Method of copying color exposures

摘要

A film has a series of exposed and developed negatives. Each negative is scanned at a multiplicity of regions, and the densities of each region in the three primary colors are measured. A blue/red density differential is derived for each region by subtracting the red density of a respective region from its blue density. The neutral density of each region is calculated, and every region is assigned a coordinate on a plot of blue/red density differential versus neutral density. According to one embodiment, the blue/red density differential for each region having a neutral density equal to or greater than a limiting value is then subtracted from the blue/red density differential given by a characteristic curve for the film. The differences obtained in this manner are analyzed, at least for selected negatives, and the minimum difference for each selected negative is determined. The region corresponding to the minimum difference is that region of a negative having the maximum blue density. The blue/red density differential for the region of maximum blue density is compared with a pair of reference values derived from respective reference curves representing blue/red density differential as a function of neutral density. Based on the results of this comparison, each selected negative is classified as to whether it was exposed by artificial light or natural light, and is assigned an appropriate color correction factor for copying. Another embodiment is employed if the characteristic curve is found to lie near one of the reference curves. Here, the steps of subtracting blue/red density differentials and analyzing the resulting differences are omitted, and all negatives of the film are immediately classified as having been exposed by artificial light.