PCXAUTO v1.1- Program to produce AutoStereogram images from PCX files.
This version - 30 January 1994
("The Software")

By Nicholas Berry
("The Author")


YOU SHOULD READ THE FOLLOWING TERMS AND CONDITIONS BEFORE USING THE SOFTWARE.
USE OF THE SOFTWARE INDICATES YOUR ACCEPTANCE OF THESE TERMS AND CONDITIONS.
IF YOU DO NOT AGREE WITH THEM, DO NOT USE THE SOFTWARE.


CONDITIONS OF USE
-----------------
None. Constructive criticism is welcome, otherwise use, delete,
or mutilate it in any way you desire or gives you satisfaction.
This program is freeware. No charge or fee is levied by The
Author for its use, and none is to be levied by any other party.
All I ask is that you send me a postcard and/or a cheap gift
from your hometown and/or best output from the program to :

Nick Berry
Headline House
Chaucer Road
Ashford
Middlesex
TW15 2QT
ENGLAND


DISCLAIMER OF WARRANTY
----------------------
PCXAUTO is supplied "as is", as seen, with no warranty of any kind. Any use
of The Software is at your own risk. The Author disclaims all warranties,
expressed or implied, including, without limitation, the warranties of 
merchantability and of fitness for any purpose. The Author accepts no 
liability for damages, direct or consequential, which may result from the
use of the software. The Author is not obliged to provide any updates to
the software.  In no event shall The Author be liable for any damages 
whatsoever (including, without limitation, incidental, direct, indirect
special and consequential damages, damages for loss of business profits,
business interruption, loss of business information, or other pecuniary 
loss) arising out of the use or inability to use The Software, even if The
Author has been advised of the possibility of such damages.


TRADEMARKS
----------
For simplicity and completeness all trade and registered marks are implicitly
acknowledged throughout the preceding text.


FILES
-----

README.TXT   Conditions of use, warranty disclaimer and instructions  
PCXAUTO.EXE  The program
DEMO<n>.PCX  Sample files to get you going


OVERVIEW
--------

PCXAUTO is a program that produces AutoStereogram images.
An AutoStereogram is a clever pattern of dots that fools the brain into 
thinking it is viewing a 3D image.  You may have seen examples of 
AutoStereogram images on posters and record covers.

It produces a 3D image in your mind because your left and right eyes see
different pictures.  Imagine a dark room containing a point light source.
If you look at the light through just your right eye it appears in one
position.  If you swap eyes, the light appears in a different place. 
The distance between these two images is proportional to how far away the
light is from your face.  An image is built up of lots of points of light.
This is how we can perceive depth - our eyes see different pictures.

An AutoStereogram is just a pattern of points of light - the trick is to get
your eyes to see 'different' pictures without the need for two screens, a pair
of glasses or some clever bits of electronics.

The program works by drawing two pixels on the screen (of a random colour) -
the separation of which is dependant on its depth.  This wouldn't fool anyone
because you would see a double picture, BUT the program carefully chooses the 
colours of the dots so that all other pixels that relate to its position 
are the same colour.  In this way your brain doesn't think "ah-ah there are 
two dots" because the colours of the dots blend into the whole image.  Simply 
- the right hand dot could be the same colour as the left hand dot of another 
pair, which could the same colour as ... Once you have coloured one dot you 
must shade all other related pixels in the same way.  Your eyes are 'sharing' 
the picture each seeing a different image and so stereopsis occurs.

This diagram may help explain it ...


                   O                 Virtual Image
          O       / |
          |\     /  |
          | \   /   |
          |  \ /    |
 ---------O---O-----O--------------  Computer Screen
         |   /  \    |               These three pixels must be the
         |  /    \   |               same colour
        |  /      \   |
        | /        \  |      <------ Lines of convergence
       | /          \ |
       |/            \|
      <*>            <*>
     Left Eye       Right Eye


Don't worry, you don't need to understand them to enjoy them.


HOW TO USE IT
-------------

PCXAUTO is driven from the command line.  It takes two arguments.  The source
filename and the destination.  These files must be 256 col PCX files.  Errors
will be reported if they are not.  The .PCX extension is not required.  If the
destination filename exists you will be given the option to overwrite.

The program should work with any sensible size of PCX file
eg (320x200, 640x480, 800x600, 1024x768).  It should work with any size of
image (eg 400x128).  There is a horizontal limit in this release of the
program to 4096 pixels.

The depth of the each pixel in the final image is dependant on the colour
of that pixel in the source image with colour 0 being the nearest to the eye
and colour 255 being the furthest away.

Note #1- depending on the resolution of the image you are processing, not all
colours have a discrete depth (The depth is derived by pixel separation and
so because of quantisment,  adjacent depths may have the same separation).

Note #2- The depth is not totally linear with colour number.

This program was designed to process images not display them.  You will need 
a package that can display 256 col PCX files to view your work and a paint
package to create your own masterpieces.  I can recommend the two packages I
use - Graphics Work Shop (Such a cool program - essential for anyone who is
doing anything with graphics on a PC) and Deluxe Paint from Electronic Arts.

The destination images are PCX files.  Because they are made up of a series
of random dots, the run-length encoding in PCX files results in huge files.
You may wish to store your prime examples in other file formats to reduce
disk space.  Don't try and use a compression system that is 'looses' 
information (well try it and look at the results!).

You don't need to have 256 cols to see the images (infact they work a treat
in black and white as well).  Experience has shown, however, that images with
more colours in are easier to see - at least that's what my colleagues who
have difficulty seeing them say.  You can reduce the colours (hello Graphics
Work Shop ..) to save disk space.

I have provided a couple of example files to get you going.  Have a look at
these files to see how they work.  Please excuse the artwork!  You should
soon pick up the idea.
                      

HINTS ON HOW TO VIEW THEM IF YOU ARE HAVING PROBLEMS
----------------------------------------------------

1. Not everyone can see them - some people see them straight away, others take
   half an hour.  Keep at it, the satisfaction of viewing the images is worth
   the wait (although with the frustration as others keep saying "Cooh look at
   this one!" it might not seem like it).  Be patient.

2. The trick is to imagine the computer screen as a window.  Imagine looking
   through the screen at something that is the same distance away from the
   screen as you are infront of it.  Some people mention that trying to focus
   on your reflection in the monitor helps.

3. Keep you head horizontal.  The images will not appear if you look at it the
   other way around.

4. Relax your eyes a little bit (but not too much) you are trying to focus on
   a virtual image that is not on the focal plane of the screen.

5. Try not to concentrate on the repeated pattern effect (waves?) that occur 
   in the image.  These occur because of how the program works.

6. Try viewing the source image then the destination so that you can see what
   you are looking for.

7. Get a friend to help and encourage you to stick at it!


SUPPORT AND COMMENTS
--------------------
As this software is "Freeware", I am not obliged to give any technical
support or produce any updates to PCXAUTO. However, I would appreciate
any constructive criticism and/or suggestions on how PCXAUTO could be 
improved.  Please don't hesitate to write to me or Email from
CompuServe Mail on :

MHS:NICK@NBMSMAIL


THANKS TO
---------

Andy and Steve for providing the bulk of the 'Shareware disclaimer' text.
Joy for the cups of tea and Ironed shirts (hint).

Thats all folks!

-----------------------------------------------------------------------------
Nick Berry M.Eng
8/2/94
-----------------------------------------------------------------------------
