Autochrome
Made accessible and popular by the Lumière brothers in 1907, autochromes were one of the first full color photographic processes available at the time. Dyed potato starch granules of red, green, and blue and a back layer of carbon black covering the glass plate create the various colors in autochromes. When developed, the unique positive image lives on the glass. This method of color photography depends on the additive color method, much like the screen you are currently reading on. This was the main method of capturing color images before Kodachrome and Agfacolor films in the 1930s.
This autochrome is also a stereograph. For a stereograph autochrome such as this one, a stereoscope would be used to hold the autochrome to view the 3D effect. The couple of circular greenish spots in the image are most likely oxidation of silver.
Another difficult process to photograph, autochromes need light projecting through the back to be viewed.
