random-dot stereogram

stereogram, random-dot (RDS) 

A stereogram in which the eye sees an array of little characters or dots of a roughly uniform texture and containing no recognizable shape or contours. The only difference is that a certain region in one target has been laterally displaced with respect to the other, to produce some retinal disparity. When they are viewed in a stereoscope, that region is seen in stereoscopic relief. The shape in that region can be any pattern. The effect is remarkable as the shape usually appears to float out from the surround. Syn. Julesz random-dot stereogram.The random-dot E test uses a polarized random test pattern and requires the use of Polaroid spectacles to detect whether a subject has stereopsis. The subject will see a raised letter E in the random-dot pattern of one of the test plates. At 50cm, the retinal disparity induced by the E is 500 seconds of arc. The TNO test for stereoscopic vision also uses random-dot stereograms in which the half-images have been superimposed and printed in complementary colours, like anaglyphs. The test plates, when viewed with red and green spectacles, elicit stereopsis. There is a series of plates inducing retinal disparities ranging from 15 to 480 seconds of arc. See stereoscopic visual acuity; anaglyph; retinal disparity; Frisby stereotest; Lang stereotest; two-dimensional test; vectogram.
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Caption: Figure 1: The dynamic of EEG activity in alpha frequency band during perception of depth with false objects appearing to be in front of the flat plane of random-dot stereogram without using a stereoscope: (a) the topo map of alpha-activity represented as a ratio of alpha oscillation power after/before the onset of the false image perception built for individual EEG recording; (b) averaged alpha oscillation power at C3O1, FP1C3, and FP2C4 recording sites, mean [+ or -] SE; * corresponds to p < 0.05.
Presenting on the busy programme was Professor Chris Tyler, famed for his invention of the first random-dot stereogram resulting in the popularised 'Magic Eye' images.
A program was written using C# to generate all random-dot stereograms. Crossed disparity was used in all test graphs.
The first issue of Holography News in 2004 included an extended explanation of random-dot stereograms, written by 3D specialist David Burder, as an alternative method of creating 3D images.
Random-dot stimuli are instantiated in both random-dot stereograms and random-dot kinematograms (RDK).
In an early study, Webb (1972) found that individuals with mental retardation were as sensitive to random-dot stereograms as individuals without mental retardation.
They all had good stereopsis (stereo acuity of 30 s of arc or better when tested with random-dot stereograms) and no clinical heterophoria with either far (5.0 m) or close (0.3 m) fixation.
Forms of such 'autostereoscopy' do already exist--the 'magic eye' pictures and we use random-dot stereograms in the consulting room.