1CPTHSV(1)                        User commands                       CPTHSV(1)
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NAME

6       cpthsv - modify hue, saturation and colour value of GMT colour palette
7       tables.
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SYNOPSIS

10       cpthsv -T transform [-h] [-o file] [-v] [-V] [file]
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DESCRIPTION

13       The cpthsv utility reads the RGB colour palette in the input, converts
14       its colours to the HSV colour-space, modifies these values in some
15       simple ways, then converts back to RGB colour space and outputs a cpt
16       file. So cpthsv can (de)saturate, brighten, darken or hue-shift.
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18       The program will read from stdin if a file is not specified as the
19       final argument, and write to stdout if the -o option is not specified.
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21       The hue value is taken to be between 0 and 360, while the saturation
22       and value components are taken to be between 0 and 1,
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OPTIONS

25       --backtrace-file path
26           Specify a file to which to write a formatted backtrace. The file
27           will only be created if there is a backtrace created, typically
28           when an error occurs.
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30       --backtrace-format format
31           Specify the format of the backtrace written to the files specified
32           by --backtrace-file, one of plain, xml or json.
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34       -h, --help
35           Brief help.
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37       -o, --output file
38           Write the output to file, rather than stdout.
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40       -T, --transform string
41           Specify a transformation to perform. One of h, s or v followed by a
42           number and optional operation. The effect of the number depends on
43           the operation: one of x (multiply by number), % (scale by
44           percentage) or +/- (add or subtract value). An RGB colour with
45           saturation 0.5 would be transformed to one with saturation 0.55 by
46           applying s1.1x or s110% or s0.05+. If the operator is not given
47           then % is assumed.
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49           Transforms which take colours outside the HSV colour-space are
50           permitted, the result is truncation (eg, increasing a saturation of
51           0.8 with s0.3+ results in a saturation of 1.0). The exception is
52           hue, which is taken modulo 360.
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54           Multiple transforms can be applied by separating transforms with
55           commas. This is to be preferred over multiple calls to the program
56           since the conversion between colour-spaces is necessarily lossy.
57           Multiple transformations are applied in the order given in the
58           argument.
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60       -v, --verbose
61           Verbose operation.
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63       -V, --version
64           Version information.
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EXAMPLE

67       Lighten by 10% and desaturate by 20%:
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69           cpthsv -v -T s80,v110 -o new.cpt old.cpt
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AUTHOR

72       J. J. Green
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SEE ALSO

75       GMT(1).
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79CPTUTILS                          8 July 2020                        CPTHSV(1)
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