[GRASS-user] Calibrating colors of a series of maps

[Glynn Clements]

Jan Hartmann wrote:

> I am working with series of old topographical maps, rangnig from 10 to 
> 600 map sheets per map. Each sheet is discolored a bit from age. How can 
> I process a complete series in such a way that there are no differences 
> visible any more between map sheets? Preferably I would like to 
> downsample them to 8 bits color table, as the originals only have a 
> small set of colors. In other words: how do I calibrate s set of maps to 
> the same optimal color table?

This is probably better done with general image-processing software,
e.g. pnmquant (from the Netpbm package) or "convert -colors ..." (from
ImageMagick).

-- 
Glynn Clements <glynn at gclements.plus.com>