Answer: CIR (color infrared) film, originally referred to as camouflage-detection
film because of its warfare applications, differs from conventional color
film because its emulsion layers are sensitive to green, red, and
near-infrared radiation (0.5 micrometers to 0.9 micrometers). Used with
a yellow filter to absorb the blue light, this film provides sharp images
and penetrates haze at high altitudes. Color infrared film also is
referred to as false-color film.
Black-and-white panchromatic (B/W) film primarily consists of a
black-and-white negative material with a sensitivity range comparable to
that of the human eye. It has good contrast and resolution with low
graininess and a wide exposure range.
Black-and-white infrared (BIR) film, with some exceptions, is sensitive
to the spectral region encompassing 0.4 micrometers to 0.9 micrometers.
It is sometimes referred to as near-infrared film because it utilizes
only a narrow portion of the total infrared spectrum (0.7 micrometers
to 0.9 micrometers).
Natural color (also referred to as conventional or normal color) film
contains
three emulsion layers which are sensitive to blue, green, and red (the
three
primary colors of the visible spectrum). This film replicates colors as
seen by the human eye. Color film is a valuable image interpretation tool
because the human eye can discern a greater variety of color tones than gray tones.
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U.S. Geological Survey