r.composite.1grass man page

r.composite — Combines red, green and blue raster maps into a single composite raster map.

Keywords

raster, composite, RGB

Synopsis

r.composite
r.composite --help
r.composite [-dc] red=name green=name blue=name [levels=integer] [level_red=integer] [level_green=integer] [level_blue=integer] output=name [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags

-d
Dither
-c
Use closest color
--overwrite
Allow output files to overwrite existing files
--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>
levels=integer
Number of levels to be used for each component
Options: 1-256
Default: 32
level_red=integer
Number of levels to be used for <red>
Options: 1-256
level_green=integer
Number of levels to be used for <green>
Options: 1-256
level_blue=integer
Number of levels to be used for <blue>
Options: 1-256
output=name [required]
Name for output raster map

Description

This program combines three raster maps to form a composite RGB map. For each input map layer, the corresponding component from the map’s color table is used (e.g. for the red map, the red component is used, and so on). In general, the maps should use a grey-scale color table.

Notes

The default number of intensity levels for each component is 32, resulting in a total of 32768 possible colors (equivalent to 15 bits per pixel). If significantly more levels than this are used, not only will r.composite take longer to run, but displaying the resulting layer with d.rast will also be significantly slower.

Floyd-Steinberg dithering is optionally used with the -d flag.

Examples

RGB composite of three satellite bands

Color composite of a LANDSAT scene (North Carolina sample dataset):

g.region raster=lsat7_2002_10
r.composite blue=lsat7_2002_10 green=lsat7_2002_20 red=lsat7_2002_30 \
            output=lsat7_2002_rgb

RGB composite with dithering

Creating a composite RGB raster using 32 color levels per layer, with dithering:

r.composite -d red=elevation.r green=elevation.g blue=elevation.b \
            output=elev.composite

See Also

d.rast, d.rgb, r.blend, r.colors, r.rgb

Wikipedia Entry: Floyd-Steinberg dithering

Author

Glynn Clements

Last changed: $Date: 2014-12-28 16:45:01 +0100 (Sun, 28 Dec 2014) $

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