Chromostereopsis

Blue–red contrast demonstrating depth perception effects
3 Layers of depths "Rivers, Valleys & Mountains"

Chromostereopsis is a visual illusion whereby the impression of depth is conveyed in two-dimensional color images, usually of red–blue or red–green colors, but can also be perceived with red–grey or blue–grey images.[1][2] Such illusions have been reported for over a century and have generally been attributed to some form of chromatic aberration.[3][4][5][6][7]

Chromatic aberration results from the differential refraction of light depending on its wavelength, causing some light rays to converge before others in the eye (longitudinal chromatic aberration or LCA) and/or to be located on non-corresponding locations of the two eyes during binocular viewing (transverse chromatic aberration or TCA).

Chromostereopsis is usually observed using a target with red and blue bars and an achromatic background. Positive chromostereopsis is exhibited when the red bars are perceived in front of the blue and negative chromostereopsis is exhibited when the red bars are perceived behind the blue.[8] Several models have been proposed to explain this effect which is often attributed to longitudinal and/or transverse chromatic aberrations.[6] However, some work attributes most of the stereoptic effect to transverse chromatic aberrations in combination with cortical factors.[1][5][7]

It has been proposed that chromostereopsis could have evolutionary implications in the development of eyespots in certain butterfly species.

The perceived differences in color's optical power span about 2 diopter (Blue: −1.5, Red +0.5).[9][self-published source][10] The effect can appear much more pronounced when suitable images are viewed while wearing eyeglasses needed to correct myopia, with the effect almost completely disappearing when the glasses are removed.

  1. ^ a b Faubert, Jocelyn (1994). "Seeing depth in colour: More than just what meets the eyes". Vision Research. 34 (9): 1165–86. doi:10.1016/0042-6989(94)90299-2. PMID 8184561. S2CID 23295319.
  2. ^ Faubert, Jocelyn (1995). "Colour induced stereopsis in images with achromatic information and only one other colour". Vision Research. 35 (22): 3161–7. doi:10.1016/0042-6989(95)00039-3. PMID 8533350. S2CID 18383292.
  3. ^ Einthoven, W. (1885). "Stereoscopie durch Farbendifferenz". Albrecht von Graefe's Archiv für Ophthalmologie. 31 (3): 211–38. doi:10.1007/BF01692536. S2CID 10772105.
  4. ^ Kishto, B.N. (1965). "The colour stereoscopic effect". Vision Research. 5 (6–7): 313–29. doi:10.1016/0042-6989(65)90007-6. PMID 5905872.
  5. ^ a b Simonet, Pierre; Campbell, Melanie C. W. (1990). "Effect of illuminance on the directions of chromostereopsis and transverse chromatic aberration observed with natural pupils". Ophthalmic and Physiological Optics. 10 (3): 271–9. doi:10.1111/j.1475-1313.1990.tb00863.x. PMID 2216476. S2CID 34856561.
  6. ^ a b Sundet, JON Martin (1978). "Effects of colour on perceived depth: Review of experiments and evaluation of theories". Scandinavian Journal of Psychology. 19 (2): 133–43. doi:10.1111/j.1467-9450.1978.tb00313.x. PMID 675178.
  7. ^ a b Ye, Ming; Bradley, Arthur; Thibos, Larry N.; Zhang, Xiaoxiao (1991). "Interocular differences in transverse chromatic aberration determine chromostereopsis for small pupils". Vision Research. 31 (10): 1787–96. doi:10.1016/0042-6989(91)90026-2. PMID 1767497. S2CID 42856379.
  8. ^ Hartridge, H. (1947). "The Visual Perception of Fine Detail". Philosophical Transactions of the Royal Society B. 232 (592): 519–671. Bibcode:1947RSPTB.232..519H. doi:10.1098/rstb.1947.0004. JSTOR 92320.
  9. ^ "Chromostereopsis".
  10. ^ Ozolinsh, Maris; Muizniece, Kristine (2015). "Color difference threshold of chromostereopsis induced by flat display emission". Frontiers in Psychology. 06: 337. doi:10.3389/fpsyg.2015.00337. PMC 4382974. PMID 25883573.