Color difference

Color difference is a quantitative or perceptual measure of how distinct two colors are. It can be calculated from coordinates in a color space or judged by human observers.

CIELAB color space: A perceptually organized color space that represents colors using lightness and two opponent-color axes. Many color-difference formulas measure distances between coordinates in this space.
Colorimetry: The science of measuring and specifying color quantitatively. Colorimetry supplies measurement procedures and reference values for comparing colors.
CIELAB color difference: The Euclidean distance between two colors represented in CIELAB coordinates. It is a simple baseline, but its perceptual accuracy varies across color regions.
Color discrimination: The ability to distinguish colors that differ in hue, lightness, or chroma. Discrimination thresholds vary with the colors being compared, challenging a single universal scale.
CIEDE2000: A CIE formula that estimates perceptual color differences in CIELAB with corrections for nonuniformity. It improves agreement with visual judgments, especially in regions where simple distances mislead.
Color quality control: The use of color measurements to keep products within specified color tolerances. Manufacturers use color differences to decide whether batches match a target.
CMC l:c: A textile-industry color-difference formula with adjustable lightness and chroma weighting. Its tunable tolerances differ from general-purpose formulas such as CIEDE2000.
MacAdam ellipse: An ellipse on a chromaticity diagram representing color differences near a barely noticeable threshold. Its changing shape and size show that equal coordinate distances need not look equal.
Euclidean distance: A measure of straight-line separation between points in a coordinate space. The simplest color-difference calculation treats color-space coordinates as points and measures their distance.
Color management: The coordinated control of color reproduction across devices and media. Color differences reveal how far reproduced colors depart from intended colors.

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