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diff --git a/pamshuffle.html b/pamshuffle.html new file mode 100644 index 00000000..e6646b7f --- /dev/null +++ b/pamshuffle.html @@ -0,0 +1,159 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.3//EN"> +<html><head><title>Pamshuffle User Manual</title></head> +<body> +<h1>pamshuffle</h1> +Updated: +<br> +<a href="#index">Table Of Contents</a> + +<h2>NAME</h2> +pamshuffle - Shuffle pixels of a Netpbm image + +<h2 id="synopsis">SYNOPSIS</h2> + +<b>pamshuffle</b> +[<b>-column</b> +[<b>-randomseed</b> <i>integer</i>]] +[<i>pamfile</i>] + +<p>Minimum unique abbreviations of option are 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>pamshuffle</b> reads a Netpbm image as input and produces an output file +with the pixels shuffled. The operation only changes the location of existing +pixels; nothing is discarded or added. + +<p>By default, pixels change location within rows independently, but it is +also possible to perform the same shuffle on every row, meaning the program is +shuffling vertical columns of pixels. Either way, there is no vertical +rearrangement; this means images consisting entirely of horizontal stripes, +such as the national banners of Germany, Thailand and Ukraine, will be +unchanged. + +<p>To shuffle vertically, or to perform a complete scramble, use +<b>pamshuffle</b> together with <b>pamflip</b>. See examples below. + +<p>Input is from Standard Input if you don't specify the input file +<i>pamfile</i>. + +<p>Output is to Standard Output. + +<p><b>pamshuffle</b> works on a multi-image stream. It operates on +each image in the stream independently and produces a multi-image +stream output. + +<p>The shuffling algorithm is the widely known +<a href="https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle"> +Fisher-Yates method</a>. + + +<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>pamshuffle</b> recognizes the following +command line options: + +<dl compact> +<dt><b>-column</b> + +<dd>Shuffle vertical columns, i.e. perform the same movement on all rows. +Without this option, the program shuffles each row independently. + +<dt><b>-randomseed</b>= <i>integer</i> + +<dd>This is the seed for the random number generator that generates the +pixels. + +<p>Use this to ensure you get the same image on separate invocations. + +<p>By default, <b>pamshuffle</b> uses a seed derived from the time of day +and process ID, which gives you fairly uncorrelated results in multiple +invocations. +</dl> + + +<h2 id="examples">EXAMPLES</h2> + +<p>In the following example, output is to Standard Output. You will probably +want to add redirection to somewhere useful. + +<ul> +<li><p><b>pamshuffle</b> is useful when you want to randomize the orderly +output of image generators such as <b>pamseq</b> and <b>pgmramp</b>. + +<p>Produce five permutations of integers 0 to 15: + +<pre> +<kbd> +pgmramp -lr -maxval=15 16 5 | pamshuffle -plain +</kbd> +</pre> + +<li>Shuffle columns: + +<pre> +<kbd> +pamshuffle -column image.ppm +</kbd> +</pre> + + +<li>Shuffle rows: + +<pre> +<kbd> +pamflip -cw image.ppm | pamshuffle | pamflip -ccw +</kbd> +</pre> + +<li>Perform complete shuffle: + +<pre> +<kbd> +pamflip -cw image.ppm | pamshuffle | pamflip -ccw | pamshuffle +</kbd> +</pre> + +</ul> + + +<h2 id="seealso">SEE ALSO</h2> + +<b><a href="pamseq.html">pamseq</a></b>, +<b><a href="pgmramp.html">pgmramp</a></b>, +<b><a href="pamflip.html">pamflip</a></b>, +<b><a href="ppmshift.html">ppmshift</a></b>, +<b><a href="ppmspread.html">ppmspread</a></b>, +<b><a href="pam.html">pam</a></b> + + +<h2 id="history">HISTORY</h2> + +<p><b>pamshuffle</b> was new in Netpbm 10.99 (June 2022). + + +<h2 id="author">AUTHOR</h2> + +By Akira F. Urushibata. Contributed to the public domain by the author. + +<hr> +<h2 id="index">Table Of Contents</h2> +<ul> +<li><a href="#synopsis">SYNOPSIS</a> +<li><a href="#description">DESCRIPTION</a> +<li><a href="#options">OPTIONS</a> +<li><a href="#examples">EXAMPLES</a> +<li><a href="#seealso">SEE ALSO</a> +<li><a href="#history">HISTORY</a> +<li><a href="#author">AUTHOR</a> +</ul> + +</body> +</html> |