<s>
ASCII	B-Algorithm
stereograms	I-Algorithm
are	O
a	O
form	O
of	O
ASCII	O
art	O
based	O
on	O
stereograms	B-Algorithm
to	O
produce	O
the	O
optical	O
illusion	O
of	O
a	O
three-dimensional	O
image	O
by	O
crossing	O
the	O
eyes	O
appropriately	O
using	O
a	O
single	O
image	O
or	O
a	O
pair	O
of	O
images	O
next	O
to	O
each	O
other	O
.	O
</s>
<s>
Once	O
the	O
3D	B-Algorithm
image	I-Algorithm
effect	O
has	O
been	O
achieved	O
(	O
)	O
,	O
moving	O
the	O
viewer	O
's	O
head	O
away	O
from	O
the	O
screen	O
increases	O
the	O
stereo	O
effect	O
even	O
more	O
.	O
</s>
<s>
Figure	O
3	O
shows	O
a	O
Single	B-Algorithm
Image	I-Algorithm
Random	I-Algorithm
Text	I-Algorithm
Stereogram	I-Algorithm
(	O
SIRTS	B-Algorithm
)	O
based	O
on	O
the	O
same	O
idea	O
as	O
a	O
Single	O
Image	O
Random	O
Dot	O
Stereogram	B-Algorithm
(	O
SIRDS	B-Algorithm
)	O
.	O
</s>
<s>
Some	O
people	O
have	O
included	O
stereograms	B-Algorithm
in	O
their	O
"	O
signature	O
"	O
at	O
the	O
end	O
of	O
electronic	O
mail	O
messages	O
and	O
news	O
articles	O
.	O
</s>
<s>
Moving	O
animated	O
versions	O
of	O
ASCII	B-Algorithm
stereograms	I-Algorithm
are	O
possible	O
too	O
.	O
</s>
