[GRASSLIST:1029] Re: patched rasters

[Maciek Sieczka]

On Sat, 6 May 2006 10:24:03 -0400
Stuart Edwards <sedwards2 at cinci.rr.com> wrote:

> Hi
> 
> Curious problem with r.patch.  I'm patching two topo maps and which  
> ever one is identified second will appear blurred on the new  
> composite image (see patch1). However, if I display them  
> independently on the same monitor, both maps are just fine (see  
> display1).  It looks like a resolution problem,

The problem is palette. Your images have indexed palettes (8 bit?), each
palette is different. You would need to:
1. move your maps to a truecolor space
2. patch
3. transform back to indexed (to reduce the size and for Grass display
sake, which is slow on more than 15 bit color).

Maybe do it this way:
1. separate each maps R,G,B component with r.mapcalc # operator:
'map_blue=b#map'
2. r.patch R, G and B layers separately
3. r.composite them

Maciek

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