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Ppm3d User Manual(0)                                      Ppm3d User Manual(0)



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


SYNOPSIS
       ppm3d [-color] [-offset=horizontal_offset] leftppmfile rightppmfile

       Deprecated optional 3rd argument: horizontal_offset


DESCRIPTION
       This program is part of Netpbm(1).

       ppm3d  reads two PPM images as input and produces a PPM as output, with the images overlapping by the specified
       number of pixels in blue-green/red format.  The idea is that if you look at the image with 3-D glasses (glasses
       that  admit  only  red  through one eye and only green or blue through the other), you see an image with depth.
       This is called an anaglyph stereogram.

       ppm3d can produce either of two kinds of anaglyph stereogram: monochrome or color.  Use the  -color  option  to
       choose.

       In  the  monochrome version, ppm3d ignores any color (actually, chrominance) in the input images and produces a
       result which is monochrome.  Viewed through red-green glasses it is yellow, but without any other color in  the
       field, your brain tends to see it as grayscale.

       In  the  color  version, ppm3d generates a result which is close to the color of the original.  It's not great,
       though, due to the fact that each eye necessarily cannot see the entire spectrum.   Red  and  cyan  don't  work
       well, but most other colors -- especially when heavily saturated -- come out quite well.

       To  view  a color analgyph stereogram, you need glasses with a left lens that admits only red light and a right
       lens that admits only blue and green light.  (The right lens may be called a cyan lens because that is its pig-
       ment  in  white  light;  don't be misled into thinking that cyan is the only color that gets through it).  Your
       brain is wired so that even though the components of light are coming in through different eyes,  they  mix  in
       your brain to form the same sensation as if you were looking at the combined light with both eyes.

       The input PPMs must be the same dimensions.

       To  make  a different kind of stereogram, use pamstereogram.  That makes a steregram that you view without spe-
       cial glasses, just by letting your eyes unfocus so that each eye sees different parts of the image.


ARGUMENTS
       The mandatory arguments are file names of the left and right input images.

       An optional third argument specifies the same thing as the value of the -offset  argument,  but  is  deprecated
       because  -offset  is easier to use and read.  Before Netpbm 10.38 (March 2007), this third argument is the only
       way to specify the offset.


OPTIONS
       -offset=horizontal_offset
              This option indicates the amount, in pixels, by which the left and image is offset to the right  of  the
              right image in the output.

              The  effect  of this option is to move the entire image forward (positive numbers) or backward (negative
              numbers).  With a zero offset, the main subject of the picture appears in the plane of the picture (i.e.
              if  the image is projected on a screen, the location of the screen).  The main subject is the subject at
              the location where the line of sight of the left camera intersects the line of sight of the right camera
              -- the main subject appears at the same location in both the left and right images.

              Default is zero.

              This  option  was new in Netpbm 10.38 (March 2007).  Before that, use the third argument instead.  Also,
              before Netpbm 10.38 the default is +30 pixels.


       -color This option causes ppm3d to generate a color anaglyph stereogram.  By default, it generates  monochrome.

              This option was new in Netpbm 10.38 (March 2007).




SEE ALSO
       pamstereogram(1) ppm(1)


AUTHOR
       Copyright (C) 1993 by David K. Drum.



netpbm documentation           20 February 2007           Ppm3d User Manual(0)