Patent ID: 7032517

Claim:
A method of reproducing spot colors with a combination of primary printing inks and at least one secondary printing ink red, green, blue, the method which comprises: (a) printing a first test form with the primary printing inks cyan, magenta, yellow, black and subjecting the first test form to a colorimetric measurement; (b) printing at least one further test form, with one of the primary printing inks cyan, magenta and yellow replaced by a substantially complementary secondary printing ink, and subjecting the further test form to a colorimetric measurement; (c) calculating an ICC color profile from the measured data of each of the test forms; (d) for each spot color to be reproduced, determining proportions of printing inks of the ICC color profile with which a lowest deviation between the spot color and a reproduced color is achieved, and selecting a printing ink combination belonging to the ICC profile; and (e) for each spot color to be reproduced, assigning the proportions of the printing inks of the selected printing ink combination to the spot color.