Subtractive 3 color: Beam-splitter camera, imbibition printing
Similar to Technicolor, the Iriscolor process needed a special beam-splitter camera for exposing three black-and-white negatives on Kodak film stock. These negatives were used for imbibition printing. Between 1940 and 1942, Tobis Tonbild-Syndikat AG ...

Ansco One-Strip Color-Separation Film, type 155

Subtractive 3 color: one-strip color separation
See Ansco Colorpak / Ansco Color, type 735, Ansco Color Release Film, type 732 and Ansco Color Duplicating Film, type 132.

Trucolor 3 color

Subtractive 3 color: Color separation on DuPont Release Positive Film