British spelling for two-color process (Technicolor, Kinemacolor). Two-filter capture-and-print system—limited color palette but more movement-friendly than three-color method.
Two-color processes like Biocolour enabled filmmakers to shoot in color from the 1920s onwards without the complexity of later Technicolor systems. Instead of three color layers, they worked with just two—typically red and green or red and cyan—which significantly simplified the optical equipment. The camera required special color filters that split the incoming light during recording; during printing, the two negative strips were combined into one print. Practically, this meant faster shooting, lower material costs, but also a significantly reduced color palette.
On set, cinematographers immediately noticed the advantages over three-color processes—exposure was less critical because the separation filters acted during recording, not just in the lab. No additional light carts were needed for more complicated color temperature control. The grain was finer, and motion sharpness was better because the exposure time was shorter. This was particularly evident in exterior shots: landscapes and skies acquired their characteristic, somewhat artificial coloration—greens appeared vibrant, blues looked greenish, and flesh tones had an orangey cast. Not ideal for portraits, but perfect for melodramas, Westerns, and dance films, where this look became part of the style.
The decisive disadvantage was the limited color information. Purples could not be represented, and transitions between colors appeared flat. This forced directors and production designers to exercise self-restraint—costumes, sets, and makeup had to be deliberately chosen within the spectrum of the two colors. Some productions turned this into a virtue: the Biocolour look became a trademark, a distinct aesthetic statement. In editing, the two negatives were worked with separately, and color corrections could still be made during printing by adjusting the intensity of each layer.
With the rise of true Technicolor and later Eastmancolor, Biocolour disappeared from professional film production—too inefficient, too limited. Today, it exists as archival material, recognizable by its characteristic, two-dimensional color. Restorers need to understand how these processes worked to correctly restore old prints. For modern filmmakers, Biocolour remains a case study on the limitations of technology as a means of artistic expression.