What is Metafile in Windows?

March 29th, 2014 by Rossy Guide


A metafile is a file containing information that describes or specifies another file. Microsoft uses this term for its Windows Metafile (WMF) format. A WMF file contains a sequence of graphical-device-interface (GDI) function calls that result in the presentation of a graphic image. Some of the function calls are equivalent to vector graphics statements and others identify stored bitmap or literal specifications of which bits to illuminate. Using WMF files rather than already-built bitmaps saves space when many bitmaps are used repeatedly by different components of the operating system or of an application. The Windows Metafile is a 16-bit metafile format that can contain both vector information and bitmap information. It is optimized for the Windows operating system.


Different types of files

There are six types of metafiles. They are,

o Bitmap

o Computer Graphics

o Clipboard

o CorelDraw!

o Enhanced

o Macintosh Picture

BMP: Windows bitmap

Windows bitmaps store a single raster image in any color depth, from black-and-white to 24-bit color. The Windows bitmap file format is compatible with other Microsoft Windows programs. It does not support file compression and is not suitable for Web pages.

CGM: Computer Graphics Metafile

The CGM metafile can contain vector information and bitmap information. It is an internationally standardized file format that is used by many organizations and government agencies, including the British Standards Institute (BSI), the American National Standards Institute (ANSI), and the United States Department of Defense.

CLP: Clipboard metafiles

Clipboard metafiles are stored in Microsoft Clipboard Viewer files (file extension .CLP) and Microsoft Windows Write files (file extension .WRI). Clipboard metafiles are also based on the standard metafile format, but are preceded by an additional 8- or 16-byte header that allows the position of the metafile on the Clipboard viewer.

CDR: CorelDraw!

The CorelDraw! metafile can contain both vector information and bitmap information. CDR is widely used in the prepress industry and the artistic design industry.

EMF: Enhanced Metafile

The Enhanced Metafile format is a 32-bit format that can contain both vector information and bitmap information. This format is an improvement over the Windows Metafile Format and contains extended features, such as the following:

o Built-in scaling information
o Built-in descriptions that are saved with the file
o Improvements in color palettes and device independence

The EMF format is an extensible format, which means that a programmer can modify the original specification to add functionality or to meet specific needs. This modification can lead to incompatibilities between different types of EMF pictures.

PICT: Macintosh Picture

The PICT file is a 32-bit metafile format for the Macintosh computer. PICT files use Run Length Encoded (RLE) internal compression, which works reasonably well. PICT files support JPEG compression if QuickTime is installed.

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