fits

FITS or Flexible Image Transport System is a digital file format used to store, transmit, and manipulate scientific and other images. FITS is the most commonly used digital file format in astronomy. Unlike many image formats, FITS is designed specifically for scientific data and hence includes many provisions for describing photometric and spatial calibration information, together with image origin metadata.

A major feature of the FITS format is that image metadata is stored in a human readable ASCII header, so that an interested user can examine the headers to investigate a file of unknown provenance. Each FITS file consists of one or more headers containing ASCII card images (80 character fixed-length strings) 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.

Specification	FITS Standard Document Definition of the Flexible Image Transport System (FITS)
Library	CFITSIO Version 3.130 - February 3, 2009 CFITSIO User's Reference Guide
Copyright	(Unpublished-all rights reserved under the copyright laws of the United States), U.S. Government as represented by the Administrator of the NASA, National Aeronautics and Space Administration.
Samples	SDK, NASA, online FITS File Verifier

File	Features	Pixel format
Lub.fit	8-bit grayscales	Lub
Lus.fit	16-bit grayscales	Lus
Li.fit	32-bit int grayscales	Li
Lf.fit	32-bit float grayscales	Lf
Ld.fit	64-bit float grayscales	Ld
LAub.fts	8-bit grayscales with alpha channel	LAub
LAus.fts	16-bit grayscales with alpha channel	LAus
LAi.fts	32-bit int grayscales with alpha channel	LAi
LAf.fts	32-bit float grayscales with alpha channel	LAf
LAd.fts	64-bit float grayscales with alpha channel	LAd
RGBub.fit	3x8-bit rgb color	RGBub
RGBus.fit	3x16-bit rgb color	RGBus
RGBi.fit	3x32-bit int rgb color	RGBi
RGBf.fit	3x32-bit float rgb color	RGBf
RGBd.fit	3x64-bit float rgb color	RGBd
RGBAub.fits	3x8-bit rgb color with alpha channel	RGBAub
RGBAus.fits	3x16-bit rgb color with alpha channel	RGBAus
RGBAi.fits	3x32-bit int rgb color with alpha channel	RGBAi
RGBAf.fits	3x32-bit float rgb color with alpha channel	RGBAf
RGBAd.fits	3x64-bit float rgb color with alpha channel	RGBAd