Modeling the Appearance of Metal-Like Packaging Printing

A study of the agreement between a visual assessment and the measurement of the reflectivity of printed metallic inks was performed. A psychophysical property for this percept was identified as visual brilliance. The visual judgments of a series of printed panels were compared with measurements from various types of specular reflectance instruments. The results showed that gloss does not linearly follow the appearance of highly reflective specular surfaces. It was observed that the visual assessment of brilliance was highly correlated to the normalized hemispherical diffuse reflectance factor difference. Further, visual brilliance could be mapped to a logarithmic function of the luminous specular reflectance factor and the measurement scale of log(Y) agreed with the scale of hemispherical diffuse reflectance. It was, thus, concluded that either of these measures may be utilized to establish aims and tolerances for production control of the reproduction of foil-like prints. (C) 2016 Wiley Periodicals, Inc. Published Online 18 February 2016 in Wiley Online Library (wileyonlinelibrary.com).