ASCII stereograms are a form of ASCII art based on stereograms to produce the optical illusion of a three-dimensional image by crossing the eyes appropriately using a single image or a pair of images next to each other.
To obtain the 3D effect (in Figure 1 for instance), it is necessary for the viewer to diverge their eyes such that two adjacent letters in the same row come together (). To help in focusing, try to make the two capital Os at the top look like three. Ensure that the image of the central dot is stable and in focus. Once this has been done, look down at the rest of the image and the 3D effect should become apparent. If the Os at the bottom of Figure 1 look like three, then the effect is reversed. It is also possible to obtain opposite 3D effects by crossing the eyes rather than diverging them ().
Figure 1: Near and far distances.                             O    On   n   n   n   n   n   n   n   n   n   n   n   n   n   n   n   nf    f    f    f    f    f    f    f    f    f    f    f    f    fe   e   e   e   e   e   e   e   e   e   e   e   e   e   e   e   ea    a    a    a    a    a    a    a    a    a    a    a    a    aa   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   ar    r    r    r    r    r    r    r    r    r    r    r    r    rr   r   r   r   r   r   r   r   r   r   r   r   r   r   r   r   r                            O       O                          
Figure 2 demonstrates the effect even more dramatically. Once the 3D image effect has been achieved (), moving the viewer's head away from the screen increases the stereo effect even more. Moving horizontally and vertically a little also produces interesting effects.
Figure 3 shows a Single Image Random Text Stereogram (SIRTS) based on the same idea as a Single Image Random Dot Stereogram (SIRDS). The word "Hi" in relief can be seen when the image clicks into place. ()
Some people have included stereograms in their "signature" at the end of electronic mail messages and news articles. Figure 4 is such an example.
Figure 2: A floor, wall and ceiling.                           O          O.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .    .    .    .    .    .    .    .    .    .    .    .    .   .     .     .     .     .     .     .     .     .     .     .     .      .      .      .      .      .      .      .      . .       .       .       .       .       .       .       .       .      .        .        .        .        .        .        .   .         .         .         .         .         .         ..          .          .          .          .          .          .|          |          |          |          |          |          ||          |          |          |          |          |          ||          |          |          |          |          |          ||          |          |          |          |          |          ||          |          |          |          |          |          ||          |          |          |          |          |          |   .         .         .         .         .         .         .      .        .        .        .        .        .        . .       .       .       .       .       .       .       .       .     .      .      .      .      .      .      .      .      .   .     .     .     .     .     .     .     .     .     .     .   .    .    .    .    .    .    .    .    .    .    .    .    . .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   ..  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
Figure 3: A single image random text stereogram.                      O              OOIWEQPOISDFBKJFOIWEQPOISDFBKJFOIWEQPOISDFBKJFOIWEQPOISDFBKJFEDGHOUIEROUIYWEVDGHOXUIEROIYWEVDGHEOXUIEOIYWEVDGHEOXUIEOIYWEKJBSVDBOIWERTBAKJBSVEDBOIWRTBAKJBSOVEDBOWRTBAKJBSOVEDBOWRTBASFDHNWECTBYUVRGSFDHNYWECTBUVRGSFDHCNYWECBUVRGSFDHCNYWECBUVRGHNOWFHLSFDGWVRGHNOWFGHLSFDWVRGHNOWSFGHLSDWVRGHNLOWSFGLSDWVRGYPOWVXTNWFECHRGYPOWVEXTNWFCHRGYPOWNVEXTNFCHRGYPWOWNVETNFCHRGSVYUWXRGTWVETUISVYUWVXRGTWVETUISVYUWVXRGWVETUISVYUWVXRGWVETUWVERBYOIAWEYUIVWVERBEYOIAWEYUIVWVERBEYOIWEYUIVWLVERBEOIWEYUIEUIOETOUINWEBYOEUIOEWTOUINWEBYOEUIOEWTOUNWEBYOETUIOEWOUNWEBYWFVEWVETN9PUW4TWFVEWPVETN9UW4TWFVETWPVET9UW4TWFBVETWPET9UW4TNOUWQERFECHIBYWNOUWQXERFECIBYWNOUWFQXERFCIBYWNOFUWFQXRFCIBYWVEHWETUQECRFVE[VEHWERTUQECFVE[VEHWQERTUQCFVE[VEOHWQERUQCFVE[UIWTUIRTWUYWQCRUIWTUYIRTWUWQCRUIWTXUYIRTUWQCRUIBWTXUYRTUWQCRIYPOWOXNPWTHIECIYPOWTOXNPWHIECIYPONWTOXNWHIECIYLPONWTXNWHIECR9UHWVETPUNRQYBR9UHWVETPUNRQYBR9UHWVETPUNRQYBR9UHWVETPUNRQYB
Figure 4: A stereogram signature. IIIIIIIIIIIIIII   IIIIIIIIIIIIIII   H ( )  |/    H   H   ( )   |/ H   H(   ) -O-    H   H  (   )  -O- H   H     )/|    H   H (     ) /| H   H======^======H   H======^======H   H- |----@-----H   H----| ---@---H   H /| @|/ @  H   H   /|@ |/@ H  H    |/  |/ H   H     |/  |/H   III^IIIIIII^III   III^IIIIIII^III  Wide eyed stereo  Wide  eyed  stereo    
Moving animated versions of ASCII stereograms are possible too.
The stereo effect can be used to highlight individual words in a text, as a sort of "secret message". The effect can be disguised when the paragraph is block justified.
Figure 5: Emphasized single words.According    to    the  According    to    thepolice      inspector,  police      inspector,Edward  John Billings,  Edward John  Billings,there  are   too  many  there  are   too  manyindividuals  too close  individuals  too closeto  the  case to  make  to  the  case to  makean  arrest.   I  asked  an  arrest.   I  askedMary  Smith to comment  Mary Smith  to commenton  the case,  but she  on  the case,  but shedeclined  to  comment,  declined  to  comment,because  she  is  soon  because  she is   soonto   be   married   to  to   be   married   toHoward  D. Fredericks,  Howard  D. Fredericks,the   victim's  uncle.  the   victim's  uncle.Charles   Wilson,  the  Charles   Wilson,  thevictim's      brother,  victim's      brother,stated that  the chaos  stated that  the chaoswas   responsible  for  was  responsible   forat least  five suicide  at least  five suicideattempts   last   week  attempts   last   weekalone.                  alone.