The color gamut in bi-level digital printers depends on the allocation of the CMY primary ink dots placed in dithering matrices. The typical color mixture model is based on Neugebauer theory, where CMY dots are placed at random, but recent digital printers don't obey that theory. The simplest method used in digital printers is “coaxial” allocation, where the CMY ink dots are placed in the same positions in each color dither matrix. The coaxial model produces sharp edges, but may generate too many secondary colors with unsaturated chromaticities. A mixture of C and M inks may produce a more brilliant bluish color when the C and M dots are placed side-by-side to avoid overlapping. In this article, “min-med”, “min-max” and “min” models with side-byside dot allocation are discussed. These are designed to suppress the occurrence of secondary colors. The corresponding color gamuts are analyzed and compared.
Ryoichi Saito, Hiroaki Kotera, "Dot Allocations in Dither Matrix with Wide Color Gamut" in Journal of Imaging Science and Technology, 1999, pp 345 - 352, https://doi.org/10.2352/J.ImagingSci.Technol.1999.43.4.art00006