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Chromakey issue in Keylight...horrible noise

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Nick Natteau
Chromakey issue in Keylight...horrible noise
on Feb 10, 2012 at 12:56:46 am

I tried to light as evenly and well as possible, but I may very well be doing everything wrong.

I have a Reflecmedia Chromaflex setup and I used 3 Litepanel 1x1s (2 floods, and 1 spot) to light my subject, spot for key and 2 floods for backlights. I made sure the subject was close to the screen as it has to be for Reflecmedia to work correctly. Apparently the rules are the exact opposite of traditional green screen (where you would normally place the subject far from the screen).

So here is my Reflecmedia setup:

photos

And here are two clips I posted:

T5

T6

I'd be very interested if anyone could experiment with these two Apple Pro Res HQ files using AE Keylight and tell me if you get noise as soon as you apply the chromakey, which has been my experience so far. The odd thing is that I don't see any noise in the original unkeyed footage only once the key is applied.

I sure I'm making a lot of mistakes because everyone else seems to be getting clean results with Reflecmedia. I just wish I could solve the problem.


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Dave LaRonde
Re: Chromakey issue in Keylight...horrible noise
on Feb 10, 2012 at 10:27:56 pm

Sorry, can't see the clips. They're not working. As I recall, Reflecmedia green screens are REALLY bright, correct? You see noise in the subject, correct? But you've checked the Keylight Status view so you know you pulled a good key, correct?

Use the noisy Keylight layer as an alpha matte for a duplicate layer with no key. The noise is gone.

It won't deal with any green spill on the subject, however. If that's the case, add keylight to the layer with no effect, and tweak the settings until you see a washed-out grayish background instead of a bright green background .

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Nick Natteau
Re: Chromakey issue in Keylight...horrible noise
on Feb 11, 2012 at 3:02:12 pm

Hi Dave,

Thanks very much. It looks like a number of people had problems viewing those clips I posted in my public dropbox folder. Will sign up with yousendit.com and notify you shortly.

Thanks again very much for your that tip.


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Nick Natteau
Re: Chromakey issue in Keylight...horrible noise
on Feb 11, 2012 at 4:22:53 pm

Hi Dave,

I tried both methods that you suggested and I'm still seeing nearly just as much noise as before and whether or not I delete Keylight from the upper layer, doesn't seem to make any difference even though the lower layer is set to "alpha matte". I'm really stumped.


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Nick Natteau
Re: Chromakey issue in Keylight...horrible noise
on Feb 11, 2012 at 4:25:39 pm

OK, upon closer examination it looks like the noise appears only where the matte is semi-transparent, semi opaque...over the subject's hair and especially close to the edges of her hair.


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Dave LaRonde
Re: Chromakey issue in Keylight...horrible noise
on Feb 11, 2012 at 4:39:52 pm

You sound confused. Here's a step-by-step:
  • Put the footage in the comp and duplicate the layer. Turn off the lower layer.
  • Apply Keylight to the upper layer. Pull the key.
  • Ensure that it's a good key with the Status view: background is all-black, subject is all-white with gray at the edges.
  • Turn back to the Final Result view and RAM Preview to see the noise in the subject.
  • Turn on the lower layer. Highlight it. In this layer's Mode-TrkMat column, use the dropdown to go from None to Alpha Matte (upper layer name)
If you didn't do that, you did it wrong.

Additionally, we haven't established that you are NOT trying to use Keylight intuitively. I'm assuming that you understand how to use the effect from reading the instructions, viewing tutorials, using the training materials from The Foundry and personal experience with the effect. Preferably all four.

I also assume that this is well-lit footage shot using the proper tools for the job: a camera capable of 4-2-2 color resolution (think Panasonic HVX 200 or similar) or at the absolute least a DSLR (which can get iffy).

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Nick Natteau
Re: Chromakey issue in Keylight...horrible noise
on Feb 11, 2012 at 5:44:35 pm

Hi Dave,

I very much appreciate your continued help. Yes, I did read your instructions very carefully and did everything exactly as you outlined. But I'm still getting this terrible noise in the picture. I shot the green screen scene with a Panasonic AF100 but going out to an Atomos Samurai as Pro Res HQ.

I believe I lit the scene well and evenly. I checked everything with the AF100's waveform monitor to ensure a flat thin line at around 50 IRE.

I'm sure it's something I'm still doing wrong somewhere down the line.

And again, I very much appreciate the time you've taken to help me.


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Nick Natteau
Re: Chromakey issue in Keylight...horrible noise
on Feb 18, 2012 at 6:33:13 pm

Hi Dave,

I just posted a reply to you in a wrong thread, I meant to post here in the AE thread.

I uploaded to Vimeo a screencast I made of the terrible noise problem I'm having in Keylight. Could you possibly just take a quick look at my screencast, it's very short. But it will show you exactly what's going, the issue I'm having regarding noise:

Screencast


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Nick Natteau
Re: Chromakey issue in Keylight...horrible noise
on Feb 18, 2012 at 6:34:11 pm

Hi Dave,

I just posted a reply to you in a wrong thread, I meant to post here in the AE thread.

I uploaded to Vimeo a screencast I made of the terrible noise problem I'm having in Keylight. Could you possibly just take a quick look at my screencast, it's very short. But it will show you exactly what's going, the issue I'm having regarding noise:



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Dave LaRonde
Re: Chromakey issue in Keylight...horrible noise
on Feb 18, 2012 at 11:37:02 pm

Yipes! That background is way, WAY too hot! I bet if you look at it on a scope, you'd discover that the background is brighter than the subject. That's the source of your problems.

Reflectmedia is tricky to use, I've been told; I have no personal experience with it. But there must be a way to drop the background luminance, which is what you need to do.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Abby Eagle
Re: Chromakey issue in Keylight...horrible noise
on Aug 28, 2015 at 1:12:50 am

Thanks Dave, by reducing the light on the green screen it has helped lessen the noise in the hair - the noise was like the hair was vibrating... but now i have discovered a new problem. When the talent moves their hands and arms quickly you see green. I am using a black background.

Abby Eagle NLP Hypnotherapy and Meditation - Gold Coast Australia http://www.abbyeagle.com


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David Sotomayor
Re: Chromakey issue in Keylight...horrible noise
on May 2, 2016 at 2:32:59 am

Wow, just wow, your solution helped me out so much, very clever alternative thank you.


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