Colour Managment Headache

I thought i was getting better at this colour management stuff but it would seem there’s aways someone bigger and tougher around the corner. I have to deliver viewing QT’s with the following spec. I’m starting with Aces 2065 EXR’s. I’m sitting looking at this and the soloution is not jumping out at me. Any advice on how to deal with this would be greatly appreciatted.
Many thanks as always

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Seems like they are giving you the color pipeline for Alexa sources. Delivery seems to be Rec709 (ACES version 1.0.1)
It also seems like they are describing it with Nuke nodes. Including the gamut compress blink script. Not sure if Flame has a way for doing an ACES Gamut Compress. It was introduced natively in ACES 1.3, I think Flame is using an older version… I could be wrong.
If this is still not available in Flame, maybe the shader here can be turn into a matchbox… if is not already:

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Hi M
Thank you. Yes these instructions are indeed for Nuke. Im going to to bat it back and see if i can get something a bit more Flame freindly.
Thank you for your help.

Ok so you have to be VERY aware as to what nuke does here in order to be able to minic their colorpipeline!!

Read node colorspace setting is not the same as tagging in flame for example, puke converts all inputs to working space first of all which is acesCG.

Way to do this above in flame →

Load in ACES 2056-1 into flame, tag it as such OR convert it to acesCG on import (whatever you want).

step 1:
→ convert source to acesCG if not done allready

(here then goes your compositing work)

→ apply gamutCompress matchbox (not sure if this is the final compress and if they want the 1.3 reference compress OR the parametric one, they will have to specify as its very very new )

→ Convert source to acesCCt

→ Apply LUT or CDL

step3.5 (optional) after the last thing your clip is acesCCT now, so you either want to go back to acesCG and tag accordingly OR leave it as CCT and tag it as such so it exports correctly for step4

Step 4
→ Export As Rec709 using flames export prefs .
→ alternatively convert to rec709 on timeline depening on what you are doing.

Make sure every operation is happening in 32bit float to match nuke.

You can set this up as a preset, viewing rule or whatever you want in one colorspace transform, Idk how many shots this is and I have no idea how to deal with shotgrades from set in flame tbh, I usually try to just throw those away and never look at them and only go through the painfull process when making dailies :frowning:


This group never cease to amaze me.

Thank you and i will go throgh this workflow tomorrow.

Much appreciate both your time to help me with this.

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this is a very common workflow for colormanaging stuff like netflix shows, so i am very versed in this, hmu if you run into issues. although ive always done this stuff in nukestudio/ in our pipeline .

There could be minimal things like the ganut compression beign different as thats really a aces 1.3 thing and not yet implemented even in nuke 13… the gamut compress blink script is kinda beta ish? idk the state of it.

Hence working before you do all the compression for dailies, just make sure you aint clipping negative values in your batch before the gamut compress.

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One good practice to adopt is to find out your delivery specs at the beginning (viewing and final) and build a null pipeline before you start work. Especially if you have to deliver back in the original color space and you might have assets you comp in. That way, if you have a hiccup in your setup, you don’t find out later, and after you created some intermediate plates, etc.

Common example I just had: Receive LogC footage, do all kind of work, give LogC footage back. Some shots have combination of Rec709 and LogC screen replacements. I run through the null pipeline with my first clip, then load it into Resolve, layer it on top of the original file, set the blend mode to difference, and if I see anything other than black, go trouble shoot.


Thanks for the heads up. Luckily we always do a loop test so we nail this before any work commences to avoid any later delights.
I can normally just about figure these things and actually enjoy working these puzzles out.
This one really got me though so thanks again everyone. Its the start of my day so i"m off to go and implement eveything I’ve learnt. I shall let you know.

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Hopefully the gamut compress blink step in there means the final ACES 1.3 version from aces-vwg-gamut-mapping-2020/reference at master · ampas/aces-vwg-gamut-mapping-2020 · GitHub and not one of the earlier development versions… if so you should be fine because there’s a matchbox version in that same folder, and it also ships with Flame since 2022.2 here: /opt/Autodesk/presets/2023/matchbox/shaders/


Ive never had to deal with gamut compression but was curious at this conversation. here is a link i found that could be useful to anyone wanting to learn more. Reference Gamut Compression User Guide - ACES Technical Documentation
I wonder why this doesnt come up as much for us who work on commercials versus a netflix/dailies viewing outputs. Essentially its to roll off those super bright highlights light sources?

So there is a lot to it, basically out of gamut values can wrack havoc on how things look, camera manufacturer have usually built that into their display luts.

Think about it, you have a blue neon sign, the camera captures values not only out of gamut (gamut is a volume!) but also out of the visual gamut of the human visual system, now you need to display those values somehow on a sdr display or whatever, you can now go and clip those values, or compress them down to “look right” , imho aces inplementation was wrong here thus you get those crazy issues.

thats very basically what it is, a “tonemapper” for colors if that makes sense

Baselight has always had the most technically sane colormanagement, there are lots of things to talk about when talking about gamut compression, its not simple.

I think not soo many people have been running aces for commercials, so the issue is usually not existent, we have had this issue on many commercials though going back a few years.

Stuff with neon lights is always fun, now add CG made neon lights to the mix, you can also get 3D renders out of gamut of course.


Ive been using Aces for commercials for a few years now, most places are aces workflow as its consistent. I guess when we do a viewable acescg to Rec709 LUT as we always do for a viewable or daily it does the gamma compression on the fly? i just never thought it was a step we needed to worry about but perhaps its all happening when we convert it to get to a smaller container for a quicktime export lets say. A few years ago i worked on something that had very very bright small plumes of flames - i was grading the shots in acescc but it didnt give me a good impression of what they were going to look like in rec. ie super blown out ( in a smaller container) so yes i created a viewing LUT to help but i think this is what we needed to approximate this way of working in acescg but compressing the gamma so we can easily see what would be a truer sense of output. thanks for the explanation finn! i love how theres so much more to continuously learn!

I’ve cracked this now thanks to this forum. I cant help thinking its quite a complexed process just to deliver a rec709 viewing copy for Avid but thats just me.

Now i just need to re lay what i’ve learnt to Digital Fusion and After FX.

Thanks again everyone.

good luck with AE I adopted a way different workflow with AE that is sending log (acescc) plstes to AE with a simple acesCC-> rec709 LUT… as AEs colormanagemebt is not up to snuff yet

what is digital fusion? Blackmagic fusion? Fusion should be fine as it can do ocio.

The problem only pops up for certain shots, only if there is stuff out of gamut, which doesnt happen in every shot so 90% of time its just fine wirhout the compression.

Aces 1.3 has ir built in i hope adsk will adobt that soon.

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Hi Fin,
This is a good idea on the After Fx front thanks. I’m showing my age, i still call it Digital Fusion but your right Blackmagic Fusion is what i mean. I was using it about 23 years ago i think.