A 1775 color triangle by Tobias Mayer.The sRGB color triangle, shown as a subset of x,y space, a chromaticity space based on CIE 1931 colorimetry
An additive color space defined by three primary colors has a chromaticitygamut that is a color triangle, when the amounts of the primaries are constrained to be nonnegative.[1][2]
After the development of the CIE system, color triangles were used as chromaticity diagrams, including briefly with the trilinear coordinates representing the chromaticity values.[4] Since the sum of the three chromaticity values has a fixed value, it suffices to depict only two of the three values, using Cartesian co-ordinates. In the modern x,y diagram, the large triangle bounded by the imaginary primaries X, Y, and Z has corners (1,0), (0,1), and (0,0), respectively; color triangles with real primaries are often shown within this space.
Maxwell's discedit
Maxwell was intrigued by James David Forbes's use of color tops. By rapidly spinning the top, Forbes created the illusion of a single color that was a mixture of the primaries:[5]
[The] experiments of Professor J. D. Forbes, which I witnessed in 1849… [established] that blue and yellow do not make green, but a pinkish tint, when neither prevails in the combination…[and the] result of mixing yellow and blue was, I believe, not previously known.
Maxwell took this a step further by using a circular scale around the rim with which to measure the ratios of the primaries, choosing vermilion (V), emerald (EG), and ultramarine (U).[6]
Initially, he compared the color he observed on the spinning top with a paper of different color, in order to find a match. Later, he mounted a pair of papers, snow white (SW) and ivory black (Bk), in an inner circle, thereby creating shades of gray. By adjusting the ratio of primaries, he matched the observed gray of the inner wheel, for example:[7]
To determine the chromaticity of an arbitrary color, he replaced one of the primaries with a sample of the test color and adjusted the ratios until he found a match. For pale chrome (PC) he found . Next, he rearranged the equation to express the test color (PC, in this example) in terms of the primaries.
A color triangle attributed to Fick in 1892, based on imaginary primaries corresponding to the three primary sensations of the human eye. In such a triangle, all real colors fall within the curved outline defined by the "pure sensations".
^Arun N. Netravali; G. Haskell (1995). Digital Pictures: Representation, Compression, and Standards (second ed.). Springer. ISBN0-306-42195-X.
^Werner Backhaus, Reinhold Kliegl and John Simon Werner (1998). Color Vision: Perspectives from Different Disciplines. Walter de Gruyter. ISBN3-11-015431-5.
^Sarah Lowengard (2008). The Creation of Color in Eighteenth-Century Europe. Columbia University Press. ISBN978-0-231-12454-6.
^Judd, Deane B. (January 1935). "A Maxwell Triangle Yielding Uniform Chromaticity Scales". JOSA. 25 (1): 24–35. doi:10.1364/JOSA.25.000024.
^James Clerk Maxwell (1855), Experiments on colour as perceived by the eye, with remarks on colour-blindness
January 01, 1970
color, triangle, color, triangle, arrangement, colors, within, triangle, based, additive, subtractive, combination, three, primary, colors, corners, 1775, color, triangle, tobias, mayer, srgb, color, triangle, shown, subset, space, chromaticity, space, based, . A color triangle is an arrangement of colors within a triangle based on the additive or subtractive combination of three primary colors at its corners A 1775 color triangle by Tobias Mayer The sRGB color triangle shown as a subset of x y space a chromaticity space based on CIE 1931 colorimetry An additive color space defined by three primary colors has a chromaticity gamut that is a color triangle when the amounts of the primaries are constrained to be nonnegative 1 2 Before the theory of additive color was proposed by Thomas Young and further developed by James Clerk Maxwell and Hermann von Helmholtz triangles were also used to organize colors for example around a system of red yellow and blue primary colors 3 After the development of the CIE system color triangles were used as chromaticity diagrams including briefly with the trilinear coordinates representing the chromaticity values 4 Since the sum of the three chromaticity values has a fixed value it suffices to depict only two of the three values using Cartesian co ordinates In the modern x y diagram the large triangle bounded by the imaginary primaries X Y and Z has corners 1 0 0 1 and 0 0 respectively color triangles with real primaries are often shown within this space Maxwell s disc editMaxwell was intrigued by James David Forbes s use of color tops By rapidly spinning the top Forbes created the illusion of a single color that was a mixture of the primaries 5 The experiments of Professor J D Forbes which I witnessed in 1849 established that blue and yellow do not make green but a pinkish tint when neither prevails in the combination and the result of mixing yellow and blue was I believe not previously known James Clerk Maxwell Experiments on colour as perceived by the eye with remarks on colour blindness 1855 Transactions of the Royal Society of Edinburgh Maxwell took this a step further by using a circular scale around the rim with which to measure the ratios of the primaries choosing vermilion V emerald EG and ultramarine U 6 Initially he compared the color he observed on the spinning top with a paper of different color in order to find a match Later he mounted a pair of papers snow white SW and ivory black Bk in an inner circle thereby creating shades of gray By adjusting the ratio of primaries he matched the observed gray of the inner wheel for example 7 0 37 V 0 27 U 0 36 E G 0 28 S W 0 72 B K displaystyle 0 37V 0 27U 0 36EG 0 28SW 0 72BK nbsp To determine the chromaticity of an arbitrary color he replaced one of the primaries with a sample of the test color and adjusted the ratios until he found a match For pale chrome PC he found 0 33 P C 0 55 U 0 12 E G 0 37 S W 0 63 B K displaystyle 0 33PC 0 55U 0 12EG 0 37SW 0 63BK nbsp Next he rearranged the equation to express the test color PC in this example in terms of the primaries This would be the precursor to the color matching functions of the CIE 1931 color space whose chromaticity diagram is shown above nbsp Drawing of Maxwell s color top nbsp Maxwell with his wheel nbsp Maxwell s color triangle nbsp A color triangle attributed to Fick in 1892 based on imaginary primaries corresponding to the three primary sensations of the human eye In such a triangle all real colors fall within the curved outline defined by the pure sensations See also editColor wheelReferences edit Arun N Netravali G Haskell 1995 Digital Pictures Representation Compression and Standards second ed Springer ISBN 0 306 42195 X Werner Backhaus Reinhold Kliegl and John Simon Werner 1998 Color Vision Perspectives from Different Disciplines Walter de Gruyter ISBN 3 11 015431 5 Sarah Lowengard 2008 The Creation of Color in Eighteenth Century Europe Columbia University Press ISBN 978 0 231 12454 6 Judd Deane B January 1935 A Maxwell Triangle Yielding Uniform Chromaticity Scales JOSA 25 1 24 35 doi 10 1364 JOSA 25 000024 Peter Michael Harman 1998 The Natural Philosophy of James Clerk Maxwell Cambridge University Press ISBN 0 521 00585 X James Clerk Maxwell 2003 The Scientific Papers of James Clerk Maxwell Dover Publications ISBN 0 486 49560 4 James Clerk Maxwell 1855 Experiments on colour as perceived by the eye with remarks on colour blindness Retrieved from https en wikipedia org w index php title Color triangle amp oldid 1219281339 Maxwell s disc, wikipedia, wiki, book, books, library,
