Specular gloss estimation by measuring the colorimetric data produced by a reflection measurement at 8° of incidence

Abstract

This paper presents an experimental investigation into the estimation of specular gloss from the colorimetric data. The 28 samples were selected from the Natural Color System (NCS) gloss scale, which had different combinations of lightness and gloss levels. The samples’ spectral reflectance and colorimetric data Y and L* were measured by a d:8° geometry reflectance spectrophotometer in both SCE (Specular Component Excluded) and SCI (Specular Component Included) modes. Additionally, the specular gloss of the samples at three common angles 20◦, 60◦, and 85◦ was measured using a gloss meter. The correlation and relationship between DYSCI-SCE and DL*SCI-SCE and the specular gloss values measured for the samples at different angles were evaluated and analyzed with linear and second-polynomial regression functions. The results were validated with a different set of data acquired from 32 random solid-coated samples. The results showed the best fitting was achieved at 60◦ of gloss measurement with a second-polynomial function. As the specular gloss of DY decreased, like in a matt sample, the estimation error of specular gloss increased with a large error of over 10%.