NAME

       makecpt - Make GMT color palette tables

SYNOPSIS

       makecpt [  -A[+]transparency ] [  -Ccpt ] [  -D[i|o] ] [  -E[nlevels] ] [  -F[R|r|h|c ][+c]] [  -Gzlo/zhi
       ]  [   -I[c][z]  ] [  -M ] [  -N ] [  -Q[i|o] ] [  -Tz_min/z_max[/z_inc[+]] | -Tztable | -Tz1,z2,…,zn ] [
       -V[level] ] [  -W[w] ] [  -Z ] [ -bibinary ] [ -dinodata ] [ -iflags ]

       Note: No space is allowed between the option flag and the associated arguments.

DESCRIPTION

       makecpt is a utility that will  help  you  make  static  color  palette  tables  (CPTs).  You  define  an
       equidistant  set  of contour intervals or pass your own z-table or list, and create a new CPT based on an
       existing master (dynamic) CPT. The resulting CPT can be reversed relative to the master cpt, and  can  be
       made  continuous  or  discrete.   For  color  tables  beyond  the standard GMT offerings, visit cpt-city:
       http://soliton.vm.bytemark.co.uk/pub/cpt-city/.

       The CPT includes three additional colors beyond the range of z-values. These are the background color (B)
       assigned to values lower than the lowest z-value, the foreground color (F) assigned to values higher than
       the highest z-value, and the NaN color (N) painted wherever values are undefined.

       If the master CPT includes B, F, and N entries, these will be copied into the new master  file.  If  not,
       the  parameters  COLOR_BACKGROUND,  COLOR_FOREGROUND, and COLOR_NAN from the gmt.conf file or the command
       line will be used. This default behavior can be overruled using the options -D, -M or -N.

       The color model (RGB, HSV or CMYK) of the palette created by makecpt will be the same as specified in the
       header of the master CPT. When there is no COLOR_MODEL entry in the master CPT, the COLOR_MODEL specified
       in the gmt.conf file or on the command line will be used.

REQUIRED ARGUMENTS

       None.

OPTIONAL ARGUMENTS

       -A[+]transparency
              Sets a constant level of transparency (0-100) for all color slices.  Prepend + to also affect  the
              fore-, back-, and nan-colors [Default is no transparency, i.e., 0 (opaque)].

       -Ccpt  Selects  the master color table CPT to use in the interpolation.  Choose among the built-in tables
              (type makecpt to see the list) or give the name of an existing CPT [Default gives a rainbow  CPT].
              Yet  another option is to specify -Ccolor1,color2[,color3,…] to build a linear continuous cpt from
              those colors automatically.  In this case colorn can be a r/g/b triplet, a color name, or an  HTML
              hexadecimal color (e.g. #aabbcc ).

       -D[i|o]
              Select  the back- and foreground colors to match the colors for lowest and highest z-values in the
              output CPT [Default uses the colors specified  in  the  master  file,  or  those  defined  by  the
              parameters  COLOR_BACKGROUND,  COLOR_FOREGROUND,  and COLOR_NAN]. Append i to match the colors for
              the lowest and highest values in the input (instead of the output) CPT.

       -E[nlevels]
              Implies reading data table(s) from given command-line files or standard input.  We  use  the  last
              data column to determine the data range; use -i to select another column, and use -bi if your data
              table  is native binary.  This z-range information is used instead of providing the -T option.  We
              create a linear color table by dividing the table data z-range into  nlevels  equidistant  slices.
              If nlevels is not given it defaults to the number of levels in the chosen CPT.

       -F[R|r|h|c][+c]]
              Force  output  CPT  to  written  with r/g/b codes, gray-scale values or color name (R, default) or
              r/g/b codes only (r), or h-s-v codes (h), or c/m/y/k  codes  (c).   Optionally  or  alternatively,
              append +c to write discrete palettes in categorical format.

       -Gzlo/zhi
              Truncate  the  incoming CPT so that the lowest and highest z-levels are to zlo and zhi.  If one of
              these equal NaN then we leave that end of the CPT alone.  The truncation takes  place  before  any
              resampling. See also manipulating_CPTs

       -I[c][z]
              Append c [Default] to reverse the sense of color progression in the master CPT. Also exchanges the
              foreground and background colors, including those specified by the parameters COLOR_BACKGROUND and
              COLOR_FOREGROUND.   Append  z  to reverse the sign of z-values in the color table.  Note that this
              change of z-direction happens before -G and -T values are used so the latter  much  be  compatible
              with the changed z-range.  See also manipulating_CPTs

       -M     Overrule background, foreground, and NaN colors specified in the master CPT with the values of the
              parameters  COLOR_BACKGROUND, COLOR_FOREGROUND, and COLOR_NAN specified in the gmt.conf file or on
              the command line. When combined with -D, only COLOR_NAN is considered.

       -N     Do not write out the background, foreground, and NaN-color fields [Default will write them].

       -Q[i|o]
              Selects a logarithmic interpolation scheme [Default is linear].  -Qi expects input z-values to  be
              log10(z),  assigns  colors,  and writes out z [Default]. -Qo takes log10(z) first, assigns colors,
              and writes out z.

       -Tz_min/z_max[/z_inc[+]] | -Tztable | -Tz1,z2,…,zn
              Defines the range of the new CPT by giving the lowest and highest z-value  and  interval.   Append
              /z_inc  to  sample  the  input CPT discretely at intervals z_inc between z_min and z_max; append a
              trailing + to interpret z_inc as the number of desired intervals instead.  Alternatively, give the
              name of a ASCII file that has one z-value  per  record,  or  provide  a  list  of  comma-separated
              z-values instead.  If -T is not given, the existing range in the master CPT will be used intact.

       -V[level] (more …)
              Select verbosity level [c].

       -W[w]  Do  not  interpolate the input color table but pick the output colors starting at the beginning of
              the color table, until colors for all intervals are  assigned.  This  is  particularly  useful  in
              combination with a categorical color table, like “categorical”. Cannot be used in combination with
              -Z.   Alternatively,  use -Ww to produce a wrapped (cyclic) color table that endlessly repeats its
              range.

       -Z     Creates a continuous CPT [Default is discontinuous, i.e., constant colors for each interval]. This
              option has no effect when no -T is used, or when using -Tz_min/z_max; in the first case the  input
              CPT remains untouched, in the second case it is only scaled to match the range z_min/z_max.

       -bi[ncols][t] (more …)
              Select native binary input. [Default is the required number of columns given the chosen settings].

       -dinodata (more …)
              Replace input columns that equal nodata with NaN.

       -icols[+l][+sscale][+ooffset][,…] (more …)
              Select input columns and transformations (0 is first column).

       -^ 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.

NOTES ON TRANSPARENCY

       The PostScript language originally had no  accommodation  for  transparency.   However,  Adobe  added  an
       extension that allows developers to encode some forms of transparency using the PostScript language model
       but  it  is only realized when converting the PostScript to PDF (and via PDF to any raster image format).
       GMT uses this model but there are some limitations: Transparency can only be controlled on  a  per-object
       or  per-layer  basis.   This  means  that  a  color  specifications  (such  as those in CPTs of given via
       command-line options) only apply to vector graphic items (i.e., text, lines,  polygon  fills)  or  to  an
       entire  layer  (which  could  include  items  such  as PostScript images).  This limitation rules out any
       mechanism of controlling transparency in such images on a pixel level.

COLOR HINGES

       Some of the GMT master dynamic CPTs are actually two separate CPTs meeting at a hinge.   Usually,  colors
       may change dramatically across the hinge, which is used to separate two different domains (e.g., land and
       ocean  across the shoreline, for instance).  CPTs with a hinge will have their two parts stretched to the
       required range separately, i.e., the bottom part up to the hinge will be stretched independently  of  the
       part  from  the  hinge to the top, according to the prescribed new range.  If the selected range does not
       include the hinge then no such partitioning takes place.

COLOR ALIASING

       For best result when -T -Z is used we recommend you do no append a specific z_inc.  This way the original
       CPT is used exactly as is but the z boundaries are adjusted to match the stated  limits.   Otherwise  you
       may, depending on the nature of the input CPT, miss aspects of the color changes by aliasing the signal.

EXAMPLES

       To  make  a  CPT  with z-values from -200 to 200, with discrete color changes every 25, and using a polar
       blue-white-red colortable:

              gmt makecpt -Cpolar -T-200/200/25 > colors.cpt

       To make an equidistant CPT from z = -2 to 6 using the continuous default rainbow of colors:

              gmt makecpt -T-2/6 -Z > rainbow.cpt

       To use the GEBCO look-alike CPT with its default range for bathymetry, run

              gmt makecpt -Cgebco > my_gebco.cpt

       or simply use -Cgebco directly in the application that needs the  color  table.   To  create  a  24-level
       rainbow  color  table  suitable  for  plotting  the  depths  in the data table depths.txt (with lon, lat,
       depths), run

              gmt makecpt -Cgebco depths.txt -i2 -Z -E24 > my_depths.cpt

       To use the gebco color table but reverse the z-values so it can be used for positive depth values, try

              gmt makecpt -Cgebco -Iz > my_positive_gebco.cpt

       To create a 24-level rainbow color table suitable for plotting the depths in the  data  table  depths.txt
       (with lon, lat, depths), run

       To  make a custom discrete color table for depth of seismicity, using red color for hypocenters between 0
       and 100 km, green for 100-300 km, and blue for deep (300-1000 km) earthquakes, use

              gmt makecpt -Cred,green,blue -T0,80,300,1000 -N > seis.cpt

       To make a continuous CPT from white to blue as z goes from 3 to 10, try

              gmt makecpt -Cwhite,blue -T3,10 -Z > cold.cpt

       To make a wrapped (cyclic) CPT from the jet table over the interval 0 to 500, i.e.,  the  color  will  be
       wrapped every 500 z-units so that we always get a color regardless of the z value, try

              gmt makecpt -Cjet -T0/500 -Ww > wrapped.cpt

BUGS

       Since  makecpt will also interpolate from any existing CPT you may have in your directory, you should not
       use one of the listed cpt names as an output filename; hence the my_gebco.cpt in the example.  If you  do
       create  a  CPT of such a name, e.g., rainbow.cpt, then makecpt will read that file first and not look for
       the master CPT in the shared GMT directory.

SEE ALSO

       gmt, grd2cpt

COPYRIGHT

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

5.4.3                                             Jan 03, 2018                                     MAKECPT(1gmt)