If I want to go build a transformation from scene linear to P3D65 using nuke’s native colorspace node, would the node alone be enough to do this transformation?
And what would be my colorspace_out , gamma2.6? I’m trying to better understand the transformations using nuke’s native colorspace node
“Scene linear” alone is not a complete description of a colour encoding. Your screenshot shows the input being scene linear with sRGB (Rec.709) primaries and D65 white. So if that is what your input is, then the settings you show are correct.
At least the settings are correct for a commonly used 2.6 gamma P3-D65 display such as a projector. Again P3-D65 alone does not fully describe a display. Apple Display P3 also uses P3 primaries and a D65 white point. But the EOTF is not 2.6 gamma (whether it is 2.2 gamma or the two part sRGB curve is a separate topic!)
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Thanks Nick!
Also, the scene_linear in this case would be ACEScg ( I didn’t realize my screenshot was still in the RGB primaries. Apologies)
Ah! That’s slightly different then. What you had before would be correct to convert display-referred linear sRGB to P3-D65 gamma 2.6 (although possibly even then you might want to add a compensation for a dark viewing environment – some do this and some don’t).
But if your linear is ACEScg it is scene-referred, which requires picture rendering, not just a colorimetric conversion to P3-D65. That cannot be done with the Nuke Colorspace node alone. In fact you could not even do a colorimetric conversion of ACEScg, because the Colorspace node only includes ACES2065-1 (linear AP0) which it simply calls “ACES”. It does not include the AP1 primaries of ACEScg.
Unless you want to build the whole process out of separate Nuke nodes, as @alexfry has done, you need to use an OCIODisplay node with an ACES config (or other suitable display transform) or something like @jedsmith’s implementation of the ACES Output Transforms.