.TH d.rgb 1grass "" "GRASS 7.6.0" "Grass User's Manual"
.SH NAME
\fI\fBd.rgb\fR\fR  \- Displays three user\-specified raster maps as red, green, and blue overlays in the active graphics frame.
.SH KEYWORDS
display, graphics, raster, RGB
.SH SYNOPSIS
\fBd.rgb\fR
.br
\fBd.rgb \-\-help\fR
.br
\fBd.rgb\fR [\-\fBn\fR] \fBred\fR=\fIname\fR \fBgreen\fR=\fIname\fR \fBblue\fR=\fIname\fR  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-n\fR" 4m
.br
Make null cells opaque
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBred\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of raster map to be used for <red>
.IP "\fBgreen\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of raster map to be used for <green>
.IP "\fBblue\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of raster map to be used for <blue>
.SH DESCRIPTION
\fIRGB\fR stands for \fBred\fR, \fBgreen\fR,
and \fBblue\fR. \fId.rgb\fR visually combines three raster maps to
form a color image. For each map, the corresponding component from the
layer\(cqs 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.
.SH NOTES
\fId.rgb\fR 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 \fIr.composite\fR 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.
.PP
If color quality of satellite image color composites seems to appear
poor, run \fIi.colors.enhance\fR
on the selected satellite channels.
.PP
An alternative is the assignment of grey color tables to each band with
\fIr.colors\fR:
.br
.nf
\fC
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
\fR
.fi
.PP
To write out the color composite to a combined R/G/B raster maps, use
\fIr.composite\fR.
.SH EXAMPLE
Visual color composite of a LANDSAT scene (North Carolina sample dataset):
.br
.nf
\fC
g.region raster=lsat7_2002_10 \-p
d.rgb blue=lsat7_2002_10 green=lsat7_2002_20 red=lsat7_2002_30
\fR
.fi
.br
\fIFigure: Visual color composite of a LANDSAT scene (North Carolina sample dataset)\fR
.SH SEE ALSO
\fI
d.colortable,
d.his,
r.blend,
r.mapcalc,
r.colors,
r.composite
\fR
.SH AUTHOR
Glynn Clements
.PP
\fILast changed: $Date: 2017\-12\-13 09:37:43 +0100 (Wed, 13 Dec 2017) $\fR
.SH SOURCE CODE
.PP
Available at: d.rgb source code (history)
.PP
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.PP
© 2003\-2019
GRASS Development Team,
GRASS GIS 7.6.0 Reference Manual