Chromostereopsis

Chromostereopsis is a visual illusion whereby the impression of depth is perceived in two-dimensional color images usually 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 coloured lights refract differently depending on the colour 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, called positive chromostereopsis, or behind the blue, representing negative chromostereopsis ^[8]. Over the years several models have been proposed to explain this effect which include longitudinal and transverse chromatic aberrations ^[9]. However, recent work attribute most of the effects to transverse chromatic aberrations. ^{[10] [11]} in combination with cortical factors ^[12]. Faubert ^[13] has demonstrated that the strength of the effect and some paradoxical observations such as the same colors seen of different depth planes and different colors seen on the same depth plane demonstrate the importance of spatial configuration and brain function in such illusions and argued that some spatial and color patterns in certain species of butterfly may have evolved to generate such illusions and create the impression of protruding eyes to the predators and that some stain glass artists were probably very aware of this effect and using it to generate protruding sometimes called "warm" and "cold" color images.

References

1. ^ Faubert, (1994). Seeing depth in colour: more than just what meets the eyes. Vision Research., 34, 1165-1186.
2. ^ Faubert, (1995) Colour induced stereopsis in images with achromatic information and only one other colour. Vision Research , 35, 3161-3167.
3. ^ Einthoven, W. (1885). Setreoscopic durch Farbendifferenz. Albrecht von Graefes Archiv fur Ophthalmologie, 31, 211-238.
4. ^ Kishto, B.N. (1965). The colour stereoscopic effect.Vision Research, 5, 313-329.
5. ^ Simonet, P., & Campbell, M.C.W. (1990). Effect of illuminance on the directions of chromostereopsis and transverse chromatic aberration observed with natural pupils. Ophthalmic and Physiological Optics, 10, 271-279.
6. ^ Sundet, J.M. (1978). Effects of colour on perceived depth. Review of experiments and evaluation of theories. Scandinavian Journal of Psychology, 19, 133-143.
7. ^ Ye, M., Bradley, A., Thibos, L.N., & Zhang, X. (1991). Interocular differences in transverse chromatic aberration determine chromostereopsis for small pupils.Vision Research, 31, 1787-1796.
8. ^ Hartridge, H. (1947). The visual perception of fine detail. Philosophical Transactions of the Royal Society, London, 232, 519-671.
9. ^ Sundet, J.M. (1978). Effects of colour on perceived depth. Review of experiments and evaluation of theories. Scandinavian Journal of Psychology, 19, 133-143.
10. ^ Simonet, P., & Campbell, M.C.W. (1990). Effect of illuminance on the directions of chromostereopsis and transverse chromatic aberration observed with natural pupils. Ophthalmic and Physiological Optics, 10, 271-279.
11. ^ Ye, M., Bradley, A., Thibos, L.N., & Zhang, X. (1991). Interocular differences in transverse chromatic aberration determine chromostereopsis for small pupils.Vision Research, 31, 1787-1796.
12. ^ Faubert, (1994). Seeing depth in colour: more than just what meets the eyes. Vision Research., 34, 1165-1186.
13. ^ Faubert, (1994). Seeing depth in colour: more than just what meets the eyes. Vision Research., 34, 1165-1186.