Is grain binary?

vicmortelmans

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Hi,

strange question, isn't it? I know that (at least b&w film) contains 'grain', which is a kind of cristal of particular size (related to sensitivity of the film, typically). It's the grain that gets dark after exposure and development.

Now my question is: is the grain either black or white, or are there gradations between? If grain is binary, film is like a grayscale image that's represented by a dithered black and white (1 bit) image.

I'm mainly asking because I wonder what effect this has on scanning film... If you scan at high resolution, and you really capture the grain, which is black or white, but not gray, even if it's part of a gray image area, then this would e.g. heavily disturb the histogram. Scanning a flat field gray image with heavy grain at high resolution, would deliver a wide histogram, while scanning the same negative at low resolution, would deliver a narrow histogram.

This could cause problems for postprocessing algorithms.

Groeten,

Vic
 
Grain is binary, however it is in clusters, which makes it possible to have a "grey" clump. Digital pixels are analog.
 
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