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Footage seems darker after key with Keylight

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Oskar ZiembaFootage seems darker after key with Keylight
by on Aug 30, 2010 at 10:45:07 am

Hello,

i have a Job rescuing a bad Key.

In order to make a better Key i divide the Footage into Layers. Since it is mostly Talking Heads i do a mask for the heads which i can then finetune, then i have another Layer for the Background. These 2 Layers are precomposed. This worked fine in 99%.

My Problem is the following:

Some of the Keys look - in comparison to the old footage - darker after applying Keylight. My settings for Keylight are "intermediate Result" and then i play around with the black & white Clipping, plus preblur 0,1 - 0,3 and soft edges. And i adjust the Despill Colour a little bit. On top of that i put a simple Choker.

First i thought i had not keyed out all of the Blue Screen, hence thats where the darkness comes from, so i clipped it really hard but nothing changes. So i reset my Keylight, just to see if it would change the effect, but nothing happens. I haven't played around with edge or foreground color correction.

Since i have a deadline every hint would be highly appreciated.

Oskar


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Dave LaRondeRe: Footage seems darker after key with Keylight
by on Aug 30, 2010 at 3:44:10 pm

We're missing a lot of information necessary to make an accurate diagnosis:
  • Your computer hardware
  • Your operating system
  • Your version of AE
  • Your graphics card
  • Whether you use Open GL to accelerate renders
  • The codec of the footage you're keying
  • The codec of any other video footage in the comp

Once we know those things, we'll be in a better position to help.

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


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Oskar ZiembaRe: Footage seems darker after key with Keylight
by on Aug 30, 2010 at 5:00:08 pm

Hello Dave,

first of all thanks for replying.

Sorry, i didn't think it would be necessary, since the Problem doesn't exist in all scenes, just in one or two.

Anyway:
- Macbook Pro (early 2008), Mac OS 10.5.8, 2.6 GHz, 4 GB Ram
- After Effects CS 4 - Keylight 1.2
- Nvidia GeForce 8600M GT
- I don't use Open GL.

- AVID DNxHD Codec

As i said before, 99% of my key in the Project are Ok. I precompose Foreground and Background footage for each Cut/scene, so i can add as much layers for the foreground footage as i need to have a decent key. The problem appears only in one or two scenes of 60 minutes footage. It appears to be darker in the destination composition and in the precomposed composition.

So, i hope i improved my description.

Cheers Oskar


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Chris ButtacoliRe: Footage seems darker after key with Keylight
by on Aug 30, 2010 at 5:18:19 pm

Can you determine if this is just an optical illusion, by comparing the RGB values of specific areas with the keylight effect enabled and disabled?

If the values do differ, is it due to the spill suppression perhaps?


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Oskar ZiembaRe: Footage seems darker after key with Keylight
by on Aug 30, 2010 at 6:20:35 pm

Hello Chris,

thanks for your reply, right now i am on the move, so i can't check the RGB Values, right now. But i suspected the same, thats why i played around with the despill bias. But it didn't change anything. All the other supressors are off. I use the intermediate Setting because i didn't want pixelation.
I didn't play around with Replace Color.

My effects are:
- Keylight
- Simple Matte choker

Of course i turned the matte Choker off, but the problem remains.
The weird Thing is that once i copied the effect and once i created the effect from scratch... but the result remained the same.

I know there are workarounds like adjusting the Brightness, but i would like to find out what the real problem is.

Cheers Oskar


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Philippe LessardRe: Footage seems darker after key with Keylight
by on Aug 30, 2010 at 8:08:25 pm

When I use Keylight and i make a mask before I applied klight, klight just dont work!!!I have to apply klight then the mask...maybe on your side it make some other weird thing.And for the replace color, just use "source".

What i like to do to color correct my keyed footage, is to track matte the original footage with the precomposed keylight setup, this way you have no problem with color.

Hope this help


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Oskar ZiembaRe: Footage seems darker after key with Keylight
by on Aug 31, 2010 at 4:00:24 pm

Hello Philippe,

i do it more or less the way you do. i experienced the same problems with masks. Thanx for your reply

@ chris: I checked the RGB Values and they are slightly off. give or take 5-10 from the original footage... so i think it has something to do with the spill suppression. as you said. but i left these untouched...

anyway, since it is only a few scenes i will just correct these.

Thanks for everything.
Oskar


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