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The Epic Interactive Encyclopedia 1997
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1992-09-02
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26 lines
strip of transparent material (usually
cellulose acetate) coated with a
light-sensitive emulsion, used in cameras to
take pictures. The emulsion contains a
mixture of light-sensitive silver halide
salts (for example, bromide or iodide) in
gelatin. When the emulsion is exposed to
light, the silver salts are invisibly
altered, giving a latent image, which is then
made visible by the process of developing.
Films differ in their sensitivities to light,
this being indicated by their speeds. Color
film consists of several layers of emulsion,
each of which records a different color in
the light falling on it.
In color film the front emulsion records blue
light, then comes a yellow filter, followed
by layers that record green and red light
respectively. In the developing process the
various images in the layers are dyed yellow,
magenta (red), and cyan (blue), respectively.
When they are viewed, either as a
transparency or as a color print, the colors
merge to produce the true color of the
original scene photographed.