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View Full Version : New Compositing Methods?

charlJoubert
09-13-2005, 10:10 AM
I've had a thought recently about blue/green screen. http://forums.cgsociety.org/images/icons/icon3.gif This is just an idea, I'd like to know what you think about it.

Would it be possible to take a video of say a scene (Camera locked off) and then another shot with the performer doing what (s)he has to do within that scene and then, using a compositing program, take the two shots and say that where the pixels are the same in both shots it should be transparent.

Given that the colour of your performer isn't the same as the background. Perhaps even a setting or something that tracks where the pixels have major changes and leave the still ones transparent.

http://forums.cgsociety.org/images/icons/icon13.gif or http://forums.cgsociety.org/images/icons/icon14.gif? And why.
Limbus
09-13-2005, 10:20 AM
I think this is called a difference matte.

Florian
charlJoubert
09-13-2005, 10:29 AM
Hmmm... I'll try that out, it rings a bell. But I don't think that would work. But I'll try nonetheless, it might work. I'm off for a while.

Later
sly
09-13-2005, 02:25 PM
Yeah it is called a difference matte and it is rarely as efficient as a chroma key. It can work fairly well if you have good contrast between your subject and your backplate. (say a guy dressed in black over a white background).

Sly
Ian Jones
09-14-2005, 12:46 AM
When combined with a good garbage matte to remove the noise you'll get in the foreground subject and the background, you should be able to pull a reasonable matte. Think of the difference matte as helping you with the edge matte of the keying and then use garbage mattes to remove the inner and outer areas.
charlJoubert
09-15-2005, 09:45 PM
Oh ok I see. I had no idea what this method was called or if it even existed so I figured I'd ask. Thanks for the enlightenment :)
hiphopcr
09-16-2005, 12:36 AM
Yeah, it's a difference matte, and generally used (if used at all) just to start the key. I've never been able to get a full matte out of it but sometimes it can fill in some holes.
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