r.composite - GRASS manual
Author: GRASS Development Team
Description: r.composite: Combines red, green and blue raster maps into a single composite raster map.
Keywords: raster, composite, RGB

## NAME

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

## SOURCE CODE

Available at: r.composite source code (history)

Accessed: Monday May 11 17:54:02 2026

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