 Panchromatic negative film is used in the camera as the rear component of a bipack in which the front film is a positive yellow dye image of the background scene.This yellow dye image is exposed on the negative by the blue light from the backing areas, but the yellow light from the foreground passes through it and records an image of the foreground at the same time.The Dunning Process, often in shorthand referred to as "process," was used in many black and white films, most notably "King Kong".Its chief limitation was that it could not be used for colour cinematography, and the process died out with the increasing move toward production of films in colour.