Per-Channel Display Transform with Wider Rendering Gamut

[ChrisBrejon (Christophe Brejon)]

Hey Derek,

sorry for the late reply. A few answers on top of my head…

@Derek

I’d be curious to know if there are things that OpenDRT does that rgbDT cannot

Probably the chromaticity-linear approach (our “ground truth”) and a proper SDR/HDR match. Without any HDR display, it is hard to say. Jed did some interesting SDR/HDR comparisons in this thread though.

@Derek

these two things which can be changed in OpenDRT with a Look Transform (via a hue shift and zone saturation) are already there in rgbDT out of the box.

Yes, we may be back to square one because of that ? A look embedded in the Display Transform.

@Derek

Is there a “gotcha” I’m missing in here somewhere?

Probably missing a “gotcha” that per-channel is the root of evil ? It does not respect the RGB ratios of the colors used by distorting hue, saturation and luminance. I have tried to describe this behaviour here.

@Derek

What is the disadvantage or limitation of using this per-channel display approach instead of OpenDRT?

I think Daniele answered this question in this thread. And rgbDT, because of its per-channel nature would probably need a new set of primaries to be invented. We did think about AP2, just like in this thread (even if that’s for a totally different purpose) !

I may add that with a flexible architecture allowing for swappable Display Transforms, people could innovate and use rgbDT as an alternative if they wanted to.

Chris