| Abstract: | Field trials of the nonlinear color-appearance model were done by using chromatic object colors under different illuminance levels. Color-appearance match and brightness match were made for Munsell color pairs by using haploscopic matching. Each color pair was only different in Munsell Chroma. The color-appearance and the brightness match were realized by adjusting the illuminance of one of the two haploscopic fields. Observed illuminances were significantly different between the color-appearance and the brightness matches for the same color pairs. The model accurately predicted the illuminances of color-appearance matches by using the metrics of lightness and chroma Q, T, P of the model, and those of brightness matches by using the metric brightness of the chromatic color Bc. In addition, the estimated contribution of colorfulness to brightness of chromatic colors was generally consistent with that predicted by the formula of Ware and Cowan. To test metric brightness Bc further, an additional experiment on haploscopic matching was done using illuminants with different Ra values. In the experiment, the same samples were used in both fields. Again, matching illuminances in this case were well predicted by using the same contribution factor of colorfulness to brightness already estimated. |
