# 17-23-035

Abney's law

empirical law stating that if two colour stimuli, A and B, are perceived to be of equal brightness and two other colour stimuli, C and D, are perceived to be of equal brightness, then the additive mixtures of A with C and B with D will also be perceived to be of equal brightness

Note 1 to entry: The validity of Abney's law depends strongly on the observing conditions.

Note 2 to entry: This entry was numbered 845-03-19 in IEC 60050-845:1987.

Note 3 to entry: This entry was numbered 17-2 in CIE S 017:2011.

Publication date: 2020-12