The Colour Difference Formula CIEDE2000 and its Performance with a Graphic Arts Data Set

The CIELAB colour space is widely used in the printing and publishing industries for such tasks as determining the acceptability of colorant formulation, specifying process control parameters and defining a reference colour space for colour management. The magnitude of colour difference which may be accepted for critical comparisons in graphic arts colour reproduction was investigated using 10 colour centres printed by offset lithography. Visual assessments were made by a panel of observers, and the data has been used to determine acceptability thresholds and optimise the parametric factors in the colour difference equations CIE94 and CIEDE2000. The performance of these equations, with and without these parametric factors, has been compared to 1976 CIELAB colour difference. The results showed a small improvement in performance for both equations, although neither model successfully predicted the visual difference of the black samples. Acceptability tolerances of 4 in CIELAB and 3 for CIE94 and CIEDE2000 are proposed, and optimised parametric factors were calculated for weighting lightness, chroma and hue of 1.5:1:0.5 respectively. Advanced colour difference formulae have been widely studied for other colorant industries, but this study remains the most extensive contribution to this subject for the graphic arts. One of the major findings is that the relationship between perceptibility and acceptability of colour matches is very different in the graphic arts from other colorant industries, and this has led to caution in the adoption of advanced colour difference formulae in the graphic arts industry