Control circuit for photographic colour printer - scans original for density and spectral distribution to determine manufacturer and/or film type

摘要

The negative, or transparency, is scanned to determine not only the density but the spectral characteristics in each colour. A simple memory compares the spectrum with set types of film and sets the copier initially for that type of film, with fine adjustment for each print. The control enables e.g. transparencies from a mixed set of films to be processed for copies in a rapid sequence, with full automatic control. For rapid indentification of film type the spectral analysis is of two separate wavelengths in the red range.