An experimental analysis of paper optical scattering is reported. The Kubelka– Munk parameters for scattering, S, absorption, K, thickness, L, and background reflectance, Rg , were measured for a variety of papers. Measurements were made of reflectance and transmittance using integrating sphere techniques, and the Kubelka– Munk Eqs. were inverted numerically to generate the corresponding S and K values. The modulation transfer function, MTF, of each paper sample was also measured by projecting a sharp edge onto the paper and measuring the resulting edge spread function. The MTF was calculated as the modulus of the Fourier transform of the derivative of the edge function. The inverse of the frequency at which the MTF = 0.5 was used as an index of the MTF and called kp . Values of kp were compared to values of the Kubelka– Munk parameters. Through a combination of theory and empirical observation, a model was developed to relate k p to S, K, and L for Rg = 0. The results strongly indicate that an additional parameter is required in order to rationalize the observed MTF of papers. This additional parameter is suggested to be the scattering homogeneity of the paper.
Department, Program, or Center
Chester F. Carlson Center for Imaging Science (COS)
Journal of Imaging Science and Technology 47N4 (2003) 339-345
RIT – Main Campus