A method and apparatus for determining a small number of parameters that spectrally characterize colorants by a small number of parameters and for using such colorant parameters to predict the spectral reflection or transmission characteristics of such colorants when laid on top of one another, either...http://www.google.ca/patents/US5933578?utm_source=gb-gplus-sharePatent US5933578 - Method and device for determining the color appearance of color overprints
