Random dot stereogram

Random-dot stereogram (RDS) is stereo pair of images of random dots which when viewed with the aid of a stereoscope, or with the eyes focused on a point in front of or behind the images, produces a sensation of depth, with objects appearing to be in front of or behind the display level. Random-dot stereogram (RDS) is stereo pair of images of random dots which when viewed with the aid of a stereoscope, or with the eyes focused on a point in front of or behind the images, produces a sensation of depth, with objects appearing to be in front of or behind the display level. The random-dot stereogram technique, known since 1919, was much used by Dr. Béla Julesz and it, along with additional research, lead to publication of an influential book detailing his theories and work on the basis of human stereo vision entitled Foundations of Cyclopean Perception. Later concepts, involving single images, not necessarily consisting of random dots, and more well known to the general public, are known as autostereograms. Dr. Julesz emigrated from Hungary to the United States following the 1956 Soviet invasion. After his arrival, he found himself working at Bell Labs. One of his projects involved detecting patterns in the output of random number generators. Dr. Julesz decided to try mapping the numbers into images and using the pattern-detecting capabilities of the human brain to look for a lack of randomness. In 1840, Sir Charles Wheatstone developed the stereoscope. Using the stereoscope, two photographs, taken a small horizontal distance apart, could be viewed with the objects in the scene appearing to be 3-dimensional. Over 100 years later, Dr. Julesz noticed that two identical random images similar to what he had produced in his previously mentioned project, when viewed through a stereoscope, appeared as if they were projected onto a uniform flat surface. He experimented with the image pair by shifting a square in the center of one of the images by a small amount. When this pair was viewed through the stereoscope, however, the square appeared to rise out from the page. Though interesting on its own as a technique for producing sensations of depth in printed images, the discovery also had implications in cognitive science and the study of perception. The random dot stereogram provided insight on how stereo vision is processed by the human brain. According to Ralph Siegel, Dr. Julesz had 'unambiguously demonstrated that stereoscopic depth could be computed in the absence of any identifiable objects, in the absence of any perspective, in the absence of any cues available to either eye alone.' Dr. Julesz termed this 'cyclopean perception' based on his theory that the brain forms a single-image mental model of a scene, as a Cyclops would, but with depth information added, despite receiving two disparate images from the eyes. His theories and work are detailed in his 1971 book. There exist several types of random dot stereotests. The stereoacuity is measured from the patient's ability to identify forms from random dot backgrounds, as presented on several plates or pages of a book.