Abstract: A method and apparatus to predict the color of an overprint of a set of colorants at a set of respective coverage percentages on a substrate of a substrate type using a printing technique. The colorants include some for which a device profile is provided. The method includes determining the colorant parameters of the device profile colorants; determining the spectrum of the substrate, providing spectral colorant parameters for the non-device profile colorants, and determining the color of the overprint. One version including modifying the data of the device profile such that the colorant parameters determined in the step of determining colorant parameters determines the colorant parameters of modified colorants that match the color of the device profile colorants and that cover at least the gamut of the device profile colorants.