This image of a tartan ribbon is the first-ever permanent color photograph, and it was taken 150 years ago yesterday by the legendary scientist James Clerk Maxwell. So just how did he create colors that would last for over a century and a half?
On May 17, 1861, Clerk Maxwell unveiled the photo during a lecture at King's College London. While his photo wasn't the first color photograph ever, it represented a massive leap forward, and professional photographers were still using his basic techniques well into the 1980s. Which is all the more remarkable when you consider that color photograph was actually a complete sham.
It's a bit tricky to provide an exact date for the invention of photography, but the earliest ancestors of modern cameras date back to around the 1820s. You can see what's commonly considered the first ever photograph on the left, which was taken by Joseph Niepce in 1826.
All photographs work on the same basic principle - a light-sensitive area (the film) records all the light reflected or emitted by nearby objects, as are observed through the lens of the camera during some set period of exposure. This process leaves behind a latent image, which can in turn be developed into a photograph.
A camera does not necessarily have to be technological. At its heart, there's nothing about the camera that couldn't be found in nature - the camera just creates a dark area around the film so that the only light that enters will form the eventual image. The camera obscura dates back at least 1000 years, and it used that basic principle to project a bright image through a pinhole into - depending on the size of the camera obscure - a darkened box or room.
Modern photography then wasn't so much about inventing a way to capture real-life images as it was to find a way to preserve these images permanently. To that end, photography pioneers employed various chemicals that could preserve the latent image created by the camera on plates or film. These chemicals, which included everything from petroleum byproducts to silver compounds, would respond to the various wavelengths of light that they came into contact with it. In this way, the different amounts of light would be recorded, which taken together creates a complete photograph.
It may not seem immediately obvious why early cameras could not record color. After all, if they were simply recording the light sources within the purview of the camera lens, shouldn't all the types of light be recorded? To understand what that wasn't the case, we would do well to consider the workings of the human eye.
We're able to see because of the photoreceptors in our eyes, which work in pretty much the exact same way the chemicals in a roll of film do - they react to the wavelengths of light that stream into the eye, and they translate that into chemical information that is then passed on to the brain. One of the two kinds of photoreceptors are known as cones, and there are three types of cones.
These three varieties are each most sensitive to a particular wavelength, which are generally thought of as the colors blue, red, and green. (This is, as you might imagine, a bit of an oversimplification, but it will do for our purposes.) It's the interaction of information from these three different photoreceptors that allows the brain to perceive an almost infinite variety of colors, which is known as trichomacy.
The point is, we can only perceive color because the brain is working from three very different sources of information. If we didn't have the different varieties of cones, everything would be interpreted simply in terms of its relative brightness, which would mean we would see everything in black and white. In a sense, we might even think of the different photoreceptors as color filters for the eyes. In fact, I advise that you do just that, because we'll be coming back to that idea in a big way later.
The first inklings of the trichomatic theory goes back to the English polymath Thomas Young, who proposed the basics of the idea way back in 1802. He got a lot of the fundamentals right - there were three different types of photoreceptors in the eye, and each was sensitive to a different wavelength of light. But it wouldn't be until 1850 that the German physicist Hermann von Helmholtz took the theory further, and it wouldn't be until all the way in 1956 that Gunnar Svaetichin provided experimental proof for the idea.
So, under the circumstances, the developers of early photography can be forgiven for not thinking in terms of trichromacy. Instead, the initial attempts to create color photography revolved around a mysterious "chameleon substance" that could - as though by magic - perfectly imitate the color of whatever light source fell upon it. That, as you might imagine, didn't really go anywhere.
One of the more famous researchers into color photography was an American minister named Levi Hill. In 1850, he debuted a process he dubbed "heliochromy", which he claimed could reproduce colors in a rudimentary way. He attracted some major supporters - most notably Samuel Morse - but most dismissed him as a fraud who hand-dyed his photos to create colors that weren't really there. A recent analysis showed the proof was somewhere in the middled: Hill's process could reproduce some very muted red and blue colors, but he had also added a few extra colors fraudulently, perhaps cracking under the strain to provide more spectacular results.
But early attempts into color photography always ran into the same basic problem - no matter how ingenious the methodology, the colors always seemed to fade away, often as soon as they were brought into the light. There wasn't much point to color photography if no one could ever actually look at the results, and a major innovation would be needed to make the process even remotely practical. The big insight would come from a Scottish genius named James Clerk Maxwell.
If there were any justice, James Clerk Maxwell's name would be mentioned in the same breath as Sir Isaac Newton and Albert Einstein. He's not exactly an obscure figure, but his contributions to the sciences were so great that anything less than everlasting glory seems to give him short shrift. Einstein himself once observed, "One scientific epoch ended and another began with James Clerk Maxwell."
Born in Edinburgh in 1831, Clerk Maxwell was educated in the Scottish city before continuing his studies at Cambridge. He taught as a professor of natural philosophy Aberdeen's Marischal College and King's College London before retiring to his Scottish estate at just 34. He died relatively young at just 48 years old in 1879. But during his lifetime, Clerk Maxwell revolutionized at least half a different fields.
He united all previous practical and theoretical work on electricity and magnetism into a single consistent framework, recognizing that they were all manifestations of a single basic phenomenon, the electromagnetic field. He also did considerable work in optic, demonstrating among other things that light was also a part of electromagnetism, and that the speed of light was in fact constant.
His work on the kinetic theory of gases provided the first statistical law of physics, and his recognition of this essentially probabilistic behavior helped lay the groundwork for the rise of the quantum mechanics in the 20th century. In recent polls of physicists, his electromagnetic equation stands as the greatest in the history of the field, and Clerk Maxwell himself is recognized as the third greatest physicist of all time, and his work is fundamental to television, cellphones, satellite communications, and a dozen other modern marvels of technology.
Considering everything else he got up to, it almost seems like a waste of his talents that Clerk Maxwell would invent color photography. But in 1855, he laid the groundwork for the first permanent color photo six years later by publishing a paper on the nature of color vision.
Recognizing the validity of the Young-Helmholtz theory and other early research into trichromacy, Clerk Maxwell took things a step further by realizing that every imaginable color could be artificially reproduced by mixing together the three primary colors red, green, and blue. It was all just a matter of getting the correct proportions in the stimulation of these various colors. Almost incidentally, Clerk Maxwell thought to apply this to photography, realizing that projecting three monochrome photographs of the same scene through the necessary color filters could create a full color photograph.
In order to illustrate a lecture on color vision on May 17, 1861, Clerk Maxwell asked Thomas Sutton, a photography innovator in his own right who had invented the first camera with a wide-angle lens, to take three separate photographs of a tartan ribbon, each time using a different filter. The result was the photograph up top, and so the three-color process was born.
James Clerk Maxwell and Thomas Sutton had hit upon the secret of color photography, and color separation became a major method of color photography for the next 130 years. As late as the 1980s, wire services transmitted color photographs around the world as three monochrome images, each with a different color filter, which could then be rephotographed and recombined to form a single color print.
So then, it almost seems churlish to point out that the whole thing was sort of a sham. Now, make no mistake: Clerk Maxwell's ideas were completely sound, and neither he nor Thomas Sutton engaged in any deliberate hoax. The problem is that the technology of the time period simply was not up to Clerk Maxwell's genius. There was just no way that the photographic materials of the time were sensitive enough to pick up red or green light for his idea to work.
The whole thing then was a bit of a happy accident. A hundred years later, R.M. Evans worked out what had really happened - the red dyes used in Sutton's filter were also able to pick up ultraviolet light, and so the tartan ribbon is not so much a composite of red, blue, and green as it is a mix of ultraviolet, blue-green, and blue wavelengths.
Still, at least Clerk Maxwell had all the basics right. His color photograph quickly fell into obscurity and would not be rediscovered until the 1890s. In the intervening decades, others had to independently reinvent his basic procedure, but these were all doomed to failure because the people responsible for them were far more artists than scientists. While a physicist like Clerk Maxwell knew that red, blue, and green were the primary colors, later photographers were under the false impression - one that persists to this day - that red, blue, and yellow were the colors needed for the primary filters.
It wouldn't be until 1873 that chemist Hermann Vogel figured out how to add the necessary sensitivity to green and red filters, bringing Clerk Maxwell's original procedure a little further into the realm of practicality. Even then, the long exposure times, prohibitive costs, and still barely adequate materials meant that color photography had to remain more a technical curiosity than a real going concern.
Finally, in 1903, the legendary Lumière brothers patented the first commercially viable color photography. Their Autochrome worked on the same fundamental principle as Clerk Maxwell's process, although they figured out how to do all the color mixing while the photograph was actually being taken. They covered the glass plates on which the image would be taken with microscopic dots of red-orange, green, and blue-violet, which was a still workable variant on the more traditional primary colors.
This so-called "mosaic screen plate" would then capture different color properties from all over the image. Because the color dots were so tiny, any given area that was actually visible to the eye would consist of a full complement of color information, as the individual dots would blend together to create a continuous color image.
It had taken 42 years since what had been perhaps the most flawed "successful" demonstration in history - not to mention an almost dizzying number of false starts in the interim - but color photography had arrived and it was, at last, here to stay. And now, 150 years after the initial demonstration, something as amazing and omnipresent as color photography can be remembered as merely a lesser legacy of one of physics's greatest geniuses.