“c” internationally used abbreviation for “color” in the sense of the number of colors that can be printed on a printing press in one run, e.b. 4c (four-color printing), 6c (4 process colors + 2 special colors), 4/4c (4 colors each in recto / verso printing, or top and bottom side of the web, or 4-color duplex digital printing).
“C” internationally used abbreviation for absorptive primary color cyan blue, thus also for the technical printing process color cyan. In large-format inkjet printing systems, the abbreviation Cc means the support of cyan with “light cyan” to enlarge the color space.
calibration calibrage resetting of the target values of a device, either according to manufacturer’s specifications or according to a standard. In color management, calibration with reproducible basic settings is a precondition for successful characterization in color space and the subsequent application validity of the created ICC profiles. In the hardware calibration of monitors, the setting of the target value and characterization are combined into one step.
camouflage color couleur de camouflage color shade or halftone-like mixture of several color shades which allows the color surface to merge visually with the environment.
CAUS Color Association of the United States.
CCR, complementary color reduction réduction des couleurs complémentaires process of achromatic composition: restriction of under color removal UCR and gray component replacement GCR on the blend colors R, G and B, which are complementary to C, M and Y; reduction of two chromatic colors each in the blackish drift range of their complementary colors.
ceramic inks and toners encre céramique printing inks and color agents which are printed either directly (screen, tampo printing) onto a ceramic surface (tiles, porcelain) or indirectly (screen, sheet-fed gravure printing) onto a transfer paper. With transfer paper, the reverse order of the covering ink films must be taken into account. In general, the sub-sequent burning-in of the glaze leads to a strong color drift (burning-in drift), which can only be predicted with costly ICC profiles.
charge-coupled device dispositif à couplage/transfert de charge device consisting of light sensitive semiconductor diodes arranged line-wise or matrix-wise; application: scanners, video and color measuring cameras; replaced by CMOS sensors on account of the slow charge displacement and susceptibility to overexposure in digital photography and spectrophotometry.
chroma chroma synonym for chromaticness; original designation for the “value C” in the Munsell color ordering system. Chroma Cosmos 5000 Japanese color ordering system
comprising 5000 color specimens, according to the Munsell principle.
chroma[ticness] chroma coordinate C* in the intuitive L*C*hab coordinate system (brightness/chromaticness/hue angle) of the CIELAB color space; difference between a hue and its equally bright achromatic stage; not to be confused with saturation S* = C*/ L*.
chromatic chromatique the technically correct term for “colored” (coloré) opposite: achromatic.
chromatic aberration aberration chromatique an aberration in optical systems in which color fringes are formed on the edges of objects in the image.
chromatic adaptation adaptation chromatique at a color temperature deviating from 5000 K, a c.a. is automatically activated in monitor hardware calibration and other color
management programs, e.g. the simple Bradford and von Kries transformations or the more complex CAT02 adaptation (CIECAM02).
chromatic/regular color separation composition chromatique conventional CMYK color separation process in which all four colors are involved in the representation of each chromaticity coordinate in all tone areas, resulting in high overall total ink coverage (up to 400%) and thus drying problems; K is only used to support the dark image parts (“skeleton black”) because the chromatic printing inks provide only inadequate details when C+M+Y are printed together. chromatic/regular color separation modifications; slight and strong under color removal (UCR), possibly combined with gray component replacement (GCR).
chromatic dispersion dispersion chromatique dispersion of a light ray into its spectral components through diffraction on a lattice or through refraction at the boundary surfaces as it passes through a prism; application: monochromator in spectral densitometers in order to be able to isolate the wavelengths contributing to the color stimulus.
chromatic stimulus simulation simulation des stimuli chromatiques experimental arrangement (light spots, gyratory color mixer) with which primary colors can be proportionately changed and additively blended in order to test a person’s color sense (e.g. for permits for certain professions such as printer and graphic designer, but also architect, bus driver, electrician, textile and fur good quality inspector).
chromaticity chromaticité family of color stimuli which differ only through their brightness, i.e. hue and chromaticness remain constant. In a cut through a color space parallel to the lightness axis the colors of one chromaticity always show the same distance from the lightness axis at each lightness level and thus always the same chromaticity coordinates.
chromaticity chart/diagram diagramme de chromaticité two-dimensional section through a color solid at a level of equal brightness. Only the hue parameters (CIExyY chromaticity chart) or chrominances (a*;b* chromaticity chart from CIELAB) are shown in this view.
chromaticity coordinates/locus [Pl. loci] coordonnées de chromaticité description of the colorimetric properties of a printing ink with the help of colorimetric values (vector
coordinates in the color space).
chromaticity shift virage changes in the chromaticity coordinates in the course of the drying of printing ink; while wet and dry color densities differ due to the diminishing wet gloss alone, with wet and dry colorimetric values the influence of the oxidation or wetting reactions or evaporation and penetration, which are characterized by changes in the solids concentration or structure, have to be added.
chromaticity/hue shift décalage de la couleur phenomenon consisting in the fact that when one of the three color attributes hue, brightness or chromaticness changes, chromaticity also changes. There is only one case in which chromaticity does not change, namely when the change in brightness is not due to a change in hue and/or chromaticness. Application: color selection tool in Adobe Creative Suite.
chrominance chrominance a chromaticity coordinate in opponent-color luminance-chrominance color spaces (CIELAB, CIELUV, YcrCb, YIQ etc.), described by its position in relation to the red-green axis (a*, a’, Cr, I) and the blue-yellow axis (b*, b’, Cb, Q). This coordinate model of color components independent of the lightness level (luminance L*, L’, Y) assumes that a color cannot be tinted red and green, or blue and yellow, at the same time.
chromogenic inks encres chromogènes printing inks with pigments which change their color temporarily or irreversibly in the event of external physical effects; c.i.s offer a great potential in packaging printing (transportation imitation-proof); most c.i.s are available for flexo printing, only from a few manufacturers for offset printing.
CIE chromaticity chart/diagram, “color triangle”, “horseshoe” diagramme (chromaticité) CIE, tableau normalisé/ triangle des couleurs, « fer à cheval » CIExyY(1931) chromaticity chart originating from the projection of the CIE colorimetric system CIEXYZ(1931).
CIE chromaticity coordinates coordonnées trichromatiques CIE the coordinates of the CIE chromaticity chart: x = X / (X + Y + Z), y = Y / (X + Y + Z), z = Z / (X + Y + Z).
Since x + y + z = 1, i.e. x and y already unequivocally describe chromaticity coordinates, the specification of z is dispensed with; instead, the standard color value Y (xyY) is specified as luminance factor A for the 2° standard observer.
CIE Commission International de l’Éclairage International Commission on Illumination; Vienna (Austria)-based commission for issuing photometric and colorimetric recommendations on which the relevant ISO standards for many different fields of
application are based, e.g. standard illuminants (D50, D65, A), standard observers (2°, 10°) and color spaces (CIEXYZ, CIELAB, CILUV) including color difference formulae. As in
the ISO, there are also Divisions here with Technical Committees (CIE TC) which prepare sector-specific standards. The most important Divisions for color communication are
1 “Vision & Color” (color vision, color difference formulae, light measuring technology, illuminants) and 8 “Image Technology”
CIE spectral distribution coefficients coefficients colorimétriques CIE see CIE tristimulus curves/functions
CIE tristimulus curves/functions fonctions trichromatiques CIE continuous function (for 2° and 10°) in the virtual CIE colorimetric system CIEXYZ, 1931 referring to the wavelength λ (at 5 nm intervals) calculated as a standardization of the real fundamental stimulus system PDT. The three function terms can be regarded as the CIE tristimulus values X, Y, Z in CIEXYZ.
CIE tristimulus values composantes trichromatiques CIE color values of the CIE colorimetric system CIEXYZ; standardized representation of the cone sensitivities X (red), Y (green) and Z (blue) whereby, through definition of the luminance factors (brightness factors) LX = 0, LY = 1 and LZ = 0, the CIE tristimulus value Y is also understood as brightness and as luminance factor A in the 2° CIE colorimetric system; see also weighted ordinates principle.
CIE94, CIE (1994) modified CIELAB color difference formula, see inside of back cover
CIECAM02, CIE colour appearance model 2002 modèle d’apparence de la couleur CIE 2002 most-used color appearance model, component of among other things Apple Color-Sync and MS WCS and of the leading color management, monitor calibration and soft copy proof applications. After the actual color values of the color stimulus (whose appearance is to be simulated), of the illuminant (of the white point to be adapted) and of the environment as well as of the ambient lightness value have been entered, it calculates the following intuitive color attributes (perception parameters): hue H, lightness J, brightness Q, chroma C, colorfulness M, saturation S and chrominances ac, bc. As algorithms it offers the chromatic adaptation CIECAT02, whose subsequent adaptation (nonlinear color space compression) and the resulting changes in the perception parameters.
CIECAT02, CIE chromatic adaptation transform 2002 transformation d’adaption chromatique CIE 2002 see CIECAM02
CIELAB(1976), CIE L*a*b* device-independent color space defined for the evaluation of small color differences, with perceptually equidistant structure, defined in 1976 by the CIE together with the trivial color difference formula ΔE*ab (Delta E = Euclidian distance in space) on the basis of the Hunter-Lab color space (1948). The luminance axis L* stands vertically on the achromatic point of the a*;b* chromaticity chart and forms a rotational solid. Brightness L*, red-green chrominance a* and yellow-blue chrominance b* are therefore cylinder coordinates that are supplemented by the intuitive CIELCH interpretation – see inside of back cover. CIELAB is based on the colorimetric values X and Y of the CIE colorimetric system CIEXYZ (1931). Although the color difference formula was improved several times – see CMC (CIELCH84), CIE94, CIEDE2000 inside of back cover – the 1976 CIELAB definitions still form the basis for all international image data exchange standards (printing process in accordance with ISO 12647 incl. process standard offset printing, ICC profile linking color space beside CIEXYZ) and various color ordering system (e.g. RAL). The suggestions for improvement of the CIELAB color model itself – CIELAB-ND(1978), LABHNU(1979- 1/-2), LABJNDS(1984) and DIN99 (DIN 6176:2001-03) by Klaus Richter (BAM) – did not gain acceptance either.
CIELCH(1976), CIE L*C*h intuitive interpretation of the CIELAB color space with its own derived coordinates – see inside of back cover; intuitive color attributes here are L* = luminance, C* = chromaticness and H* hue or h° hue angle.
CIELUV(1976), CIE L*u*v* device independent color space defined for the assessment of small color differences, issued by the CIE in 1976 together with the trivial color difference formula