A photoelectric scanning instrument is described which gives granularity values in terms that can be converted into the graininess values that would be obtained by an observer viewing a magnified image of the sample under standard conditions. The procedure is to determine the critical scanning aperture that results in a signal corresponding to the threshold-gradient sensitivity of the eye for the density of the sample. The techniques for making two types of routine graininess measurements are described in detail. Class I measurements give the graininess of samples at a density of 0.8. Class II measurements give granularity numbers that indicate the relative graininess to be expected of matched prints made from the negatives.
L. A. JONES, G. C. HIGGINS, K. F. STULTZ, and H. F. HOESTEREY, "Photographic Granularity and Graininess. IX. Techniques and Equipment for the Objective Measurement of Graininess," J. Opt. Soc. Am. 47, 312-318 (1957)