What I'm seeing is NOT what I'm getting

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Stephen Dixon

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What I'm seeing is NOT what I'm getting

PostMon Aug 21, 2017 7:23 am

I'm using Resolve Studio public beta 14.0.0B.051 and I'm having trouble exporting a grade successfully.

The clips in question are shot on a BMCC in raw, with an interview subject against a white background. In the grade I am slightly clipping the whites to remove a little vignetting and to make it pure white.

In my scopes I'm seeing that the background is pure white, but when I export I'm getting colour shifts in some of the videos, with the white becoming cyan.
How it looks in resolve
Image

What the scopes say
Image

What the final result looks like
Image

Is this a colour profile thing? I'm using Rec.709 Gamma 2.4 as my timeline colour space, and the clip has the BMCC Film to Rec709V2 LUT applied. The image at the bottom is taken from a h.264 encode, but I had the same result when I exported using DNxHR and Cineform.
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Andrew Kolakowski

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Re: What I'm seeing is NOT what I'm getting

PostMon Aug 21, 2017 9:12 am

It probably gets clipped on export. Try lowering highlights or gain to move your scopes down so they are below 1023.
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Marc Wielage

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Re: What I'm seeing is NOT what I'm getting

PostTue Aug 22, 2017 1:52 am

I would also put a second of SMPTE color bars and a grayscale ramp at the head of the file, render that out, and see where they wind up on the scopes. If it's right on the scopes, then it should be fine.

There could be issues with interpreting Video/Full Data Levels. I would check that as well.
marc wielage, csi • VP/color & workflow • chroma | hollywood
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Stephen Dixon

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Re: What I'm seeing is NOT what I'm getting

PostTue Aug 22, 2017 1:55 am

@Andrew, I don't understand. If it's getting clipped why aren't the whites staying white?

Also how do I set up the render so it doesn't get clipped. I.E. I'd like to be able to render and have the result actually match what I'm seeing on screen and in the scopes. Otherwise what is the actual point?
Last edited by Stephen Dixon on Tue Aug 22, 2017 2:01 am, edited 1 time in total.
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Stephen Dixon

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Re: What I'm seeing is NOT what I'm getting

PostTue Aug 22, 2017 2:00 am

Thanks Marc, when you say
There could be issues with interpreting Video/Full Data Levels. I would check that as well.
, could you explain how I do that?
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Uli Plank

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Re: What I'm seeing is NOT what I'm getting

PostTue Aug 22, 2017 2:06 am

Your scopes don't show that the background is pure white, they show it's clipped. Different channels can clip at different points and that will be a color.
Tell us more about your system: how are you monitoring? Is it a current Mac or a PC?
How are your settings for export (aka Delivery), "Auto" "Video" or "Full" (under Advanced Settings)?
Try the two you didn't use yet.

You can try this:
Apply a curve to your clip and pull down all channels equally until nothing clips, then post a shot of the scopes.
Resolve Studio and Fusion Studio
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Peter Cave

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Re: What I'm seeing is NOT what I'm getting

PostTue Aug 22, 2017 4:14 am

This issue can be caused by the computer monitor not displaying the full range of the video.
In 8 bit it means that bits 236-255 get clipped, but only on the display, which is why a rendered output of the full signal looks different and can have colour casts among other issues.

I can see the cyan hue in the RGB parade image. I have also seen issues where studio shoots on white backgrounds were comped with travelling masks. The composite looked great on the computer but the final render had all the mask edges visible because the white levels differences were in that 236-255 bit range.

This is one reason why so many colourists who use a full external monitoring setup argue against using computer monitors for grading work!

This article has a good clear explanation of video levels: http://shootdatapost.com/blog/2012/8/1/ ... ended.html
Resolve 15.3 & 16.0
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Uli Plank

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Re: What I'm seeing is NOT what I'm getting

PostTue Aug 22, 2017 5:03 am

Great article you linked to. Yes, it was my idea too that something is going on beyond 'legal' video range.
Resolve Studio and Fusion Studio
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