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Photographic film is a sheet of plastic ( polyester , PET , nitrocellulose or cellulose acetate ) coated with an emulsion containing light-sensitive silver halide salts ( bonded by gelatin ) with variable crystal sizes that determine the sensitivity , contrast and resolution of the film .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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