A Quick Story About Color

Crisp, colour photogrpahy has been around longer than you might think.

I once saw the picture of a Khan, dressed in bright blue, barrel chested, with a sword by his side. I saw the description beneath the photo, but I could not believe what I was seeing. This was not the work of a modern artist, who digitally painted an old picture, this was a truly breathtaking, original, colour photo showing the past. The REALLY old past, and I didn’t think we were supposed to get pictures of that.

The old past happened before anyone you know was alive, but the really old past happened before we learned how to take good pictures of things. We won’t ever get the see the really old past, but here, seeing the Khan, I was seeing a man living in an environment that had hardly changed over the millennia preceding him. Looking at him was like looking at a man who could have been of the court of Genghis Khan! But how does this picture exist? At the time when it was taken, pictures were supposed to look like this:

Pictures were alright back then, but without the colour, it’s hard for them to grab us the way that pictures can today. The black and white, grainy photo invokes in us a feeling that we are observing a world that is different from our own, whereas colour photos are like portals to places we can imagine stepping into. When I saw the photo of the Khan, I found myself imagining being in front of the Khan himself. Colour photography, as far I knew, was an invention of the 1950s, if not the 60s.   As I dug into the picture, looked into who took it, and how colour photography was possible at the time, I found myself astounded by what I learned.

Colour photography, in analogue and digital form, was made possible thanks to an idea had by James Clerk Maxwell. In 1855, he published a paper in which he described his theory on how our eyes see. He postulated that inside our eyes, we have three different types of cone cells, each of which is sensitive to a certain range of the visible light spectrum.

As you might, or might not know, colour as we see it only exists insofar as our eyes are there to pick it up. Without eyes, which use colours to abstract the world, there is only light at varying wavelengths, bouncing off objects in all directions. What we call colour, physically, is merely light travelling into our eyes at various wave lengths. Light waves with periods (intervals) of 700 nanometers look red to our sight organs, and wavelengths of approximately 450-495 nanometers appear as blue. How does this process work? 

Imagine light being generated (by the sun for example). It emanates from that point bearing a very large range of wavelengths. Some of it shoots out at very short wavelengths (ultraviolet, gamma rays, x-rays, etc), and some of it shoots out at medium wavelengths (visible colour), and some of it shoots out at very long wavelengths (infrared, radio waves). Short, medium, and long all shoot out together. Basically, light carries with it all the colours, including the ones we can’t see (but other eyes, evolved by other animals and insects, can sometimes see different parts of the spectrum from our own, such as the spider, which is equipped to perceive the ultraviolet spectrum). When this pure, melting pot of light enters our eyes, we detect it as white light; colourless.

Imagine a certain quantity of white light striking an object, and the properties of this object, such as its texture and density absorbs certain ranges of wavelengths and steals them away from this travelling quantity of light. This quantity of light, after bouncing off the object in question, continues into our eyes. This quantity of light, now having certain wavelengths deleted from it, is no longer perceived by us as white: it is now colourful, and from this phenomenon, the shapes of the world appear to us. Shades of grey allow us to perceive depth, and colour, to distinguish where one object begins, and another ends. Remember that in the real world, there are no lines making up the contour of shapes, as we see in drawings. Only by perceiving the difference in wavelengths of light which have bounced off objects, can we see the physical world. 

As I mentioned above, James Clerk Maxwell believed that the mechanism which allowed our eyes to pick up colour was rather simple. He explained that we have three special receptors in our eyes, named cone cells, which are each made to be sensitive to lightwaves of a very narrow part of the light spectrum. He supposed that one of these three cone cell was sensitive to red wavelengths, that another was sensitive to green, and another to blue. These three different quantities of wavelengths absorbed, our brains then combined and superimposed the data, thus inferring all the colours of the rainbow that we see, much like when a painter combine paints to produce new colours.

To sum up; light becomes encoded with colour when it strikes objects which steal away some of the light’s spectrum. Our eyes then absorb three different slices of this incoming spectrum, and then our brain uses these three slices to infer the colour we are seeing, additively, like a painter mixing colours. 

From what I gather, Maxwell oversimplified things. I’m not going to get on his case, he was the pioneer, but in fact, these cone cells, and our complex vision, colourful as it is, is far more complex than the notion that we have three different cell types that receive different ranges of light, and that our brain does the rest. Nevertheless, he was on the right path, and for the purposes of engineering colour photography, which is infinitely simpler than the mystery of our sight, it was enough.

One of Maxwell’s assumptions was the additive theory of colour, previously explained by reference to a painter mixing paints. It supposes that all the colours we have in the world can be attained by mixing the three previously named colours; red, green and blue (I’d be curious to know why he settled on these colours, since we are always taught that the three primary colours are red, blue and yellow, but anyhow).  Maxwell thought that if this was true, then the reverse should be true as well… If all the colours could be created by mixing red, green and blue, then all the colours of the rainbow could also un-mixed into his three primary colours! A student of his would later test this theory through a practical experiment, using photography.

Thomas Sutton thought that all the colours of the rainbow could be encoded as retreivable data by taking three different black and white photos of the same thing, with one of the pictures using a red filter over the lense, another with a green filter, and the last with a blue filter. Thomas Sutton figured it out, and in 1861, he was able to produce a blurry colour photo, the first of its kind. It would inspire others to follow suit. Black and white photography had been around in the 1820s (or even further back if you count the Camera Obscura), so it took 35ish years for the first breakthrough in colour photography to happen after the invention of the camera.

This discovery presented a number of challenges to the engineers of colour photography. First was the problem of simply taking the same picture three times. At the time, cameras required a much longer exposure time; in other words, photographers could wait many seconds, and even minutes, for a picture to be recorded on film. In that time, natural lighting could change, people could move, and these changes would ruin a good photo. From what I hear, this is why most people look so miserable in old photos; having to wait for so long for the picture to be taken, it was easier to maintain a neutral facial expression than a smiling one, which is often still a struggle today (only now we usually wait for the photographer, rather than for the camera).

One idea had been to have three different cameras mounted together, but this produced slightly different perspectives, which ruined finished products. Eventually, with the use of mirrors, some cameras were engineered to divide the light which passed through the aperture into three identical, equally bright jets of light, which were filtered through three different filters: one of red, one of green, and one blue. Thus, three pictures of an identical scene, encrypting quantities of three different wavelengths, could be taken with one camera.

But how did these three, separate, colourless pictures, get combined to create one picture with colour? It’s all based on the previously mentioned additive theory of colour (I’ll call it the Painter’s Theory), that any colour can be produced by mixing only three colours. This is how it went: three black and white pictures were taken, each tinted by one of three colour filters, and these black and white tinted photos were turned into transparents. Think of the negatives you used to bring to the store to have developed (in fact they were quite different, sometimes made of glass… we don’t need to get into it). These transparents were created using materials tinted the same colour which had previously tinted the photo, and these three transparents then sandwiched one atop another. Then, white light was shown through the assembly of superimposed transparents, and on the otherside, a colour photo.

This additive theory of colour really is fascinating. It has been used for tens of thousands of years by painters in caves and castles. It provided us with colour photography, and more recently, the additive theory of colour is being used by every digital screen in the world. Pixels display all the colours we know by individually adding various amounts of red, green and blue to themselves.

In fact, there is just too much to tell about this subject. I initially wanted to tell you about the photographer who took the picture of the Khan, for he is responsible for an unbelievable collection of early colour photos. Then, I spoke to you about Cameras without even mentioning the Lumière Brothers, which is tantamount to blasphemy. Instead, we got to talk about some physics, biology, and dare I say, we may have even dabbled in some cognitive science. For now, this is where this story ends.