Difference matting

[skier-hughes]

Hi,
I'm not sure I have the right name here either, it could be mapping :)

I believe it's similar to green screening, where you have two videos with the same fixed background (of anything - like a kitchen) but independant moving foreground.

Can edius do this?

If not, any recommendations of what can?

Preferablly Mac based, but windows will do.

Ta
Graham

[GrassValley_BH]

EDIUS does true chroma or luma key, you could use the Difference Blend keyer to negate the background, then key over for a similar (though not quite as good) effect.

Serious Magic's (now part of Adobe) Ultra does difference keying, IIRC. Also, I think Ultra is available in larger Creative Suites - I know it's part of the CS3 Master Collection.
Windows-only though.

Depends on whether this is a one-shot deal or something you'll be doing often.

[skier-hughes]

I'm not doing it, it's something my son has to do at Uni.
The background needs to stay the same, whereas it's the foreground that needs to change.
I think they have access to Adobe products, so I'll mention Ultra magic and see if he can look at it.

[GrassValley_BH]

Since your son is in school, check with the campus - Adobe's pretty good about academic discounts. You want Ultra CS3.

Just to make sure we're talking about the same thing here...

Unless you invert the key, anything that doesn't change would be "knocked out" - so for example if my "static background" is my chair, then I go sit in my chair (assuming chair doesn't move), then it'd look like I'm sitting on nothing (the background would be a "hole").

If you were to invert the key, then my chair would be there, and there would be a "hole" where I was sitting.

[Aristotelis]

If I remember corectly this feature can be found as a standard in Combustion from Autodesk as well...