Colorimetric characterization of a desktop drum scanner using a spectral model

Abstract

A desktop drum scanner was colorimetrically characterized to an average CIELAB error of less than unity for Kodak Ektachrome transparencies and Ektacolor paper, and Fuji Photo Film Fuflchrome transparencies and Fujicolor paper. Independent verification on spectrally similar materials yielded an average z Eb error of less than 2. 1. The image formation of each medium was first modeled using either Beer-Bouguer or Kubelka-Munk theories and eigenvector analysis. Scanner digital values were then empirically related to dye concentrations using polynomial step-wise multiplelinear regression. These empirical matrices were required because the scanner's system spectral responsivities had excessively wide bandwidths. From these estimated dye concentrations, either a spectral transmittance or spectral reflectance factor was calculated from an a priori spectral analysis of each medium. The spectral estimates can be used to calculate tristimulus values for any illuminant and observer of interest. The methods used in this research are based on historical methods commonly used in photographic science.