VFX Element 2

Hi

I have a vfx wall hit footage element against white background. I used Extract key in AE to remove the white background, but because of dust from the wall, I didn't get clean key. How to remove white background in a situation like that?

Thanks

Would have to see the footage, but maybe copy the layer and mess with the brightness/contrast untill you can get one that you can use as a mask/matte for the original layer.

or make a garbage matte... or use the matte choker if you have CS3

put a hue saturation on it, drag the saturation slider to 0%.

then put a levels on it, and adjust until the white it all white and the blacks are very black.

use this as a Luma matte on the original footage.

then you can adjust the levels sliders in realtime to adjust your key.

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	hype wrote:
	put a hue saturation on it, drag the saturation slider to 0%. then put a levels on it, and adjust until the white it all white and the blacks are very black. use this as a Luma matte on the original footage. then you can adjust the levels sliders in realtime to adjust your key.

Very nice, I'll remember this one.

In this scenario it might be helpful to try using a Channel > Remove Color Matting effect set to white to reduce the white spill in the semi-transparent areas.

the technique i described isn't a one-stop key, though... for example, if there's a flash of flame or something, or white smoke or dust, that stuff is going to look horrible, probably transparent. So you might have to garbage roto some of the details back over top if any of those details don't survive the keying process.

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if it's not fun, what's the point?
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My tutorials, if you're into that sort of thing.
http://www.mackdadd.com/html/visualfx.html

A nice clean white background? Sounds like a job for transfer modes to me. Try "multiply" or "darken". You may have to use a "levels" or "curves" adjustment to get the results you're looking for.

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