A New Approach to Dot Gain Modelling

The quality of image formation on paper is a many faceted issue. One of the most important problems of tone rendering concerns the ubiquitous optical dot gain of ink on paper. Several attempts to model the dot gain of ink on paper have been made over the years with the Murray-Davis approach being one of the first. This approach was modified by Yule and Nielsen to account for the trapping in the substrate of internally scattered light. A distinction was thus drawn between mechanical dot gain and optical dot gain. This paper will describe a simple but yet effective model for optical dot gain that explains the decrease in the modulation transfer function towards higher screen rulings. The model also sheds some light on reasons for the variation in dot gain with different screen dot geometries. The model allows for the determination of dot gain characteristics in the form of parameters in the model description.