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Uncompressed 10-Bit Gamma Shift
The short film I’m producing is currently being color graded at a post-production house.
I need to pull the graded film back into Final Cut Pro for audio mastering e.t.c. They can only provide a 10-bit uncompressed QuickTime as final output, but have advised there will be a slight gamma shift with this export format.
My question is – how much of a shift will occur, and what steps can I take to remedy this on my end? I’m also going to need to convert the uncompressed file into a ProRes format as my machine won’t be able to adequately edit an uncompressed file (I’m not on a high-end setup!) – how much of an issue will this prove?
We are on a shoestring budget and we’ve had compromise the whole way through our production. Appreciate that this is less than ideal, but what do you experts suggest as best way to fix gamma shift?
Best,
Adam -
15 Replies
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3 way CC and look at it on the scopes. maybe it just needs to have the blacks lowered a little.
export that as ProRes.sounds like they may have been grading with after effects?
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[Adam White] “but have advised there will be a slight gamma shift with this export format. “
What are they grading on?
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Hey Jeremy – thanks for response.
They are grading on latest version of Blackmagic DaVinci Resolve.
Adam
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What would they rather give you so there’s no shift?
Unless they are talking RGB to YUV
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The only other option is ProRes 4:2:2 or 4:4:4. But this is a more problematic for them – I should add that this has been done for us as for free after I called in some favours and so we aren’t in a position to ask for more resources and/or time in all honesty.
It’s looking like Uncompressed 10-Bit is the only practical option for us at this stage (and we need this completed ASAP) so that in mind, what should I do to the file on my end with either Final Cut Pro or Color to resolve this gamma shift issue?
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I would say probably nothing. Take a look at the footage and see. I’d have them render out a grey scale/color bars you have sent them through their system, and you’ll be able to see what is going on a bit better. I can’t imagine it will be a huge shift.
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Jeremy – many thanks for your input!
I thought myself that the shift would be negligible but wasn’t too sure. If I can I’ll definitely have them render out a gray scale/color bars – a great suggestion!
Which flavour of Apple ProRes do you suggest I convert the Uncompressed 10-Bit QT to? And are there any color/gamma settings I need to be aware of when converting the file?
Thanks for all your help,
Adam -
ProRes HQ
[Adam White] “And are there any color/gamma settings I need to be aware of when converting the file? “
Use Compressor and turn frame controls on. In the video codec tab, make sure to set the gamma correction to none from automatic.
Jeremy
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Great.
Just a couple last questions about specific settings;
– Enable chroma filtering for 4:4:4 sources?
– Output Color Space: Default for Encoder or Preserve Source?And lastly, I assume all three variables in resizing and retiming controls need to be set to “Best”?
Adam
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[Adam White] “- Enable chroma filtering for 4:4:4 sources? “
No.
[Adam White] “- Output Color Space: Default for Encoder or Preserve Source? “
Preserve Source which should be rec 709.
[Adam White] “And lastly, I assume all three variables in resizing and retiming controls need to be set to “Best”? “
No, they don’t. They can all be left to fast, but turning the frame controls on ensures a 10bit conversion.
Jeremy
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