Delta E, ΔE or dE, is a way of measuring the visible difference, or error between two colors mathematically. It is very useful for sorting “closeness” of paints to a scanned sample and has obvious applications in industrial and commercial quality control.
The LAB color system is used as a base system to calculate Delta E, as the LAB system’s perceptually uniform nature makes these calculations more accurate than in other non uniform systems such as RGB or CMYK.
To put it simply, the Delta E of two colors is the distance between them in LAB color space. This is also called Delta E 76 or Delta E 1976 as it was first standardized in the year 1976. We now use a more accurate formula that takes into account new and improved models of the human eye, this formula is Delta E 2000. Even though the Delta E 76 formula is still very popular, Nix Sensor Ltd. recommends always using the Delta E 2000 formula for maximum accuracy and excellent real world results.
Note: A smaller Delta E value represents a better or closer color match. A Delta E of 0 would be interpreted as both colors being exactly/mathematically the same. The Delta E system does not have negative numbers.
Even though a Delta E of 0 between two colors represents a perfect mathematical match, it is possible for two colors to look exactly the same to the human eye with a non zero Delta E. This is due to the physical limitations of human eyesight. The exact Delta E that colors become indistinguishable from each other is dependent on the industry, surface finish of the material, texture, gloss, and the individual person viewing the color. Typically though, a just noticeable difference between two colors is about in the range of Delta E of 1.0 – 2.0.