PPMSHIFT

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 animations. Still, it might give
      interesting results on still images.

DEMONSTRATION

      Let a.ppm be a portable pixmap.
      The following command will shift each line up to 10 pixels:
	ppmmerge ppmshift 10 a.ppm > ashift.ppm

BEFORE

AFTER

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