False-color infrared film

Description

Film in which various color dyes are activated by exposure to visible and infrared radiation. Color infrared film was developed by Kodak and became commercially available in the 1960s. Kodak Ektachrome® type 2236 film has three emulsion layers sensitive to infrared, red and green radiation. The infrared layer releases a red dye when activated, the red layer releases a green dye and the green layer releases a blue dye. The overall effect is an image whose colors are not an accurate representation of the object, thus giving the film its name of false-color. Combinations of the absorption of infrared and visible light can indicate composition for some pigments. Blue pigments in particular show significant variation with false-color infrared film (Hoeniger 1991). All colors vary with exposure conditions and should be run concurrently with standards. The film must be stored at cold temperatures (~ -20 C) to maintain sensitivity (Moon et al 1992).

Synonyms and Related Terms

false color film; Ektachrome® IR film type 2236 [Kodak]

Resources and Citations

• T.Moon, M.Schilling, S.Thirkettle "A Note on the Use of False-color Infrared Photography in Conservation" Studies in Conservation, 37:42-52, 1992.

• C.Hoeniger, "The Identification of Blue Pigments in Early Sienese Paintings by Color Infrared Photography" JAIC 30:115-124, 1991.