<html> <head> <title>GIF -- Graphics Interchange Format</title> </head> <body bgcolor="#ffffff"> <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 .wld extension, it will be read and used to establish the geotransform for the image.<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> Interlaced (progressive) GIF files can be generated by supplying the <b>INTERLACING=ON</b> option on creation. <p> By default GDAL does not support the creation of LZW compressed GIF files due to the usual LZW patent issues; however, it is possible to build GDAL from source with LZW compression support if the LZW supporting version of <b>giflib</b> is installed.<p> GDAL's GIF support is implemented based on source from the libungif 4.0 library written by Gershon Elbor, Eric Raymond and Toshio Kuratomi. It 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> See Also:<p> <ul> <li> <a href="http://prtr-13.ucsc.edu/~badger/software/libungif/">Libungif Home Page</a><p> </ul> </body> </html>
