Problems in Measuring the Quality of Black Solid Prints.

The numerical evaluation of print quality is vital to the study of printability, whether it be of inks or papers print quality is defined as the aggregate effect of the various appearance characteristics of printed matter. The most readily evaluated type of print, the black solid, has been the subject of the initial printability studies at Lehigh. The quality of a black solid print depends primarily on its average diffuse reflectance or color density, average specular reflectance or gloss, and uniformity of both color density and gloss. Several instruments for measuring these properties are available, but this work shows that an instrument chosen at random may not produce meaningful results. The photovolt and the Densichron were used for measuring diffuse reflectance. Investigations of the differences between these two instruments involved comparisons with a goniophotometer and experiments with standard lighting and viewing conditions for rating prints visually. The initial studies indicated that the goniophotometer and the Densichron correlated best with visual rating performed under diffuse 45 lighting and perpendicular viewing, and the photovolt correlated best with visual rating performed with perpendicular lighting and 45 viewing.