The e-ILV provides free access to all the terms and definitions contained in the international standard CIE S 017:2020 ILV: International Lighting Vocabulary, 2nd edition.

To search for another term please use  "Back to the list" to return to the main page or the e-ILV.

For the complete set of terms and definitions CIE S 017:2020 can be purchased from the CIE Webshop. Members of a CIE National Committee or Associate National Committee have access to a 66,7 % discount on the purchase price of the standard.

For advice on CIE Publications contact Note the CIE Helpdesk cannot assist with technical enquiries.


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.

Publication date: 2020-12
Copyright © CIE 2020. All Rights Reserverd.