The first color photograph was unveiled 150 years ago at a lecture at the Royal Institution in London by James Clerk Maxwell, the Chair of Natural Philosphy at King's College.

The subject, a tartan ribbon, was made by projecting three different color-filtered exposures into one image using lanterns. This "three-color process" is the basis of every color photograph taken ever since.
Maxwell was a physicist and his three-color process started life as one of his many theoretical papers on the physics of light and color theory.