Delta E (dE or ∆E) is a measurand for determining color accuracy, i.e. for quantifying the distance, colloquially difference, between a given color value and the value achieved in reproduction by print media or displays.
Since visual color perception is strongly dependent on the viewer, a quantification by mathematically measurable reference values offers the possibility of an objective evaluation.
When specifying color distances according to the dE formal, the value denotes a difference that the human eye no longer perceives.
Generally applies: the smaller the distance, the smaller the color differences. A color distance of dE <0.2 is considered invisible, a distance below dE 1.0 still as small.
Delta E is frequently used in the field of digitization as an objective measurement variable in the color profiling of grayscale and RGB primary colors for quality determination.