[Mapserver-users] reducing RGB maps to 8bit

[Jan Hartmann]

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