Bt709 into BT2020 convert/correction

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nestim

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Bt709 into BT2020 convert/correction

PostThu Jun 14, 2018 3:20 am

Hi there,

Does anyone know a way to get a clip from the BT709 color space into the BT2020 with color adaption to the new color space in DaVinci Resolve?
I heared it would be possible. I tried the color space correction in the software but this function didn't have the result that I wished for.
I am new to this software and will be thankful for every tip.


thanks alot

Marc


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JPOwens

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Re: Bt709 into BT2020 convert/correction

PostThu Jun 14, 2018 4:39 pm

nestim wrote:didn't have the result that I wished for.


You're asking the genie in the bottle for a different version of your wish?

Whatever the reason for your colorspace choices, you might have better luck with normalizing your cross-colorspace versions in ACES first, then using a computed IDT/ODT transform to manage the values. However, if your source media was gathered in 709, it doesn't really seem like there would be anything gained in the conversion -- another application of "bigger must be better" -- unless you intend on overcorrecting the 709 CIE gamut to synthesize HDR dynamic range. In that case, I hope your bit-depth on the original media is deep.

jPo, CSI
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Andrew Kolakowski

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Re: Bt709 into BT2020 convert/correction

PostThu Jun 14, 2018 5:22 pm

nestim wrote:Hi there,

Does anyone know a way to get a clip from the BT709 color space into the BT2020 with color adaption to the new color space in DaVinci Resolve?
I heared it would be possible. I tried the color space correction in the software but this function didn't have the result that I wished for.
I am new to this software and will be thankful for every tip.


thanks alot

Marc


Sent from my iPhone using Tapatalk


This should work absolutely fine, same way as Rec.709 to P3. It's math.
I done same thing few days ago. Converted Rec.709 to Rec.2020. Then as a test back to Rec.709 and all looked good (the same as source).
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Cary Knoop

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Re: Bt709 into BT2020 convert/correction

PostFri Jun 15, 2018 5:20 am

nestim wrote:Does anyone know a way to get a clip from the BT709 color space into the BT2020 with color adaption to the new color space in DaVinci Resolve?

Use YRGB Color Managed mode (or the Color Space Transform OFX in a Node).
Select 'Use separate Color Space and Gamma'
Set Input Gamut = Rec.709
Set Timeline (and output) Gamut = Rec.2020.

Obviously it should look exactly the same, it's like taking a beer in a small glass and putting it in a larger glass, it will taste the same. The opposite may not work that well, the small glass may be too small to contain all the beer and in that case you would have to map the larger color space onto the smaller one with some color loss.
Last edited by Cary Knoop on Fri Jun 15, 2018 8:01 pm, edited 1 time in total.
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Andrew Kolakowski

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Re: Bt709 into BT2020 convert/correction

PostFri Jun 15, 2018 2:44 pm

If you start with Rec.709 gamut then going to Rec.2020 and back to Rec.709 does look identical to the eye. Mathematically it's not going to be 100% the same, but this is not that important.
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Cary Knoop

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Re: Bt709 into BT2020 convert/correction

PostFri Jun 15, 2018 4:56 pm

Andrew Kolakowski wrote:If you start with Rec.709 gamut then going to Rec.2020 and back to Rec.709 does look identical to the eye.

Yes, but having a source in Rec.709 going to Rec.2020 should look identical as well as there are no colors in Rec.709 that cannot be represented by Rec.2020.

However the other way around going from Rec.2020 to Rec.709 may be different because the color volume of Rec.202 is larger than Rec.709. But it will only be different if the source has Rec.2020 colors that cannot be represented by Rec.709.
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Andrew Kolakowski

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Re: Bt709 into BT2020 convert/correction

PostFri Jun 15, 2018 7:41 pm

Yes, this is the point.
Mathematically even Rec.709 originated sources won't be 100% the same after this double conversion, but it's not that important.
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MIMMO61

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Re: Bt709 into BT2020 convert/correction

PostSun Aug 14, 2022 7:59 am

Good morning guys.
I am resuming this old discussion as I need some advice.
I am not an expert in color grading and would like to ask for advice on how to act on color grading to convert the color space from BT.709 to BT.2020 (HDR).
I come to the question, I shot vacation footage shot with a GoPro 4K @59.94fps (no HDR) once I edited the footage I went to the "Project Settings>Color Management" section.
I only acted on the "Color Space &Transform" section, leaving everything else default.

Image

The result on my oled are very strong unnatural colors, so I kindly ask , if possible some advice or references, on how to act in the section to make a proper transfer.
Sincerely thank you


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shebbe

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Re: Bt709 into BT2020 convert/correction

PostSun Aug 14, 2022 10:15 am

What is your setup exactly? Are you monitoring in HDR on the OLED TV? If you are grading on a 'normal' SDR display with sRGB/Rec.709 gamut you can't grade in HDR. If you see a big rise in saturation it's probably because you graded it in SDR and view the export in HDR.
If you were already working in Color Managed but in SDR and graded it in SDR you can't just switch it to HDR. You should only switch the output to HDR otherwise it messes up your timeline working color space which can affect your grading.
Also make sure the footage's Input Color Space is tagged correctly, for GoPro that would be Rec.709.

That said I want to ask, why do you want to convert the video to HDR if the content itself is SDR? An OLED can display SDR content just fine and it will look more proper that putting it in an HDR container because the display's SDR picture mode is more accurate for it.
Unless you are really grading and monitoring in HDR and the footage quality is good enough to push colors outside Rec.709 where applicable and create higher brightness levels where it makes sense I see no point.
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Jim Simon

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Re: Bt709 into BT2020 convert/correction

PostSun Aug 14, 2022 2:00 pm

I had the same though as Sheb above. If all of your footage is Rec.709, there's really no point in going to Rec.2020 or HDR.

For HDR work, ideally you want to be shooting in a Log format.
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MIMMO61

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Re: Bt709 into BT2020 convert/correction

PostSun Aug 14, 2022 3:22 pm

I thought it could be done with footage, since I noticed on the web that they upscale movies from SDR to HDR.
However I don't want to mess with it more I'm leaving the original REC.709 color space.
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Andrew Kolakowski

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Re: Bt709 into BT2020 convert/correction

PostSun Aug 14, 2022 8:19 pm

Good decision. Without having good source assets going to HDR is about pointless.

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