1Ppm3d User Manual(0)                                      Ppm3d User Manual(0)
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NAME

6       ppm3d  -  convert two PPM images into an anaglyph (red/blue 3d glasses)
7       PPM
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SYNOPSIS

11       ppm3d [-color] [-offset=horizontal_offset] leftppmfile rightppmfile
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13       Deprecated optional 3rd argument: horizontal_offset
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DESCRIPTION

17       This program is part of Netpbm(1).
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19       ppm3d reads two PPM images as input and produces a PPM as output,  with
20       the  images  overlapping  by  the  specified  number of pixels in blue-
21       green/red format.  The idea is that if you look at the image  with  3-D
22       glasses  (glasses that admit only red through one eye and only green or
23       blue through the other), you see an image with depth.  This  is  called
24       an anaglyph stereogram.
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26       ppm3d  can  produce  either  of two kinds of anaglyph stereogram: mono‐
27       chrome or color.  Use the -color option to choose.
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29       In the monochrome version, ppm3d ignores any color  (actually,  chromi‐
30       nance)  in  the input images and produces a result which is monochrome.
31       Viewed through red-green glasses it is yellow, but  without  any  other
32       color in the field, your brain tends to see it as grayscale.
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34       In  the  color  version, ppm3d generates a result which is close to the
35       color of the original.  It's not great, though, due to  the  fact  that
36       each  eye  necessarily  cannot  see  the entire spectrum.  Red and cyan
37       don't work well, but most other colors -- especially when heavily satu‐
38       rated -- come out quite well.
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40       To  view a color analgyph stereogram, you need glasses with a left lens
41       that admits only red light and a right lens that admits only  blue  and
42       green light.  (The right lens may be called a cyan lens because that is
43       its pigment in white light; don't be misled into thinking that cyan  is
44       the only color that gets through it).  Your brain is wired so that even
45       though the components of light are coming in  through  different  eyes,
46       they  mix in your brain to form the same sensation as if you were look‐
47       ing at the combined light with both eyes.
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49       The input PPMs must be the same dimensions.
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51       To make a different kind of stereogram, use pamstereogram.  That  makes
52       a steregram that you view without special glasses, just by letting your
53       eyes unfocus so that each eye sees different parts of the image.
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ARGUMENTS

57       The mandatory arguments are file names of  the  left  and  right  input
58       images.
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60       An optional third argument specifies the same thing as the value of the
61       -offset argument, but is deprecated because -offset is  easier  to  use
62       and read.  Before Netpbm 10.38 (March 2007), this third argument is the
63       only way to specify the offset.
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OPTIONS

67       -offset=horizontal_offset
68              This option indicates the amount, in pixels, by which  the  left
69              and  image is offset to the right of the right image in the out‐
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72              The effect of this option is to move the  entire  image  forward
73              (positive  numbers) or backward (negative numbers).  With a zero
74              offset, the main subject of the picture appears in the plane  of
75              the  picture  (i.e.  if  the image is projected on a screen, the
76              location of the screen).  The main subject is the subject at the
77              location  where  the line of sight of the left camera intersects
78              the line of sight of  the  right  camera  --  the  main  subject
79              appears at the same location in both the left and right images.
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81              Default is zero.
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83              This  option was new in Netpbm 10.38 (March 2007).  Before that,
84              use the third argument instead.  Also, before Netpbm  10.38  the
85              default is +30 pixels.
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88       -color This  option  causes  ppm3d  to generate a color anaglyph stere‐
89              ogram.  By default, it generates monochrome.
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91              This option was new in Netpbm 10.38 (March 2007).
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SEE ALSO

97       pamstereogram(1) ppm(1)
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AUTHOR

101       Copyright (C) 1993 by David K. Drum.
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105netpbm documentation           20 February 2007           Ppm3d User Manual(0)
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