Gonio-spectrophotometric analysis of white and chromatic reference materials Original Research Article

White and chromatic specimens, including barium sulfate plaque, Spectralon, Everwhite and BCRA tiles, which are used as reference materials, were measured by a gonio-spectrophotometer, and from the spectral directional reflectance factor for each geometric condition, colorimetric values were calculated. These specimens were also measured by a spectrophotometer having an integrating sphere, by specular component including and excluding conditions. From the results of these measurements, at first, the uniformity of angular distribution of reflected light in a near normal direction, when specimens were illuminated from −45° direction, was examined. Then the spatial distribution of reflected light in a near specular direction for −45° incidence was examined. Specularly reflected components from some kinds of surfaces were spread over a considerably wide range from the regular direction. Finally, luminous reflectance and chromaticity changes with geometric condition were examined, and colorimetric values under the usual geometric conditions, i.e. d/0, D/0, −45/0 and −7/45, were compared.