Current color-printing technologies may use three or more inks, e.g., CMY, CMYK, CMYKcm, CMYKGO, CMYKRGB. When the number of inks exceeds three, there is the usual color-management one-to-many mapping problem. Because the spectral properties of many modern inks are optimized for maximum color gamut and in some cases, black ink may not be used for pictorial images, many prints have poor color constancy. Changes in lighting dramatically change color balance, particularly for neutrals. An algorithm was developed for multi-ink printing in which the one-to-many mapping problem was overcome by selecting ink combinations with the best color constancy between illuminants F11 and D50. The algorithm was tested using a pigmented-ink inkjet proofing printer. CMYKGO prints color-separated using this algorithm were compared with a generic ICC profile for CMYKcm prints. The CMYK inks were common to both prints. The new algorithm improved color constancy significantly.
Yongda Chen, Roy S. Berns, Lawrence A. Taplin, Francisco H. Imai, "A Multi-Ink Color-Separation Algorithm Maximizing Color Constancy" in Proc. IS&T 11th Color and Imaging Conf., 2003, pp 277 - 281, https://doi.org/10.2352/CIC.2003.11.1.art00048