Computer Graphics Metafile

Computer Graphics Metafile

Filename extension	.cgm
Internet media type	image/cgm
Developed by	ANSI, ISO/IEC, W3C
Initial release	1986 (ANSI X3 122-1986)
Type of format	Vector image format
Extended from	Graphical Kernel System
Standard	ISO/IEC 8632
Website	ISO/IEC 8632

Computer Graphics Metafile (CGM) is a free and open international standard file format for 2D vector graphics, raster graphics, and text, and is defined by ISO/IEC 8632.

Overview

All 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 primitive operations. It has been adopted to some extent in the areas of technical illustration and professional design, but has largely been superseded by formats such as SVG and DXF.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 (ANSI X3 committee)
• 1987 – ISO 8632-1987 (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 JTC1/SC24)
• December 17, 2001 – WebCGM (W3C)
• January 30, 2007 – WebCGM 2.0 (W3C)
• March 1, 2010 – 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.

See also

• Comparison of graphics file formats

External links

General

• Overview of CGM Standards
• CGM File Format Summary
• WebCGM Resource Page
• Technology Reports: WebCGM
• Use of CGM as a Scalable Graphics Format
• CGM Open - Reference documents & related materials for CGM and WebCGM

Standards

• WebCGM 1.0, W3C Recommendation, 17 December 2001
• WebCGM 2.0, W3C Recommendation, 30 January 2007
• WebCGM 2.1, W3C Recommendation, 1 March 2010
• ISO/IEC 8632-1:1999 Part 1: Functional specification
• ISO/IEC 8632-1:1999 Part 1: Technical Corrigendum 1
• ISO/IEC 8632-1:1999 Part 1: Technical Corrigendum 2
• ISO/IEC 8632-3:1999 Part 3: Binary encoding
• ISO/IEC 8632-4:1999 Part 4: Clear text encoding

Other

• WebCGM and SVG: A Comparison
• CGM Examples