ppmshift Man page

ppmshift General Commands Manual ppmshift


ppmshift – shift lines of a portable pixmap left or right by a random


ppmshift shift [ppmfile]


Reads a portable pixmap as input. Shifts every row of image data to the
left or right by a certain amount. The ‘shift’ parameter determines by
how many pixels a row is to be shifted at most.

Another one of those effects I intended to use for MPEG tests. Unfor‐
tunately, this program will not help me here – it creates too random
patterns to be used for animations. Still, it might give interesting
results on still images.

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 800×600 pixels:
# take the upper half, and leave it like it is
pnmcut 0 0 800 300 cs.ppm >upper.ppm

# take the lower half, flip it upside down, dim it and distort it a little
pnmcut 0 300 800 300 cs.ppm | pnmflip -tb | ppmdim 0.7 |
ppmshift 10 >lower.ppm

# and concatenate the two pieces
pnmcat -tb upper.ppm lower.ppm >newpic.ppm
The resulting picture looks like the image being reflected on a water
surface with slight ripples.


ppm(5), pnmcut, pnmflip, ppmdim, pnmcat


Copyright (C) 1993 by Frank Neumann

16 November 1993 ppmshift