[GRASSLIST:4587] Re: Transparent null values in output images.

[Hamish]

> I have some rasters with large null areas.
> 
> I would like to output these as images (r.out.png or r.out.tiff) with
> the null values represented by transparent pixels.
> 
> I can't see any flags on these commands to enable this.
> 
> Is this possible?


some clues:

set $GRASS_TRANSPARENT to "TRUE"
  then d.out.png (or d.mon start=PNG etc)

Set $GRASS_WIDTH & $GRASS_HEIGHT to region settings for cols & rows to
get 1:1 scaling (as with r.out.png).


d.out.png then merge alpha in the GIMP?
r.out.ppm -> gimp?

see the second half of this email:
  http://article.gmane.org/gmane.comp.gis.grass.devel/4943
  http://freegis.org/cgi-bin/viewcvs.cgi/grass/src/general/g.pnmcomp/



Hamish