Autocorrelation and Granularity Part II Results on Flashed Black-and-White Emulsions*

The relation of Selwyn’s granularity measure to the character of the autocorrelation function and the granularity spectrum is discussed. The shape of the autocorrelation function as experimentally obtained leads to the conclusion that Selwyn’s granularity function σD·d should be essentially constant and independent of d. The fact that it is found to increase with d can be explained by (a) the existence of macroscopic variation in density (which can be largely eliminated) and (b) a combination of finite grain size and imperfect imagery. Jones and Higgins’s data on the perception of graininess are combined with the present data on granularity to provide a measure of granularity for uniformly flashed black-and-white emulsions, which is approximately independent of the area of the scanning spot and the density of the sample.