1Ppmwheel User Manual(0)                                Ppmwheel User Manual(0)
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NAME

6       ppmwheel - make a PPM image of a color wheel
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SYNOPSIS

10       ppmwheel diameter [{-huevalue | -huesaturation}] [-maxval=N]
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DESCRIPTION

15       This program is part of Netpbm(1).
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17       ppmwheel  produces a PPM image of a color wheel of the specified diame‐
18       ter inside a white square just large enough to hold it.
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20       The color wheel is based on the HSV color model.  Hues are distributed
21         angularly around the circle and the values and saturations  are  dis‐
22       tributed
23         radially.
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25       You can generate three kinds of color wheel:
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28       ·      Hue-value: Select this with a -huevalue option.
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30              The  saturation is 100% everywhere.  The value goes from zero to
31              100%
32                linearly, from the center of the wheel to the  edge.   So  the
33              center is black.
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35              Hence,  the  image consists of all of the secondary colors based
36              on the
37                red, green, and blue primary colors.  A secondary color is one
38              that is
39                composed of light of at most two of the three primary colors.
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42       ·      Hue-saturation: Select this with a -huesaturation option.
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44              The  value is 100% everywhere.  The saturation goes from zero to
45              100%
46                linearly, from the center of the wheel to the  edge.   So  the
47              center is white.
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50       ·      Ppmcirc:  Select  this  by  not  specifying any other wheel type
51              option.
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53              The saturation is 100% everywhere.  The value is a strange func‐
54              tion of
55                the distance from the center, increasing as the square root of
56              the distance
57                until halfway out, then decreasing as the 8th root of the dis‐
58              tance the rest
59                of  the  way.  We don't know what the point of this is, but it
60              is what the
61                program Ppmcirc by Peter Kirchgessner in 1995  does,  and  was
62              the only option
63                in ppmwheel from its inception in 2003 to 2019.
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ARGUMENTS

70       You must specify one non-option argument: the radius of the color wheel
71       in pixels.
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73       This is also the height and width of the output image.
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OPTIONS

78       In addition to the options common to all programs  based  on  libnetpbm
79       (most notably -quiet, see
80        Common  Options  ⟨index.html#commonoptions⟩ ), ppmwheel recognizes the
81       following command line options:
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85       -huevalue
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87              This selects a hue-value color wheel.
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89              This option was new in Netpbm 10.86 (March 2019).
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92       -huesaturation
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94              This selects a hue-saturation color wheel.
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96              This option was new in Netpbm 10.86 (March 2019).
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99       -maxval=N
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101              This selects the maxval for the image.  The default is 255.
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103              This option was new in Netpbm 10.86 (March 2019).
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SEE ALSO

110       ppmcie(1), ppmrainbow(1), ppm(1)
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HISTORY

114       ppmwheel was added to Netpbm in Release 10.14 (March 2003).
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AUTHOR

119       Copyright (C) 1995 by Peter Kirchgessner
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DOCUMENT SOURCE

122       This manual page was generated by the Netpbm tool 'makeman'  from  HTML
123       source.  The master documentation is at
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125              http://netpbm.sourceforge.net/doc/ppmwheel.html
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127netpbm documentation           03 February 2019        Ppmwheel User Manual(0)