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.

       ·       NAME

       ·       SYNOPSIS

       ·       DESCRIPTION

       ·       OPTIONS

       ·       PARAMETERS

       ·       EXAMPLES

       ·       SEE ALSO

       ·       HISTORY

       ·       AUTHOR



netpbm documentation             18 April 2004    Pamstereogram User Manual(0)

Man(1) output converted with man2html