| Abstract: | Several different sets of weighting functions are, or have been, in routine use in colour-measurement systems employed in industry to represent the same pairings of illuminant and observer. Exactly the same inputs to different weight-sets purporting to represent the same pairing give, often significantly, different outputs (e. g. colour-difference reports), leading to confusion, arguments between suppliers and their customers, and loss of faith in the capabilities of systems. The extent of variation between weight-sets is exemplified by those employed, at some time, by some of the major system suppliers to represent TL84. The practical effect of these variations is examined and a recommendation is made to use the weight-sets in ASTM E308-96. The relevant content of E308-96 is summarised and means of determining whether E308-96 weights are installed in a system are given. Tables of E308-96 weighting functions for CIE illuminants A, D65 and F11 (TL84) are appended. |
