The transition between electronic and chemical photography will require the digitization of large volumes of source material currently on photographic film. For efficient conversion, the resolution and number of quantization levels must be well matched to the information content of the film and the display device. The grain noise levels for 5 readily available commercial color photographic films were measured. These measurements are compared to an empirical model that predicts the noise in the transmission coefficient from the manufacturers' quoted granularity values. For all the emulsions measured, the film grain noise does not seem to warrant retaining more than 8 bits, i.e. 256 levels, in the green channel for images displayed on a conventional CRT. The noise in the red and blue channels was found to be equal to or greater than that measured in the green channel with the behavior being highly dependent on the specific emulsion type. For monochrome photographic emulsions, the grain noise is usually assumed to vary as the inverse of the square root of the sampling area. For the five color emulsions measured, the noise was found to vary as the inverse cube root of the sampling area or slower. These results suggest that it can be difficult to significantly decrease image noise by increasing the film format size.
Richard V. Kollarits,
"Noise in images digitized from photographic film", Proc. SPIE 2654, Solid State Sensor Arrays and CCD Cameras, (25 March 1996); doi: 10.1117/12.236101; https://doi.org/10.1117/12.236101