CIE
Division 8 - TC8-03: Survey of Gamut Mapping Papers
Katoh & Ito (1996)
The approach taken in this paper consists in first defining a functional
model whose parameters are then chosen on the basis of experimental data.
It suggests that out-of-gamut colours should be clipped to colours on the
reproduction gamut boundary, which have the smallest E value calculated
using a weighted colour difference formula in CIELAB:
where *L*, *C* and *H* are differences in lightness, chroma and
hue predictors respectively and Kl, Kc and Kh are the corresponding weighting
coefficients. Based on a psychophysical experiment, the authors found that
the most accurate reproductions were obtained when the (Kl:Kc:Kh) coefficients
were set to (1:2:1) or (1:2:2). This indicates that larger changes are
acceptable in chroma than in hue and that the smallest change is tolerated
in lightness.
Last updated: 17 August 1999 by Jan
Morovic