Spectral workflows in printing aim at achieving an illuminant-invariant visual match between an original and its reproduction and require the spectral reflectance of the original as input. When printing on a fluorescing substrate, the reflectance factor of the reproduction is however no longer independent of the illumination. In the present work, we propose an extension of a spectral gamut mapping and separation algorithm accounting for the fluorescence of the substrate. The forward model relies on an extended Neugebauer model accounting for the attenuation by the ink halftones of the incident excitation radiation and emitted light. The algorithm searches for all reproducible paramers of each particular target under one spectral power distribution (SPD) with UV included and minimize the colour difference under subsequent SPDs. We test the framework on a set of 1269 Munsell patches by simulating the output of a CMYKRGB printer on a fluorescing paper and show that the proposed framework leads to significantly lower multi-illuminant colour differences as compared to a framework only taking as input the measured spectral reflectance in one single SPD.
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