[GRASS-user] standardizing raster color tables

[Patton, Eric]

I'm not sure if this is what you're looking for, but I wrote a pretty basic
script to parse a series of input rasters and copy the same color table to
all of them. Let me know if you're interested and I can provide it.

~ Eric. 

-----Original Message-----
From: grassuser-bounces at grass.itc.it
To: GRASS user list
Sent: 7/6/2006 2:01 PM
Subject: [GRASS-user] standardizing raster color tables

Hello all,

I have a series of geotiff files that are 8-bit paletted pseudocolor  
images. I imported these into GRASS rasters with r.in.gdal.  
Unfortunately each separate image file has a different color table,  
though they are a sort of DRGs so the original scans had  
approximately all the same colors.

I would like to convert all the rasters to have a standard color  
table, so that, e.g., I can merge the files into a single image,  
perform other GIS operations, etc.

Is there any way using GRASS tools that I can give all of my  
individual images the same color table?  The image files are large  
(ca. 2000x3000 pixels), but I could convert them temporarily to rgb  
images and then reduce the colors.  I have a standard color table in  
another geotiff file.

I have tried to do this using the imagemagick tool: convert -map  
<file> <infile> <outfile> but this process is impossibly slow.

Any suggestions for (standardized, semi-automated) color reduction  
for DRG's would be much appreciated.

Thanks,

Jed Kaplan

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