CIEDE2000

CIEDE2000, often referred to as ΔE00, is a color-difference formula published by the International Commission on Illumination (CIE) in 2000. It provides a single numeric value for the perceived difference between two colors described by the CIE L*a*b* color space (L*, a*, b*).

The method was designed to address perceptual nonuniformities in the earlier CIELAB-based ΔE*ab, by introducing correction terms for lightness, chroma, and hue, as well as a rotation term that accounts for interactions between chroma and hue. The computation involves transforming the original L*a*b* coordinates into adjusted quantities (L', C', h'), computing differences ΔL', ΔC', and ΔH' (the latter derived from the hue-angle difference), and applying weighting functions SL, SC, SH along with a chroma–hue interaction term RT. The standard form for the color difference is ΔE00 = sqrt( (ΔL'/(kL SL))^2 + (ΔC'/(kC SC))^2 + (ΔH'/(kH SH))^2 + RT*(ΔC'/(kC SC))*(ΔH'/(kH SH)) ), with commonly used weighting factors kL = kC = kH = 1 under standard viewing conditions.

CIEDE2000 is widely used in color quality control, printing, textiles, plastics, and display manufacturing, where perceptual color differences must be assessed reliably. While generally more accurate than ΔE*ab, it remains dependent on viewing conditions and color range, and its interpretation can vary with context. In practice, values around 1 are often just noticeable, with larger values indicating greater perceptual differences.