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buzzing/flickering hair in key?

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Aaron Doenges
buzzing/flickering hair in key?
on Sep 7, 2018 at 9:22:28 pm

I'm having a lot of difficulty keying hair from a recent shoot. It was shot and lit professionally (Prores 4:2:2) and visually doesn't look like I should have any issues. I've tried Ultra Key in Premiere, Keylight in AE, and even tried a trial of Primatte, and no matter what I do, I end up with noisy buzzing around this guy's hair. I've watched and read everything I can find and I didn't encounter anyone with a similar issue - most tutorials were very simple, saying they pretty much click a few different areas of green, find the best one, and adjust clip black/white a little and it's done. I've spent hours sampling different areas of the green screen and adjusting every setting available, and am making very little progress.

One thing to note - this footage was shot with S-Log2. However, I put the correct LUT on top and made a new composition for the key. Would this effect anything somehow?

Any and all advice is greatly appreciated. I've attached a picture of the problem area for reference - although the issue isn't as noticeable until you play the video. The hair just looks staticky, flickery, and unusable.

Thanks!

Keyed:
Source:


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Andrew Somers
Re: buzzing/flickering hair in key?
on Sep 7, 2018 at 10:12:45 pm
Last Edited By Andrew Somers on Sep 7, 2018 at 10:36:38 pm

Hi Aaron, just FYI, Prores 422 is NOT the "professional" way to shoot green or blue screen. Green and blue screen needs to be shot Prores 4444 (or other format that retains full color resolution).

With 422, the COLOR information is HALF the resolution of the luminance information. This is fine for most things, but TERRIBLE for pulling a clean key.

The best choice for AE is the Red Giant Key Suite which includes Primatte. But Ultimatte (only available in Nuke) is a better choice IMO.

To help you with what you have: Don't try and key everything inside the keying plugin. Try multiple layers, one to generate the alpha, one to remove spill, etc. On the alpha layers you can use the LEVELS control on the alpha to adjust gamma (which alters the edge) and also using BLUR to affect the edge. I discuss "Gamma Blur" in this article.

ALSO, you might find working in 32 bit linear light helps.

Andrew Somers
VFX & Title Supervisor
http://www.GeneralTitles.com


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Aaron Doenges
Re: buzzing/flickering hair in key?
on Sep 11, 2018 at 2:37:32 pm

Thanks for the advice and the link! Unfortunately, I can't do anything about the 4:2:2 footage. Seems like everyone is suggesting the best way to handle this is to split the keying into multiple layers.


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Simon Ubsdell
Re: buzzing/flickering hair in key?
on Sep 8, 2018 at 6:22:05 pm
Last Edited By Simon Ubsdell on Sep 8, 2018 at 6:43:25 pm

Deleted.


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Stephen Smith
Re: buzzing/flickering hair in key?
on Sep 10, 2018 at 5:14:42 pm

Try keying just the hair. And doing another key for just the face. If you want to send me a clip I can look at it for you.

Stephen Smith

Utah Video Productions

Check out my Vimeo page


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Aaron Doenges
Re: buzzing/flickering hair in key?
on Sep 11, 2018 at 2:39:55 pm

Thanks for the advice! And you know what, I will take you up on that offer. Here is a short clip of that problem hair if you ever get a chance: https://tinyurl.com/ya93gqzp


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Stephen Smith
Re: buzzing/flickering hair in key?
on Sep 11, 2018 at 5:40:12 pm

Holy smokes, what in the world camera was this shot with?

Stephen Smith

Utah Video Productions

Check out my Vimeo page


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Stephen Smith
Re: buzzing/flickering hair in key?
on Sep 11, 2018 at 6:14:10 pm

A few things.

Prores 4444 VS Prores 422.
I've keyed Prores 422 HQ footage all day long without any trouble. The footage I downloaded said it was Prores 4444. If that is the case, converting 422 to 4444 won't help you at all. It will just make your file a lot bigger. Think of it like pouring a 8oz can of coke into a gallon of milk jug. You still have 8oz of coke at the end of the day. Putting it into a bigger container won't help.

Noise
The thing you are really battling is noise. This is the noisest clip I've ever tried to key....and I've worked with some noising footage in the past. What camera did you use? Speaking of that, was it filmed in ProRes 422 or did you convert it to 422? I prefer to work with the RAW footage or color grade it in Resolve and then key it. That being said, if you really want to solve this problem you will have to reduce the amount of noise it has. I have the Pro version of Resolve and use that. There are a few Noise Reduction plug-ins for AE. Such as Neat video: https://www.neatvideo.com/ or Red Gian DeNoiser: https://www.redgiant.com/products/magic-bullet-denoiser/

Solution
I reduced the noise in DaVince Resolve and then exported out the clip and keyed it. It made a big difference. Here is a sample for you to look at. Please keep in mind it isn't perfect and there is still "buzzing" in his hair but it is minimal. https://vimeo.com/289335221/45202ead67 One thing to help flickering hair is the "Key Cleaner" effect that comes with After Effects.

Best of luck with your project.

Stephen Smith

Utah Video Productions

Check out my Vimeo page


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Aaron Doenges
Re: buzzing/flickering hair in key?
on Sep 11, 2018 at 7:46:52 pm

Wow, that looks so much better than my attempts so far! Thanks a ton for taking a look at it. About the 4:2:2 vs 4:4:4... I rendered this clip out on a PC and with the lack of a Prores export, I just went with an Animation codec to make sure we didn't lose any information in transit. Must have gotten 4:4:4 on the metadata from the export. I don't want to get myself in NDA trouble with camera details but for the time being, 4:2:2 is our best option. Normally, it's great! Apparently not the case this time.

Sounds like tackling the noise needs to be my main focus to get the best key from this footage. I'll definitely look into those options you suggested and if I'm lucky, maybe I'll end up with a new plugin because of it. Thanks again and good luck with your projects as well.


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Stephen Smith
Re: buzzing/flickering hair in key?
on Sep 11, 2018 at 7:57:32 pm

Best of luck. If you need any more help let me know.

Stephen Smith

Utah Video Productions

Check out my Vimeo page


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