Testing Performance of Whiteness Formulas

Abstract

Whiteness is an important characteristic for surface color, especially in printing and textile industries. The widely used CIE whiteness formula had two shortcomings, i.e. firstly, the formula was only defined under standard D65 illuminant, and secondly, the boundary was found to be too limited. With these in mind, several modified whiteness formulas were developed. In this study, an experiment was conducted to test the performance of whiteness formulas. In the experiment, the whiteness appearance of 88 samples containing FWA (fluorescent whitening agent) were estimated under four lighting conditions with four different correlated color temperatures (3000, 4000, 5000 and 6500 K) at high UV radiation, by 20 observers. The data were used to test the performances of the developed whiteness formulas. The results indicated that generally the CIE whiteness formula with the CAT02 chromatic adaptation transform had good performances when predicting samples under each lighting condition separately. However, when combining all the data including all the lighting conditions, the performance of whiteness formula with the CAT02 chromatic adaptation transform did not perform better than other formulas. It was found that this is due to the incomplete chromatic adaptation under low CCT conditions.