Coloroid
Encyclopedia
The Coloroid Color System is a colour space
developed between 1962 and 1980 by Prof. Antal Nemcsics at the Budapest University of Technology and Economics
for use by "architects and visual constructors". Since August 2000, the Coloroid has been registered as Hungarian Standard MSZ 7300.
Like the OSA-UCS
and Munsell
systems, the Coloroid attempts to model a perceptually uniform color space or UCS. However the UCS standard applied in the Coloroid system is equal appearing increments in color when the entire range of colors is presented to the viewer, in contrast to the standard of equal "just noticeable" or small color differences between pairs of similar colors presented in isolation.
Colors in the Coloroid color space are fundamentally specified according to the perceptual attributes of "luminosity" (luminance factor, V), "saturation" (excitation purity, T) and hue (the matching or dominant spectral wavelength, A).
The VAT components are used to define a cylindrical color geometry, with V as the achromatic vertical axis (lightness or brightness), T as the horizontal distance from the achromatic axis (chroma), and A as the hue angle around the hue circle. The circumferential limits of this cylinder are defined by the spectrum locus, or colors as they appear in a single wavelength of light (or a mixture of single "violet" and "red" wavelengths); this ambit varies vertically in V around the hue circle, showing whether the relative luminance or brightness of each wavelength is high (yellow hue) or low (violet blue hue). This defines the outer perceptual limits of the color space.
Within this is the smaller perceptual volume defined by the limit of colors it is possible to reproduce with physical media (material colors). Here the VAT perceptual attributes can be approximately matched using the three stimulus or material color components of pure hue or pure colorant (p), white colorant (w) and black colorant (s) in relative proportions whose sum must always equal 1. (Implicitly, p may be any matching single "spot" colorant or matching mixture of two "primary" colorants.)
The Coloroid technical documentation defines the conceptual equations necessary to transform the Coloroid perceptual components VAT into the corresponding stimulus components, using the CIE XYZ 1931 colormatching functions with the D65 CIE illuminant. Hues are identified according to the hue angle ψ, measured on the CIE 1931 xy chromaticity plane. These stimulus attributes in turn must be standardized or gamut mapped into a specific colorant system or color reproduction technology in order to reproduce the Coloroid color space as physical color exemplars or a color atlas. However, a Coloroid Colour Atlas is available that provides color exemplars at 16 levels of lightness out to as many as 13 increments in saturation for each of for 48 hue planes.
Within the Coloroid system, color harmonies or "harmonics" can be defined through simple linear or geometrical combinations of colors.
Color space
A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components...
developed between 1962 and 1980 by Prof. Antal Nemcsics at the Budapest University of Technology and Economics
Budapest University of Technology and Economics
The Budapest University of Technology and Economics , in hungarian abbreviated as BME, English official abbreviation BUTE, is the most significant University of Technology in Hungary and is also one of the oldest Institutes of Technology in the world, having been founded in 1782.-History:BME is...
for use by "architects and visual constructors". Since August 2000, the Coloroid has been registered as Hungarian Standard MSZ 7300.
Like the OSA-UCS
OSA-UCS
In colorimetry, the OSA-UCS is a color space or chromaticity diagram first published in 1974 and developed by the Optical Society of America's Committee on Uniform Color Scales; presently the 1976 edition is adopted. It is based on and compatible with the CIE 1931 chromaticity diagram. Like the...
and Munsell
Munsell color system
In colorimetry, the Munsell color system is a color space that specifies colors based on three color dimensions: hue, value , and chroma . It was created by Professor Albert H...
systems, the Coloroid attempts to model a perceptually uniform color space or UCS. However the UCS standard applied in the Coloroid system is equal appearing increments in color when the entire range of colors is presented to the viewer, in contrast to the standard of equal "just noticeable" or small color differences between pairs of similar colors presented in isolation.
Colors in the Coloroid color space are fundamentally specified according to the perceptual attributes of "luminosity" (luminance factor, V), "saturation" (excitation purity, T) and hue (the matching or dominant spectral wavelength, A).
The VAT components are used to define a cylindrical color geometry, with V as the achromatic vertical axis (lightness or brightness), T as the horizontal distance from the achromatic axis (chroma), and A as the hue angle around the hue circle. The circumferential limits of this cylinder are defined by the spectrum locus, or colors as they appear in a single wavelength of light (or a mixture of single "violet" and "red" wavelengths); this ambit varies vertically in V around the hue circle, showing whether the relative luminance or brightness of each wavelength is high (yellow hue) or low (violet blue hue). This defines the outer perceptual limits of the color space.
Within this is the smaller perceptual volume defined by the limit of colors it is possible to reproduce with physical media (material colors). Here the VAT perceptual attributes can be approximately matched using the three stimulus or material color components of pure hue or pure colorant (p), white colorant (w) and black colorant (s) in relative proportions whose sum must always equal 1. (Implicitly, p may be any matching single "spot" colorant or matching mixture of two "primary" colorants.)
The Coloroid technical documentation defines the conceptual equations necessary to transform the Coloroid perceptual components VAT into the corresponding stimulus components, using the CIE XYZ 1931 colormatching functions with the D65 CIE illuminant. Hues are identified according to the hue angle ψ, measured on the CIE 1931 xy chromaticity plane. These stimulus attributes in turn must be standardized or gamut mapped into a specific colorant system or color reproduction technology in order to reproduce the Coloroid color space as physical color exemplars or a color atlas. However, a Coloroid Colour Atlas is available that provides color exemplars at 16 levels of lightness out to as many as 13 increments in saturation for each of for 48 hue planes.
Within the Coloroid system, color harmonies or "harmonics" can be defined through simple linear or geometrical combinations of colors.
See also
- colour spaceColor spaceA color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components...
- Munsell colour systemMunsell color systemIn colorimetry, the Munsell color system is a color space that specifies colors based on three color dimensions: hue, value , and chroma . It was created by Professor Albert H...
- OSA-UCSOSA-UCSIn colorimetry, the OSA-UCS is a color space or chromaticity diagram first published in 1974 and developed by the Optical Society of America's Committee on Uniform Color Scales; presently the 1976 edition is adopted. It is based on and compatible with the CIE 1931 chromaticity diagram. Like the...
External links
- Coloroid color space, handprint.com.