Evaluation of a Light Diffusion Model for Dot Gain

In two previous TAGA papers [1][2], we have presented a model for optical dot gain based on a physical model of light diffusion within the paper sheet. The model centered around a point spread function for diffuse reflection, which we calculated by simulations on a supercomputer. We now relate the parameters of our simulation model to the traditional Kubelka-Munk parameters K and S, and we also present a few ideas for obtaining the point spread function by digital image analysis. Finally, we extend the model to color printing, and show that the optical dot gain has a considerable impact on the color gamut of the reproduction process. A large optical dot gain yields a larger color gamut. For comparison, a simple model of physical dot gain is presented, and it is shown that a large physical dot gain also expands the color gamut. This could well account for reports that stochastic screening yields a larger color gamut than conventional screening.