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Alexa ProRes 4444 + LUT = strange results

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Seth Thy
Alexa ProRes 4444 + LUT = strange results
on May 15, 2016 at 6:36:02 am

Hi,
I'm grading a short shot with Alexa Mini in ProRes4444 2K.
It was edited in FCP 7 and sent to me as QT file. I used Scene Cut to cut it in Resolve.
I'm not used to using LUTs, tried them a few times, didn't like the results.
But this is my first time working with Alexa and I read in some thread here that because of the way that Arri LUTs are created, saturation curve is going to be much better than if you doing it manually in Resolve.
And since I don't have DOP with me I thought it would be great to use LUT and see what they have seen while shooting.
So I tried Alexa Log to REC709 LUT in Resolve and it looks awful!
It's really over saturated and contrast is to strong. Especially indoor/night scenes. Skin tones under tungsten are really really red.
Am I doing something wrong? I thought maybe something is wrong with LUT so I tried Arri LUT generator, but it's a bit confusing and I'm not sure how to chose the right one.
Could be camera settings or something in workflow?
I'm just wondering because I don't think they shot it the way I see it on my screen with LUT.
Thank you
Seth


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Geoff Johnston
Re: Alexa ProRes 4444 + LUT = strange results
on May 15, 2016 at 12:47:05 pm

Bump!

Gonna work with Alexa soon, so would love to see where this thread goes.


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Michael Gissing
Re: Alexa ProRes 4444 + LUT = strange results
on May 15, 2016 at 11:18:16 pm

It sounds like you were sent an new flattened Quicktime file from FCP7 not an xml and original files. If so then the file from FCP7 may have had some basic grade applied (sat boost & contrast or gamma tweak) and so the LUT looks too saturated and contrasty.

A better workflow is to get an xml and the camera originals, not a flattened QT file and cut it back into individual shots.


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Seth Thy
Re: Alexa ProRes 4444 + LUT = strange results
on May 16, 2016 at 7:57:14 am

I'll try to get original files, but I'm pretty sure there are no filters applied in FCP.


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Marc Wielage
Re: Alexa ProRes 4444 + LUT = strange results
on May 16, 2016 at 1:31:20 am

[Seth Thy] "But this is my first time working with Alexa and I read in some thread here that because of the way that Arri LUTs are created, saturation curve is going to be much better than if you doing it manually in Resolve. "
Says who? It works fine.

You could ask the editor to send you a compressed reference file (say, ProRes LT) and then use that as a visual reference. Assuming they're using standard Arri LUTs, you can get very close to the normal saturation and gamma levels just with curves and primaries. It's not that hard to do.

You need to determine how to come up with a decent starting point, and using the Temp controls and Offset controls, you should be able to get a reasonable balance to start off with.


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Seth Thy
Re: Alexa ProRes 4444 + LUT = strange results
on May 16, 2016 at 7:59:19 am

[Marc Wielage] "Temp controls and Offset controls"

Hi Marc,
you meand Temp controls in Raw or...?
Cause I didn't get raw, just ProRes 4444


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Joseph Owens
Re: Alexa ProRes 4444 + LUT = strange results
on May 16, 2016 at 3:15:08 pm

"Color temperature" controls (in reality a "mired shift" slider because there is no whitepoint definition) is a new feature of Resolve 12.5 which can be used to modify the cyan/amber color balance in a clip.

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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Seth Thy
Re: Alexa ProRes 4444 + LUT = strange results
on May 20, 2016 at 9:04:06 am

ok, thanks J.
i'm still on version 12.3, time to upgrade than.
s


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Marc Wielage
Re: Alexa ProRes 4444 + LUT = strange results
on May 21, 2016 at 3:22:57 am

[Joseph Owens] ""Color temperature" controls (in reality a "mired shift" slider because there is no whitepoint definition) is a new feature of Resolve 12.5 which can be used to modify the cyan/amber color balance in a clip."
Very true. It's not the same as the temp control within (say) a Red Raw file or an Alexa Raw file.


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Jens Winkler
Re: Alexa ProRes 4444 + LUT = strange results
on May 17, 2016 at 8:12:40 am

Hi there,
might it be possible that you got your QT with REC709 burned in to it already? Which means you would have applied another REC709 in Resolve and that looks really over saturated and the contrast is to strong...Post a picture-grap of an image with no LUT and one with the LUT please.
Hope that helps...Jay


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Seth Thy
Re: Alexa ProRes 4444 + LUT = strange results
on May 20, 2016 at 9:07:34 am

Hi Jens,
they've edit it on FCP7, so I'm pretty sure they didn't use any LUTs to REC709.
I'm not allowed to post anything online until movie is out, but I'll try to at least post part of an image.
S


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Jens Winkler
Re: Alexa ProRes 4444 + LUT = strange results
on May 25, 2016 at 7:02:38 am

Hi Seth,
did you solve you problem yet? One more thing, just open the QT file and press info. Does it say Apple ProRes 4444?
cheers J


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