Provided by: grass-doc_7.4.0-1_all bug


       d.rgb  - Displays three user-specified raster maps as red, green, and blue overlays in the
       active graphics frame.


       display, graphics, raster, RGB


       d.rgb --help
       d.rgb [-n] red=name green=name blue=name  [--help]  [--verbose]  [--quiet]  [--ui]

           Make null cells opaque

           Print usage summary

           Verbose module output

           Quiet module output

           Force launching GUI dialog

       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>


       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.


       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 image.1
       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.


       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)


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


       Glynn Clements

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


       Available at: d.rgb source code (history)

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