Manual: pamshuffle

Pamshuffle User Manual(1)			   General Commands Manual			   Pamshuffle User Manual(1)

Updated:

NAME
       pamshuffle - Shuffle pixels of a Netpbm image

SYNOPSIS
       pamshuffle [-column [-randomseed integer]] [pamfile]

       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.

DESCRIPTION
       This program is part of Netpbm(1).

       pamshuffle  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.

       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 rearrange‐
       ment; this means images consisting entirely of horizontal stripes, such as the national banners of Germany,  Thailand
       and Ukraine, will be unchanged.

       To shuffle vertically, or to perform a complete scramble, use pamshuffle together with pamflip.	See examples below.

       Input is from Standard Input if you don't specify the input file pamfile.

       Output is to Standard Output.

       pamshuffle  works  on  a	 multi-image  stream.	It operates on each image in the stream independently and produces a
       multi-image stream output.

       The shuffling algorithm is the widely known  Fisher-Yates method .

OPTIONS
       In addition to the options common to all programs based on libnetpbm (most notably  -quiet,  see	  Common Options  ),
       pamshuffle recognizes the following command line options:

       -column
	      Shuffle  vertical columns, i.e. perform the same movement on all rows.  Without this option, the program shuf‐
	      fles each row independently.

       -randomseed= integer
	      This is the seed for the random number generator that generates the pixels.

	      Use this to ensure you get the same image on separate invocations.

	      By default, pamshuffle uses a seed derived from the time of day and process ID, which gives you quite uncorre‐
	      lated results in multiple invocations.

EXAMPLES
       In the following example, output is to Standard Output.	You will probably want to add redirection to somewhere	use‐
       ful.

       •

	      pamshuffle is useful when you want to randomize the orderly output of image generators such as pamseq and pgm‐
	      ramp.

	      Produce five permutations of integers 0 to 15:

	      pgmramp -lr -maxval=15 16 5 | pamshuffle -plain

       •      Shuffle columns:

	      pamshuffle -column image.ppm

       •      Shuffle rows:

	      pamflip -cw image.ppm | pamshuffle | pamflip -ccw

       •      Perform complete shuffle:

	      pamflip -cw image.ppm | pamshuffle | pamflip -ccw | pamshuffle

SEE ALSO
       pamseq(1), pgmramp(1), pamflip(1), ppmshift(1), ppmspread(1), pam(1)

HISTORY
       pamshuffle was new in Netpbm 10.99 (June 2022).

AUTHOR
       By Akira F. Urushibata.	Contributed to the public domain by the author.

DOCUMENT SOURCE
       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation is at

	      http://netpbm.sourceforge.net/doc/pamshuffle.html

netpbm documentation										   Pamshuffle User Manual(1)