pamstereogram



Pamstereogram User Manual(0)                      Pamstereogram User Manual(0)



Table Of Contents


pamstereogram - create a PAM single-image stereogram from a PAM height map



pamstereogram [-help] [-verbose] [-pbm | -pgm | -ppm] [-maxval value] [-pat-


file pnmfile] [-pam] [-xshift pixels] [-yshift pixels] [-magnifypat scale]


[-guidesize pixels] [-dpi resolution] [-crosseyed] [-makemask] [-eyesep


inches] [-depth fraction] [infile]




OPTION USAGE

       Minimum unique abbreviation of option is acceptable.  You may use  dou-
       ble  hyphens  instead  of single hyphen to denote options.  You may use
       white space in place of the equals sign to separate an option name from
       its value.



       This program is part of Netpbm(1).

       pamstereogram inputs a height map (a map of the distances from your eye
       of the points in a scene) and outputs a single-image stereogram  (SIS).
       A  SIS  is  a  2-D image specially designed to appear three dimensional
       when viewed with relaxed, slightly  unfocused  eyes.   What’s  exciting
       about  single-image  stereograms  is  that  they  don’t require special
       glasses to view, although it does require a bit of  practice  to  train
       your eyes to unfocus properly.  pamstereogram program provides a wealth
       of control over how the stereogram is generated, including the  follow-
       ing:



       ·      black and white, grayscale, or color output


       ·      single-image  random-dot  stereograms  (SIRDS)  or  single-image
              stereograms (SIS) using a tiled image


       ·      images targeting a given device resolution and eye separation


       ·      optional guide boxes to assist in focusing


       ·      the ability to trade off depth levels for easier viewing


       ·      choice of ordinary or cross-eyed stereograms


       The output is a PAM image on  Standard  Output.   Options  control  the
       exact  format  of the PAM.  If you want a PNM (PBM, PGM, or PPM) image,
       use pamtopnm on the output.

       To make a red/green type of stereogram (that you view with 3-D glasses)
       instead, see ppm3dx



       -verbose
              Display messages about image sizes and formats and properties of
              the stereogram being generated.


       -blackandwhite
              Produce a single-image random-dot black  and  white  stereogram.
              This is the default.


       -grayscale
              Produce a single-image random-dot grayscale stereogram.


       -color Produce a single-image random-dot color stereogram.


       -maxval=value
              Designate  the  maximum value of each gray/color component, i.e.
              the color resolution.  Smaller values make the output image have
              smaller  numbers  of  unique grays/colors.  If you don’t specify
              -maxval, pamstereogram uses the maxval of the input image.  This
              option has no effect with -blackandwhite.


       -patfile=pnmfile
              Specify an image to use as a repeated background pattern for the
              stereogram instead of a random-dot  pattern.   Intricate  images
              generally produce a crisper 3-D effect that simpler images.  The
              output file will have the same  maxval  and  format  (black  and
              white,  grayscale  or  color)  as  the pattern file.  You cannot
              specify  the  -patfile   option   along   with   -blackandwhite,
              -grayscale, -color, or -maxval.


       -xshift=pixels
              Shift the pattern image (designated by -patfile) to the right by
              pixels pixels (default: 0).  -xshift is  helpful  when  creating
              "true-color"  stereograms.  This option is valid only along with
              -patfile.


       -yshift pixels
              Shift the pattern image (designated by  -patfile)  downwards  by
              pixels  pixels  (default: 0).    This option is valid only along
              with -patfile.


       -magnifypat=scale
              Magnify each pixel in the pattern file or  each  random  dot  by
              integral  scaling factor scale.  Note that pamstereogram applies
              the pattern magnification after pattern  shifting  (-xshift  and
              -yshift).


       -guidesize=pixels
              Draw  a  pair of pixels by pixels black squares on a white back-
              ground underneath the stereogram proper.  These squares help you
              guide  your  eyes  into proper focus to view the 3-D image.  The
              trick is to focus your eyes  some  distance  behind  the  image,
              causing  you  to  see four black squares, then continue altering
              your focus distance until the middle two black squares fuse into
              a  single  black square.  At that point, a crisp, 3-D image will
              appear.

              If pixels is negative, pamstereogram will draw the guide squares
              above  the  stereogram  instead  of below it.  If pixels is zero
              (the default), pamstereogram will draw no guide squares.


       -dpi=resolution
              Specify the resolution of the output device in  dots  per  inch.
              The  default  is  96 DPI, which represents a fairly crisp screen
              resolution.


       -crosseyed
              Invert the gray levels in the height map (input image)  so  that
              the 3-D image pops out of the page where it would otherwise sink
              into the page and vice versa.  Some people are unable to diverge
              their  eyes  and  can  only  cross  them.  The -crosseyed option
              enables such people to see the 3-D image as intended.


       -makemask
              Instead of a stereogram, output a PAM mask image showing  color-
              ing constraints.  New pixels will be taken from the pattern file
              where the mask is black.  Copies  of  existing  pixels  will  be
              taken from the pattern file where the mask is white.  The -make-
              mask option can be used to help create more  sophisticated  pat-
              tern  files  (to  use with -patfile) Note that -makemask ignores
              -magnifypat; it always produces masks that assume a pattern mag-
              nification of 1.


       -eyesep=inches
              Specify the separation in inches between your eyes. The default,
              2.5 inches (6.4 cm), should be sufficient for  most  people  and
              probably doesn’t need to be changed.


       -depth=fraction
              Specify  the  output  image’s  depth of field. That is, fraction
              represents the fractional distance of the near  plane  from  the
              far  plane.   Smaller  numbers make the 3-D image easier to per-
              ceive but flatter.  Larger numbers make the 3-D image more  dif-
              ficult  to  perceive but deeper.  The default, 0.3333, generally
              works fairly well.




       The only parameter, infile, is the name of an  input  file  that  is  a
       height map image.  If you don’t specify infile, the input is from Stan-
       dard Input.

       The input is a PAM image of depth 1.  Each sample represents  the  dis-
       tance  from  the  eye  that  the  3-D image at that location should be.
       Higher numbers mean further from the eye.

       pamstereogram pays no attention the the image’s tuple type and  ignores
       all planes other than Plane 0.

       Like  any  Netpbm program, pamstereogram will accept PNM input as if it
       were the PAM equivalent.

       A good initial test is to input an image consisting of a solid image of
       distance 0 within a large field of maximum distance.



       Generate  a SIRDS out of small, brightly colored squares and prepare it
       for display on an 87 DPI monitor:

          pamstereogram heightmap.pam                  -dpi 87 -verbose -color -maxval 1 -magnifypat 3                  >3d.pam

       Generate a SIS by tiling a PPM file (a prior run  with  -verbose  indi-
       cates how wide the pattern file should be for seamless tiling, although
       any width is acceptable for producing SISes):

          pamstereogram myheights.pam -patfile mypattern.ppm >mysis.pam





       ·       pam(1)

       ·       ppm3d(1)


       ·      Harold W. Thimbleby, Stuart Inglis, and Ian H. Witten.  Display-
              ing  3D  Images:  Algorithms  for Single Image Random Dot Stere-
              ograms. In IEEE Computer, 27(10):38-48, October 1994.





HISTORY

       pamstereogram was new in Netpbm 10.22 (April 2004).




AUTHOR

       Copyright (C) 2004 Scott Pakin, scott+pbm@pakin.org.




Table Of Contents

       ·       NAME

       ·       SYNOPSIS

       ·       DESCRIPTION

       ·       OPTIONS

       ·       PARAMETERS

       ·       EXAMPLES

       ·       SEE ALSO

       ·       HISTORY

       ·       AUTHOR



netpbm documentation             18 April 2004    Pamstereogram User Manual(0)

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