.TH r.colors 1grass "" "GRASS 7.6.0" "Grass User's Manual"
.SH NAME
\fI\fBr.colors\fR\fR  \- Creates/modifies the color table associated with a raster map.
.SH KEYWORDS
raster, color table
.SH SYNOPSIS
\fBr.colors\fR
.br
\fBr.colors \-\-help\fR
.br
\fBr.colors\fR [\-\fBrwldngae\fR]  [\fBmap\fR=\fIname\fR[,\fIname\fR,...]]   [\fBfile\fR=\fIname\fR]   [\fBcolor\fR=\fIstyle\fR]   [\fBraster\fR=\fIname\fR]   [\fBraster_3d\fR=\fIname\fR]   [\fBrules\fR=\fIname\fR]   [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-r\fR" 4m
.br
Remove existing color table
.IP "\fB\-w\fR" 4m
.br
Only write new color table if it does not already exist
.IP "\fB\-l\fR" 4m
.br
List available rules then exit
.IP "\fB\-d\fR" 4m
.br
List available rules with description then exit
.br
If a color rule is given, only this rule is listed
.IP "\fB\-n\fR" 4m
.br
Invert colors
.IP "\fB\-g\fR" 4m
.br
Logarithmic scaling
.IP "\fB\-a\fR" 4m
.br
Logarithmic\-absolute scaling
.IP "\fB\-e\fR" 4m
.br
Histogram equalization
.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 "\fBmap\fR=\fIname[,\fIname\fR,...]\fR" 4m
.br
Name of raster map(s)
.IP "\fBfile\fR=\fIname\fR" 4m
.br
Input file with one map name per line
.br
Input map names can be defined in an input file in case a large amount of maps must be specified. This option is mutual exclusive to the map option.
.IP "\fBcolor\fR=\fIstyle\fR" 4m
.br
Name of color table
.br
Options: \fIaspect, aspectcolr, bcyr, bgyr, blues, byg, byr, celsius, corine, curvature, differences, elevation, etopo2, evi, fahrenheit, gdd, grass, greens, grey, grey.eq, grey.log, grey1.0, grey255, gyr, haxby, inferno, kelvin, magma, ndvi, ndwi, oranges, plasma, population, population_dens, precipitation, precipitation_daily, precipitation_monthly, rainbow, ramp, random, reds, roygbiv, rstcurv, ryb, ryg, sepia, slope, soilmoisture, srtm, srtm_plus, terrain, viridis, water, wave\fR
.br
\fB aspect\fR: aspect oriented grey colors [range: map values]
.br
\fB aspectcolr\fR: aspect oriented rainbow colors [range: 0 to 360]
.br
\fB bcyr\fR: blue through cyan through yellow to red [range: map values]
.br
\fB bgyr\fR: blue through green through yellow to red [range: map values]
.br
\fB blues\fR: white to blue [range: map values]
.br
\fB byg\fR: blue through yellow to green [range: map values]
.br
\fB byr\fR: blue through yellow to red [range: map values]
.br
\fB celsius\fR: blue to red for degree Celsius temperature [range: \-80 to 80]
.br
\fB corine\fR: EU Corine land cover colors [range: 111 to 995]
.br
\fB curvature\fR: for terrain curvatures (from v.surf.rst and r.slope.aspect) [range: map values]
.br
\fB differences\fR: differences oriented colors [range: map values]
.br
\fB elevation\fR: maps relative ranges of raster values to elevation color ramp [range: map values]
.br
\fB etopo2\fR: colors for ETOPO2 worldwide bathymetry/topography [range: \-11000 to 8850]
.br
\fB evi\fR: enhanced vegetative index colors [range: \-1 to 1]
.br
\fB fahrenheit\fR: blue to red for Fahrenheit temperature [range: \-112 to 176]
.br
\fB gdd\fR: accumulated growing degree days [range: 0 to 6000]
.br
\fB grass\fR: GRASS GIS green (perceptually uniform) [range: map values]
.br
\fB greens\fR: white to green [range: map values]
.br
\fB grey\fR: grey scale [range: map values]
.br
\fB grey.eq\fR: histogram\-equalized grey scale [range: map values]
.br
\fB grey.log\fR: histogram logarithmic transformed grey scale [range: map values]
.br
\fB grey1.0\fR: grey scale for raster values between 0.0\-1.0 [range: 0 to 1]
.br
\fB grey255\fR: grey scale for raster values between 0\-255 [range: 0 to 255]
.br
\fB gyr\fR: green through yellow to red [range: map values]
.br
\fB haxby\fR: relative colors for bathymetry or topography [range: map values]
.br
\fB inferno\fR: perceptually uniform sequential color table inferno [range: map values]
.br
\fB kelvin\fR: blue to red for temperature in Kelvin scale [range: 193.15 to 353.15]
.br
\fB magma\fR: perceptually uniform sequential color table magma [range: map values]
.br
\fB ndvi\fR: Normalized Difference Vegetation Index colors [range: \-1 to 1]
.br
\fB ndwi\fR: Normalized Difference Water Index colors [range: \-200 to 200]
.br
\fB oranges\fR: white to orange [range: map values]
.br
\fB plasma\fR: perceptually uniform sequential color table plasma [range: map values]
.br
\fB population\fR: color table covering human population classification breaks [range: 0 to 2e+09]
.br
\fB population_dens\fR: color table covering human population density classification breaks [range: 0 to 1e+09]
.br
\fB precipitation\fR: precipitation color table (0..2000mm) [range: 0 to 7000]
.br
\fB precipitation_daily\fR: precipitation color table (0..1000mm) [range: 0 to 10000]
.br
\fB precipitation_monthly\fR: precipitation color table (0..1000mm) [range: 0 to 1000]
.br
\fB rainbow\fR: rainbow color table [range: map values]
.br
\fB ramp\fR: color ramp [range: map values]
.br
\fB random\fR: random color table [range: map values]
.br
\fB reds\fR: white to red [range: map values]
.br
\fB roygbiv\fR:  [range: map values]
.br
\fB rstcurv\fR: terrain curvature (from r.resamp.rst) [range: map values]
.br
\fB ryb\fR: red through yellow to blue [range: map values]
.br
\fB ryg\fR: red through yellow to green [range: map values]
.br
\fB sepia\fR: yellowish\-brown through to white [range: map values]
.br
\fB slope\fR: r.slope.aspect\-type slope colors for raster values 0\-90 [range: 0 to 90]
.br
\fB soilmoisture\fR: soilmoisture color table (0.0\-1.0) [range: 0 to 1]
.br
\fB srtm\fR: color palette for Shuttle Radar Topography Mission elevation [range: \-11000 to 8850]
.br
\fB srtm_plus\fR: color palette for Shuttle Radar Topography Mission elevation (with seafloor colors) [range: \-11000 to 8850]
.br
\fB terrain\fR: global elevation color table covering \-11000 to +8850m [range: \-11000 to 8850]
.br
\fB viridis\fR: perceptually uniform sequential color table viridis [range: map values]
.br
\fB water\fR: water depth [range: map values]
.br
\fB wave\fR: color wave [range: map values]
.IP "\fBraster\fR=\fIname\fR" 4m
.br
Raster map from which to copy color table
.IP "\fBraster_3d\fR=\fIname\fR" 4m
.br
3D raster map from which to copy color table
.IP "\fBrules\fR=\fIname\fR" 4m
.br
Path to rules file
.br
\(dq\-\(dq to read rules from stdin
.SH DESCRIPTION
\fIr.colors\fR allows the user to create and/or modify the color
table for a raster map or several raster maps at once.
The raster maps (specified on the command line
by \fBmap\fR or as \fBfile\fR using an input file with one map name per line)
must exist in the user\(cqs current mapset search path.
.PP
The \fBraster\fR option allows user to specify a raster map \fIname\fR
from which to copy the color map.
.PP
The \fBraster_3d\fR option allows user to specify a 3D raster
map \fIname\fR from which to copy the color map.
.PP
The \fB\-e\fR flag equalizes the original raster\(cqs color table. It can
preclude the need for \fIgrey.eq\fR rule, when used as
\fB\-e color=\fR\fIgrey\fR. Note however, that this will not yield
a color table identical to \fIcolor=grey.eq\fR,
because \fIgrey.eq\fR scales the fraction by 256 to get a grey
level, while \fB\-e\fR uses it to interpolate the original color
table. If the original color table is a 0\-255 grey scale, \fB\-e\fR
is effectively scaling the fraction by 255. Different algorithms are
used. \fB\-e\fR is designed to work with any color table, both the
floating point and the integer raster maps.
.PP
The \fB\-g\fR flag divides the raster\(cqs grey value range into 100
logarithmically equal steps (where \(dqstep\(dq is a rule with the
same grey level for the start and end points). It can preclude the
need for \fIgrey.log\fR rule, when used as \fB\-g
color=\fR\fIgrey\fR. Note however, that this will not yield a
color table identical to \fIcolor=grey.log\fR. Different algorithms
are used. Unlike \fBcolor=\fR\fIgrey.log\fR, \fB\-g\fR is designed
to work with both floating point and integer rasters, without
performance issues with large datasets, of any original color
table. Logarithmic scaling doesn\(cqt work on negative values. In the
case when the value range includes zero, there\(cqs no realistic
solution.
.PP
The \fB\-e\fR and \fB\-g\fR flags are not mutually exclusive.
.PP
If the user specifies the \fB\-w\fR flag, the current color table file for
the input map will not be overwritten. This means that the color table is
created only if the \fImap\fR does not already have a color table. If this
option is not specified, the color table will be created if one does not
exist, or modified if it does.
.PP
.PP
Color table types \fIaspect, grey, grey.eq\fR (histogram\-equalized
grey scale), \fIbyg\fR (blue\-yellow\-green), \fIbyr\fR
(blue\-yellow\-red), \fIgyr\fR (green\-yellow\-red), \fIrainbow, ramp,
ryg\fR (red\-yellow\-green), \fIrandom\fR, and \fIwave\fR are
pre\-defined color tables that \fIr.colors\fR knows how to create
without any further input.
.PP
In case several input raster maps are provided the range (min, max) of all maps
will be used for color table creation. Hence the created color table will span from
the smallest minimum to the largest maximum value of all input raster maps and
will be applied to all input raster maps.
.PP
In general, tables which associate colors with percentages (aspect, bcyr, byg,
byr, elevation, grey, gyr, rainbow, ramp, ryb, ryg and wave) can be applied to
any data, while those which use absolute values (aspectcolr, curvature, etopo2,
evi, ndvi, population, slope, srtm, and terrain) only make sense for data with
certain ranges.
One can get a rough idea of the applicability of a colour table by reading the
corresponding rules file ($GISBASE/etc/colors/<name>).
For example the \fIslope\fR rule is defined as:
.br
.nf
\fC
0  255:255:255
2  255:255:0
5  0:255:0
10 0:255 255
15 0:0:255
30 255:0:255
50 255:0:0
90 0:0:0
\fR
.fi
.PP
This is designed for the slope map generated
by \fIr.slope.aspect\fR, where the
value is a slope angle between 0 and 90 degrees.
.PP
Similarly, the \fIaspectcolr\fR rule:
.br
.nf
\fC
0 white
1 yellow
90 green
180 cyan
270 red
360 yellow
\fR
.fi
.PP
is designed for the aspect maps produced
by \fIr.slope.aspect\fR, where the
value is a heading between 0 and 360 degrees.
.PP
The \fBrules\fR color table type will cause \fIr.colors\fR to read
color table specifications from standard input (stdin) and will build
the color table accordingly.
.PP
Using color table type \fBrules\fR, there are two ways to
build a color table:  by category values and by
\(dqpercent\(dq values.
.PP
To build a color table by category values\(cq indices, the user should
determine the range of category values in the raster map with which
the color table will be used. Specific category values will then be
associated with specific colors. Note that a color does not have to be
assigned for every valid category value because \fIr.colors\fR will
interpolate a color ramp to fill in where color specification rules
have been left out. The format of such a specification is as follows:
.br
.nf
\fC
category_value color_name
category_value color_name
\&.. ..
\&.. ..
category_value color_name
end
\fR
.fi
.PP
Each category value must be valid for the raster map, category values
must be in ascending order and only use standard GRASS color names
(aqua, black, blue, brown, cyan, gray, green, grey, indigo, magenta,
orange, purple, red, violet, white, yellow).
.PP
Colors can also be specified by color numbers each in the range
0\-255. The format of a category value color table specification using
color numbers instead of color names is as follows:
.br
.nf
\fC
category_value red_number:green_number:blue_number
category_value red_number:green_number:blue_number
\&.. .. .. ..
\&.. .. .. ..
category_value red_number:green_number:blue_number
end
\fR
.fi
.PP
Specifying a color table by \(dqpercent\(dq values allows one to
treat a color table as if it were numbered from 0 to 100. The format
of a \(dqpercent\(dq value color table specification is the same
as for a category value color specification, except that the category
values are replaced by \(dqpercent\(dq values, each from 0\-100, in
ascending order. The format is as follows:
.br
.nf
\fC
percent_value% color_name
percent_value% color_name
\&.. ..
\&.. ..
percent_value% color_name
end
\fR
.fi
.PP
Using \(dqpercent\(dq value color table specification rules,
colors can also be specified by color numbers each in the range
0\-255. The format of a percent value color table specification using
color numbers instead of color names is as follows:
.br
.nf
\fC
percent_value% red_number:green_number:blue_number
percent_value% red_number:green_number:blue_number
\&.. .. .. ..
\&.. .. .. ..
percent_value% red_number:green_number:blue_number
end
\fR
.fi
.PP
Note that you can also mix these two methods of color
table specification; for example:
.br
.nf
\fC
0 black
10% yellow
78 blue
100% 0:255:230
end
\fR
.fi
.PP
To set the NULL (no data) color, use the \(dqnv\(dq (null values) parameter:
.br
.nf
\fC
0 black
10% yellow
nv white
end
\fR
.fi
.PP
To set the color to used for undefined values (beyond the range of the
color rules) use the \(dqdefault\(dq parameter:
.br
.nf
\fC
0 red
1 blue
default grey
end
\fR
.fi
.SH NOTES
All color tables are stored in $GISBASE/etc/colors/. Further
user\-defined color tables can also be stored in this directory for
access from the \fIcolor\fR parameter or in a user defined directory.
See also \fIr.colors.out\fR for printing color tables easily to the
terminal.
.PP
The color table assigned to a raster map is stored in
$GISDBASE/location/mapset/colr/.
.SH EXAMPLES
The below example shows how you can specify colors for a three
category map, assigning red to category 1, green to category 2, and
blue to category 3. Start by using a text editor to create the
following rules specification file (save it with the
name \fIrules.file\fR):
.br
.nf
\fC
1 red
2 green
3 blue
end
\fR
.fi
.PP
The color table can then by assigned to map \fIthreecats\fR by the
following GRASS commands (two ways are available):
.br
.nf
\fC
# read input from stdin
cat rules.file | r.colors map=threecats rules=\-
# read directly from file
r.colors map=threecats rules=rules.file
\fR
.fi
.PP
To create a natural looking lookup table (LUT) for true map layer
\fIelevation\fR, use the following rules specification file. It will
assign light green shades to the lower elevations (first 20% of the
LUT), and then darker greens (next 15%, and next 20%) and light browns
(next 20%) for middle elevations, and darker browns (next 15%) for
higher elevations, and finally yellow for the highest peaks (last 10%
of LUT).
.br
.nf
\fC
0% 0:230:0
20% 0:160:0
35% 50:130:0
55% 120:100:30
75% 120:130:40
90% 170:160:50
100% 255:255:100
\fR
.fi
.PP
To invert the current rules:
.br
.nf
\fC
r.colors map=current_raster \-n rast=current_raster
\fR
.fi
.SH SEE ALSO
\fI
d.colortable,
d.histogram,
d.legend,
r.colors.out
r.colors.stddev,
r.support,
r.univar,
v.colors,
v.colors.out,
r3.colors,
r3.colors.out
\fR
.PP
See also wiki
page Color
tables (from GRASS User Wiki)
.PP
ColorBrewer is an online tool designed to
help people select good color schemes for maps and other graphics.
.SH AUTHORS
Michael Shapiro and David Johnson
.br
Support for 3D rasters by Soeren Gebbert
.PP
\fILast changed: $Date: 2018\-02\-21 11:25:20 +0100 (Wed, 21 Feb 2018) $\fR
.SH SOURCE CODE
.PP
Available at: r.colors source code (history)
.PP
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.PP
© 2003\-2019
GRASS Development Team,
GRASS GIS 7.6.0 Reference Manual