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Keylight leaving grainy footage, blue screen - black magic camera

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Dan PelcKeylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 4:45:02 am

I shot some footage on a Black Magic pocket cinema camera. When I pull the key in keylight, the matte is really grainy and looks horrible. Here is a screen shot of the original shot and what it looks like with keylight.







Thanks!


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Kalle KannistoRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 7:54:55 am

The original seems to have compression artifacts. What recording format did you use?


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Dan PelcRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 5:26:48 pm

the originial format is CinemaDNG. I exported from Da Vinci Resolve as an mpeg, and its flat because its still just RAW with no color grading.


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Frank FeijenRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 9:29:03 am

Having the 'replace method' set to 'none' in stead of 'soft colour' might help. I usually tend to use another method for spillcorrection rather than the builtintokeylight correction.


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Tero AhlforsRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 11:51:36 am

Choose intermediate result under the view dropdown instead of final result.


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Dave LaRondeRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 3:43:31 pm

Sorry, but you have a lot of things working against you in this shot.

Did you intentionally get the shot so it looks washed-out?

That key wall isn't a very vibrant blue -- i.e. not chroma key blue -- which makes the job of pulling a good key tougher.

Those tracking markers stuck on the background don't have to contrast as much as they do -- they could be a different shade of blue, which would make getting rid of them a lot easier.

I also see the footage is mp4, which isn't helping matters. If that camera of yours can shoot in a better codec, I'd use it.

In short, if there's any chance of a re-shoot, I'd do it. I think you'll be much happier with the result. If you can't, grab a pot of coffee -- you'll be working after-hours to get this shot looking good.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Kalle KannistoRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 4:50:32 pm
Last Edited By Kalle Kannisto on Oct 6, 2015 at 5:29:38 pm

For greenscreen work, use Prores HQ.

You should also test using video gamma instead of film gamma. At least it is worth a try. I used to use film gamma to eventually conclude it will mostly just lengthen the color correction stage considerably without (usually) adding much to the look. In many cases it works just as well the other way, you can desaturate and decrease contrast from footage shot with video gamma to get a filmlike look, but the original footage will be much closer to the final look right out of camera. That's my experience on that matter. (Obviously, this in not true in all cases. Sometimes you will definitely want the film gamma. But perhaps not as often as you might think.)


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Dan PelcRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 5:31:48 pm

It is so washed out because I shot it in CinemaDNG raw and isn't color graded at all. But I exported it from Black Magic Da Vinci Resolve as an MPEG and brought that into after effects.

So I could always reexport from Da Vinci as another video file with a better codec. Is my main problem that it is flat from being shot as a RAW file and would maybe key out better if it was color graded?

Thanks
Dan


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Frank FeijenRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 6:14:39 pm
Last Edited By Frank Feijen on Oct 6, 2015 at 6:15:16 pm

Can't you work with the original DNG's in AE? I was under the impression that this was possible, but haven't tried it.
If not, go for the highest bitrate possible, for instance prores444.

You might be able to improve the key by grading (adjusting the levels and pushing the saturation to 'standard' levels) prior to keying (no need for inbetween renders, just apply these effects on the same layer first).

Shooting flat scenes in Raw seems to have become the standard, but I've always wondered if it doesn't 'downgrade' the images when it comes to visual fx work.
The way I see it: you can have only X-amount of data per frame. Every bit that you throw away when grading is a waste. If you could shoot so that every bit of data is necessary, than you'd have more data available to pull that perfect key...


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Dan PelcRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 6, 2015 at 7:43:54 pm

I've been working in cs5.5 so I just downloaded premiere CC 30 day trial and I was able to directly import .dng directly in. It isn't the flat look, it has a rec709 lut color grade to it. I still get a slightly grainy matte when I key. Is this footage more realistic to get a good key out of?



Thanks
Dan


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Chris WrightRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 7, 2015 at 2:07:32 am

https://forums.creativecow.net/readpost/2/1066654


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Dan PelcRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 7, 2015 at 3:15:29 am

Thank you!!


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Bracer JackRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 7, 2015 at 8:38:05 am

Hey I am the creator of that tutorial!
I am glad I am able to help Dan Pelc :)

And thank you Chris Wright for suggesting it :)


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Kalle KannistoRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 7, 2015 at 2:47:39 pm

"Is this footage more realistic to get a good key out of?"

I don't see why you couldn't get a decent key out of that footage. The blue screen is fairly textured, but you don't have any really tricky stuff like semitransparent areas or tiny details here, so should be able to pull a key from that, as you can be quite radical with the black and white cut-offs, even preblur the footage.


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Elliot FrahsRe: Keylight leaving grainy footage, blue screen - black magic camera
by on Oct 7, 2015 at 10:39:22 am

Try working directly with the Cinema DNG files in AE. If you need to, give it a "video" grade that isn't so washed out and work with that. Your goal is to pull a matte - after that work is done, you can always apply that matte to a differently-graded layer. The extra advantage is fine control over spill suppression in your final graded layer.


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