Systems of colour reproduction in which the visible spectrum is divided into blue-green and orange-red regions for recording and presentation.
Although extensively used in early colour film processes, the inherent inability of two components to reproduce a satisfactory range of hues rendered all such systems obsolete when three-colour processes became readily available. 1
See also Bi-pack, Technicolor
References
1 1969, The Focal Encyclopedia of Film and Television Techniques, Focal Press, London, New York