Patented in 1903 by the Lumière brothers in France and first marketed in 1907, the Autochrome was one of the few commercially successful additive color processes, available since 1907 until 1935.
Autochromes are color transparencies on glass plates that are viewed either in special viewers called diascopes or projected onto a screen. They were also commonly placed on window panes using a brass frame with two suspension hooks.
Autochromes were made by coating a glass plate with a mosaic of minute potato starch grains dyed to approximate the primary additive colors of light. This was then coated with a panchromatic silver emulsion. Exposed in a camera so that the color mosaic filtered the light before it reached the emulsion layer, the plate was processed to create a black-and-white positive. This, in combination with the color mosaic, created a photographic image in natural colors.
All the information about this early color process you can find here
Many thanks to David Joyall, Senior Photographer at NEDCC who kindly gave me the Autochromes from his collection to illustrate this post.
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