1Ppmshift User Manual(0)                                Ppmshift User Manual(0)
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NAME

6       ppmshift - shift lines of a PPM image left or right by a random amount
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SYNOPSIS

10       ppmshift shift [ppmfile]
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DESCRIPTION

14       This program is part of Netpbm(1).
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16       ppmshift reads a PPM image as input.  Shifts every row of image data to
17       the left or right by a random amount, within a range of  shift  pixels.
18       The random distribution is uniform, centered at zero movement.
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20       The  randomness  in  the image is limited before Netpbm 10.37 (December
21       2006) -- if you run the program twice in the same second, you  may  get
22       identical output.
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24       This  is another one of those effects I intended to use for MPEG tests.
25       Unfortunately, this program will not help me here - it creates too ran‐
26       dom patterns to be used for animations.  Still, it might give interest‐
27       ing results on still images.
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EXAMPLE

31       Check this out: Save your favourite model's picture from something like
32       alt.binaries.pictures.supermodels   (ok,  or  from  any  other  picture
33       source), convert it to ppm, and process it e.g. like this, assuming the
34       picture is 800x600 pixels:
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36            #take the upper half, and leave it like it is
37            pamcut -top=0 -width=800 -height=300 cs.ppm >upper.ppm
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39            #take the lower half, flip it upside down, dim it and distort it a little
40            pamcut -top=300 -width=800 -height=300 cs.ppm | \
41                pamflip -topbottom | \
42                ppmdim 0.7 | \
43                ppmshift 10 >lower.ppm
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45            #and concatenate the two pieces
46            pnmcat -topbottom upper.ppm lower.ppm >newpic.ppm
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49       The  resulting  picture looks like the image being reflected on a water
50       surface with slight ripples.
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SEE ALSO

54       ppm(1), pamcut(1), pamflip(1), ppmdim(1), pnmcat(1)
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AUTHOR

59       Copyright (C) 1993 by Frank Neumann
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63netpbm documentation           20 November 2008        Ppmshift User Manual(0)
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