Model-based spectral calibration of color scanners

摘要

A target-less calibration system for calibrating a scanner for a particular input medium without using a dedicated calibration target on that medium is disclosed. The system employs the (predetermined) spectral response of the scanner and representative spectral measurements of the input medium to achieve the calibration. The representative spectral measurements of the input medium are used to infer the set of feasible spectra for the medium. Corresponding to a given scanner signal output, another set representing the candidate spectra that could have resulted in the given scanner output are determined using the predetermined scanner spectral response. Combining the two requirements, a spectrum in the intersection of the thus determined sets of scanner candidate spectra and prenoted feasible media spectra provides an estimated spectrum of the input sample. Repeating the process over the range of scanner outputs provides a complete spectral calibration for the scanner for the given medium.