chromatic icons 5: the tartan ribbon

Today’s chromatic icon is a small piece of tartan ribbon. Or rather, it’s an image of a small piece of tartan ribbon. And why might this image be so iconic? This image of tartan is important for the vital role it played in the advancement of knowledge about the human perception of light and hue – an advancement which eventually led to the birth of colour photography. The fact that this piece of ribbon is tartan is important because the man responsible for the image was, of course, a Scotsman.

An insatiably curious young man who grew up in Glenlair, Maxwell became one of the nineteenth century’s most distinguished physicists. Maxwell was responsible for important discoveries in electromagnetic radiation and thermodynamics and his research laid the groundwork for many fields in modern physics, from chaos theory to electrical engineering. Much like Isaac Newton, Maxwell was fascinated by the physics of light, and developed an interest in optics, colour perception, and the operation of the human eye.

Earlier in the nineteenth century, Thomas Young had argued that human visual perception operated through three different colour channels. Maxwell explored Young’s trichomatic theory through experiments using rotating discs with different red, green, and blue coloured sections.

Maxwell’s disc experiments demonstrated the existence of three different types of light-sensitive cells in the human eye (now known as cones). These cones were essentially monochromatic – each being individually tuned to light frequencies of red, green or blue – but working together, these monochrome cones allowed the human eye to perceive the world in full, glorious colour. Maxwell had proved the trichomatic theory, but how was he to demonstrate his discovery to the public?

. . . with tartan! Woven with multiple, differently coloured threads, Scotland’s iconic national cloth provided the ideal chromatic subject with which Maxwell might demonstrate what he had discovered about human colour vision. When called upon to deliver a lecture about his colour discoveries in 1861, Maxwell asked photographer, Thomas Sutton to create three different images of a tartan ribbon, under three different lights – red, green and blue. Sutton duly created three separate glass plate photographs. . . .

. . . then by overlaying Sutton’s glass plates, and projecting the results with bright light onto a large white screen, Maxwell showed his audience how an image in full colour might be both generated, and perceived.

With his projected image of the tartan ribbon, James Clerk Maxwell had essentially created colour photography: setting in motion the scientific developments which, just a few decades later, were to result in photographic technologies like autochrome and cinematic ones like technicolor.

The three-colour theory, demonstrated by Clerk-Maxwell’s iconic tartan ribbon is the basis of virtually all modern chromatic processes, from chemistry to electronics. And who knew that a tiny piece of Scottish tartan was responsible for what graphic designers and photographers around the world now think of as RGB, or additive colour?

Find out more about the life and work of James Clerk Maxwell, in this short documentary presented by Scots poet, Rab Wilson