Spectral-Based Six-Color Separation Minimizing Metamerism

A spectral-based six-color printer model was derived in determining the six color separations for an input spectral image that yields the least metameric reproduction relative to the original. Confined by the ink-trapping limitation, the six-color halftone printer modeling effort is a union of ten four-color halftone printer modeling efforts in addition to a four-ink selector. The four-ink selector defines a set of the best four inks providing the closest spectral fit to an input pixel requiring reproduction in a continuous tone approximated space. Then the four-ink backward halftone printer model corresponding to the selected ink set for an input pixel calculates the ink amount in terms of fractional dot areas for synthesizing the pixel. This completes the proposed spectral six-color separation algorithm. This article will discuss the construction of the four-ink selector, approaches on dividing the six-color printer model into ten four-color printer models, performance in terms of colorimetric and spectral accuracy of the model, and, finally, the colorimetric and spectral performance comparison between the proposed six-color and conventional four-color printer models.