The Noise-Power Spectrum of Colour Negative Film with Incorporated Couplers

ABSTRACT

The derivation is given of formulae for noise-power spectra for two mathematical models of colour-negative film having incorporated dye-forming coupler. The two models assume different dye-cloud morphologies; one assumes sharp-edged clouds, the other, clouds with a Gaussian distribution of dye density. Computed families of curves for each model and for varying dye-cloud diameters are compared with experimental results obtained for a series of model single-layer coatings in which development inhibition is used to modify the dye-cloud shape and size.

Comparison of dye-cloud sizes from the models and from photomicrographs suggests that the Gaussian distribution gives the best predictions for these coatings. It is also found that a combination of two dye-cloud sizes gives the best agreement between theory and experiment. Correlation is noted between the two dye-cloud diameters used to give the best agreement and the mean sizes as indicated in the photomicrographs of single clouds and groups of intermingling clouds.