MAKECPT(1)

NAME
makecpt - Make GMT color palette tables

SYNOPSIS
makecpt [ -Ctable ] [ -I ] [ -N ] [ -Q[i|o] ] [ -Tz0/z1/dz | -Tztable] [ -V ] [ -Z ]

DESCRIPTION
makecpt is a utility that will help you make color palette tables (cpt files). You define an equidistant set of contour intervals or pass your own z-table, and create a new cpt file based on an existing master cpt file. The resulting cpt file can be reversed relative to the master cpt, and can be made continuous or discrete.

OPTIONS

-C  Selects the master color table table to use in the interpolation. Choose among the built-in tables (type makecpt to see the list) or give the name of an existing cptfile [Default gives a rainbow cpt file].

-I  Reverses the sense of color progression in the master cptfile.

-N  Do Not write out the background, foreground, and NaN-color fields [Default will write the parameters COLOR_BACKGROUND, COLOR_FOREGROUND, and COLOR_NAN in your .gmtdefaults4 file.

-Q  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.

-T  Defines the range of the new cptfile by giving the lowest and highest z-value and the interval. Alternatively, give the name of a ASCII file that has one z-value per record. If not given, the existing range in the master cptfile will be used intact.

-V  Selects verbose mode, which will send progress reports to stderr [Default runs "silently"].

-Z  Creates a continuous cpt file [Default is discontinuous, i.e. constant colors for each interval].

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

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

To make an equidistant cpt file from z = -2 to 6, in steps of 1, using continuous default rainbow colors:

makecpt -T-2/6/1 -Z > rainbow.cpt

To make a GEBCO look-alike cpt file for bathymetry, run

makecpt -Cgebco > my_gebco.cpt

BUGS
Since makecpt will also interpolate from any existing .cpt file you may have in your directory, you cannot use one of the listed cpt names as an output filename; hence the my_gebco.cpt in the example.

SEE ALSO
gmt(1), grd2cpt(1)