THE FIRST BLACK & WHITE RANDOM dot stereogram was invented by Dr. Bela Julesz in 1959 as an experiment to test stereopsis, the ability to see in 3D. By using uniform, randomly distributed dots (fig. 1.), Dr. Julesz eliminated the depth cues that are inherent in recognizable images.
Consider this example. First create a rectangle of randomly arranged dots. (fig 1). Within the rectangle select a group of dots that make up a small shape. In this example the small shape is a circle and the selected dots are the dots that fall within the area shown by the blue circle. (fig. 2).
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| Fig. 1 | Fig. 2 |
NEXT, CREATE a new rectangle identical to the original rectangle, except that the dots within the small shape have been shifted to the left. (fig. 3). When the two rectangles are viewed together as a stereo pair, the image of the circle appears to float above the background. (fig. 4)
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| Fig. 3 | Fig. 4 | |||
In 1979, Christopher Tyler, a student of Dr. Julesz, assisted by computer programmer Maureen Clarke, discovered that the offset scheme could be applied to a single image. This was the birth of the black and white, single-image, random dot stereogram, or autostereogram.
Fig. 5