Ppmshift User Manual(0) Ppmshift User Manual(0)NAMEppmshift - shift lines of a PPM image left or right by a random amount
SYNOPSISppmshift shift [ppmfile]
DESCRIPTION
This program is part of Netpbm(1).
ppmshift reads a PPM image as input. 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 another one of those effects I intended to use for MPEG tests.
Unfortunately, this program will not help me here - it creates too ran‐
dom patterns to be used for animations. Still, it might give interest‐
ing results on still images.
EXAMPLE
Check this out: Save your favourite 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
pnmcat -topbottom upper.ppm lower.ppm >newpic.ppm
The resulting picture looks like the image being reflected on a water
surface with slight ripples.
SEE ALSOppm(1), pamcut(1), pamflip(1), ppmdim(1), pnmcat(1)AUTHOR
Copyright (C) 1993 by Frank Neumann
netpbm documentation 20 November 2008 Ppmshift User Manual(0)
