BSDF Reconstruction of Inks and Paints for Light Guiding Plates

Abstract

The work is devoted to the investigation of the best and reasonable methods to reconstruct the scattering properties of inks and paints widely used in modern electronic devices containing various light guiding plates and fibers. Typically scattering properties for inks have a volume scattering nature however it can be complicated with surface scattering because of the microroughness of ink layers. Both the volume and surface scattering reconstruction are considered in the given paper. Typically scattering properties of inks are described with bidirectional scattering functions (BSDF) and the BSDF is required from the internal side of the material of light-guiding elements. It cannot be measured directly because neither detector of the measuring device nor the light source cannot be placed inside the material. The only way to solve the problem of BSDF extraction for such cases is to build computer models of volume and surface scattering for inks and then with optimization procedures reconstruct parameters for these models which can provide surface scattering close enough to scattering of real samples of inks and paints. Light propagation in ink media is very complex requiring a long calculation time. As a result, the selection of an effective optimization procedure is the key point of the task. Several more typical real samples with printed inks are selected for investigation. The achieved results of BSDF extraction show very good agreement with data obtaining by real measurement. The comparison is based on numerical comparison of light scattering of ink samples as well as its visual appearance.

Extraction of Characteristics of Solid Pigments from Paint Samples

“…Then, usually the front paint surface, even if specially polished, is not ideally flat, and thus Fresnel reflectance from it is diffuse. This diffuse BRDF sums with the BRDF of the paint sample and this may lead to serious distortions [14]. At last, the ultimate goal of the work with paints is color matching.…”

“…It can be suggested several such methods that use different number of paint samples prepared in different conditions and process their measurements differently. Some alike fitting based methods had been used in the past to obtain scattering properties of turbid plastics [14][15][16][17]. Sometimes the results were god but sometimes the calculated BRDFs deviated much from the measured ones.…”

“…We describe their operation and compare their robustness. It happened that among 4 proposed methods one is much more accurate, while others (close to [14][15][16][17]) produced large errors in our benchmarks.…”