Arri LOG C Linear work flow in After Effects. HELP!

[kudtfitufough]

I am struggling to get this linear workflow working correctly and I am seeing a brightness increase when rendering out. There are so many LUT options I dont know best way to interperate the footage!

What i need to do is import Alexa LOG C work with it in linear do my compositing then render back out to Log C. When I try this with any of the Arri LUTS available I see a shift in brightness

So the question is what Colourspace should I be selecting in "Project settings" and what LUT should I use on the Alexa footage when "interpreting" it?

Thanks for any your help in advance! My head hurts!

[tillp35050168]

I am curious for an answer as well!

[Astonishing_Songbird98A4]

OK, here we go:

Do NOT use After Effects 2020 as it is completely useless when dealing with EXR files or anything to do with Arri LOG C files.  The last comp I made started to flicker madly and I thought it was me drinking too many cappucinos until i opened the comp in a new AE version (currently using 2022) and it was fine!!

1. Launch AE and set your project (Project Settings) to:
Depth: 32bit per channel, Working Space: Rec709 (any flavor you like) or even sRGB IE61966-2.1 is OK too because this is just Non-Destructive Color Mangement.

Check - Linearize Workspace
Check - Compensate for Scene Referred Profiles
2. Import your Arri LOG C Footage.  (There it is in all it's washed out grayness)

3. Ctrl-Opt-G (Interpret Footage) - Color Management Tab:  Assign Profile: ARRI LOG C Wide Color Gamut 400 (choose any of the 160-1600 EI [exposure values] and see which looks best on screen)

4. Drag the footage into a new comp and it should look almost normal with brighter colors and higher contrast.

5. Resist the urge to throw a levels, LUTs or curves on it.  That will mess up your final renders back out to LOG C.

6. Drag the comp into the render queue and go to Output Mudule Settings > Color Management Tab.  Make this exactly the same setting you used for interpreting the footage > ARRI LOG C Wide Color Gamut 400

7. Render it out, then bring it back in to make sure it's the same dull washed out gray footage you started with. It should be identical.

Be careful with LUTs. If you use them you'll have to turn them back off before render time or they'll be "baked in" to your renders which your Colorist will not be happy with.

[tillp35050168]

Hi! Great! Thanks! Thats works for me in AE 2022.

How do you deal with LUTs (generated on set by the DP) in linear working  space ... AE seems to correctly apply LUTs only in gamma encoded working spaces . Nuke does it correctly in linear working space. (apply log to lin effect before the LUT doesnt do the trick). 

[adamg19221863]

A very solid explanantion, thanks. I tried this in AE 2022.5 but it didn't work for me at first. One factor you didn't mention is, should Interpret Footage and Output Module use "Interpret as Linear Light" on or off? 

I had to try all the combinations before I figured out: Turn "Interpret as Linear/Convert to Linear" OFF on input and output.

Maybe this is implied by "LOG", lol, but color mgmt is utterly baffling to me. I appreciate your simple pipeline that solves this use case. 

[Roei Tzoref]

I would do one of these workflow depending on the task at hand
https://www.youtube.com/watch?v=lns6AuJzBnIhttps://www.youtube.com/watch?v=dHY5rMnBUz8&lc

[tillp35050168]

THANKS!