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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.3//EN">
<html><head><title>Pamhue User Manual</title></head>
<body>
<h1>pamhue</h1>
Updated: 07 January 2018
<br>
<a href="#index">Table Of Contents</a>
<h2>NAME</h2>
pamhue - change a Netpbm image's hues
<h2 id="synopsis">SYNOPSIS</h2>
<b>pamhue</b>
[<b>-huechange=</b>[<i>degrees</i>]]
<i>filename</i>
<p>Minimum unique abbreviation of option is acceptable. You may use
double hyphens instead of single hyphen to denote options. You may use
white space in place of the equals sign to separate an option name
from its value.
<h2 id="description">DESCRIPTION</h2>
<p>This program is part of <a href="index.html">Netpbm</a>.
<p><b>pamhue</b> shifts the hue of every pixel in an image by the same amount.
<p>If the image is in a black and white or grayscale format, the image is
fully desaturated, so the hue is meaningless and <b>pamhue</b> leaves the
image unchanged.
<p>Hue-Saturation-Value, or HSV, is one way to represent a color, like the
more well-known RGB. Hue is an indication of the secondary color with the
same brightness that most closely approximates the color. A secondary color
is made of a combination of at most two of the primary colors.
<p>In the HSV model, hue is an angular position on the color wheel.
<p>With <b>pamhue</b>, you indicate an angle by which to change all the hues
in the image; for example you can say move it 60 degrees clockwise. That
would change all red pixels to yellow and all yellow pixels to green, etc.
<p>To modify the saturation and value components of the colors, use
<b>pambrighten</b>.
<h2 id="examples">EXAMPLES</h2>
<p>To shift the color of each pixel 120 degrees clockwise:
<pre>
pamhue -huechange=120
</pre>
<p>To shift the color of each pixel 120 degrees counterclockwise:
<pre>
pamhue -huechange=-120
</pre>
<h2 id="options">OPTIONS</h2>
<p>In addition to the options common to all programs based on libnetpbm
(most notably <b>-quiet</b>, see <a href="index.html#commonoptions">
Common Options</a>), <b>pamhue</b> recognizes the following
command line option:
<dl>
<dt><b>-huechange=</b><i>degrees</i>
<dd>This option specifies the amount to shift each color. It is in degrees,
with positive meaning clockwise and negative meaning counterclockwise. It may
be fractional and may be more than a full revolution.
<p>This option is mandatory.
</dl>
<h2 id="history">HISTORY</h2>
<p><b>pamhue</b> was new in Netpbm 10.86 (March 2019).
<h2 id="seealso">SEE ALSO</h2>
<a href="pambrighten.html">pambrighten</a>,
<a href="ppmflash.html">ppmflash</a>,
<a href="ppmhist.html">ppmhist</a>,
<a href="ppm.html">ppm</a>
<h2 id="author">AUTHOR</h2>
<p>Copyright (C) 2018 by Willem van Schaik.
Copyright (C) 1990 by Brian Moffet.
Copyright (C) 1989 by Jef Poskanzer.
<p>
Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted, provided
that the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation. This software is provided "as is" without express or
implied warranty.
<hr>
<h2 id="index">Table Of Contents</h2>
<ul>
<li><a href="#synopsis">SYNOPSIS</a>
<li><a href="#description">DESCRIPTION</a>
<li><a href="#examples">EXAMPLES</a>
<li><a href="#options">OPTIONS</a>
<li><a href="#history">HISTORY</a>
<li><a href="#seealso">SEE ALSO</a>
<li><a href="#author">AUTHOR</a>
</ul>
</body>
</html>
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