d.rgb(1grass) GRASS GIS User's Manual d.rgb(1grass)
NAME
d.rgb - Displays three user-specified raster maps as red, green, and
blue overlays in the active graphics frame.
KEYWORDS
display, graphics, raster, RGB
SYNOPSIS
d.rgb
d.rgb --help
d.rgb [-n] red=name green=name blue=name [--help] [--verbose]
[--quiet] [--ui]
Flags:
-n
Make null cells opaque
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
red=name [required]
Name of raster map to be used for <red>
green=name [required]
Name of raster map to be used for <green>
blue=name [required]
Name of raster map to be used for <blue>
DESCRIPTION
RGB stands for red, green, and blue. d.rgb visually combines three
raster maps to form a color image. For each map, the corresponding com-
ponent 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 input raster
maps should use a grey-scale color table.
NOTES
d.rgb does not attempt to quantize the combined image into a fixed num-
ber of colors. Nor does it have an option to generate a composite layer
(see r.composite for that). The image and raster maps 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 i.colors.enhance on the selected satellite channels.
An alternative is the assignment of grey color tables to each band with
r.colors:
r.info -r image.1
min=0
max=255
r.colors map=image.1 color=grey
r.colors map=image.2 rast=image.1
r.colors map=image.3 rast=image.1
To write out the color composite to a combined R/G/B raster maps, use
r.composite.
EXAMPLE
Visual color composite of a LANDSAT scene (North Carolina sample
dataset):
g.region raster=lsat7_2002_10 -p
d.rgb blue=lsat7_2002_10 green=lsat7_2002_20 red=lsat7_2002_30
Figure: Visual color composite of a LANDSAT scene (North Carolina sam-
ple dataset)
SEE ALSO
d.colortable, d.his, r.blend, r.mapcalc, r.colors, r.composite
AUTHOR
Glynn Clements
SOURCE CODE
Available at: d.rgb source code (history)
Accessed: unknown
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GRASS 7.8.7 d.rgb(1grass)
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