Perception of graininess in complex photographic images through objective and subjective comparison

A model previously used for the perception of graininess in uniform-density images that exist in electrophotography, has been verified for use in silver-halide photography. In addition, a model has been developed which estimates the sensation of graininess in photographic images of non -uniform density. Given the relationship between graininess and density in uniform-density images, the graininess in a complex image is weighted by the frequency of occurrence of each measured density in the image. Such an analysis is compared to subjective evaluations. It is shown that the graininess model is useful in predicting the sensation of graininess in photographs