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Stereoscopy (also called stereoscopics) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. The word ''stereoscopy'' derives .〔(στερεός Tufts.edu ), Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus Digital Library〕〔(σκοπέω ), Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus Digital Library〕 Any stereoscopic image is called a stereogram. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope. Most stereoscopic methods present two offset images separately to the left and right eye of the viewer. These two-dimensional images are then combined in the brain to give the perception of 3D depth. This technique is distinguished from 3D displays that display an image in three full dimensions, allowing the observer to increase information about the 3-dimensional objects being displayed by head and eye movements. ==Background== Stereoscopy creates the illusion of three-dimensional depth from given two-dimensional images.〔(Exercises in Three Dimensions: About 3D ), Tom Lincoln, 2011〕 Human vision, including the perception of depth, is a complex process which only begins with the acquisition of visual information taken in through the eyes; much processing ensues within the brain, as it strives to make intelligent and meaningful sense of the raw information provided. One of the very important visual functions that occur within the brain as it interprets what the eyes see is that of assessing the relative distances of various objects from the viewer, and the depth dimension of those same perceived objects. The brain makes use of a number of ''cues'' to determine relative distances and depth in a perceived scene, including:〔Flight Simulation, J. M. Rolfe and K. J. Staples, Cambridge University Press, 1986, page 134〕 * ''Stereopsis'' * ''Accommodation of the eye'' * ''Overlapping of one object by another'' * ''Subtended visual angle of an object of known size'' * ''Linear perspective (convergence of parallel edges)'' * ''Vertical position (objects higher in the scene generally tend to be perceived as further away)'' * ''Haze, desaturation, and a shift to bluishness'' * ''Change in size of textured pattern detail'' (All the above cues, with the exception of the first two, are present in traditional two-dimensional images such as paintings, photographs, and television.)〔(Exercises in Three Dimensions ), Tom Lincoln, 2011〕 Stereoscopy is the production of the illusion of depth in a photograph, movie, or other two-dimensional image by presenting a slightly different image to each eye, and thereby adding the first of these cues (stereopsis) as well. Both of the 2D offset images are then combined in the brain to give the perception of 3D depth. It is important to note that since all points in the image focus at the same plane regardless of their depth in the original scene, the second cue, focus, is still not duplicated and therefore the illusion of depth is incomplete. There are also primarily two effects of stereoscopy that are unnatural for the human vision: first, the mismatch between convergence and accommodation, caused by the difference between an object's perceived position in front of or behind the display or screen and the real origin of that light and second, possible crosstalk between the eyes, caused by imperfect image separation by some methods. Although the term "3D" is ubiquitously used, it is also important to note that the presentation of dual 2D images is distinctly different from displaying an image in three full dimensions. The most notable difference is that, in the case of "3D" displays, the observer's head and eye movement will not increase information about the 3-dimensional objects being displayed. Holographic displays or volumetric display are examples of displays that do not have this limitation. Similar to the technology of sound reproduction, in which it is not possible to recreate a full 3-dimensional sound field merely with two stereophonic speakers, it is likewise an overstatement of capability to refer to dual 2D images as being "3D". The accurate term "stereoscopic" is more cumbersome than the common misnomer "3D", which has been entrenched after many decades of unquestioned misuse. Although most stereoscopic displays do not qualify as real 3D display, all real 3D displays are also stereoscopic displays because they meet the lower criteria as well. Most 3D displays use this stereoscopic method to convey images. It was first invented by Sir Charles Wheatstone in 1838,〔Contributions to the Physiology of Vision.—Part the First. On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision. By CHARLES WHEATSTONE, F.R.S., Professor of Experimental Philosophy in King's College, London. (Stereoscopy.com )〕〔Welling, William. Photography in America, page 23〕 and improved by Sir David Brewster who made the first portable 3D viewing device.〔International Stereoscopic Union, 2006, "Stereoscopy", Numbers 65-72, p.18〕 Wheatstone originally used his stereoscope (a rather bulky device)〔''Stereo Realist Manual'', p. 375.〕 with drawings because photography was not yet available, yet his original paper seems to foresee the development of a realistic imaging method:〔''Stereo Realist Manual'', pp. 377–379.〕 For the purposes of illustration I have employed only outline figures, for had either shading or colouring been introduced it might be supposed that the effect was wholly or in part due to these circumstances, whereas by leaving them out of consideration no room is left to doubt that the entire effect of relief is owing to the simultaneous perception of the two monocular projections, one on each retina. But if it be required to obtain the most faithful resemblances of real objects, shadowing and colouring may properly be employed to heighten the effects. Careful attention would enable an artist to draw and paint the two component pictures, so as to present to the mind of the observer, in the resultant perception, perfect identity with the object represented. Flowers, crystals, busts, vases, instruments of various kinds, &c., might thus be represented so as not to be distinguished by sight from the real objects themselves.〔 Stereoscopy is used in photogrammetry and also for entertainment through the production of stereograms. Stereoscopy is useful in viewing images rendered from large multi-dimensional data sets such as are produced by experimental data. An early patent for 3D imaging in cinema and television was granted to physicist Theodor V. Ionescu in 1936. Modern industrial three-dimensional photography may use 3D scanners to detect and record three-dimensional information.〔Fay Huang, Reinhard Klette, and Karsten Scheibe: Panoramic Imaging (Sensor-Line Cameras and Laser Range-Finders). Wiley & Sons, Chichester, 2008〕 The three-dimensional depth information can be reconstructed from two images using a computer by corresponding the pixels in the left and right images. Solving the Correspondence problem in the field of Computer Vision aims to create meaningful depth information from two images. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Stereoscopy」の詳細全文を読む スポンサード リンク
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