Autochrome

Autochrome, or Autochrome Lumière, is an early color photography process developed by the Lumière brothers and introduced commercially in 1907. It produced color positive transparencies by encoding color through a layer of microscopic dyed starch grains that acted as a mosaic of color filters on a glass plate.

A glass plate was coated with a transparent panchromatic photographic emulsion. Over this emulsion lay a layer containing countless dyed potato starch grains in colors that approximate red, green, and blue. The grains formed a mosaic acting as a color filter, so light passing through the scene was filtered before exposure. After processing, the grains remained in place, and the image was viewable by light transmitted from behind, yielding a direct color positive.

Autochrome plates required long exposure times and careful handling. Cameras were fitted to accept the plates and featured a plate-holder. The final images were soft by modern standards, with a characteristic speckled, pointillist look due to the grain mosaic. The color reproduction was generally faithful but with limited saturation and dynamic range.

Autochrome was the first widely marketed color photography method and dominated color still photography in the 1910s and 1920s. It was gradually displaced in the 1930s by film-based color processes such as Kodachrome and Agfacolor. Today Autochrome is valued by historians and collectors for its historical significance and distinctive aesthetic.