Sigmoid OKLab CTL script

sigmoid oklab age.7z (2.4 KB)

A per-channel tonemapper with the option of restore hue and lightness from the OKLab color space.

  • rec2020 gamut limit is a fast agmut clipping/saturation limiter algo, it bring back imaginary colors inside the spectral locus and it gives a smooth path to white.

  • restore oklab hue and restore oklab lightness use OKLab

The default vales for these three options (in the first screenshot) should be touched only for creative effects, I think that generally users should use only the exposure, brightness, contrast and vibrance sliders.

Hower I’m adding a Sigmoid that use Ycbcr instead of oklab.
sigmoid-ycbcr.7z (2.5 KB)


Thanks for the script! Just some quick feedback: the brightness slider acts backwards which is a bit strange. Also, maybe you could consider an option to limit gamut to rec709? I think it might be more generally useful (although it might desaturate too much in some cases… It’s always a trade off)


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