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File Formats
Vector Graphics
Same as object-oriented graphics, refers to software and hardware
that use geometrical formulas to represent images. The other method for
representing graphical images is through bit
maps, in which the image is composed of a pattern of dots. This is sometimes
called raster
graphics. Programs that enable you to create and manipulate vector
graphics are called draw programs, whereas programs that manipulated
bit-mapped images are called paint programs.
Vector-oriented images are more flexible than bit maps because they can be
resized and stretched. In addition, images stored as vectors look better on
devices (monitors and printers) with higher resolution, whereas bit-mapped
images always appear the same regardless of a device's resolution. Another
advantage of vector graphics is that representations of images often require
less memory than bit-mapped images do.
Almost all sophisticated graphics systems, including CAD systems and
animation software, use vector graphics. In addition, many printers (PostScript
printers, for example) use vector graphics. Fonts represented as vectors are
called vector fonts, scalable fonts, object-oriented fonts,
and outline fonts.
Note that most output devices, including dot-matrix printers, laser printers,
and display monitors, are raster devices (plotters are the notable exception).
This means that all objects, even vector objects, must be translated into bit
maps before being output. The difference between vector graphics and raster
graphics, therefore, is that vector graphics are not translated into bit maps
until the last possible moment, after all sizes and resolutions have been
specified. PostScript printers, for example, have a raster
image processor (RIP) that performs the translation within the printer. In
their vector form, therefore, graphics representations can potentially be output
on any device, with any resolution, and at any size.
Vector Graphics File Formats
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Format
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Description
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AI
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Adobe Illustrator
Graphic File a graphic created in this program
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CDR
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Corel Draw Graphic File
a graphic created in this program
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CGM (Computer Graphics Metafile)
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A format developed by several
standards organizations, CGM is supported by many PC software products.
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DXF (Data Exchange File)
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A format created by AutoDesk.
Almost all PC-based CAD systems support DXF.
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EPS (Encapsulated PostScript)
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The file format for the PostScript
language. EPS uses a combination of PostScript commands and TIFF or PICT
formats.
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GEM
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The graphics file format used by
GEM-based applications. GEM is a graphical user interface (GUI) developed by
Digital Research.
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HPGL (Hewlett-Packard Graphics Language)
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One of the oldest file formats.
Although it is not very sophisticated, it is supported by many PC-based
graphics products.
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IGES (Initial Graphics Exchange Specification)
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An ANSI standard for
three-dimensional wire frame models. IGES is supported by most PC-based CAD
systems.
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PIC (Lotus Picture File)
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A relatively simple file format
developed by Lotus for representing graphs generated by Lotus 1-2-3. PIC is
supported by a wide variety of PC applications.
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PICT
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Developed by Apple Computer in 1984
as the standard format for storing and exchanging graphics files. It is
supported by all graphics programs that run on a Macintosh.
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WMF (Windows Metafile Format)
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A file format for exchanging
graphics between Microsoft Windows applications. WMF files can also hold
bit-mapped images.
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Bit mapped graphics or Raster graphics

Refers to hardware
and software
that represent graphics
images as bit maps.
The other method for representing images is known as vector
graphics. Raster graphics have the ability to be imbedded in a vector
graphic so you must be careful not to save a raster graphic in a vector format
and expect it to work like a vector it won't. If a vector graphic is
saved as in a raster format it's vector capabilities will be removed and it will
be a raster graphic. This process can not be reversed.
Bit-Mapped (Raster) Graphics File Formats
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Format
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Description
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BMP
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The bit-mapped file format used by Microsoft Windows.
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GIF
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The bit-mapped file format used by CompuServe and
many other BBSs.
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PCX
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Originally developed by ZSOFT for its PC Paintbrush
program, PCX is a common graphics file format supported by many graphics
programs, as well as most optical scanners and fax modems.
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TIFF (Tagged Image File Format)
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A standard file format for storing images as bit
maps. It is used especially for scanned images because it can support any
size, resolution, and color depth.
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