In the year 1962, Bela Julesz and J. Miller were able to show that a sense of depth can arise just from stereopsis. So they used several computer-generated pictures made up of randomly placed dots. Because the dot pictures did not contain any other information, like color or shapes, they could be sure that when their subject saw the picture it was a true 3D-impression (although the displayable „objects" were very limited). Note that they used a Stereoscope to view the pictures, therefore they found the basis for Autostereograms but did not invent them.
Tyler and Clarke realized that it is possible to put the images for both eyes into one picture, regardless of the information. This is the second step: Bela Julesz was just able to produce "random" images, usable for viewing through a Stereoscope, but now "real" scenes can be presented without technical support. The idea is to overlay both images with placing the dots carefully in a way that each serves simultaneously for two parts of the image. (This technique is explained in the next section.)
Overlaying the images for the left and the right eye into an "Autostereogram"
Depending on the method for generating this "Autostereograms" (Autostereogram means that no hardware is needed) one can distinguish SIS, SIRDS and SIRTS.
SIRDS (Single Image Random Dot Stereograms) are the original form, directly derived
from Bela Julesz´ ideas. They consist of a random pattern of dots, each representing
two pixels of the object
SIS (Single Image Stereograms) are the most common variation nowadays, where the picture
consists of (slightly modified) tiles. They are a bit more complicated to generate but
the basics of the algorithm are identical.
SIRTS (Single Image Random Text Stereograms). SIRTS are technically identical to
SIRDS but use characters instead of pixels, thereby limiting the resolution.
- 1962:
- Bela Julesz and J. E. Miller show that a sense of depth arises purely from stereopsis, without relying on other cues such as perspective or colours. They used random pat-terns of dots, which, although meaningless when viewed single-eyed, created a depth impression when viewed in a Stereoscope. (Bela Julesz had started his research when he had seen two pictures of a Spitfire-Aeroplane flying over an ice-covered river in 1940. The pictures had been taken at slightly different times and the ice had floated down the river, therefore the ice-patterns were slightly different in both pictures. This resulted in a depth parallax between the pictures and when they were stereoscopically fused there seemed to be a deep valley in the middle of the river, nobody could explain that phenomenon.)
- 1971:
- Bela Julesz writes "Foundations of Cyclopean Perception", describing photographic techniques producing random dot stereograms (invented in the 1950s) and his computer-based approach of the 1960s. He now uses Anaglyphs for Red-Green-Glasses instead of a Stereoscope for viewing his pictures.
- 1979:
- D. Marr and T. Poggio describe computational models of the visual processes that are involved in interpreting random dot stereograms in their article "A computational theory of human stereo vision" in the Proceedings of the Royal Society of London. (This article can be concidered as the basis for the Autostereograms.)
- 1983:
- Ch. Tyler introduces SIRDS as "a new type of Autostereogram decided for free fusion without the need for a Stereoscope or Anaglyph-Glasses, basing on the repetition of a random pattern".
- 1986:
- L. L. Kontsevich describes a technique for producing a picture using a series of tiles. (He seems to be the inventor of SIS.)
- 1988:
- J. Ninio and I. Herlin experiment with complex patterns (triangles, lines, blotches, and images) in the initial noise fields of their Stereograms. [NINI 1988]
- 1989:
- In Germany, the DIN 4531 Stereogram format (basing on Paul S. Boyer´s article "Stereographic technique for illustrating geologic specimens" in the Bulletin of New Jersey academy of Science) is introduced.
- 1990:
- Ch. Tyler and M. B. Clarke describe a simple, but asymmetric algorithm for producing SIRDS. Asymmetric means that some people can only see the intended effect when the picture is held upside-down.
- 1991:
- The first commercial use of SIRDS is made by Tom Baccei, President of "Pentica Systems", with publishing "Pentica Loves Puzzles".
- 1992:
- Mike Bielinski (a computer freak) and Paul Herber (a painter) found "NVision", a company producing Holusion 3D Prints.
- 1993:
- N. E. Thing Enterprises with Tom Baccei gets several RDS algorithms patented, for example the "Salitsky dot" algorithm and a method for making RDS-images loose their colors. Tom Baccei publishes "Magic Eye", a commercial very successful book showing several SIS.
- 1994:
- The successor of "Magic Eye", "Magic Eye II" is published and many people around the world start working on the subject of Stereograms (see the last chapter for books and internet-adresses).