Per-Channel Display Transform with Wider Rendering Gamut

Hey Derek,

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

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.

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

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.

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

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Thanks for that clarification Chris. Given those differences it seems OpenDRT with a look is the clear winner. If one wants the look of rgbDT this is easy to get with an LMT in OpenDRT.

@ChrisBrejon let me add that I am reading through this with great interest.
Of course I’m appreciating the technical content and “color nerd” insights. But perhaps more importantly I appreciate the humble and learning approach you take in the paper. I resonate a lot with those feelings you express. That humility (both towards oneself and towards others) makes learning and grown possible (both for oneself and for others), and without it that’s where we get stuck in a fixed mindset. So thank you for modeling that – both in that paper and on these discussion boards.

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Thank you. The humility is because I’m relatively new to Color Management and I know nothing basically.

I have been checking my examples from May 12th (like 5 months ago…) and even if rgbDT seems to be fixing some stuff visually, we still have some gamut clipping on ACEScg primaries sweep and a path-to-white (or path-to-maximal-brightness) converging towards Notorious 6.

I thought for a long time that the OT VWG was about fixing issues. And rgbDT could almost be a candidate for that. But I guess we need to see the bigger picture as explained in this reply. Fixing the issues will only satisfy a minority of users and productions. That’s my take on it.

Chris

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