Few people know that Scottish physicist James Clerk Maxwell, best known for his development of electromagnetic theory, dabbled in color theory throughout his life, eventually producing the first color photograph in 1861. On the same year that he helped found Edinburgh Photographic Society, he demonstrated his method of developing color films to the Royal Institution in London
It was based on a specification he outlined in a paper to the Royal Society of Edinburgh in 1855. He arranged for three photographs of a tartan ribbon to be taken by the professional photographer, Thomas Sutton. Each was made using a black+white slide. These slides were exposed respectively through red, green and blue filters. He then projected the slides simultaneously using three lanterns, .creating a composite image, which included nearly all of the original colours on the ribbon.
In due process, Maxwell was also able to prove his three-color human vision theory. Newton had proposed that there were four visual primaries: red, yellow, green, and blue. Later, others including Maxwell argued that there were three primaries: red, green, and blue.
Here is also an interesting post on where Maxwell got wrong on this above experiement.