Although the n-color printing process increases the color gamut, it creates a challenge in generating color separations. This article evaluates different methods of implementing the inverse printer model to obtain the color separation for n-color printing of discrete (spot) colors. The constrained optimization and lookup table based inversion methods were evaluated for n-color printing processes. The colorant space was divided into sectors of four inks and the inverse printer models were applied to each sector.

The results were found to be adequate, with the mean CIEDE2000 values between the measured colors and the model predicted colors below 1.5 for most of the models. The lookup table based inversion was faster than the constrained optimization approach. The nine-level lookup table model gave accurate prediction without costing excessive processing time. It can be used to replace spot colored inks with the seven-color printing process in packaging printing to achieve significant cost savings.