An ink separation algorithm is introduced for printing with 6 to 9 inks. A spectral gamut mapping algorithm is also introduced that projects an input reflectance onto the manifold of the printer spectral gamut space The ink separation, which is finding the best ink combination to reproduce a given reflectance, is done by applying an interpolation between printer gamut points neighboring a projected point point's geodesic location. The technique finds the best manifold projection using ISOMAP. The algorithm searches for the lowest dimensionality that holds the spectral information accurately. Using this method we were able to find a good ink combination given an input reflectance for both a 6-ink and 9-ink printer model.
Behnam Bastani, Brian Funt, "Geodesic Based Ink Separation for Spectral Printing" in Proc. IS&T 16th Color and Imaging Conf., 2008, pp 67 - 72, https://doi.org/10.2352/CIC.2008.16.1.art00013