## 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 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 input raster maps should use a grey-scale color table.

## NOTES

d.rgb 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 (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 sample dataset)

## SEE ALSO

d.colortable, d.his, r.blend, r.mapcalc, r.colors, r.composite

## AUTHOR

Glynn Clements

Last changed: $Date: 2017-12-13 09:38:31 +0100 (Wed, 13 Dec 2017) $