Dithered Colour Correction for 4k and Beyond

This is how digital colour correction works:

If you change the brightness for any part of the image, all the selected pixels are affected in the same way.

In one of my previous rants, I proposed that resolution was more important than bit-depth… Since then, I’ve been wondering why, in practice, this is never the case. After some thought, I realised that the way digital colour correction works is different from changing the exposure of film.

Changing the exposure of film, on microscopic level, affects the image like this:

The individual grains are not affected uniformly. It’s that a percentage of the grains become exposed (or not), not that every grain becomes more exposed. To the viewer, the result from a distance is that the affected region is brighter. It’s also the reason that grain structures are visible.

Until now, it didn’t make sense for colour correction software to work like this: the resolution of images was too small to make sense. However, for 4k and beyond, non-uniform (or dithered) colour-correction may very well yield superior control over the colour-correction process.

So the question I find myself asking is, why don’t any high-end colour grading systems offer this kind of functionality?

Posted: April 19th, 2008
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