Impossible colors or forbidden colors are hues that cannot be perceived in ordinary viewing conditions from light that is a combination of various intensities of the various frequencies of visible light. Examples of impossible colors are bluish-yellow and reddish-green.[1] This does not mean the muddy brown color created when mixing red and green paints, or the green color from mixing yellow and blue paints, but rather colors that appear to be similar to, for example, both red and green, or both yellow and blue. Other colors never experienced in ordinary viewing, but perceivable under special artificial laboratory conditions, would also be termed impossible colors.
Contents |
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.
In 1983, Hewitt D. Crane and Thomas P. Piantanida carried out tests using a device that had a field of a vertical red stripe adjacent to a vertical green stripe (or in some cases, yellow–blue). In contrast to apparatus used in simpler tests the device had the ability to track involuntary eye movement, and adjust mirrors so that the image would appear to be completely stable. The boundary of the red–green stripes was stabilised on the retina of one eye while the other eye was patched and the field outside the stripes was blanked with occluders. This allowed for a mixing of the two colors in the brain, producing neither green for a yellow–blue test, nor brown for a red green test, but new colors entirely. Some of the volunteers for the experiment even reported that afterwards, they could still imagine the new colors for a period of time.[1]
Other researchers dispute the existence of colors forbidden by opponency theory and claim they are, in reality, intermediate colors.[2] See also binocular rivalry.
In 1927, American horror fiction author H. P. Lovecraft wrote a short story called "The Colour Out of Space" in which a meteorite crashed into a family farm in rural New England. The meteorite contained a mysterious globule of a color that was "almost impossible to describe," with a note that it was "only by analogy" that professors studying the globule called it a color at all.
David Lindsay in A Voyage to Arcturus described ulfire and jale, two colors visible under the sun Alppain: "Just as blue is delicate and mysterious, yellow clear and unsubtle, and red sanguine and passionate, so he felt ulfire to be wild and painful [and] jale [to be] dreamlike, feverish, and voluptuous."
In 1955, the poet Robert Graves wrote "Welsh Incident," in which something unusual from the sea caves of Criccieth is described as "mostly nameless colours, colours you'd like to see."
Octarine is Terry Pratchett's imaginary eighth color, described as a "greenish-yellow purple."
A hoax or spoof recording by Negativland, featuring the fictional character Crosley Bendix, purports to describe the newly discovered, "fourth primary" color, named "squant."
"hTun" is an impossible color that is "similar to brown" in the book Fairest, by Gail Carson Levine.
In episode 4 of the first series of Nebulous, "Holofile 333: Madness Is a Strange Colour", Vartox Paint Company's new color, Garrow (a sort of yellowy black but with more of a pinky green feel...), is sending people insane.
In "Resurection", the final episode of Futurama's sixth season, the Colorama segment ends with Fry accidentally creating an entirely new color in a rainbow. Since the entire segment is in black & white, this new color appears as just another shade of grey to the viewer.