Editing Computer Graphics Metafile

{{short description|Image file format family}}
{{Infobox file format
| name                   = Computer Graphics Metafile
| icon                   = 
| logo                   = 
| screenshot             = 
| caption                = 
| extension              = {{mono|.cgm}}
| mime                   = {{mono|image/cgm}}<ref>[https://www.iana.org/assignments/media-types/image/ IANA Image Media Types]</ref>
| type code              = 
| uniform type           = 
| magic                  = 
| owner                  = [[American National Standards Institute|ANSI]], [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]], [[World Wide Web Consortium|W3C]]
| released               = {{Start date and age|1986}}<br />(ANSI X3 122-1986)
| latest release version = 
| latest release date    = 
| genre                  = [[vector graphics|Vector image format]]
| container for          = 
| contained by           = 
| extended from          = [[Graphical Kernel System]]
| extended to            = 
| standard               = [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] 8632
| url                    = {{URL|standards.iso.org/ittf/PubliclyAvailableStandards/index.html|ISO/IEC 8632}}
}}
'''Computer Graphics Metafile''' ('''CGM''') is a [[free file format|free]] and [[open standard|open]] [[international standard]] file format for 2D [[vector graphics]], [[raster graphics]], and [[Character (computing)|text]], and is defined by '''[[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] 8632'''.<ref>[http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html ISO/IEC 8632]</ref>

==Overview==
All [[computer graphics|graphical]] elements can be specified in a textual [[source file]] that can be compiled into a [[binary file]] or one of two text representations.  CGM provides a means of graphics data interchange for computer representation of 2D graphical information independent from any particular application, system, platform, or device.

As a [[metafile]], i.e., a file containing information that describes or specifies another file, the CGM format has numerous elements to provide functions and to represent entities, so that a wide range of graphical information and geometric primitives can be accommodated.  Rather than establish an explicit [[graphics file format]], CGM contains the instructions and data for reconstructing graphical components to render an image using an object-oriented approach.

Although CGM is not widely supported for web pages and has been supplanted by other formats in the graphic arts, it is still prevalent in engineering, aviation, and other technical applications.

The initial CGM implementation was effectively a streamed representation of a sequence of [[Graphical Kernel System]] (GKS) primitive operations. It has been adopted to some extent in the areas of [[engineering drawing|technical illustration]] and professional [[Industrial design|design]], but has largely been superseded by formats such as [[Scalable Vector Graphics|SVG]] and [[AutoCAD DXF|DXF]].

The [[World Wide Web Consortium]] has developed '''WebCGM''', a profile of CGM intended for the use of CGM on the Web.

==History==
*1986 – ANSI X3 122-1986 ([[American National Standards Institute|ANSI]] X3 committee)
*1987 – ISO 8632-1987 ([[International Organization for Standardization|ISO]])
*1991 – ANSI/ISO 8632-1987 (ANSI and ISO)
*1992 – ISO 8632:1992, a.k.a. CGM:1992 (ISO)
*1999 – ISO/IEC 8632:1999, 2nd Edition (ISO/IEC [[ISO/IEC JTC 1|JTC1/SC24]])
*December 17, 2001 – WebCGM ([[World Wide Web Consortium|W3C]])
*January 30, 2007 – [http://www.w3.org/TR/2007/REC-webcgm20-20070130/ WebCGM 2.0] (W3C)
*March 1, 2010 – [http://www.w3.org/TR/2010/REC-webcgm21-20100301/ WebCGM 2.1] (W3C Recommendation)

==Further reading==
*Arnold, D.B. and P.R. Bono, ''CGM and CGI: Metafile and Interface Standards for Computer Graphics'', Springer-Verlag, New York, NY, 1988.
*Henderson, L.R., and Gebhardt, ''CGM: SGML for Graphics'', The Gilbane Report, Fall 1994.
*Henderson, L.R., and A.M. Mumford, ''The CGM Handbook'', Academic Press, San Diego, CA, 1993.
*Bono, P.R., J.L. Encarnacao, L.M. Encarnacao, and W.R. Herzner, ''PC Graphics With GKS'', Prentice-Hall, Englewood Cliffs, NJ, 1990.
*Vaughan Tay (2001) ''Making It Work'', 5th ed

==See also==
*[[Comparison of graphics file formats]]

==References==
{{reflist|30em}}

==External links==
===General===
*[http://www.itl.nist.gov/div897/ctg/graphics/cgm_std.htm Overview of CGM Standards]
*[https://www.fileformat.info/format/cgm/egff.htm CGM File Format Summary]
*[http://www.cgmopen.org/webcgm/index.html WebCGM Resource Page]
*[http://xml.coverpages.org/webCGM.html Technology Reports: WebCGM]
*[http://www.w3.org/TR/NOTE-cgm-970618.html Use of CGM as a Scalable Graphics Format]
*[http://www.cgmopen.org/technical/index.html CGM Open - Reference documents & related materials for CGM and WebCGM]

===Standards===
*[http://www.w3.org/TR/REC-WebCGM/ WebCGM 1.0], W3C Recommendation, 17 December 2001
*[http://www.w3.org/TR/webcgm20/ WebCGM 2.0], W3C Recommendation, 30 January 2007
*[http://www.w3.org/TR/webcgm21/ WebCGM 2.1], W3C Recommendation, 1 March 2010
*[http://standards.iso.org/ittf/PubliclyAvailableStandards/c032378_ISO_IEC_8632-1_1999(E).zip ISO/IEC 8632-1:1999] Part 1: Functional specification
*[http://standards.iso.org/ittf/PubliclyAvailableStandards/c044114_ISO_IEC_8632-1_1999_Cor_1_2006(E).zip ISO/IEC 8632-1:1999] Part 1: Technical Corrigendum 1
*[http://standards.iso.org/ittf/PubliclyAvailableStandards/c050315_ISO_IEC_8632-1_1999_Cor_2_2007.zip ISO/IEC 8632-1:1999] Part 1: Technical Corrigendum 2
*[http://standards.iso.org/ittf/PubliclyAvailableStandards/c032380_ISO_IEC_8632-3_1999(E).zip ISO/IEC 8632-3:1999] Part 3: Binary encoding
*[http://standards.iso.org/ittf/PubliclyAvailableStandards/c032381_ISO_IEC_8632-4_1999(E).zip ISO/IEC 8632-4:1999] Part 4: Clear text encoding

=== Other ===
*[http://www.cgmopen.org/technical/webcgm_svg.htm WebCGM and SVG: A Comparison]
*[http://www.agocg.ac.uk/train/cgm/examples/cgmindex.htm CGM Examples]
{{List of International Electrotechnical Commission standards}}
{{Vector graphics markup languages|state=uncollapsed}}
{{ISO standards}}
{{Graphics file formats}}
[[Category:Graphics file formats]]
[[Category:Vector graphics markup languages]]
[[Category:Open formats]]
[[Category:Graphics standards]]
[[Category:American National Standards Institute standards]]
[[Category:World Wide Web Consortium standards]]
[[Category:ISO standards]]
[[Category:IEC standards]]