Pamstereogram User Manual(0) Pamstereogram User Manual(0)
Table Of Contents ⟨#contents⟩
NAMEpamstereogram - create a single-image stereogram from a PAM height map
SYNOPSISpamstereogram [-help] [-verbose] [-blackandwhite | -grayscale | -color]
[-maxval=value] [-patfile=pamfile] [-xshift=pixels] [-yshift=pixels]
[-magnifypat=scale] [-guidesize=pixels] [-dpi=resolution] [-crosseyed]
[-makemask] [-eyesep=inches] [-depth=fraction] [-randomseed=integer]
[infile]
DESCRIPTION
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. The 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 wall-eyed 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. There is no need to convert if you will
use the image as input to a current Netpbm program, but many other pro‐
grams don't know what a PAM is.
To make a red/green type of stereogram (that you view with 3-D glasses)
instead, see ppm3d.
OPTIONS
You may use either single or double hyphens to denote options. You may
use either whitespace or an equals sign to separate an option name from
its value.
-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 spec‐
ify 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). 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 -makemask
option can be used to help create more sophisticated pattern
files (to use with -patfile) Note that -makemask ignores -magni‐
fypat; it always produces masks that assume a pattern magnifica‐
tion 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.
-randomseed=integer
Specify a seed to be used for the random number generator. The
default is to use a seed based on the time of day, to one second
granularity.
It is useful to specify the seed if you want to create repro‐
ducible results. With the same random seed, you should get
identical results every time you run pamstereogram.
This is irrelevant if you use a pattern file (-patfile option),
because there is no random element to pamstereogram's behavior.
This option was new in Netpbm 10.32 (February 2006).
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 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 shape of
distance 0 within a large field of maximum distance (e.g., a black
square on a white background).
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 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
SEE ALSO
·
pam(1)
·
pamsistoaglyph(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. DOI
10.1109/2.318576 ⟨http://dx.doi.org/10.1109/2.318576⟩ .
HISTORYpamstereogram was new in Netpbm 10.22 (April 2004), but probably broken
beyond usability until Netpbm 10.32 (Februrary 2006) and Netpbm
10.26.23 (January 2006).
AUTHOR
Copyright (C) 2006 Scott Pakin, scott+pbm@pakin.org.
Table Of Contents
·
SYNOPSIS ⟨#synopsis⟩
·
DESCRIPTION ⟨#description⟩
·
OPTIONS ⟨#options⟩
·
PARAMETERS ⟨#parameters⟩
·
EXAMPLES ⟨#examples⟩
·
SEE ALSO ⟨#seealso⟩
·
HISTORY ⟨#history⟩
·
AUTHOR ⟨#author⟩
netpbm documentation 6 January 2006 Pamstereogram User Manual(0)
