Specular Gloss: A study on instrumental and visual quantification at three illumination/observation geometries

In the present study, attempts were made to find the correlation between visually perceived and instrumentally measured specular gloss of a series of black samples. To this end, a black physical scale of specular gloss was prepared using a lithographically printed black paper. The samples were visually evaluated by a panel of 14 observers, by utilizing an also prepared color constant lightness scale, in an especially designed unidirectional illumination cabinet at the 20˚, the 60˚ and the 85˚ illumination/observation geometries. Analyzing the correlation between visually percepted and instrumentally measured specular gloss showed that the 60˚ geometry is efficiently capable of quantifying specular gloss in a manner that human observer perceives.