CIEFarbtheorie

CIEFarbtheorie, also written as CIE Farbtheorie, refers to the set of colorimetric concepts and standards developed by the International Commission on Illumination (CIE) to describe, compare, and reproduce colors in a device-independent framework. Central to the theory is the CIE 1931 XYZ color space, defined by the three color matching functions x̄(λ), ȳ(λ), and z̄(λ) for a standard observer (commonly 2°). A spectral stimulus is represented by tristimulus values X, Y, Z, and chromaticity coordinates x = X/(X+Y+Z) and y = Y/(X+Y+Z). These coordinates form the CIE chromaticity diagram, a convenient visualization of hue and saturation independent of luminance.

To achieve perceptual uniformity, the CIE also defines color spaces such as CIE L*a*b* and CIE L*u*v* (CIELAB, CIELUV). Luminance is given by Y, while a and b (or u and v) encode chromatic information. More advanced models, such as CIECAM02, attempt to predict perceived color under varying viewing conditions.

The theory underpins device-independent color management. By converting device color representations to and from XYZ or LAB, colors can be matched across printers, displays, and lighting. Color difference formulas, notably ΔE and its refinements like ΔE00, quantify perceptual differences between colors.

Applications span photography, printing, display technology, lighting design, and quality control. While foundational, the CIE spaces have limitations in uniformity and metamerism, leading to ongoing refinements and alternative models in color science.