User:Karam91/Chromostereopsis
From Wikipedia, the free encyclopedia
Chromostereopsis is a visual illusion whereby the impression of depth is perceived in two-dimensional color images, usually of red-blue or red-green[1]colors, but can also be perceived with red-grey or blue-grey images.[2] Such illusions have been reported for over a century [3] and have generally been attributed to some form of chromatic aberration.[4][5][6][7] Chromatic aberration results from the fact that different colors of light refract differently depending on the wavelength, causing some light rays to converge before others in the eye (longitudinal chromatic aberration or LCA) and to be located on non-corresponding locations of the two eyes during binocular viewing (transverse chromatic aberration or TCA). The usual stimulus for the study of chromostereopsis consists of a target with red and blue regions where the red portion is either perceived in front of the blue, referred to as positive chromostereopsis, or behind the blue, representing negative chromostereopsis.[8] Over the years several models have been proposed to explain this effect which includes aspects of both longitudinal and transverse chromatic aberrations.[9] However, recent work attributes most of the effects to transverse chromatic aberrations[10][11] in combination with cortical factors.[1] Faubert [1] has demonstrated that the strength of the effect and some paradoxical observations, such as the same colors being seen on different depth planes and different colors being seen on the same depth plane, highlight the importance of spatial configuration and brain function in such illusions. Faubert has also argued that some spatial and color patterns in certain species of butterfly may have evolved to generate such illusions to create the impression of protruding eyes to the predators. Additionally, some stained-glass artists were probably very aware of this effect, using it to generate protruding or receding, sometimes referred to as "warm" and "cold", color images.