Theoretical and Experimental Investigations on Colour Film Granularity and Its Dependence on Coupler and Coating Parameters

Abstract

An extended granularity model for single layer colour coatings is presented, which allows all quantities characterizing granularity to be calculated from coupler and coating parameters. It represents a combination of the kinetical theory of dye cloud formation with existing granularity theories. In the first step, the dye concentration within an isolated dye cloud is calculated by solving a reaction/diffusion equation for quinonediimine. It is shown that at least three measurable quantities can be derived from the dye distribution: the two-dimensional density profile of a dye cloud and the relative noise power spectrum, by appropriate integration over this distribution, and the absolute granularity-density curve, by Monte-Carlo-simulation. These three quantities were measured for a set of model layers, two of them being discussed in this paper, by a high-resolution microdensitometer allowing sub-micron scanning. Satisfactory agreement with the calculated curves was found for each of the three quantities employing one set of coupler data and the given coating parameters. Moreover, it is discussed how coupler data of real film layers can be estimated by measuring the three quantities mentioned above.