This is a form of photographic printing, mentioned here because it appears almost identical as a photograph. The process was patented by Walter Woodbury in 1866, and is similar to the carbon process. The great feature of the Woodbury process is that a photograph in gelatine is caused by enormous pressure to indent a sheet of lead.

The quality of the pictures was remarkable, with no grain, and the process was widely used until the turn of the century.

(from: A History of Photography, by Dr. Dr. Robert Leggat FRPS)