[Mapserver-users] reducing RGB maps to 8bit
Jan Hartmann
jhart@frw.uva.nl
Tue, 23 Mar 2004 10:53:30 +0100
Hi,
Not a specific MapServer question, but I guess there are people on this
list who know something about this. I have about 600 historical
cadastral maps dating from about 1830. They have been scanned as 24bits
jpg files, and each map is about 4000*4000 pixels. To display them
efficiently with MapServer I need to transform them to 8bit, all in the
same palette. Colors on the different maps don't match exactly, due to
two centuries of wear and tear The question is: does anyone know a way
to compute some sort of optimal colormap for this amount of data,
something like "imagemagick -display" or the gdal-utility "rgb2pct.py",
not for a single file, but for a large set of images. There is some
literature about it, e.g. "comp.graphics.algorithms 3.02" and "graphics
gems", but before I start programming myself, perhaps someone knows an
easier way.
Thanks,
Jan
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