ACEScc vs ACEScct

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(Nick Shaw) #21

There is only a problem if you use ACESproxy output of a camera. Since systems like LiveGrade and Prelight can apply an IDT themselves, you can take the feed from the camera in its native log format, and apply your live grade in ACEScct.

(Willian Aleman) #22

Nick Shaw, thanks for your prompt response and the workaround. Indeed, it’s a very helpful response to my question.

(Jordanacomba) #23

Sorry for being late here…

I am tasked with pulling VFX plates for a RED show and I want to make sure we export in a format that can be sent by the VFX vendors to online in the same format we are delivering them.

I need to select a software, Resolve or RED Cine X, to pull the preferred format of 4K 16bit image sequences. Then I need to select the colour management settings within that software. As I am more familiar with Resolve I have started there.

We are shooting in 6k with DragonColor + REDLogFilm as a base with an applied REDGamma2 and CDL to achieve the dailies look.

After importing the source I select the Resolve colour management settings tab and see the two ACES options of cc and cct. Within the other color management options of Resolve I can select the starting point in our colour workflow - DragonColor and REDLogFilm - which seems to make sense. Then there are the colour science options, ACEScc, cct and DaVinci YRGB.

Colour science question…

If I choose one of the ACES, which of cc or cct will best achieve the desired result?

Settings options questions include:

Linear or Not?

  1. ‘Process Node LUTs’ setting can be toggled between either AP0 Linear or AP1 Timeline Colour Space?

Output Tranform to the HDR Delivery Spec Requirement or leave the image sequences in the timeline export setting of DragonColor and REDLogFilm?

  1. ‘Aces Output Transform’ which has a variety of options for P3 D65 (nit 1000-4000)? Which is our finishing colour space for the HDR 4k delivery.


(Nick Shaw) #25

If you have applied your ASC CDL corrections in REDlogFilm, you have not been using an ACES pipeline. So the CDL values you used will not be applicable. You will need to grade from scratch if you want to finish in ACES.

The choice of ACEScc or ACEScct is a personal preference. Through the majority of the range they are identical, but the shadows respond differently to grading operations. Try both and see which you prefer the “feel” of.

This only makes a difference if you are using LUTs in any nodes. LUTs need to be constructed for the colour space that they will be applied in. Generating LUTs for use in linear spaces requires the person constructing the LUT to have technical understanding of how to construct a LUT for linear input. So if in doubt, you are probably better choosing to apply LUTs in the timeline space.

You certainly do not want to set an Output Transform that matches your source footage, unless you have a very specific non-standard workflow in mind. You should set the Output Transform to match your required deliverable, and use a monitor set to receive a signal in that format.

ACES makes it possible to work with one type of monitor with the corresponding Output Transform, and then change Output Transform to match a different format. However, when you change Output Transform you still need to review the film on the new type of monitor, and make trims to the grade if necessary. For example, you would never want to grade on an SDR monitor, and then switch Output Transforms and deliver “sight unseen” in HDR.

(Jordanacomba) #26

Thanks for the considered response!