CPTCONT(1) User commands CPTCONT(1) NAME cptcont - create a continuous GMT colour palette table (cpt) file based on the colours of a non-continuous cpt file. SYNOPSIS cptcont [-b rgb] [-f rgb] [-h] [-M] [-n rgb] [-o path] [-p percent] [-v] [-V] [-z] [-Z] [-4] [-5] [-6] [path] DESCRIPTION The cptcont program converts a (possibly) discontinuous colour palette in the input to a continuous palette in the output. This is achieved by re- placing the endpoints of segments at which a discontinuity occurs by their mean colour. The program will read from stdin if a file is not specified as the final argument, and write to stdout if the --output option is not specified. OPTIONS -b, --background rgb, --no-background Set or remove the background colour of the output. --backtrace-file path Specify a file to which to write a formatted backtrace. The file will only be created if there is a backtrace created, typically when an er- ror occurs. --backtrace-format format Specify the format of the backtrace written to the files specified by --backtrace-file, one of plain, xml or json. --comments-read path Read the comments from the specified path and add them to the output gradient. The format is custom XML which should be fairly easy to generate, see the output of --comments-write for examples. --comments-write path Write the comments in the input to the specified path. --comments-retain Use the comments in the input file as the comments for the output file. --comments-generate Create a comment with summary data (the date of creation, name and ver- sion of the cptutils package) in the output file. -f, --foreground rgb, --no-foreground Set or remove the foreground colour of the output. -h, --help Brief help. --hinge value Specify the z-value of the hinge in the cpt file. If there is no hinge directive (i.e., a SOFT_HINGE or HARD_HINGE) in the input, then this option has no effect. When normalising (with the --z-normalise option), this gives the z-value in the input which is mapped to zero. That z-value must be one of the stops in the input. When denormalising (with the --z-denormalise option), this gives the value in the output to which zero in the input is mapped. This option can be viewed as the counterpart to the +hvalue appended to the -C op- tion for the makecpt(1). --hinge-active If the input cpt has a SOFT_HINGE directive, then activate that hinge (resulting in independent scaling of the two halves of the gradient ei- ther side of the hinge). If the input does not have such a directive, then this option has no effect. -M, --midpoint Split each input segment into two output segments with the colour at the common point being the colour of the original segment. This gives a more faithful conversion of gradients with "corners", such as diverging gradients, albeit at the cost of larger files. -n, --nan rgb, --no-nan Set or remove the NaN (no data) colour of the output. -o, --output path Write the output to path, rather than stdout. -p, --partial percentage The endpoints are moved the specified percentage towards the mean colour, so that a value of 100 (the default) moves the endpoints to the mean colour, 50 moves them half-way there, and so on. Negative values and values greater than 100 are permitted (these can give interesting effects, but are not really suitable for publica- tion-quality plots). -v, --verbose Verbose operation. -V, --version Version information. -z, --z-normalise Normalise the z-values in the cpt output into the range 0/1 (or to -1/1 if a hinge is present) and add a RANGE directive if not present in the input. This is the form used in GMT master files. This option requires that output cpt version is at least 5. -Z, --z-denormalise Set the z-values in the cpt output into the range given by the RANGE directive, and remove that directive. If there is no RANGE then this option does nothing. -4, --gmt4 Use GMT 4 conventions when writing the cpt output: the colour-model code is uppercase, and the colours are separated by spaces. This is incompatible with the -5 and -6 options of course. At present this option is the default, but that will change at some point. So specify this option if your use of the output depends on the GMT 4 layout (consumed by a custom parser, for example). -5, --gmt5 Use GMT 5 conventions when writing the cpt output: the colour-model code is lowercase, and the colours are separated by a solidus for RGB, CMYK, by a dash for HSV. This is incompatible with the -4 and -6 options of course. -6, --gmt6 As the -5 option, but allows the HARD_HINGE and SOFT_HINGE directives in place of the explicit HINGE = directive. This is incompatible with the -4 and -5 options of course. EXAMPLE Create an almost-continuous table: cptcont -v -p 66 -o new.cpt old.cpt AUTHOR J.J. Green cptutils 1.85 30 September 2025 CPTCONT(1)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLE | AUTHOR
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