Sasan Gooran, Mahziar Namedanian, Henrik Hedman
Printed dots appear bigger than their reference size in the original bitmap. This is because of the physical and optical dot gain. In order to overcome the problem original images are compensated for dot gain. The compensation is usually done by using a dot gain curve for each colour separation. In this paper we firstly show that using only one dot gain curve works well for black, but not for any of the other three colours, i.e. cyan, magenta or yellow. We also present a new approach to calculate colour values where three different curves are used for each colour separation. In order to evaluate the proposed approach we compare the results of our method with the results when only one dot gain curve is used for each colour, both for Murray-Davies and Yule-Nielsen models. In the case of only one dot gain curve for each separation we use the curve that gives a minimized ∆ELab using least squares method. The experiments and calculations show that our approach gives a better approximation of the resulting colour coordinates.
Keywords: Dot Gain, Colour Calculation, Halftone Print