ON DYE CLOUD DIFFUSION AND THE IMAGE QUALITY OF COLOR NEGATIVE PHOTOGRAPHIC MATERIALS

The impact of dye cloud diffusion on the signal recording and noise properties of a colour negative photographic material has been studied. A mathematical model has been established which quantitatively links modulation transfer function (MTF), noise power spectrum and granularity to the size and morphological features of dye clouds for a large variation in cloud diffusion. The basic features of the model have been experimentally examined using three techniques for varying the extent of dye diffusion; 1) A variation in image coupler laydown, 2) Adding a black-and-white developing agent to the colour developer solution and, 3) immersing a fully exposed and processed film strip in an alkaline alcohol-water solution. In all cases, the model was seen to describe image structure performance realistically. Also the link between colour negative dye cloud diffusion and predicted final print sharpness and graininess has been quantified.