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Old 10th August 2018, 20:45   #20  |  Link
videoh
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Join Date: Jul 2014
Posts: 1,667
3D LUTs are used for all kinds of transforms, e.g., full HDR to SDR, which is the context of this thread. If you think the following process is not intensive, then I'll leave you to your own world:

Convert YCbCr to normalized float RGB.
Convert to linear float RGB (undo 2084).
Convert to a perceptually uniform color space.
Tonemap.
Perform gamut mapping using one of many different designs.
Convert back to linear float RGB.
Apply SDR gamma curve.
Convert back to YCbCr for output.

Tonemapping is one small piece of the puzzle.

The point of a LUT is that you can perform this process for each color value and store the results for lookup.

Last edited by videoh; 10th August 2018 at 20:50.
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