Color compensating filters with infrared film

A series of aircraft flights at altitudes of 20,000 and 40,000 ft is carried out to test the film/filter capabilities of type-2443 Kodak aerochrome infrared film having three dye layers known as yellow, magenta, and cyan. The use of color compensating filters (CC filters) in the CC20 range resulted in two types of density increase. The first type concerns the attenuation of reflected energy in certain spectral regions. The second type of density increase, called an attenuation factor, concerns the attenuation of the other dye layers present in the film; this attenuation factor is independent of the photographic CC filter factor. A statistical analysis of density values measured on operational test film revealed that the density increases are measurable and normally large enough to cause the characteristic curves to shift in the direction of increased density, i.e., toward the red characteristic curve.