Note: This document is for an older version of GRASS GIS that is outdated. You should upgrade, and read the current manual page.
NAME
d.rgb - Displays three user-specified raster maps as red, green, and blue overlays in the active graphics frame.
KEYWORDS
display, raster, RGB
SYNOPSIS
d.rgb
d.rgb help
d.rgb [-ox] red=name green=name blue=name [--verbose] [--quiet]
Flags:
- -o
- Overlay (non-null values only)
- -x
- Don't add to list of commands in monitor
- --verbose
- Verbose module output
- --quiet
- Quiet module output
Parameters:
- red=name
- Name of raster map to be used for 'red'
- green=name
- Name of raster map to be used for 'green'
- blue=name
- Name of raster map to be used for 'blue'
DESCRIPTION
RGB stands for red, green, and blue. This program
visually combines three raster map layers to form a color
image. For each layer, the corresponding component from
the layer's color table is used (e.g. for the red layer,
the red component is used, and so on). In general, the
layers should use a grey-scale color table.
OPTIONS
Flags:
- -o
- Overlay the resulting raster map layer onto whatever is already
displayed in the active graphics frame. Any no-data areas in any of
the named raster maps will seem transparent, and reveal the underlying
image previously displayed in the graphics frame. If the -o
flag is set, only cells containing non-null values will be displayed
from the overlaid raster map. All other areas (i.e., the
portions of the overlaid map that contain null values) will leave the
underlying display untouched.
Parameters:
- red=name
- Name of raster map layer to be used for RED component.
- green=name
- Name of raster map layer to be used for GREEN component.
- blue=name
- Name of raster map layer to be used for BLUE component.
NOTES
This is a new version of d.rgb, which sends the
data to the graphics monitor in true-color RGB format.
Unlike the previous version, it does not attempt to
quantize the combined image into a fixed number of colors.
Nor does it have an option to generate a composite layer.
The image and raster map layers will not display properly
if the graphics device does not have a reasonable sampling
of the RGB color-space.
If color quality of satellite image color composites seems to appear poor,
run r.colors on the selected satellite
channels.
Example:
- r.info -r image.1
min=0
max=255
- r.colors map=image.1 color=rules
<< EOF
0 black
255 white
EOF
- r.colors map=image.2 rast=image.1
- r.colors map=image.3 rast=image.1
Note: Future GRASS versions may do this for you automatically.
To write out the color composite to a R/G/B raster maps, use
r.composite.
SEE ALSO
d.colors
d.colortable
d.his
r.blend
r.mapcalc
r.colors
r.composite
AUTHOR
Glynn Clements
Last changed: $Date: 2011-11-08 03:23:06 -0800 (Tue, 08 Nov 2011) $
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