ALEXA muddy look in ACES (ACES vs REC709 in Davinci Resolve)

This might be a very blunt question. As much as i am trying to understand the ACES workflow I am getting confused. Here is my case.

I am a director and I have shot my film in Alexa Mini with a REC 709 viewing monitor. It is a near final look we achieved. When the Alexa footage flows into ACES, the IDT transform results in contrast and saturated look which is muddy. I know the extra contrast and saturation is expected but even with the graded version from my post house I still see the muddy look.

How can i achieve the REC709 ARRI equivalent look in ACES a starting point ? We only need basic corrections as we have already achieved the intended look almost on the set. With ACES i feel, to go back to an equivalent REC709 look as a starting point seems impossible. Is there a transform that we can use inside ACES that can help us to get the REC709 equivalent look ?

Here is a screenshot about the muddy and smoky issue I was talking about

Even if there is no way to bring the REC709 equivalent ; tell me how can i match the ACES image (second image) to mimic the first image with a smooth wall gradient and skin tones as a starting point ?

Please help.

You may want to read this thread.

Note: Please avoid posting the same question in multiple places.

A. LMT made from the K1S1 LUT, such that:
ARRI_IDT + LMT + RRT + Rec.709_ODT == K1S1 LUT

B. LMT designed from scratch to capture the vague feel of K1S1

Do you mean that even though with A, the start point will (within reasonable tolerances) exactly match the look of K1S1, grading in ACEScct through it will not feel the same as grading the original in LogC through a K1S1 LUT?

I acknowledge that this is true. Grading operations will still “feel like ACEScct”, particularly in the way the shadows drop to black as you lower them.

It depends what the aim is. If you simply want to have a base look in ACES which matches an existing look, I would argue that is possible. How useful that start point is as soon as you want to diverge from it is a more complex discussion. Hence my suggestion that approach B may be preferable.

I read the article referenced. If i wanted to choose the option “B” how can i go forward. To design a LMT from scratch to capture the vague feel of K1S, is that something already worked and available for download or this is something a color scientist have to work on ? How tough or easy is that.

Also please remember in my case; i have to only apply the look on node basis for a certain portions of scenes and not the entire project to start with K1S1 look. How flexible and easy is option B considering my situation ?

If you want a tone curve similar to K1S1, start with a custom curve in Resolve with a shape based on the one in the plot from that post.

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