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TIFF and LibTiff Mail List Archive

Thread

2005.08.20 11:12 "[Tiff] libtiff question", by Moseley, Ben
2005.09.08 16:12 "Re: [Tiff] libtiff question", by Frank Warmerdam
2005.09.08 16:21 "Re: [Tiff] libtiff question", by Joris Van Damme

2005.09.08 16:21 "Re: [Tiff] libtiff question", by Joris Van Damme

Ben,

I was wondering do you have any code for converting file format from tiff to gif?

Please choose your subject line more wisely, since it plays a major role in efficiency of search engines on archive content.

Converting from TIFF to GIF is not just a file format issue. GIF is much more restrictive when it comes to encoding of the pixel color data. While TIFF may contain just about anything, from RGB to L*a*b* to grayscale with 7 extra alpha channels to infrared photography of the earth with added floating point elevation maps, GIF can only contain color data with a palette of at most 256 entries. As such, any convertion code, even if starting from plain RGB TIFF images, will have to do a lot of additional processing to a) derive a good palette, b) convert to the palette. The terms 'quantizing' and 'dithering' come to mind, you may want to Google on that.

Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be/
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