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Summary:
Since most of printing devices use a limited number of colored inks, color images are separated into these colors before being halftoned. Usually the printing devices use the four colors Cyan, Magenta, Yellow and Black. The most straight forward way of halftoning a color image is to halftone its color separations independently. It has been shown in literature that halftoning the color separations dependently and using dot-off-dot printing as much as possible results in smoother halftone patterns and hence improves the print quality. It has also been shown that using the dot-off-dot printing strategy for cyan and magenta channels reduces the amount of consumed inks. In this paper we are going to investigate and compare different aspects of three printing strategies, namely independent, dot-on-dot and dot-off-dot, in detail. Firstly, we will illustrate how these three printing strategies fill the color gamut of the investigated Desk-jet printer and offset print. Secondly, the three strategies are compared with each other in terms of consumed inks. The comparisons are firstly made using Murray-Davies model which assumes the optical dot gain to be negligible. The same comparisons are then made using the Yule-Nielsen model for optical dot gain. The impact of the optical dot gain on the resulting colors is obviously dependent not only on the utilized halftoning method but also on the printing strategy being used. The effect of optical dot gain on these three printing strategies is also investigated and illustrated in this paper.