sRGB vs Rec 709 in Nuke

[Martincito]

I’m a little confused about the differences between sRGB and rec709.
The monitor in my workstation is set as sRGB, I’m working in an HD project. As far as I know the color space standard for HD is Rec709.

What’s the correct color space workflow for HD projects in Nuke?

If you are reading HD files coming from a telecine session.
How do you set your Read node in Nuke?
sRGB or Rec709?

I have to export my renders and import them later on Flame to output them to an HD tape.

How should I set the color space in my Write Node, as sRGb or Rec709?

What about the Viewer, sRGb or Rec709?

Thanks

[Richard]

Digitized HD material should be Rec709, that being said, it´s quite possible to digitize in sRGB as well, so it´s not a sure thing. Since Rec709 is a slightly wider gamut, you should see a sligt increase in detail in most footage when you switch the reader node to rec709 form sRGB, you don’t perceive any change (even when you gamma up) then the material was mostly likely capture as sRGB.

[Eli Lapointe]

i also am interested in more infos on this topic…

thanks!

sly

[filip]

I’ll try to answer my own question.

If you use a sRGB in your read node and in your write node the result is the same that using rec709 in both nodes.
The curve that Nuke applies to the read node is exactly the negative of the one use in the write node. So the result is always the same.
The differences start to getting important when you are mixing CG elements rendered in linear exr with your sRGB or rec709 shots.
Based in the tests that I was doing I realized that if you keep the color space rec709 the result gets too contrasty.
If I create color bars in Nuke and write them with the write node set to 709 and then I import them on the Flame the Nuke bars are darker than the Flame ones. To match the color space I have to render the bars in Nuke using sRGB.
So basically I use Nuke in sRGB (when working in video) because I always end up laying down to tape from Flame and the color bars that matches are the sRGB ones.

[Author]

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