The basic form, Delta E*ab, is the straight-line distance between two points in CIELAB space. A difference under about 1 is hard for most people to see side by side, while 2 to 3 is obvious to a trained eye on a white or pastel. Formulas such as dE00 weight lightness, chroma and hue differently to track perception better, so a spec must name the formula as well as the limit.
Delta E to the master is 1.4, inside the 2.0 limit, but the customer grades by eye under their own lights.
A single Delta E hides direction, so look at which of L*, a* and b* moved before touching the dye pumps.
Also heard as
- dE
- total color difference
Related terms
CIELAB
Color space describing a color by lightness L* plus a* for red-green and b* for yellow-blue.
Shade
The exact color of a paper grade measured against its approved standard, for whites as well as tinted sheets.
Off shade
Describes paper whose color has drifted outside the tolerance of its approved standard.
Metamerism
Two samples matching in color under one light but not under another, because their reflectance curves differ.