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 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. 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][+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,  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  +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  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].

       -Rxmin/xmax/ymin/ymax[+r][+uunit] (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
              just use -).

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

COPYRIGHT

       2018, P. Wessel, W. H. F. Smith, R. Scharroo, J. Luis, and F. Wobbe