Ppmshift User Manual(1) General Commands Manual Ppmshift User Manual(1)
NAME
ppmshift - shift lines of a PPM image left or right by a random amount
SYNOPSIS
ppmshift shift [ppmfile]
DESCRIPTION
This program is part of Netpbm(1).
ppmshift reads a PPM image as input. It shifts every row of image data
to the left or right by a random amount, within a range of shift pixels.
The random distribution is uniform, centered at zero movement.
The randomness in the image is limited before Netpbm 10.37 (December
2006) -- if you run the program twice in the same second, you may get
identical output.
This is an effect the author intended to use for MPEG tests. Unfortu-
nately, this program is not useful for that - it creates too random pat-
terns to be used for animations. Still, it might give interesting re-
sults on still images.
OPTIONS
There are no command line options defined specifically for ppmshift, but
it recognizes the options common to all programs based on libnetpbm (See
]8;;index.html#commonoptions\ Common Options]8;;\ .)
EXAMPLE
Check this out: Save your favorite model's picture from something like
alt.binaries.pictures.supermodels (ok, or from any other picture
source), convert it to ppm, and process it e.g. like this, assuming the
picture is 800x600 pixels:
#take the upper half, and leave it like it is
pamcut -top=0 -width=800 -height=300 cs.ppm >upper.ppm
#take the lower half, flip it upside down, dim it and distort it a little
pamcut -top=300 -width=800 -height=300 cs.ppm | \
pamflip -topbottom | \
ppmdim 0.7 | \
ppmshift 10 >lower.ppm
#and concatenate the two pieces
pamcat -topbottom upper.ppm lower.ppm >newpic.ppm
The resulting picture looks like the image being reflected on a water
surface with slight ripples.
SEE ALSO
ppm(1), pamcut(1), pamflip(1), ppmdim(1), pamcat(1)
AUTHOR
Copyright (C) 1993 by Frank Neumann
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/ppmshift.html
netpbm documentation 20 November 2008 Ppmshift User Manual(1)
Generated by dwww version 1.16 on Tue Dec 16 06:30:35 CET 2025.