Opponent colors based on experiment. Protanopes will see little difference between the top and bottom colors in the central column.

The color opponent process is a color theory that states that the human visual system interprets information about color by processing signals from cones and rods in an antagonistic manner. The three types of cones have some overlap in the wavelengths of light to which they respond, so it is more efficient for the visual system to record differences between the responses of cones, rather than each type of cone's individual response. The opponent color theory suggests that there are three opponent channels: red versus green, blue versus yellow, and black versus white (the latter type is achromatic and detects light-dark variation, or luminance). Responses to one color of an opponent channel are antagonistic to those to the other color. Image File history File links Opponent_colors. ... Image File history File links Opponent_colors. ... Color blindness in humans is the inability to perceive differences between some or all colors that other people can distinguish. ... In the arts of painting, graphic design, and photography, color theory is a body of practical guidance to color mixing and the visual impact of specific color combinations. ... The visual system is the part of the nervous system which allows organisms to see. ... Color is an important part of the visual arts. ... Normalised absorption spectra of human cone (S,M,L) and rod (R) cells Cone cells, or cones, are cells in the retina of the eye which only function in relatively bright light. ... The wavelength is the distance between repeating units of a wave pattern. ... This article or section does not cite any references or sources. ... Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 625–750 nm. ... Mossy, green fountain in Wattens, Austria. ... YOU SUCK!!!!! ... A yellow Tulip. ... Black cat, thought by some to cause bad luck (see superstition) Black is the shade of objects that do not reflect light in any part of the visible spectrum. ... A white rose. ... Chromatic aberration is caused by the dispersion of the lens material, the variation of its refractive index n with the wavelength of light. ... Luminance (also called luminosity) is a photometric measure of the density of luminous intensity in a given direction. ...

Although, according to the trichromatic theory, the retina of the eye allows the visual system to detect color with three types of cones, the opponent process theory accounts for mechanisms that receive and process information from cones. Though the trichromatic and opponent processes theories were initially thought to be at odds, it later came to be understood that the mechanisms responsible for the opponent process receive signals from the three types of cones and process them at a more complex level^[1]. Normalised absorption spectra of human cone (S,M,L) and rod (R) cells Trichromatic color vision is the ability of humans and some other animals to see different colors, mediated by interactions among three types of color-sensing cone cells. ... Human eye cross-sectional view. ... // A human eye. ...

The three types of cones, S, M, and L, respond best to short-, medium- and long-wavelength light respectively. Information from the cones is passed to bipolar cells in the retina, which may be the cells in the opponent process that transform the information from cones. The information is then passed to ganglion cells, of which there are two major classes: magnocellular, or large-cell, and parvocellular or small-cell layers^[1]. He thought that the colors red, yellow, green, and blue are special in that any other color can be described as a mix of them, and that they exist in opposite pairs. That is, either red or green is perceived and never greenish-red. (Note that although yellow is a mixture of red and green in the RGB color theory, the eye does not perceive it as such.) As a part of the retina, the bipolar cell exists between photoreceptors (rod cells and cone cells) and ganglion cells. ... A ganglion cell (or sometimes called a gangliocyte) is a type of neuron located in the retina that receives visual information from photoreceptors via various intermediate cells such as bipolar cells, amacrine cells, and horizontal cells. ... Magnocellular can refer to: Magnocellular part Magnocellular neurosecretory cell Category: ... Drawing of the structure of cork as it appeared under the microscope to Robert Hook from Micrographia which is the origin of the word cell. POOP Cells in culture, stained for keratin (red) and DNA (green). ... Parvocellular can refer to: Parvocellular part part of the Paraventricular nucleus Category: ...

ERN Griggs, MD expanded the concept to reflect a wide range of opponent processes for biological systems in this book Biological Relativity (c) 1967

In 1957 Leo Hurvich and Dorothea Jameson provided quantitative data for Hering's color opponency theory^[2]. Year 1957 (MCMLVII) was a common year starting on Tuesday (link displays the 1957 Gregorian calendar). ...

In 1970 Richard Solomon expanded Hurvich's general neurological opponent process model to explain emotion, drug addiction, and work motivation.

The opponent color theory can be applied to computer vision and implemented as the Gaussian color model^[3]. Computer vision is the science and technology of machines that see. ...

Reddish green and yellowish blue

Under normal circumstances, there is no hue one could describe as a mixture of opponent hues; that is, as a hue looking "redgreen" or "yellowblue". However, in 1983 Crane and Piantanida^[4] carried out an experiment proving that, under special viewing conditions involving the use of an eye tracker, it is apparently possible to override the opponency mechanisms and, for a moment, get some people to perceive novel colors: An eye tracker is a device for measuring eye positions and eye movements. ...

"[s]ome observers indicated that although they were aware that what they were viewing was a color (that is, the field was not achromatic), they were unable to name or describe the color. One of these observers was an artist with a large color vocabulary. Other observers of the novel hues described the first stimulus as a reddish-green."^[5]

Other uses

Opponent processes have been used to explain color vision, pain, touch, emotions, smell, hearing, taste, and balance. It is basically an idea that for every stimulus there is an opposite neurological organization or struture to neutralize the response generated by the stimulus.^{[citation needed]}

See also

• color vision
• Natural Color System

Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths (or frequencies) of the light they reflect or emit. ... The Natural Color System (NCS) is a perceptual color model published by the Scandinavian Colour Institute of Stockholm, Sweden. ...

References

1. ^ ^{a b} Kandel ER, Schwartz JH and Jessell TM, 2000. Principles of Neural Science, 4th ed., McGraw-Hill, New York. pp577-80.
2. ^ Hurvich LM and Jameson D, 1957. An opponent-process theory of color vision, Psychological Review, 64:384-404)
3. ^ Geusebroek JM, van den Boomgaard R, Smeulders AWM and Geerts H, 2001. Color invariance. IEEE Transactions on Pattern Analysis and Machine Intelligence, 23(12):1338-50.
4. ^ *Crane HD and Piantanida TP, 1983. On Seeing Reddish Green and Yellowish Blue. Science, 221:1078-80.
5. ^ Suarez J and Nida-Rümelin M, Reddish Green - A Challenge for Modal Claims about Phenomenal Structure [1]

Further reading

• Baccus SA, 2007. Timing and computation in inner retinal circuitry. Annu Rev Physiol, 69:271-90.
• Masland RH, 2001. Neuronal diversity in the retina. Curr Opin Neurobiol, 11(4):431-6.
• Masland RH, 2001. The fundamental plan of the retina. Nat Neurosci. 4(9):877-86.
• Sowden PT and Schyns PG, 2006. Channel surfing in the visual brain. Trends Cogn Sci. 10(12):538-45.
• Wässle H, 2004. Parallel processing in the mammalian retina. Nat Rev Neurosci, 5(10):747-57.