Back in the days when I used to sell Zeiss microscopes I used to look at exposed/processed photographic materials at a variety of magnifications up to 1000X.
Traditional black and white materials always showed an emulsion consisting of a clear medium, gelatine, containing silver grains generated in situ. Apart from autoradiography plates or nuclear track emulsions this gelatine+silver structure was unique to photography.
Colour materials, except Kodachrome, showed gelatin with dye clouds generated in situ. Also present were millions of minute highly refractile resin beads which served as the anchor points for colour couplers.
Give me one of those nice microscopes now and I reckon I will pick real photographs from look-a-likes 100% of the time.