[GRASS-user] Not being able to produce decent-look color-composites

Daniel Victoria daniel.victoria at gmail.com
Thu Feb 16 19:34:01 EST 2012

I see what you mean. Never though off that because so far, I did not
have to work with too many images together or color consistencies
across time. So maybe a histogram equalize function would fit this
problem nicely?


On Thu, Feb 16, 2012 at 10:16 PM, Glynn Clements
<glynn at gclements.plus.com> wrote:
> Daniel Victoria wrote:
>> what I normally do is first run r.colors -e color=grey on each band so
>> I get a equalized color composite. Then I run r.composite. So far I've
>> got good results...
> The main problem with equalisation (or just using the raster's range)
> is that the resulting mapping is specific to that particular map. If
> you have multiple maps, regions which are identical may appear
> different due to each map using a different mapping.
> If you have all of the maps in advance, you can create some kind of
> mixture, generate a colour table for that, then apply it to the
> individual maps. But that won't work if you're producing maps on a
> regular basis and you need tomorrow's map to be consistent with
> today's.
> --
> Glynn Clements <glynn at gclements.plus.com>
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