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how to screen out black from a layer but then use in a precomp

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Craig Ricker
how to screen out black from a layer but then use in a precomp
on Feb 11, 2013 at 11:14:59 pm

Its killing me that I cant work this out. It seems like there is something simple I'm missing.

Simply put. I have a video of a flame on a black background.
I create an image of a candle and then use screen on the flame layer to remove the black.

Now I wish to precomp that candle with its flame into a composition that has the cake in it, and then distribute candles around the cake, but some are in 3d space so that they sit behind others.

The candles infront are showing the black around the flame blocking out whats behind them?

If I use screen on the precomp, it makes the candle pictures seeish through as they are dark colours in the candle base.

How can I render out the candle as a stand alone video with transparency. If I look at the transparency of the precomp it still has the black around the candle?

Mac Pro 2 x 2.4Ghz, 16GB RAM, GTX 660


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Dave LaRonde
Re: how to screen out black from a layer but then use in a precomp
on Feb 11, 2013 at 11:43:31 pm

There are a couple of pretty good ways to do this.
You can remove the black around the flame by using the Remove Color Matting Effect. Or try the Extract effect.

There are a boatload of other ways to create the transparency you want, and other folks will doubtlessly contribute their favorite ones.

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


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Chris Buttacoli
Re: how to screen out black from a layer but then use in a precomp
on Feb 12, 2013 at 3:10:43 am

I suppose an easier way would be to comp in just the candles first, without flames. Then place duplicates of the flame animation in your main composition over each candle, scaling down for the ones in the background, and only screen these layers. An added bonus is you can now re-time the flames slightly for each candle so the flicker animates differently.

And the Lord said, "Come forth and receive eternal life." But I came fifth and all I got was a set of steak knives!


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Vishesh Arora
Re: how to screen out black from a layer but then use in a precomp
on Feb 12, 2013 at 3:28:24 am

Craig

This can be done in many ways. One of the Simplest way is to use Knoll Unmult.

Vishesh Arora
3D and Motion Graphics Artist
Films Rajendra

Blog:
http://digieffects.wordpress.com

2011 3D Demo Reel:








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Chris Buttacoli
Re: how to screen out black from a layer but then use in a precomp
on Feb 12, 2013 at 4:50:45 am

The way I'm reading this is it's not a pre-multiplication issue. This isn't just an edge problem at all. It's not having an alpha for the flame footage. And when he brings the candle/flame precomp into his main comp, the screen mode is also making the candle transparent along with the flame. At least that's how I took his problem.

Craig, your time to chime in....

And the Lord said, "Come forth and receive eternal life." But I came fifth and all I got was a set of steak knives!


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Vishesh Arora
Re: how to screen out black from a layer but then use in a precomp
on Feb 12, 2013 at 8:45:48 am

Craig

This tutorial may help :

Four Candles, One Legend: Layering and Keying Footage

Vishesh Arora
3D and Motion Graphics Artist
Films Rajendra

Blog:
http://digieffects.wordpress.com

2011 3D Demo Reel:








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Darby Edelen
Re: how to screen out black from a layer but then use in a precomp
on Feb 16, 2013 at 8:47:46 am

Set your candle and flame layer to 3D inside your pre-comp, then enable collapse transformations on each instance of that pre-comp in your main cake comp.

That should do it.

If you need to adjust material options as well (if there are lights) you'll need to do this inside the pre-comp for the flame and candle layers. The material options don't do anything on a composition with the collapse transformations switch enabled.

If you still need an alpha for some reason you can either use Knoll Unmult or Set Matte set to Luminance + Remove Color Matting to generate one for the flame.

Darby Edelen


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