What made the Lumiere brothers think to employ the humble potato as part of their process remains a mystery. It was not their first thought, but perhaps living in Lyon surrounded by farm country provided the inspiration. Using the additive process (see Colour), created glass photographic covered with a mixture of minuscule starch grains that had been dyed red- orange, violet, and green, and finished with a layer of light-sensitive material. When put in the camera, bare glass side exposed to the light, the grains functioned as tiny filters After development into a unique direct positive image, and viewed in bright sunlight or with an artificial light source, the small glass plates glowed like coloured jewels.