Abstract

The objective quantity, “granularity,” which refers to the spatial variations in transmitting or reflecting characteristics of a developed photographic material, has been determined for a group of materials differing widely in sensitivity and grain size. These measurements were made by several different methods which have been proposed by various workers. The psychophysical quantity, “graininess,” which refers to the visual appearance of the granular structure in a developed photographic material, has been measured by the method proposed by Jones and Deisch. These measurements of graininess were made on the same samples as those which were used in the evaluation of granularity. None of the methods of measuring granularity give the same functional relation between granularity and the density of the silver image as that existing between graininess and density. However, by choosing arbitrarily a density level which is not the same for all of the objective methods, all these methods can be made to give granularity values which place the different photographic materials in approximately the same order as the graininess values, but for no method is the order exactly the same. Moreover, even when the order is the same, the granularity values are not proportional to the graininess values. These results indicate that the objective methods measure one or more, but not all, of the factors which determine graininess.

© 1945 Optical Society of America

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