grd2rgb(1) GMT grd2rgb(1)
NAME
grd2rgb - Write r/g/b grid files from a grid file, a raw RGB file, or
SUN rasterfile
SYNOPSIS
grd2rgb infile -Gtemplate [ -Ccpt ] [
-Ixinc[m|s][/yinc[m|s]] ] [ -Llayer ]
-Rregion
-V[level] [ -Wwidth/height[/n_bytes] ] [ -r ]
Note: No space is allowed between the option flag and the associated
arguments.
DESCRIPTION
grd2rgb reads one of three types of input files: (1) A Sun 8-, 24-, or
32-bit raster file; we the write out the red, green, and blue compo-
nents (0-255 range) to separate grid files. Since the raster file
header is limited you may use the -R, -I, -r options to set a complete
header record [Default is simply based on the number of rows and col-
umns]. (2) A binary 2-D grid file; we then convert the z-values to red,
green, blue via the provided CPT. Optionally, only write out one of the
r, g, b, layers. (3) A RGB or RGBA raw raster file. Since raw raster-
files have no header, you have to give the image dimensions via the -W
option.
REQUIRED ARGUMENTS
infile The (1) Sun raster file, (2) 2-D binary grid file, or (3) raw
raster file to be converted.
-Gtemplate
Provide an output name template for the three output grids. The
template should be a regular grid file name except it must con-
tain the string %c which on output will be replaced by r, g, or
b.
OPTIONAL ARGUMENTS
-Ccpt name of the color palette table (for 2-D binary input grid
only).
-Ixinc[unit][+e|n][/yinc[unit][+e|n]]
x_inc [and optionally y_inc] is the grid spacing. Optionally,
append a suffix modifier. Geographical (degrees) coordinates:
Append m to indicate arc minutes or s to indicate arc seconds.
If one of the units e, f, k, M, n or u is appended instead, the
increment is assumed to be given in meter, foot, km, Mile, nau-
tical mile or US survey foot, respectively, and will be con-
verted to the equivalent degrees longitude at the middle lati-
tude of the region (the conversion depends on PROJ_ELLIPSOID).
If y_inc is given but set to 0 it will be reset equal to x_inc;
otherwise it will be converted to degrees latitude. All coordi-
nates: If +e is appended then the corresponding max x (east) or
y (north) may be slightly adjusted to fit exactly the given
increment [by default the increment may be adjusted slightly to
fit the given domain]. Finally, instead of giving an increment
you may specify the number of nodes desired by appending +n to
the supplied integer argument; the increment is then recalcu-
lated from the number of nodes and the domain. The resulting
increment value depends on whether you have selected a grid-
line-registered or pixel-registered grid; see App-file-formats
for details. Note: if -Rgrdfile is used then the grid spacing
has already been initialized; use -I to override the values.
-Llayer
Output only the specified layer (r, g, or b). [Default outputs
all 3 layers].
-Rxmin/xmax/ymin/ymax[+r][+uunit] (more a|)
Specify the region of interest.
-V[level] (more a|)
Select verbosity level [c].
-Wwidth/height[/n_bytes]
Sets the size of the raw raster file. By default an RGB file
(which has 3 bytes/pixel) is assumed. For RGBA files use n_bytes
= 4. Use -W for guessing the image size of a RGB raw file, and
-W=/=/4 if the raw image is of the RGBA type. Notice that this
might be a bit slow because the guessing algorithm makes uses of
FFTs.
-r (more a|)
Set pixel node registration [gridline].
-^ or just -
Print a short message about the syntax of the command, then
exits (NOTE: on Windows just use -).
-+ or just +
Print an extensive usage (help) message, including the explana-
tion of any module-specific option (but not the GMT common
options), then exits.
-? or no arguments
Print a complete usage (help) message, including the explanation
of all options, then exits.
EXAMPLES
To use the color palette topo.cpt to create r, g, b component grids
from hawaii_grv.nc file, use
gmt grd2rgb hawaii_grv.nc -Ctopo.cpt -Ghawaii_grv_%c.nc
To output the red component from the Sun raster radiation.ras file, use
gmt grd2rgb radiation.ras -Lr -Gcomp_%c.nc
SEE ALSO
gmt(1), gmt.conf(5), grdedit(1), grdimage(1), grdmath(1), grdview(1)
COPYRIGHT
2017, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe
5.4.2 Jun 24, 2017 grd2rgb(1)
gmt5 5.4.2 - Generated Wed Jun 28 18:09:52 CDT 2017