pamstereogram
Updated: 18 April 2004
Table Of Contents
NAME
pamstereogram - create a PAM single-image stereogram from a PAM
height map
SYNOPSIS
pamstereogram
[-help]
[-verbose]
[-pbm | -pgm | -ppm]
[-maxval value]
[-patfile pnmfile]
[-pam]
[-xshift pixels]
[-yshift pixels]
[-magnifypat scale]
[-guidesize pixels]
[-dpi resolution]
[-crosseyed]
[-makemask]
[-eyesep inches]
[-depth fraction]
[infile]
Minimum unique abbreviation of option is acceptable. You may use
double 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.
DESCRIPTION
This program is part of Netpbm.
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 following:
- 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
OPTIONS
- -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 background 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 coloring
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 -makemask option can
be used to help create more sophisticated pattern files (to use with
-patfile) Note that -makemask ignores
-magnifypat; it always produces masks that assume a pattern
magnification 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
perceive but flatter. Larger numbers make the 3-D image more
difficult to perceive but deeper. The default, 0.3333, generally
works fairly well.
PARAMETERS
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 Standard Input.
The input is a PAM image of depth 1. Each sample represents the
distance 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.
EXAMPLES
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 indicates 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
SEE ALSO
- pam
- ppm3d
- Harold W. Thimbleby, Stuart Inglis, and Ian H. Witten.
Displaying 3D Images: Algorithms for Single Image Random Dot
Stereograms. In IEEE Computer, 27(10):38-48,
October 1994.
pamstereogram was new in Netpbm 10.22 (April 2004).
Copyright (C) 2004 Scott Pakin,
scott+pbm@pakin.org.