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Term: Interpositives, duplicate negatives, and transparencies

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Term: Interpositives, duplicate negatives, and transparencies


Pertains to the copying of photographic negatives and color transparencies, i.e., items used or viewed by transmitted light. For many years, library and archive preservation programs created duplicate negatives or transparencies in order to have a surrogate for the original in the event of damage or loss, or to reduce the handling and use of the original. The typical method for producing a duplicate negative entails making an interpositive (the positive image that results when copying a negative onto negative film stock), which is then recopied (and undergoes a second polarity reversal) to produce a duplicate negative. When a transparency (already a positive) is copied, color reversal stock is usually employed, yielding a duplicate transparency.

In the digital realm, reversals of polarity are carried out electronically; thus the production of digital images that can be used as surrogates for original photographic negatives and transparencies is more straightforward than the production of film-based duplicate negatives and transparencies.

See also:
Copy negatives and transparencies