Mobiles Wallpaper Biography
source(google.com.pk)Wallpapers Biography: An autostereogram is a single-image stereogram (SIS), designed to create the visual illusion of a three-dimensional (3D) scene from a two-dimensional image in the human brain. In order to perceive 3D shapes in these autostereograms, the brain must overcome the normally automatic coordination between focusing and vergence.The simplest type of autostereogram consists of horizontally repeating patterns and is known as an autostereogram is a single-image stereogram (SIS), designed to create the visual illusion of a three-dimensional (3D) scene from a two-dimensional image in the human brain. In order to perceive 3D shapes in these autostereograms, the brain must overcome the normally automatic coordination between focusing and vergence.
The simplest type of autostereogram consists of horizontally repeating patterns and is known as a wallpaper autostereogram. When viewed with proper vergence, the repeating patterns appear to float above or below the background. The Magic Eye books feature another type of autostereogram called a random dot autostereogram. One such autostereogram is illustrated above right. In this type of autostereogram, every pixel in the image is computed from a pattern strip and a depth map. Usually, a hidden 3D scene emerges when the image is viewed with the correct vergence.
Autostereograms are similar to normal stereograms except they are viewed without a stereoscope. A stereoscope presents 2D images of the same object from slightly different angles to the left eye and the right eye, allowing the brain to reconstruct the original object via binocular disparity. With an autostereogram, the brain receives repeating 2D patterns from both eyes, but fails to correctly match them. It pairs two adjacent patterns into a virtual object based on wrong parallax angles, thus placing the virtual object at a depth different from that of the autostereogram image.
There are two ways an autostereogram can be viewed: wall-eyed and cross-eyed. Most autostereograms (including those in this article) are designed to be viewed in only one way, which is usually wall-eyed. Wall-eyed viewing requires that the two eyes adopt a relatively parallel angle, while cross-eyed viewing requires a relatively convergent angle. An image designed for wall-eyed viewing if viewed correctly will appear to pop out of the background, while if viewed cross-eyed it will instead appear as a cut-out behind the background and will be difficult to bring entirely into focus.
In 1838, the British scientist Charles Wheatstone published an explanation of stereopsis (binocular depth perception) arising from differences in the horizontal positions of images in the two eyes. He supported his explanation by showing pictures with such horizontal differences, stereograms, separately to the left and right eyes through a stereoscope he invented based on mirrors. When people looked at these flat, two-dimensional pictures, they experienced the illusion of three-dimensional depth.
Between 1849 and 1850, David Brewster, a Scottish scientist, improved the Wheatstone stereoscope by using lenses instead of mirrors, thus reducing the size of the device.
Brewster also discovered the "wallpaper effect". He noticed that staring at repeated patterns in wallpapers could trick the brain into matching pairs of them as coming from the same virtual object on a virtual plane behind the walls. This is the basis of wallpaper-style "autostereograms" (also known as single-image stereograms).
In 1959, Bela Julesz, a vision scientist, psychologist and MacArthur Fellow, invented the random dot stereogram while working at Bell Laboratories on recognizing camouflaged objects from aerial pictures taken by spy planes. At the time, many vision scientists still thought that depth perception occurred in the eye itself, whereas now it is known to be a complex neurological process. Julesz used a computer to create a stereo pair of random-dot images which, when viewed under a stereoscope, caused the brain to see 3D shapes. This proved that depth perception is a neurological process.
In 1979, Christopher Tyler of Smith-Kettlewell Institute, a student of Julesz and a visual psychophysicist, combined the theories behind single-image wallpaper stereograms and random-dot stereograms to create the first "random-dot autostereogram" (also known as single-image random-dot stereogram). This type of autostereogram allows a person to see 3D shapes from a single 2D image without the aid of optical equipment. This is an example of a wallpaper with repeated horizontal patterns. Each pattern is repeated exactly every 140 pixels. The illusion of the pictures lying on a flat surface (a plane) further back is created by the brain. Non-repeating patterns such as arrows and words, on the other hand, appear on the plane where this text lies.
Stereopsis, or stereo vision, is the visual blending of two similar but not identical images into one, with resulting visual perception of solidity and depth.In the human brain, stereopsis results from complex mechanisms that form a three-dimensional impression by matching each point (or set of points) in one eye's view with the equivalent point (or set of points) in the other eye's view. Using binocular disparity, the brain derives the points' positions in the otherwise inscrutable z-axis (depth)
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