History
pattern as the background. They are always generated from a pair of two images with a random dot pattern. Bela Julesz invented this type of stereogram in which spatial perception is influenced by the lateral shift of the two otherwise identical images. The shift is called cross-disparity and is given in arcseconds. Test figures with small cross-disparity appear at a small distance from the background, while larger ones make the distance larger.
Random dot stereograms are often used to test precise stereopsis, which is particularly needed for fine motor activities.
