During the capturing of the film a beam-splitter in combination with filters in the camera divided the incoming light into a red and a green separation negative on black-and-white stock. When projected in the cinema the two images were combined simultaneously by additive mixture through corresponding red and green filters into one picture consisting of red and green colored light. The reduction of the whole color range to two colors (and their additive combinations) was necessary because of the complex optical arrangement.
The Kodachrome process was invented in 1913 by John G. Capstaff for still photography and subsequently adapted to motion pictures. For the process two frames were advanced simultaneously, one located above the other. The light passed either through two lenses or through a beam-splitter, fitted with red and green filters. The release print was exposed through a beam-splitter whereby the alternate frames were projected onto either side of double-coated stock. After development by a usual b/w process, the film was tanned to harden the exposed areas. The soft areas were dyed red-orange and blue-green respectively.
“The Konicolor system, introduced by Konishiroku Shashin Kogyo (Now Konica Minolta Holdings, Inc.), split the image into three colors and shot them separately onto three b&w films. In that sense it had something in common with the US ‘Technicolor system’, but this was not a contact print with color dye to create positive film, but used coated emulsion to develop each color in a triple process, which is peculiar. […].”
“In 1930 Mannes and Godowsky were invited to join the staff of the Kodak Research Laboratory, where they concentrated on methods of processing multilayer films, while their colleagues worked out ways of manufacturing them. The result was the new Kodachrome film, launched in 1935. Three very thin emulsion layers were coated on film base, the emulsions being sensitised with non-wandering dyes to red, green and blue light, the red-sensitive layer being at the bottom.” (Coe, Brian (1978): Colour Photography. The First Hundred Years 1840-1940. London: Ash & Grant, pp. 121 ff.)