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Spectral Selectivity
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Spectral Selectivity
Spectral Selectivity
by Ed Scott dotted.dog@worldnet.att.net
and Hollis Bewley hbewley@wco.com
Spectral selectivity is a technique for creating images which uses intentionally limited ranges of radiation
in the ultraviolet, visible or infrared portions of the spectrum. It has uses in artistic and scientific
photography.
Early day photographers often needed to work around the inherent spectral sensitivity limitations of the
photographic materials available to them. Their photographic materials were sensitive primarily to blue
light. Rich blue skies photographed much too light while vegetation and skin photographed too dark.
Look closely at the actors and actresses in early motion pictures. Often the white powder makeup they
used did not get applied too close to their eyes and the result can be quite comical in close-ups.
Fortunately, current photographic materials extend well past the approximately 500 nanometer upper
limit of early day imaging.
Modern photographic materials are available with sensitive to a wide portion of the spectrum, ranging
from 250 nanometers (ultraviolet) to 925 nanometers (infrared). There are many applications for the
selective use of this spectrum. Specific characteristics of a subject can be emphasized or selected out by
limiting the range of spectrum used to create an image. Colored filters are the primary tool for selective
use of spectrum with conventional photography. Digital image editors open up some new possibilities
for the creative use of spectral selectivity.
The topics linked below provide an introduction to spectral selectivity, some technical information for
http://www.photo.net/photo/edscott/spectsel (1 of 4)7/3/2005 2:16:52 AM