As part of a project to develop improved analytical techniques for the characterization of print gloss, a study has been carried out on the chromatic effects on specular reflections. Fresnel's reflection law suggests one kind of chromatic effect. An increase in index of refraction occurs in a material as the wavelength of light approaches the wavelength of absorption, and the increased index results in an increased Fresnel reflection. However, analysis of C, M, and Y electrophotographic images did not reveal any evidence of this effect. Another very strong effect was found to be the contribution of Fresnel type reflections from sub-layers of the image to the first surface reflection. These sub layer effects were observed to contribute significantly to the total specular reflectance, provided the colorant layer had a minimum absorptance. For example, for measurements of C, M, and Y toner fused on paper, measured in R, G, and B light, the minimum amount of specular reflection was measured for Cyan in Red, Magenta in Green, and Yellow in Blue. Quantitative modeling of this multiple specular reflec-tion has been consistent with experimental measurements.
Department, Program, or Center
Chester F. Carlson Center for Imaging Science (COS)
IS&T's NIP20: International Conference on Digital Printing Technologies (2004) 445-449
RIT – Main Campus