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Digital Breakdown in Blacks when doing a key.

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Hugh Noonan
Digital Breakdown in Blacks when doing a key.
on Nov 21, 2017 at 1:20:32 pm

Hello all

I am using greenscreen for the first time and think I have run into a problem.

I am trying to key my subject who is man in a black suit in front of a greenscreen. When I go through both PP + AE CC 2018 and key out my green, what I get is my subject keyed out but with a lot of digital noise/ breakdown in the blacks of his suit.

I have tried de-noising with NEAT software, keylight + key cleaner + advanced spill surpressor but am having no solution to it yet.

Green screen was shot on Canon 60D at 1080p @ 25 fps.
Trying to export to h.264 as end product.

Working on a HP Zbook 15 G3 with 32gb RAM and Intel XEON E3 processor at 2.80GHz.

Is this a situation of not good enough hardware with too much compression in a h.264 file for greenscreen?

Thanks for any info you can offer.

H


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Dave LaRonde
Re: Digital Breakdown in Blacks when doing a key.
on Nov 21, 2017 at 6:38:17 pm

Keying DSLR video is never, EVER a treat, but you should be able to get something. It won't be award-winning, but it'll be something.
  • Use the Intermediate Result in keylight rather than the Finished Result. It's a dropdown in the effect.
  • Add the un-keyed video to the comp, and use the keyed video as an Alpha Matte
.
Either ought to do the trick, and you can use other spill suppressors if you have a lot of spill. We don't know what you're up against -- no screen grab.

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


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Hugh Noonan
Re: Digital Breakdown in Blacks when doing a key.
on Nov 22, 2017 at 11:17:44 am

Hi Dave

Thanks for adding to this thread.

This link should show you want I was up againest : 11882_denoisetest1.mp4.zip

The above link is the first export of the video and is stored here on CreativeCow. Hopefully it should provide you with an idea of what I was talking about.

Still curios to know your thoughts on it.

UPDATE:
I think I discovered that I didn't light my background/ subject properly. As his black suit was picking up flecks of green that were being keyed out. Hence some pixels were becoming transparent and "jumpy" when played in final render.

I used a series of techniques from Video co-pilot and manged to lower the intensity of the key, got some more detail back in the suit. The background is now a gray and still has some "digital jumpyness" in it but it is not that huge a problem.

Is there something else that I am missing?

Thanks

H


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Doyle Lewis
Re: Digital Breakdown in Blacks when doing a key.
on Nov 22, 2017 at 2:49:58 pm

So yes, It definitely was in the way it was shot. Not only was the lighting probably not right, looking at it, it looked like you probably had him standing too close to the green screen. The closer someone stands to a green screen the more green spill that is cast on them. To that point the further you can put them from the green screen the better, this means you actually usually need 2 light set ups. When I set a green, I use 2 to 4 lights (and softboxes) to create a even wash across the screen. Then put my subject no less then 7 to 10 feet from the green screen. I use one hard light behind the screen to shoot the back of his head as a rim light and usually a single softbox as a key. If able I also use different temps for my subject and screen lights. My wash lights I generally do daylight balance to sort of push the screen to cooler colors and I use tungsten balanced for my subjects light so that the reds in his skin separate better from the now cool bluish green screen. Just gives a bit more distinction for your key to use.

My last piece of advice is probably the easiest but makes THE MOST DIFFERENCE and is probably the #1 mistake new shooters make in this sort of talk to camera video. If your plan is to have someone talk with the infinite white background... then shoot it on a white background. Shooting a white background is just as simple as shooting a green and then you don't have to do any keying at all. What you capture on camera is what you get.

Here is a white backdrop for $12. Just drape it over whatever you have your green screen draped over. I promise you no green screen infinite white shot by anyone has ever looked as good as white screen infinite white.

https://www.amazon.com/Neewer-Collapsible-Background-Photography-Television...

Doyle Lewis,
Location Assistant
ABC Studios




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Dave LaRonde
Re: Digital Breakdown in Blacks when doing a key.
on Nov 22, 2017 at 10:09:51 pm

[Hugh Noonan] "Still curios to know your thoughts on it....
Is there something else that I am missing?"


Just follow Doyle's lighting advice and white screen tip and you'll be okay. And try to use a better camera than a DSLR when shooting green screens. They pretty much stink at the job.

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


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