A STUDY OF COLOR-FILM GRANULARITY AND PRINT-IMAGE GRAININESS

The relationship between objective granularity and subjective grainine ss is reviewed and a new relationship based on real, as opposed to syn thetic, colour image structure is discussed. The granularity of a nega tive colourfilm image is calculated from the Wiener noise-power spectr um; the granularity of the print-image is calculated using the Doerner equation; the graininess of the print-image is assessed using a ratio scaling technique. The resulting equations are used to determine the minimum granularity of a negative film that is just perceptible in a p rint-image, at a defined magnification. A measure of the just-noticeab le difference in print-image graininess is also obtained.