Emulsion Colours

Emulsions are thin, gelatinous, light-sensitive coatings on film that react chemically to capture the colour and shadings of a scene. The four layers pictured here show the same image as it would appear on different emulsions in photographic film after the first stage of developing. For black-and-white photographs, only one emulsion is required, because it is the amount of light, not the colour, that activates the chemical reaction. Colour film requires three layers of emulsion, each of which is sensitive to only one of the primary colours of light: blue, green, or red. As light passes through the layers, each emulsion records areas where its particular colour appears in the scene. When developed, the emulsion releases dye that is the complementary colour of the light recorded: blue light activates yellow dye, green light is magenta, and red light is cyan (bluish-green). Complementary colours are used because they produce the original colour of the scene when the film is processed.

Eastman Kodak Company

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Photographic Techniques

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