Correct Redgamma to Lin conversion?

[SimonBjork]

I often end up using DPX sequences with REDs own gamma luts (Redgamma, Redgamma2). When using them in VFX applications, how do I correctly convert them to linear light? In Nuke for example, I set my color space in the read node to srgb, which means that Nuke assumes that the source is srgb when it converts it to linear. This must be an incorrect conversion, right? Also, I do the same in After Effects. So how are you guys using these type of files in vfx?

 

[Graeme Nattress]

For VFX export either REDLogFilm which inverts out with Nuke's Log2Lin node, or export an EXR. If you send the REDLogFilm to grading, you can send your VFX output via the Lin2Log in Nuke and it will match back up.

Graeme

 

[SimonBjork]

Absolutely, I always use that if I can choose. But often I get files delivered that are gamma encoded with Redgamma for example. How do I deal with those? sRGB? Rec709?

 

[Graeme Nattress]

Those would be approximate only. That's why we went with the REDLogFilm and EXR export so that VFX people can get proper linear light and matching to grading.

Graeme

 

[SimonBjork]

Any plans of releasing the actual curves? I mean, in Nuke there's already both Redlog and Redspace, and on Prolost Stu Mashowitz gave an example of a Redlog to Lin conversion in AE. Whish of sRGB and REC709 would be best to use?

 

[Alexander Somma]

Hi and Merry Christmas all!

I hope you can help me as well.

So in REDCINE-X I did the following:

1. set the color space to REDcolor and the gamma space to REDgamma
2. used the colorpicker to set the white balance
3. set all other settings to default
4. exported an OpenEXR sequense

In NUKE I loaded the EXR sequense and left the read node at the default setting (linear).

This is correct right?

Now if I want to do some vfx in After Effects, how do I match it up with whats coming out of nuke?


Alex

 

[Gunleik Groven]

You should set it at RedlogFilm, and possibly Redcolor2.

I'd have prefered to grade from redcolor2 anyhow...

 

[SimonBjork]

Alexander:

If you export EXR it doesn't matter what gamma lut you set in Redcine, it will export as linear, since EXRs are linear by nature. You're setting it up correctly in Nuke, and to do the same in After Effects, just set the Project Space to something like sRGB 32bpc and Linearize the project. I really like the EXR output and prefere it over RLF.

 

[Alexander Somma]

Hi,

I've been using redcine to make RedLogFilm dpx's for nuke. This works great as they match nuke's reading of the r3d files - i.e. they look the same.

However, I now need to use Storm to take out dpx files, but the Storm dpx files when using RedLogFilm are totally different than the dpx's made with redcine.

In short:
Redcine RedLogFilm dpx exports looks the same as r3d's read in Nuke.
Storm RedLogFilm dpx exports looks different than r3d's read in Nuke.

I'm assuming Nuke is correctly interpreting the r3d files?
How can I get dpx's out of storm that matches the r3d's in Nuke

Please help me understand this!

Alex