Maxwell also made contributions to the area of optics and colour vision, being credited with the discovery that colour photographs could be formed using red, green, and blue filters. He had the photographer Thomas Sutton photograph a tartan ribbon three times, each time with a different colour filter over the lens. The three images were developed and then projected onto a screen with three different projectors, each equipped with the same colour filter used to take its image. When brought into focus, the three images formed a full colour image. The three photographic plates now reside in a small museum at 14 India Street, Edinburgh, the house where Maxwell was born.