Colour prediction of metallic coatings
Illuminating and viewing geometries may strongly affect the colour appearance of metallic coatings, which can be characterised accurately by bidirectional reflectance distribution function (BRDF) measurement devices. However, such devices with hundreds or even thousands of different geometries are usually expensive and complex. Accordingly, two modified models were developed in a new study, based on the distribution of aluminum-flake pigments in the coatings, to, respectively, estimate the spectral radiance factors and the CIE tristimulus values of metallic coatings utilising the measurements at six common geometries of portable multiangle spectrophotometers.
Results show effectiveness of methods
Their performance was examined with 65 achromatic and 20 chromatic metallic coating samples under D65, A, and F11 illuminants. The average CIEDE2000 colour differences over all 19 geometries were found to be less than 1.8 for both models, while the average CAM02-SCD and CIELAB color differences can, respectively, reach 1.7 and 2.0, indicating the effectiveness of the methods.
The study is published in: Journal of Coatings Technology and Research September 2018, Volume 15, Issue 5, pp 957–966.
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