[GRASSLIST:67] Re: making a "true-color" landsat composite

[Ian MacMillan]

Dylan, are you sure that you used 3,2,1?  Could it be that another band 
is accidentally subbed in?  If not, what I usually do with my landsat 
images if they look funky is to use d.histogram (or whatever that is 
now) to look at the color ramp.  I then stretch the colors with 
r.recode.

An alternate method is to average bands 2 and 4 using r.mapcalc and 
then using that in the green channel.  It tends to make 'true' color 
images a bit more vibrant.

Hope that helps,
Ian

On Mar 13, 2006, at 6:55 PM, Dylan Beaudette wrote:

> Hi everyone,
>
> I was working on constructing some "true color" landsat composite 
> images today
> from bands 3,2,1 -- and came across some strange inconsistencies. Data 
> from
> one source produces "nice" true color images:
>
> http://casoilresource.lawr.ucdavis.edu/drupal/node/211
>
> whereas, another source produces somewhat muddy true color composites. 
> I tried
> playing a bit with an equalized grey colormap for each band via 
> r.colors
> color=grey.eq with the following results:
>
> http://casoilresource.lawr.ucdavis.edu/drupal/node/215
>
>
> Does anyone have any tips on how to tweak color ramps for the various 
> bands so
> as to get a better looking "true color" composite?
>
> Thanks!
>
>
> -- 
> Dylan Beaudette
> Soils and Biogeochemistry Graduate Group
> University of California at Davis
> 530.754.7341
>


-------------------------------------------------------------
This message has been scanned by Postini anti-virus software.