Gradation trajectories of ideal initial printing colorants in electrophotography: Discrete computation

Accuracy of the color reproduction during printing is strongly determined by the fine tuning of the gradation curves of the printing systems (tone reproduction curves). The curves are constructed by sequentially changing the tone of the main dyes (most often it is CMYK). However, this approach does not take into account the effect of shading changes when initial colorants overlap. Moreover, the traditional method does not take into account the nonlinearity of the tone increment in the areas of high and low densities. We have proposed an alternative color correction model based on the gradation trajectories as an analogue of gradation curves in the CIE Lab space. The method is devoid of the main drawbacks of the common approach. The authors have previously described the approach, its extension to double overlays of colors (gradation surfaces), as well as its analytical and discrete implications. In this paper, we propose to apply the gradation trajectories as geodesic lines of double overlaps to determine the color of the “true” initial colorants, which are free of nonlinearities in the high density domain. An experimental test was performed using an electrophotographic printer.