color indexing (In French indexation des couleurs) processing of true color files (8 bpp) in image processing programs which only accept considerably lower pixel depths (a total of 8 bits); in this case a color palette which has been reduced to 256 colors is invoked, and the 16.7 million true color hues are represented with losses on this palette.

Color Index, C.I. international name classification of color agents introduced in 1925; the name is composed of “C.I.”, “Class” (dyes, pigments), “Color name” (chromatic color from the color circle or a tertiary tone, achromatic color, metallic), “Type number” (consecutive index number for the various chemical substance and application types, e.g. acid/alkaline substances, diazo dyes, color couplers, food colors, optical brighteners, bleaching agents), “Constitution number” (consecutive chemical modification number), e.g. C.I. Pigment Blue 15:1.

color imposition (In French emplacement des couleurs) in color printing, the distribution of the separation colors of a print job between the available printing units, in sheet-fed offset for example on a six-color machine 2/4 or 6/0, in newspaper printing for example in four-high units or satellite units 4/4, 2/4, 3/3 etc.

color guide, color swatch (book) (In French nuancier) color selection system for designing printed matter; color sample on different substrates, e.g. uncoated paper, coated paper, newspaper or films; examples: HKS, Pantone.

(color graphics) display (In French moniteur) visual inspection device on the user interfaces of graphic workplaces and soft copy proof-to-press solutions. An LCD display consists of an active matrix panel, backlighting (cold white fluorescent lamps or white light LEDs), housing with electronic control unit (including its own graphics card with calibration-capable CLUT) and a hood. The pixels with their subpixels R, G, B work according to the additive color blend principle. Further parameters: see NEC.

color graphic design, coloring (In French coloration, mise en couleurs) artistic-design-based selection and placing of hues.

CIELUV(1976), CIE Luv* 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

CIELCH(1976), CIE LCh 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.

CIELAB(1976), CIE Lab* 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 ΔEab (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…

CIECAT02, CIE chromatic adaptation transform 2002 (In French transformation d’adaption chromatique CIE 2002) see CIECAM02

CIECAM02, CIE colour appearance model 2002 (In French 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…

CIE94, CIE(1994) modified CIELAB color difference formula, see inside of back cover

CIE tristimulus values (In French 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 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.

CIE tristimulus curves/functions (In French 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 spectral distribution coefficients (In French coefficients colorimétriques CIE) see CIE tristimulus curves/functions.

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…

CIE chromaticity coordinates (In French 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…

CIE chromaticity chart/diagram, “color triangle”, “horseshoe” (In French 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).

chromogenic inks (In French 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.

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.