ppmshift(1)                                           ppmshift(1)

NAME
       ppmshift  - shift lines of a portable pixmap left or right
       by a random amount

SYNOPSIS
       ppmshift shift [ppmfile]

DESCRIPTION
       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.  Unfortunately, this program will not help me  here
       -  it  creates  too  random patterns to be used for anima-
       tions. Still, it might give interesting 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
         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.

SEE ALSO
       ppm(5), pnmcut(1), pnmflip(1), ppmdim(1), pnmcat(1)

AUTHOR
       Copyright (C) 1993 by Frank Neumann

                         16 November 1993                       1