Extending Printing Color Gamut by Optimizing the Spectral Reflectance of Inks

A computer simulation was performed to investigate the optimum combinations of three- and four-chromatic inks in order to maximize the color gamut for halftone printing. A virtual printing model was created based on the Yule-Nielsen-spectral-Neugebauer equations and Kubelka-Munk turbid media theory and was used to predict the spectral reflectances and colorimetric coordinates of prints. In this manner, the spectral properties of a printer's entire color gamut were predicted from the spectral properties of ink and paper. A new method was developed to derive plausible ink spectral properties based on two Gaussian functions. The results showed that the optimum three-chromatic inks, as expected, were cyan, magenta and yellow. For four chromatic inks, several optimal results were found.