r.colors(1grass) GRASS GIS User's Manual r.colors(1grass)
NAME
r.colors - Creates/modifies the color table associated with a raster
map.
KEYWORDS
raster, color table
SYNOPSIS
r.colors
r.colors --help
r.colors [-rwldngae] [map=name[,name,...]] [file=name]
[color=style] [raster=name] [raster_3d=name] [rules=name]
[--help] [--verbose] [--quiet] [--ui]
Flags:
-r
Remove existing color table
-w
Only write new color table if it does not already exist
-l
List available rules then exit
-d
List available rules with description then exit
If a color rule is given, only this rule is listed
-n
Invert colors
-g
Logarithmic scaling
-a
Logarithmic-absolute scaling
-e
Histogram equalization
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
map=name[,name,...]
Name of raster map(s)
file=name
Input file with one map name per line
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.
color=style
Name of color table
Options: aspect, aspectcolr, bcyr, bgyr, blues, byg, byr, celsius,
corine, curvature, differences, elevation, etopo2, evi, fahrenheit,
forest_cover, gdd, grass, greens, grey, grey.eq, grey.log, grey1.0,
grey255, gyr, haxby, inferno, kelvin, magma, ndvi, ndwi, nlcd, or-
anges, plasma, population, population_dens, precipitation, precipi-
tation_daily, precipitation_monthly, rainbow, ramp, random, reds,
roygbiv, rstcurv, ryb, ryg, sepia, slope, soilmoisture, srtm,
srtm_plus, terrain, viridis, water, wave
aspect: aspect oriented grey colors [range: map values]
aspectcolr: aspect oriented rainbow colors [range: 0 to 360]
bcyr: blue through cyan through yellow to red [range: map values]
bgyr: blue through green through yellow to red [range: map values]
blues: white to blue [range: map values]
byg: blue through yellow to green [range: map values]
byr: blue through yellow to red [range: map values]
celsius: blue to red for degree Celsius temperature [range: -80 to
80]
corine: EU Corine land cover colors [range: 111 to 995]
curvature: for terrain curvatures (from v.surf.rst and r.slope.as-
pect) [range: map values]
differences: differences oriented colors [range: map values]
elevation: maps relative ranges of raster values to elevation
color ramp [range: map values]
etopo2: colors for ETOPO2 worldwide bathymetry/topography [range:
-11000 to 8850]
evi: enhanced vegetative index colors [range: -1 to 1]
fahrenheit: blue to red for Fahrenheit temperature [range: -112 to
176]
forest_cover: percentage of forest cover [range: 0 to 100]
gdd: accumulated growing degree days [range: 0 to 6000]
grass: GRASS GIS green (perceptually uniform) [range: map values]
greens: white to green [range: map values]
grey: grey scale [range: map values]
grey.eq: histogram-equalized grey scale [range: map values]
grey.log: histogram logarithmic transformed grey scale [range: map
values]
grey1.0: grey scale for raster values between 0.0-1.0 [range: 0 to
1]
grey255: grey scale for raster values between 0-255 [range: 0 to
255]
gyr: green through yellow to red [range: map values]
haxby: relative colors for bathymetry or topography [range: map
values]
inferno: perceptually uniform sequential color table inferno
[range: map values]
kelvin: blue to red for temperature in Kelvin scale [range: 193.15
to 353.15]
magma: perceptually uniform sequential color table magma [range:
map values]
ndvi: Normalized Difference Vegetation Index colors [range: -1 to
1]
ndwi: Normalized Difference Water Index colors [range: -200 to
200]
nlcd: US National Land Cover Dataset colors [range: 0 to 95]
oranges: white to orange [range: map values]
plasma: perceptually uniform sequential color table plasma [range:
map values]
population: color table covering human population classification
breaks [range: 0 to 2e+09]
population_dens: color table covering human population density
classification breaks [range: 0 to 1e+09]
precipitation: precipitation color table (0..2000mm) [range: 0 to
7000]
precipitation_daily: precipitation color table (0..1000mm) [range:
0 to 10000]
precipitation_monthly: precipitation color table (0..1000mm)
[range: 0 to 1000]
rainbow: rainbow color table [range: map values]
ramp: color ramp [range: map values]
random: random color table [range: map values]
reds: white to red [range: map values]
roygbiv: [range: map values]
rstcurv: terrain curvature (from r.resamp.rst) [range: map values]
ryb: red through yellow to blue [range: map values]
ryg: red through yellow to green [range: map values]
sepia: yellowish-brown through to white [range: map values]
slope: r.slope.aspect-type slope colors for raster values 0-90
[range: 0 to 90]
soilmoisture: soilmoisture color table (0.0-1.0) [range: 0 to 1]
srtm: color palette for Shuttle Radar Topography Mission elevation
[range: -11000 to 8850]
srtm_plus: color palette for Shuttle Radar Topography Mission ele-
vation (with seafloor colors) [range: -11000 to 8850]
terrain: global elevation color table covering -11000 to +8850m
[range: -11000 to 8850]
viridis: perceptually uniform sequential color table viridis
[range: map values]
water: water depth [range: map values]
wave: color wave [range: map values]
raster=name
Raster map from which to copy color table
raster_3d=name
3D raster map from which to copy color table
rules=name
Path to rules file
"-" to read rules from stdin
DESCRIPTION
r.colors 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 map or as file using an input file with one map
name per line) must exist in the user’s current mapset search path.
The raster option allows user to specify a raster map name from which
to copy the color map.
The raster_3d option allows user to specify a 3D raster map name from
which to copy the color map.
The -e flag equalizes the original raster’s color table. It can pre-
clude the need for grey.eq rule, when used as -e color=grey. Note how-
ever, that this will not yield a color table identical to
color=grey.eq, because grey.eq scales the fraction by 256 to get a grey
level, while -e uses it to interpolate the original color table. If the
original color table is a 0-255 grey scale, -e is effectively scaling
the fraction by 255. Different algorithms are used. -e is designed to
work with any color table, both the floating point and the integer
raster maps.
The -g flag divides the raster’s grey value range into 100 logarithmi-
cally equal steps (where "step" is a rule with the same grey level for
the start and end points). It can preclude the need for grey.log rule,
when used as -g color=grey. Note however, that this will not yield a
color table identical to color=grey.log. Different algorithms are used.
Unlike color=grey.log, -g 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’t work on negative
values. In the case when the value range includes zero, there’s no re-
alistic solution.
The -e and -g flags are not mutually exclusive.
If the user specifies the -w 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 map 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.
Color table types aspect, grey, grey.eq (histogram-equalized grey
scale), byg (blue-yellow-green), byr (blue-yellow-red), gyr (green-yel-
low-red), rainbow, ramp, ryg (red-yellow-green), random, and wave are
pre-defined color tables that r.colors knows how to create without any
further input.
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.
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 (as-
pectcolr, 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 corre-
sponding rules file ($GISBASE/etc/colors/<name>). For example the
slope rule is defined as:
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
This is designed for the slope map generated by r.slope.aspect, where
the value is a slope angle between 0 and 90 degrees.
Similarly, the aspectcolr rule:
0 white
1 yellow
90 green
180 cyan
270 red
360 yellow
is designed for the aspect maps produced by r.slope.aspect, where the
value is a heading between 0 and 360 degrees.
The rules color table type will cause r.colors to read color table
specifications from standard input (stdin) and will build the color ta-
ble accordingly.
Using color table type rules, there are two ways to build a color ta-
ble: by category values and by "percent" values.
To build a color table by category values’ indices, the user should de-
termine the range of category values in the raster map with which the
color table will be used. Specific category values will then be associ-
ated with specific colors. Note that a color does not have to be as-
signed for every valid category value because r.colors 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:
category_value color_name
category_value color_name
.. ..
.. ..
category_value color_name
end
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).
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:
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
Specifying a color table by "percent" values allows one to treat a
color table as if it were numbered from 0 to 100. The format of a "per-
cent" value color table specification is the same as for a category
value color specification, except that the category values are replaced
by "percent" values, each from 0-100, in ascending order. The format is
as follows:
percent_value% color_name
percent_value% color_name
.. ..
.. ..
percent_value% color_name
end
Using "percent" 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:
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
Note that you can also mix these two methods of color table specifica-
tion; for example:
0 black
10% yellow
78 blue
100% 0:255:230
end
To set the NULL (no data) color, use the "nv" (null values) parameter:
0 black
10% yellow
nv white
end
To set the color to used for undefined values (beyond the range of the
color rules) use the "default" parameter:
0 red
1 blue
default grey
end
NOTES
All color tables are stored in $GISBASE/etc/colors/. Further user-de-
fined color tables can also be stored in this directory for access from
the color parameter or in a user defined directory. See also r.col-
ors.out for printing color tables easily to the terminal.
The color table assigned to a raster map is stored in $GISDBASE/loca-
tion/mapset/colr/.
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 cat-
egory 3. Start by using a text editor to create the following rules
specification file (save it with the name rules.file):
1 red
2 green
3 blue
end
The color table can then by assigned to map threecats by the following
GRASS commands (two ways are available):
# read input from stdin
cat rules.file | r.colors map=threecats rules=-
# read directly from file
r.colors map=threecats rules=rules.file
To create a natural looking lookup table (LUT) for true map layer ele-
vation, 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 eleva-
tions, and finally yellow for the highest peaks (last 10% of LUT).
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
To invert the current rules:
r.colors map=current_raster -n rast=current_raster
SEE ALSO
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
See also wiki page Color tables (from GRASS User Wiki)
ColorBrewer is an online tool designed to help people select good color
schemes for maps and other graphics.
AUTHORS
Michael Shapiro and David Johnson
Support for 3D rasters by Soeren Gebbert
SOURCE CODE
Available at: r.colors source code (history)
Accessed: unknown
Main index | Raster index | Topics index | Keywords index | Graphical
index | Full index
© 2003-2022 GRASS Development Team, GRASS GIS 7.8.7 Reference Manual
GRASS 7.8.7 r.colors(1grass)
Generated by dwww version 1.14 on Sun Dec 29 18:56:19 CET 2024.