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,  because  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 anaglyph 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  pigment  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 stereogram that you view without
       special 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

       In addition to the options common to all programs based on libnetpbm (most notably  -quiet,  see   Common
       Options ), ppm3d recognizes the following command line 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.

DOCUMENT SOURCE

       This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The  master  documentation
       is at

              http://netpbm.sourceforge.net/doc/ppm3d.html

netpbm documentation                            20 February 2007                            Ppm3d User Manual(1)