Abstract

This paper investigates the optical phenomenon responsible for the colored shine that sometimes appears at the surface of ink layers in the specular direction, often called “bronzing” or “gloss differential.” The prediction of this shine effect relies on the Fresnel formulas of the air/ink interface. The complex refractive index of the ink must therefore be determined, which is made difficult because of the roughness of inked printing supports. We propose a generic method that can be applied to any ink, without any prior knowledge of its composition or the printing substrate. In order to reduce light scattering, a solid colored area is printed with the studied ink on a glossy paper previously printed with black ink. By ellipsometry, we determine the effective refractive index of the sample. The intrinsic complex refractive index of the ink can then be extracted by modeling the optical response of the inked surface with a set of Gaussian oscillators, among which one of them approaches residual scattering. With this data, we could proceed to a fine colorimetric analysis of the bronzing color of some cyan, magenta, and yellow inks. In particular, we show that this gloss color is slightly shifted from the complementary of the ink’s usual color in diffuse reflection.

© 2023 Optica Publishing Group

Reflectance and transmittance model for recto-verso halftone prints

Mathieu Hébert and Roger David Hersch
J. Opt. Soc. Am. A 23(10) 2415-2432 (2006)

Spectral reflectance and transmittance prediction model for stacked transparency and paper both printed with halftone colors

Jacques Machizaud and Mathieu Hébert
J. Opt. Soc. Am. A 29(8) 1537-1548 (2012)

Reflectance and transmittance model for recto-verso halftone prints: spectral predictions with multi-ink halftones

Mathieu Hébert and Roger David Hersch
J. Opt. Soc. Am. A 26(2) 356-364 (2009)

Spectral prediction model for color prints on paper with fluorescent additives

Roger David Hersch
Appl. Opt. 47(36) 6710-6722 (2008)

Characterization of inks and ink application for ink-jet printing: model and simulation

Li Yang
J. Opt. Soc. Am. A 20(7) 1149-1154 (2003)