1. A computer-implemented method comprising: obtaining a plurality of measured spectral reflectance values, each value being representative of a measured spectral reflectance of a halftone portion of a printed output generated by a particular printing device, each halftone portion being printed with one or more printing fluids at a particular area coverage, one or more printing fluids at a particular area coverage being expressed as a Neugebauer Primary area coverage value for printing; deriving parameters for at least one color model, the color model mapping at least one Neugebauer Primary area coverage value to at least one spectral reflectance value; computing estimated spectral reflectance values by applying the color model to the Neugebauer Primary area coverage values for printing; minimizing a distance metric between the estimated spectral reflectance values and the measured spectral reflectance values to generate a multi-dimensional correction parameter; and updating the color model to include the multi-dimensional correction factor.