Primaries on Display

I was thinking about primaries today and had a thought that I suspect is wrong.

If you have a comp that has SRGB primaries and display it on a rec2020 display, shouldn’t you be able to wind up the saturation/scale the primaries via a color transform, and if so, is there any real danger in that?

I see the value in working in a wide gamut color space in the non-destructive sense, but I’m wondering how much “color damage” is really done by going down to sRGB and back up.

Is this another thing like 16vs32 float where there are differences but outside of very specific instances (UV maps) those differences don’t matter on a human scale?

How much you loose realy depends on scene. Most normal colors we see in our life falls in sRGB/rec709 or standart gamut. Something vibrant and saturated (like neon sign) would be out of it but such cases is realy rear. If you think about Star Wars film - most scenes will be inside standard primaries, but light sables, laser shot and explosions will be out of it. But if you watch Star Wars trailer on youtube (trimmed to standart gamut) - you perceive light sables like something bright and vibrant. Of course in theatre it will looks more epic.

Modern (and correct) way of work color wise - use some kind of wide gamut/HDR colorspace for whole pipeline (like ACES), and trim only when needed (rendering a particular master)

I’m still doing mainly Rec709 TVC work, so I could only guess, but following out of curiosity. There might be something here of interest:

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First two links disscuss some rear cases, color fall not only outside of sRGB gamut, but also falls outside working ACES AP1 primaries (they are called ACEScg in Flame). Such errors is fixed now by applying standard Blue Highlights Fix LMT. It`s part of ACES implementation since several years. Last one - discussion about how to avoid such arrors in future ACES version called ACESnext.