NAME

       grd2rgb - Write r/g/b grid files from a grid file, a raw RGB file, or SUN rasterfile

SYNOPSIS

       grd2rgb   infile   template   [   cpt   ]   [   xinc[m|s][/yinc[m|s]]  ]  [  layer  ]  region  [level]  [
       width/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  components (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 columns]. (2) A binary 2-D grid file; we then convert the z-values to
       red, green, blue via the provided CPT file. Optionally, only write out one of the r, g, b, layers. (3)  A
       RGB  or RGBA raw raster file. Since raw rasterfiles 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 contain 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][=|+][/yinc[unit][=|+]]
              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, nautical mile or US survey foot, respectively, and will be converted to
              the equivalent degrees longitude at the middle latitude 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 coordinates: If = 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 + to the supplied integer
              argument; the increment is then recalculated  from  the  number  of  nodes  and  the  domain.  The
              resulting  increment  value  depends  on  whether  you  have  selected  a  gridline-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].

       -R[unit]xmin/xmax/ymin/ymax[r] (more ...)
              Specify the region of interest.

       -V[level] (more ...)
              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 ...)
              Set pixel node registration [gridline].

       -^ or just -
              Print a short message about the syntax of the command, then exits (NOTE: on Windows use just -).

       -+ or just +
              Print an extensive usage (help) message, including the explanation 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 options, then exits.

       --version
              Print GMT version and exit.

       --show-datadir
              Print full path to GMT share directory and exit.

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, gmt.conf, grdedit, grdimage, grdmath , grdview

COPYRIGHT

       2015, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe

5.2.1                                           January 28, 2016                                   GRD2RGB(1gmt)