[Mapserver-users] reducing RGB maps to 8bit

[Lowell Filak]

To add to the previous discussion...
I agree with Rich - you deal with some of the oldest & coolest maps I
know of.
I wonder if Imagemagick could compose a palette across multiple images
with something like "montage -colors 256 image1.jpg image2.jpg
image3.jpg ... output.tif".?

Lowell

The following message was sent by Jan Hartmann <jhart at frw.uva.nl> on
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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