Autochrome of flowers in a greenhouse, c 1908.
© National Media Museum / Science & Society Picture Library
Autochromes were the first commercially available colour process, invented by Auguste (1862-1954) and Louis Lumiere (1865-1948),, patented in 1904 and marketed in 1907. A glass plate was covered with potato starch, dyed green, red and blue, producing a random pattern of coloured dots and then coated with emulsion. This plate was then exposed in the camera with the glass side toward the lens, so that the starch acted as a colour filter on the light before it reached the emulsion. There followed a complex reversal development process to produce a positive image on the plate which was then covered with another piece of glass to protect it.