CIE
Division 8 - TC8-03: Survey of Gamut Mapping Papers
Ito & Katoh (1999)
This paper is a continuation of Katoh and Ito (1996) describing the evaluation
of advanced colour difference formulæ in gamut clipping. An extensive
selection of colour difference formulæ - E*ab, E*uv (CIE, 1986),
E94 (CIE, 1995), ECMC (Clarke et al., 1984), EBFD (Luo and Rigg, 1987)
and Ewt (Katoh and Ito, 1996) - were used in a number of colour spaces
- CIELAB, CIELUV, CIECAM97s, IPT (Ebner and Fairchild, 1998b) and NC-IIIC
(Ikeda and Obara, 1991). A pair comparison experiment was conducted to
determine which if these colour difference formulæ and colour spaces
ought to be used for minimum colour difference clipping to give the most
accurate reproductions. Overall the experimental results suggested the
use of E94 in CIELUV and EBFD in CIELAB as being the best choices.
The main purpose of this study was to correct for the hue shift caused
by the curvature of blue hue loci in CIELAB. Experimental results indicate
that the *C*H term in the BFD colour difference formula compensates for
the curvature of blue hue loci. It was also reported that CIELUV performs
better than CIELAB in terms of hue linearity. Indeed, this question has
also been the focus of papers by Braun and Fairchild (1998) and Marcu (1998).
Last updated: 17 August 1999 by Jan
Morovic