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

Glynn Clements glynn at gclements.plus.com
Mon Feb 13 17:16:12 EST 2012

Luisa Peña wrote:

> I'have 3 layers of Landsat (Green, Red and Near-Infrared) and I'm trying to
> produce a false-color composite (r.composite( with those but... I'm getting
> very frustrated because I'm producing very bad look composites. My layers
> are reflectances from 0-1.8 or something. Shall I rescale them to 0-255?

r.composite uses the colour table associated with each map to convert
the map's value to an intensity.

If 1.8 represents "full intensity", then use e.g.:

	r.colors mapname rules=- <<EOF
	0.0 black
	1.8 white

If you want a non-linear relationship, you can either contruct a
colour table using a piecewise-linear approximation, or apply the
transformation to the data with r.mapcalc.

Glynn Clements <glynn at gclements.plus.com>

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