Photochrom is a process for producing colorized images from a single black-and-white photographic negative via the direct photographic transfer of the negative onto lithographic printing plates. The process is a photographic variant of chromolithography (color lithography). Because no color information was preserved in the photographic process, the photographer would make detailed notes on the colors within the scene and use the notes to hand paint the negative before transferring the image through colored gels onto the printing plates. The process was invented in the 1880s by Hans Jakob Schmid (1856–1924). Amongst the first commercial photographers to employ the technique were French photographer Félix Bonfils, British photographer Francis Frith and American photographer William Henry Jackson, all active in the 1880s. The photochrom process was most popular in the 1890s, when true color photography was first developed but was still commercially impractical. [1]