(Photo courtesy of Ciba-Geigy)
AUTOCHROME #113 (End of Series)
Artist’s sitting room
Taking the principle of three-color synthesis which had been simultaneously stated by Louis Ducos du Hauron and Charles Cros in 1869, Louis Lumière had the idea of coating a glass plate with a thin layer of equally mixed green, violet, and orange-red dyed starch grains. These grains would then be coated with a panchromatic sensitive emulsion. When exposing the back of the plate, light would be transmitted through the “screen” formed by the transparent grains and depending on their colour and relative light absorption or reflection, the image would be impressed upon the light sensitive emulsion. After a reversal process, this would give a positive silver image which acted as a mask. By viewing the plate as a transparency, a positive color image would be seen as the light, blocked by the mask, passed through the colored starch grains.
(via inthefollies)





