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Keying with Keylight / Primatte

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Klemens HerthaKeying with Keylight / Primatte
by on Jun 4, 2014 at 5:13:49 pm


Everytime, we get a keying-job to do, we run into more or less the same kind of problems, most of the time with motionblur and / or hair. We've already tried multiple different cameras and different techniques but in the end it's always just annoying and unsatisfying that it takes hours to key a single simple shot and still the result is not as expected. This time we tried out the Blackmagic Production Cam and we were shooting in 4K ProRes. Again some problems and now I thought I'm gonna upload an example and hope that some of you could give me some helpul tips. We use Keylight or Primatte in AE...

First a frame of the untreated greenscreen-shot of an upcoming toothbrush-TV-commercial:

Then my best result so far using Keylight, a restrained SpillKiller and a little Color Correction using Color Finesse:

Especially in motion it looks really good. The motionblur is well preserved, no greenspill, all fine except one thing: The toothbrush is orange instead of yellow! And this is not from the SpillKiller, it's from Keylight. Of course I know that there's green contained within yellow, but it still should work, right? Especially with such a strong yellow?

So with Keylight the only way to preserve the yellow for me was to turn the Screen Balance all the way down to 0. The result is this:

Heavy spill that I don't get rid of except using SpillKiller which again turns the toothbrush orange. And even if I would use the SpillKiller somehow, this dirty gray border around the arm remains.

Last try was with Primatte:

The toothbrush looks almost as it should look like but as you can see I had to cut away far too much of the edges, nevertheless there remains green spill and also the whole motionblur is gone and the result just looks awful!

There must be a way without masking the whole scene manually?! Any help is greatly appreciated!


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Dave LaRondeRe: Keying with Keylight / Primatte
by on Jun 4, 2014 at 5:42:50 pm

I'd use Keylight, referring to the Status window to make sure that I KNOW the key is right. Then I would use this as an alpha matte for the same footage, adding spill supression to this layer as necessary.

You may also want to redeuce the amount of light falling on the green screen. Keylight performs best using a background that's darker than the one I see.

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

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Michael SzalapskiRe: Keying with Keylight / Primatte
by on Jun 4, 2014 at 5:45:20 pm

Have you tried using the intermediate result on Keylight? That will eliminate Keylight's spill suppression.

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Todd KoprivaRe: Keying with Keylight / Primatte
by on Jun 4, 2014 at 9:22:03 pm

When we release the new version of After Effects (soon!), have a look at the Key Cleaner and Advanced Spill Suppressor effects. These effects recover a lot of detail that is lost by keying effects, as well as not damaging the colors of the image as the built-in spill suppression in Keylight (and other keying effects) can do.

Todd Kopriva, Adobe Systems Incorporated
After Effects quality engineering
After Effects team blog

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Klemens HerthaRe: Keying with Keylight / Primatte
by on Jun 5, 2014 at 10:25:56 am

Thanks for your answers!

@Dave: Which status window you refer to? Anyway, I've also already tried using an alpha matte, but the spill supression needed would again turn the toothbrush orange.
Regarding the amount of light: Really? Darker? Cause in my experience it's often more difficult, the darker the green is, because you also have more noise in the footage which makes keying especially of hair far more difficult and also the results often look worse. At least in my opinion. Am I wrong?
But it would be an important information as we soon have our next greenscreen shooting. Also which cameras do you guys prefer for greenscreen shootings?

@Michael: Yes, I've tried that too. The problem is that the toothbrush indeed stays yellow but it is not opaque. To make it opaque I have again to turn screen balance or Clip White down which again leaves me with that ugly border around the arm.

@Todd: Good News! Althoug we've also bought the Keying Suite which comes with Primatte Keyer which has similar effects included but maybe the new ones included with AE perform better!? I hope so and I'm looking forward to it!

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Matthew WoodsRe: Keying with Keylight / Primatte
by on Jun 5, 2014 at 11:37:25 am

Have you tried Premiere's chroma key? It has fewer options for tuning, but I have been really impressed with it and find it often gives better results than Keylight. I'd love to see it added to AE as an alternative to keylight.


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Darby EdelenRe: Keying with Keylight / Primatte
by on Jun 5, 2014 at 4:56:44 pm

I think you'll need a separate key for the toothbrush to keep it opaque.

As for keeping the yellow from turning orange you should use a red limited despill. There's almost no blue in the yellow of the toothbrush so a red/blue averaged limit will reduce the green in the toothbrush dramatically and turn it orange.

Darby Edelen

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Dave LaRondeRe: Keying with Keylight / Primatte
by on Jun 5, 2014 at 5:33:52 pm

If none of the other keying suggestions work, you may want to try rotobrush on a precomp of the shot, around which a garbage matte of just the toothbrush has been animated.

The reason I suggest darker lighting on the chroma key background comes from personal experience. I find that Keylight in particular responds better to a green backgraound that's at about 65 IRE.

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

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