Thursday, 23 July 2009

The Concept of Colour Space from the practitioners standpoint

Colour and the Moving Image

Colour is a phenomenon of mind and eye - what you now perceive as colour, is shape and form rendered as experience. Visible light is electromagnetic radiation with wavelengths between 400 and 700 nanometers. It is remarkable that so many distinct causes of colour should apply to a small band of electromagnetic radiation to which the eye is sensitive, a band less than one "octave" wide in an electromagnetic spectrum of more than 80 "octaves." When thinking about the issue of synesthesia, remember that it occurs in a very limited sensorium.

Above are two representations of colour space. In each, the coloured area represents the visual field that evolution has endowed us with. This is one octave of possible experience.

Trying to systematize the idea of colour and naming that understanding ‘colour space’ has historical precedents which I’ll discuss later, but the notion of systematizing the concept grows out of ‘Enlightenment’ desires to know the world in a material way by mapping and planning, then proceeding into Victorian methods derived from, indexing and cataloging – which comes from a desire to create the experience of understanding from methodology, an idea who’s dominance is still with us.

Colour has been formulated by intellectual cartographers but is not a map – colour is experiential as the cinematographer well knows. In photographic terms colour as a function of seeing and meaning came late to the form. Because of this, notions of areas of containment of colour grew – as if colour had been graphically applied to an area - thus denying its inherence in form. This is in fact true in terms of late analogue televisual forms – but not true of digital electronic cinematography.

Film is exposed and latently holds an image, then is developed to ‘reveal’ that image. Film was and is a medium that had and still has many intricate and alchemical processes before its exhibition and revelation of a captured reality in the cinema: a temple built for the purpose of ritual display, where all who enter are required to suspend their disbelief. Film asks us to deny the actual material reality of the environment we are in and also to deny something of our own self.

Colour in this environment too was to be a function of the act of belief in the unreal. The generation of the idea of Colour space is an umbrella concept under which sets of ideas coalesced around the organisation of that function and as such took on various methodologies for its assemblage.

Because we are the ape that we are, mathematics quickly becomes for us a key organising factor in the description of this functionality.

“A colour model is an abstract mathematical model describing the way colours can be represented as tuples of numbers, typically as three or four values or colour components - for instance RGB and CMYK”.

“Most colour models begin as three dimensional forms because when you distribute the values in 2D space, that space cannot hold all the necessary axes relevant to the distribution of those values”.

In one of the examples above, there is a simple distribution of values that charts how a display from a computer is related to a display from a printer - in other words what the computer can display and what a printer can display.

The other example of colour space seeks to demonstrate the relationship of the visible spectrum to film, print and the computer.

“The range of colours varies enormously across different media. Of the billions of colours in the visible spectrum, a computer screen can display millions, a high-quality printer in the order of thousands, and older computer systems may support only 216 colours across different platforms.”

I could elucidate further on variations of description of print colour space, film colour space and computer colour space, I could elucidate further on whether those spaces are best displayed in their respective display co-ordinates of RGB or CMYK.

I could try to tell a history of film space and how electronic space addressed that, of how Kodak generated the cineon file system which was created for electronic encoding of film colour space with later developments of Digital Picture Exchange (or DPX), both of which generate a set of separate files each of which is one frame of film taken over into one digital frame of display - of how each carried meta-data about the conditions under which the image was generated in - and so on and so forth - but I won’t because that is for further reading - if you are interested.

What I will do and I’m trying to do it right now, is to indicate that simple technical terms that are understood by ‘the industries’ are replete with not only cultural and social meaning - but also exist within paradigms of understanding that are now changing – primarily due to the advent of the digital.

The Practitioner

I wish to turn now to the practical act of the cinematographer entering into the concept of colour space and how that can be achieved.
The early issues of video and film are now behind us and in some senses a rapprochement between film and the latest representative of the electronic – digital electronic cinematography - has occurred.

Original electronic imaging was analogue in form – as was film – yet the formulation of the capturing of an image was different from film.

Film has a large latitude – one could make an intelligent ‘mistake’ and rework the material and formulate a sense of ‘atmosphere’ within the image. This is commonly known as ‘the Look’.

Analogue video was clean and clinical and you had to get the exposure right – in the early days, if you didn’t get exposure correct then you didn’t get focus. Colour itself was grafted on to an already set formulation of image capture – PAL - it was effectively an afterthought: Phase Alternate Line.

I shot one of the first features, generated on video and transferred to film for theatrical distribution; this was Birmingham Film and Video Workshops production ‘Out of Order’. I approached the task by imagining video as being like a reversal stock – with very little latitude for mistakes in exposure. The transfer to film was adequate, but when compared to today’s digital transfer techniques, was not good in terms of colour.

With the advent of electronic cinematography something very important has happened in the capturing of the image. In both photo-chemical and electronic cinematography until the image is developed, the image resides in a latent form in both the silver halides and the un-rendered data. Development, the bringing forth of the image in film is similar to the rendering of the image in the digital and electronic domain – and importantly, colour is within the bit-depth of electronic data and is therefore an integral part of its material form.

This developing practical understanding in the professional realm is counter to arguments that circulate within media theory – for instance: New Media A Critical introduction latest publication 2009, Lister, et al, claims an essential virtuality to new media where the precise immateriality of digital media is stressed over and over again.

However, industrial and professional expertise now challenges academic convention by seeking to re-inscribe digital image making as a material process.

One of the first films that took a material film base and dealt with colour in the electronic realm was ‘O Brother Where are thou’. When Roger Deakins was asked by the Coen Brothers to shoot this, being a creative and intuitive cinematographer, he knew that he was being offered a chance to cross the bridge between the ‘convergent’ and the ‘integrative’ paradigm. Deakins job as he saw it was to enact the kind of colour space seen in the faded, poignant, postcards of the twenties. Deakins knows his film colour space. He’s had enough practice.

I want to tell you the kind of method that a practitioner like Roger Deakins employs to understand the function of colour in the world when faced with a multi-million dollar set of technologies - also adopted by a friend of mine when shooting a quarter of a billion dollar production recently.

If you decide that you’re going for a certain look, because intellectually you’ve justified to yourself that this look in some way underlines the intention of the director - and after you and he or she has toured the galleries, looked through the books, seen the movies that seem to relate to the project – and after you’ve jettisoned all of that because you know that referencing is mostly an act of creative failure and after every residue of resistance has gone, then and only then you turn to your intuition about the way you must proceed.

It might be that that intuition is to evoke green as a colour - or maybe it’s a magenta cast - or it has a warm glow which at the dramatic end you feel has to be taken away from the audience and supplanted by its opposite....

Which ever of these tactics you decide to embrace to achieve your goal, you accept the fact that you have to enter a colour space and live in that space until you know it fully - so fully that you can reveal its nature to both yourself and then the audience.

So you buy yourself some sunglasses.

If the world you need to reveal is green, you find the right colour green and wear those sunglasses for a month or for however long you need to wear them to know the world that has that particular shade of green.
Conversely, but with a little more risk, you can take the opposite approach and buy a pair of sunglasses that are the complimentary opposite colour of the world you eventually wish to invoke.

In so doing you exposure yourself to the opposite world of colour so that when you take the glasses off, the complimentary opposite of the world is revealed with even greater intensity – more so than the continuous appraisal of the world by seeing the correct colour continuously. That moment is a moment of incomparable intensity.


I now want to give you a brief idea of how we began to systematise the idea of colour:

Aristotle developed the first known theory of colour. He postulated that God sent down colour from the heavens as celestial rays. He identified four colours corresponding to the four elements: earth, fire, wind, and water.

Leonardo da Vinci was the first to suggest an alternative hierarchy of colour. In his Treatise on Painting, he said that while philosophers viewed white as the "cause, or the receiver" of colours and black as the absence of colour, both were essential to the painter, with white representing light, and black, darkness. He listed his six colours and within this is the age old symbolic system of alchemy.

The Enlightenment project then later stimulated a material examination of our physical state so that eventually theories developed that began to mirror and explain how we next believed that we ‘really’ perceive colour.

Isaac Newton created a colour wheel of perception in response.

Moses Harriss wrote the Natural System of Colours in 1776.

J. W. Goethe developed a colour harmony theory on the basis of his hue circle. In this circle, colours are categorised into two sides, the positive and the negative.

Ewald Hering (1834-1918) devised the first accurate theory of colour vision. And so on and so forth until we truly enter the physiological description of ‘reality’:

“Colour is a response of the eye and brain to data received by the visual systems evolved from the immediate environment. Objects emit light in various mixtures of wavelengths. Our minds perceive those wavelength-mixtures as a phenomenon we call colour, and this perception creates questions that current colour theory tries to explain”.

Vertebrate animals were primitively tetrachromatic. Tetrachromacy is the condition of possessing four independent channels for conveying colour information, or possessing four different types of cone cells in the eye.

With the trichromacy normal in humans, the gamut of colours construed by our perception will not cover all possible colours. Human trichromatic colour vision is a recent evolutionary novelty that first evolved in the common ancestor of the Old World Primates. Placental mammals lost both the short and mid wavelength cones. Human red-green colour blindness occurs because the two copies of the red and green opsin genes remain in close proximity on the X chromosome.

So we humans have a weak link in our chain with regards to colour - we are not 4 cone tetrochromats, we have three and in some cases only two - in extremely rare cases we have one!

We are now within a profoundly material description of our experience, yet this is incomplete, especially in terms of emotion and intelligence as has been brought out in other papers - I want to bring in another idea that relates to this description which is called: the Modular Transfer Function.

We humans value detail and sharpness more than resolution in an image. High resolution is synonymous with preservation of detail and sharpness, but high pixel count - which is generally regarded as being a measure of how good an image is - does not always translate into high resolution.

“As you try to increase the amount of information on the screen, the contrast that you get from a small resolution element to the next smallest resolution element is diminished. The point where we can no longer see contrast difference is called the limit of visual acuity. It’s the law of diminishing returns, and a system’s ability to preserve contrast at various resolutions is described by the modulation transfer function (MTF).“

The point of this technical description is that, as Alice observed on traveling through the looking glass, the smaller you go, the rounder you get. As Ivan Illych noted in his analysis of the creation of systems, there are drawbacks within the actual material construct of the system that you design. And this is especially so with colour: for instance a camera might be at 4k resolution in red – but it might only be 2k resolution in blue.

What I’m trying to come to here, is that I regard the area that each colour space covers as being a footprint of understanding, demonstrative of a world view - and world views, as we know, have many ramifications.


In film alone, compare Technicolour of the '50's with Colour film in the Eastern Block in the 80's and Chinese colour film in the 40’s. Surely a statement about national psyches and all existing within different film colour spaces.... The dominant colouration of these spaces speak about the state of the nations zeitgeist at the time of production.

The recent electronic and data based colour space is a statement about this particular time and the new possible epistemologies of understanding that are developing beyond the simple systems of materialist thought and materialist theory.


Using the metaphor of ‘modular transfer function’, that a chain of information and in this case a chain of understanding, is only as wide and as deep and as strong, to mix my metaphors, as the weakest link in that chain. Then only in the narrow optical region, just that region to which the human eye is sensitive, is the energy of light well attuned to the electronic structure of matter from which colour derives.

But we must not confuse this attunement as a metaphor of complete meaning - there are many meanings to be obtained within the concept of colour space, many emotional spaces, many spiritual and many intellectual spaces – and above all, many experiential spaces.

We see within a matrix of words when considering the subject, but when simply experiencing it, we do so on a different level of comprehension.

1 With the advent of the digital and our necessary remediation of it via older analogue understandings, we are upon the brink of constructing new concepts, to utilise the metaphor of colour, that will enable us to see outside of our current visible spectrum and therefore gain understanding to illuminate our intellectual world with greater intensity and detail. In this ‘seeing’, new language will be generated, new ideas, new uses of light and new concepts of colour and understanding that will begin to match what is now intimated through the development of digital colour space.

To effect this change at a more rapid and experiential pace – to achieve revelation: let us all buy a new pair of sunglasses.