SAOImageDS9 SAOImage DS9 Astronomical Data Visualization Application Harvard Smithsonian Center for Astrophysics PyFITS Space Telescope Science Institute Archived from the original on 2015 07 26 Retrieved 2013 11 04 FITS Working Group 2016 07 22 Definition of the Flexible Image Transport System FITS PDF Retrieved 2018 03 05 Recent FITS Activities and Issues 2016 07 22 Retrieved 2018 03 05 a b c d e FITS Standard Document FITS Documentation Page High Energy Astrophysics Science Archive Research CenterExternal links EditOfficial website Goddard Support Office FITS Birthday Announcement Historical note from Don Wells on the events leading up to the birth of the FITS format in 1979 FITS I O Libraries a list of software for reading and writing FITS files for various languages SAOImage DS9 Retrieved from https en wikipedia org w index php title FITS amp oldid 1091431488, wikipedia, wiki, book, books, library,
