colour equation

algebraic or vector representation of the match of two colour stimuli, of which, for instance, one can be an additive mixture of three reference colour stimuli

EXAMPLE [C] ≡ X[X] + Y[Y] + Z[Z]
In this equation, the sign "≡" indicates a colour match and is read as "matches". The unbracketed symbols represent the amounts of the stimuli indicated by the bracketed symbols: thus R[R] means R units of stimulus [R], and the sign "+" means an additive mixture of colour stimuli. In such an equation, a minus sign means that the stimulus is added to those on the other side of the equation when the colour match is made.

Note 1 to entry: The reference stimuli are represented as [R], [G] and [B] in which case the sign "≡", read as "matches", should be used. As an alternative, the colour equation can be written using boldface Roman letters when the equal sign "=", read as "equals" should be used: C = XX + YY + ZZ.

Note 2 to entry: This entry was numbered 845-03-24 in IEC 60050-845:1987.

Note 3 to entry: This entry was numbered 17-209 in CIE S 017:2011.