COLOUR SCIENCE TECH
so that it can be implemented across devices and the things that control them. Ideally, this avoids the inconstancy of control mechanisms like hue, saturation and intensity, which usually don’t specify the colour that results from a particular set of numbers. Sending CIE xy commands to lights is theoretically less equivocal, but crews typically prefer to discuss colour based on a correlated colour temperature (from reddish to blueish) and tint (from green to magenta). Those are familiar from filters and gels, even though the exact origins and definition of CCT and tint are not widely understood. Implementing plus- and minus-green features on colour-mixing LED lights involves some historical research on the nature of filters. The work of translating between CCT- plus-tint user inputs and CIE xy control data will often fall on lighting control devices, and not all (one exception being grandMA3) have implemented it. Meanwhile, camera manufacturers have always seemed keen to keep colour and brightness handling proprietary, and as more cameras start to rely on post- production to handle large parts of the image processing pipeline, a universal solution seems unlikely. Old-school engineers might shake their heads at the lack of standardisation – or, again, the huge range of per-camera, per-light
approaches, each designed around the priorities of a particular manufacturer and its engineering team. THE REALITY For sheer usability, the widespread adoption of a standard is unavoidably more important than that standard being ideal. Standardisation involves mutual acceptance of what something should do, inevitably circumscribed by what it shouldn’t. The early days of cinematography saw a huge variety of film gauges, many of which had to fall by the wayside before the world converged on a manageable number of options. It remains to be seen whether rationalisation will lead us back toward the halcyon days of tungsten-halogen lighting, which matched effortlessly, and without giving up all the conveniences that the modern world has developed. There is some comfort, perhaps, in the knowledge that the human visual system is almost certainly the most sensitive colour-comparison instrument on any film set. If two sunbeams are well matched on a monitor, they will probably look well matched in the viewer’s lounge, too, even though studies remind us that humans can only remember colours for a few scant seconds. That may not have much to do with on-set arguments about the exact shade of a sunset. Nevertheless, so long as all the sources of sunlight in a scene are the same colour, the likelihood of anyone continuing to complain that the sun is microscopically too green falls quickly after less than ten seconds of looking in the other direction. BRIGHTNESS WAS DEFINED BY whatever a cathode tube could achieve ”
mourned. Solutions are difficult, if only because manufacturing processes are variable enough that eyes and cameras can see the difference. To be fair, that was absolutely the case with HMI and fluorescent, but the sheer variability of LED has complicated the situation. Within those limits, initiatives such as the ASC White Point, developed by the lighting committee of the society’s Motion Imaging Technology Council (MITC), have sought to define white light
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DEFINITIONMAGS
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