CIEDE 2000
The difference or distance between two colors is an important metric in our field. The most recent edition of a formula presented by The International Commission on Illumination (CIE) is CIEDE2000 (or ΔE2000).
In summary, CIEDE2000 uses weight functions S as positional corrections to the lack of uniformity of CIELAB, and also parametric factors K as corrections accounting for the influence of experimental viewing conditions. There are numerous studies indicating that CIEDE2000 is superior to other color differencing formulas.