"Influence of halftone patterns on the appearance of coated prints: modelling and visual application" by Fanny Dailliez

Seminar by Fanny Dailliez, PhD student at UJF Grenoble / LGP2

Abstract

In the printing industry, prints are often overlaid with a transparent layer, i.e. varnish or lamination layer, which modifies the colors of the print. Recent investigations have shown that the color variations are related to the position-dependent multiple reflections of light between the printed support and the surface of the coating, and depend on the coating thickness. This effect can be rather accurately predicted thanks to an optical model that we have developed, by means of microscopic multispectral pictures of the prints of periodic line patterns before coating. The overall color difference between the predictions and the measurements was ΔE*₀₀ = 0.92. In this paper, we analyze the influence of the halftone patterns on the color changes. In theory, the effect is stronger in case of line halftones than any other halftone pattern shapes, but we also observe in practice an influence of the real pattern size, due to the influence of the dot gain effect related to the diffusion of light and inks within the substrate. Simulations were then conducted on the reflectance profiles, showing that prints without dot gain are more impacted by the halo effect than the ones already subject to dot gain.

This seminar will be held in english.

Lien Cisco Webex :   https://ujmstetienne.webex.com/meet/ImageSCV