ASCII stereogram

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   O n   n   n   n   n   n   n   n   n   n   n   n   n   n   n   n   n f    f    f    f    f    f    f    f    f    f    f    f    f    f e   e   e   e   e   e   e   e   e   e   e   e   e   e   e   e   e a    a    a    a    a    a    a    a    a    a    a    a    a    a a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a   a r    r    r    r    r    r    r    r    r    r    r    r    r    r r   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             O OIWEQPOISDFBKJFOIWEQPOISDFBKJFOIWEQPOISDFBKJFOIWEQPOISDFBKJF EDGHOUIEROUIYWEVDGHOXUIEROIYWEVDGHEOXUIEOIYWEVDGHEOXUIEOIYWE KJBSVDBOIWERTBAKJBSVEDBOIWRTBAKJBSOVEDBOWRTBAKJBSOVEDBOWRTBA SFDHNWECTBYUVRGSFDHNYWECTBUVRGSFDHCNYWECBUVRGSFDHCNYWECBUVRG HNOWFHLSFDGWVRGHNOWFGHLSFDWVRGHNOWSFGHLSDWVRGHNLOWSFGLSDWVRG YPOWVXTNWFECHRGYPOWVEXTNWFCHRGYPOWNVEXTNFCHRGYPWOWNVETNFCHRG SVYUWXRGTWVETUISVYUWVXRGTWVETUISVYUWVXRGWVETUISVYUWVXRGWVETU WVERBYOIAWEYUIVWVERBEYOIAWEYUIVWVERBEYOIWEYUIVWLVERBEOIWEYUI EUIOETOUINWEBYOEUIOEWTOUINWEBYOEUIOEWTOUNWEBYOETUIOEWOUNWEBY WFVEWVETN9PUW4TWFVEWPVETN9UW4TWFVETWPVET9UW4TWFBVETWPET9UW4T NOUWQERFECHIBYWNOUWQXERFECIBYWNOUWFQXERFCIBYWNOFUWFQXRFCIBYW VEHWETUQECRFVE[VEHWERTUQECFVE[VEHWQERTUQCFVE[VEOHWQERUQCFVE[ UIWTUIRTWUYWQCRUIWTUYIRTWUWQCRUIWTXUYIRTUWQCRUIBWTXUYRTUWQCR IYPOWOXNPWTHIECIYPOWTOXNPWHIECIYPONWTOXNWHIECIYLPONWTXNWHIEC R9UHWVETPUNRQYBR9UHWVETPUNRQYBR9UHWVETPUNRQYBR9UHWVETPUNRQYB

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.

Text emphasis
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    the police     inspector,  police      inspector, Edward John Billings,  Edward John  Billings, there are   too  many  there  are   too  many individuals too close  individuals  too close to the  case to  make  to  the  case to  make an arrest. I asked  an  arrest. I asked Mary Smith to comment  Mary Smith  to comment on the case,  but she  on  the case,  but she declined to  comment,  declined  to  comment, because she  is  soon  because  she is   soon to  be   married   to  to   be   married   to Howard  D. Fredericks,  Howard  D. Fredericks, the  victim's  uncle. the  victim's  uncle. Charles  Wilson,  the  Charles   Wilson,  the victim's     brother,  victim's      brother, stated that the chaos  stated that  the chaos was  responsible  for  was  responsible   for at least five suicide  at least  five suicide attempts  last   week  attempts   last   week alone. alone.