|Artists have been capturing the
impression of a solid world since 1838 by creating a picture for each eye
and using a stereoscope to view them. Invented by Sir Charles Wheatstone,
the stereoscope comprised two vertically mounted mirrors which came to
a point where the viewer stood. With his nose in line with the join, each
eye saw a different mirror with one of the pictures reflected in it. The
first Random Dot Stereogram was created in 1939 by Boris Kompaneysky
and consisted of two blobby designs. Viewed with a stereoscope, differences
between the two apparently random pictures slowly built an image of Venus.
It was not until forty years later that Dr. Christopher W. Tyler, inspired
by the research of Dr. Bela Julesz at the Bell Telephone Research Laboratory,
invented the one frame Autostereogram. It is this which can be viewed by
the naked eye and is called a "stereogram".
|Just by viewing a repeating pattern
stereoscopically, it appears to sink away from the page. Sir David Brewster
first observed this effect in Victorian wallpaper, shortly after the discovery
of stereoscopic vision. This "wallpaper effect" can be seen wherever there
is a horizontally repeating pattern, such as inside bank envelopes and
with Cortina roof linings.
|To see stereograms, you must not
look at the computer screen where the stereogram lies, but instead look
beyond it. That is ... you have to "unfocus" your eyes and stare off into
space beyond the stereogram. Unfortunately, beginners always seem to have
a horrible time doing this, so there are a few techniques you can use.
You can get the idea of what you need to do by holding your pointer finger
up about a foot or so from your face and stare through it to the wall.
You see two fingers, right? That's what you're supposed to do with stereograms.
It's a lot of fun to do this with people, staring beyond their heads, and
seeing that they really do have four eyes (an affect of this double-vision