The Autochrome Lumière is an early color photography process. Patented in 1903 by the Lumière brothers and marketed in 1907 it remained the only color photography process available on the market until 1935.
Autochrome is an additive color process: the media contains a overlaying random mosaic of microscopic grains of potato starch, with lampblack filling
the space between grains, atop a black and white film base. The grains are a mixture of those dyed orange, green and blue, and
act as color filters. The film is processed as a slide, and the starch grains must remain in
alignment with the film base after processing in order to allow the colors to be seen properly.
The patent application describes the process somewhat differently: the grains are Red, Yellow and Blue (no blacklamp filling) and there are two layers of them, therefore when grains of different colors superimpose, this creates Orange, Violet and Green zones as well. The total surface is therefore covered with 6 different tints. It is necessary to invert the image to obtain a positive.
Autochromes were glass plaques until the 1930s when a film format appeared as well.
Autochrome film was gradually replaced by other processes, including Kodachrome, Agfacolor Neue and Kodacolor .
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