Patent ID: 6882451

Claim:
A method for transforming image-bearing signals, derived by scanning a photographic medium, to image-bearing signals that include the relative exposure values of said photographic medium, said method comprising the steps of: a) transforming said image-bearing signals to density values; b) transforming said density values to remove the chromatic interdependencies of said values so as to produce channel-independent density values; c) determining a reference density vs. exposure relationship for each color channel of said photographic medium; d) performing at least one measurement of at least one area of minimum density of said photographic medium; e) forming, for each color channel, an estimated density vs. exposure relationship of said photographic medium by adjusting the density values of said reference density vs. exposure relationship according to a difference of the minimum density value of said reference density vs. exposure relationship and the measured minimum density value of said photographic medium; and f) transforming, for each color channel, the channel-independent density values using the corresponding estimated density vs. exposure relationship to produce image-bearing signals that include the relative exposure values of the photographic medium.