Influence of colour-matching functions on threshold and large colour differences

In the present work, we study the influence of colour-matching functions on the determination of colour-threshold differences (part I) and of greater size (part II). For this, we have used the colour-matching functions of 16 different observers, the five CIE centres and 200 Munsell samples. A previously operated and fully automated Wright colorimeter was used for the determination of colour-matching functions and colour-discrimination thresholds. The results for part I indicate that the discrimination ellipses obtained with different colour-matching functions (with some exceptions) had highly similar orientations, semiaxis relationships and areas, whereas the centres appeared to shift with respect to each other, primarily in the blue area. The results for part II reveal important discrepancies between the different observers in evaluating any colour, and close agreement in evaluating colour differences. On the basis of the overall study, we deduce that the colour-matching functions of the observers have significant influence on the specification of individual colours, but only slight effects on the determination of small or large colour differences.