EVOLUTION-MANAGER

Edit File: frmt_gif.html

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<title>GIF -- Graphics Interchange Format</title>
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<h1>GIF -- Graphics Interchange Format</h1>

GDAL supports reading and writing of normal, and interlaced GIF files.  Gif
files always appear as having one colormapped eight bit band. GIF files have
no support for georeferencing.<p>

A GIF image with transparency will have that entry marked as having
an alpha value of 0.0 (transparent).  Also, the transparent value will
be returned as the NoData value for the band.<p>

If an ESRI world file exists with the .gfw, .gifw or .wld extension, it will be read and
used to establish the geotransform for the image.<p>

Starting with GDAL 1.9.0, XMP metadata can be extracted from the file, and will be
stored as XML raw content in the xml:XMP metadata domain.<p>

<h2>Creation Issues</h2>

GIF files can only be created as 1 8bit band using the "CreateCopy" mechanism.
If written from a file that is not colormapped, a default greyscale colormap
is generated.  Tranparent GIFs are not currently supported on creation.<p>

<b>WORLDFILE=ON</b>: Force the generation of an associated ESRI world
file (.wld).<p>

Interlaced (progressive) GIF files can be generated by supplying the 
<b>INTERLACING=ON</b> option on creation. <p>

Starting with GDAL 1.7.0, GDAL's internal GIF support is implemented based
on source from the giflib 4.1.6 library (written by Gershon Elbor, Eric Raymond
and Toshio Kuratomi), hence generating LZW compressed GIF.<p>

The driver was written with the financial support of the <a href="http://www.dmsolutions.ca/">DM
Solutions Group</a>, and <a href="http://www.ciet.org/">CIET 
International</a>.<p>