Colour film was a slow revolution. It was commercially available in the 1930s, but not predominant until the 1960s. The highly-saturated Technicolor look from this era is now iconic, and the choices made over film stock and lighting largely determined the colour reproduction of the finished film.

(I’m not forgetting the importance of Art Direction here. This is the major factor in any film’s colour palette. In fact, in recognition of the challenges that colour represented, separate Best Art Direction Academy Awards were given for black and white and colour films between 1940-1966.)

But these days we shoot digitally and grade digitally. Consequently nearly all decisions about colour made during production can be changed in post-production. Digital grading makes it possible to retrospectively alter everything.

We have greater control over colour than ever before and this has been as much of a revolution as surround sound, 3D, HD and photo-real computer-generated effects. But it is very much overlooked and this is not without certain qualifications.

The colour grade of a film is critical in selling it. The grade is obvious from the first frame of the trailer and at the first glimpse of the poster. It imparts a sense of the style, production values and tone quicker than any other aspect of the marketing arsenal. I love it when a film has a complex interesting grade – although it must be said that the most stylised grades are often the most banal films.

But everything digital has its drawbacks. The resolution of compressed video images is relatively poor compared to film. Not just in terms of how sharp the image is, but also in terms of its “colour space” which essentially means how well the colour spectrum is represented in the digital image.

In nature, colour is a continuous spectrum, but representing it digitally means the spectrum is broken up. The richness we expect of the smooth colour gradients we see in skies and sunsets is lost. We know this implicitly – photos of beautiful sunsets never match the real thing. The image below is an exaggerated representation of these kind of discontinuites.

The problems inherent in digitisation have more subtle and compounding effects on the recorded image too. For example, many digital cameras tend to favour capturing the detail in greens and blues (rather than reds) because our eyes are also more attuned to those colour ranges. Consequently garish bold colours, which are relatively less common in nature, are afforded less of the “colour space” and consequently appear more jagged and pixellated in digital images.

Finally, many digital displays can’t accurately depict certain colours. The optical illusion below called “The Eclipse of Mars” shows you the colour cyan – never seen before on a PC screen! (Click for larger version.)

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This post was inspired by a recent post on Pete Emslie’s blog which made me think about how we think about colour in movies.

For further reading, check out Graeme Nattress’ excellent and comprehensive analysis of colour in digital video.