Reverse Mask

VmusicV wrote on 10/12/2009, 7:15 PM

Hi,
I am new to Vegas (sorry) - I have a movie I am editing. On the bottom video layer is a picture of outer space, above this layer I have a video layer of an explosion which I downloaded from a site. It's great because other than the explosion, the rest of the video is the color black.

I want to composite/mask this such that ANY PLACE in the top video layer there is black, the bottom video layer will show through. I know this is kind the 'opposite' of how simple composites work.

Thanks In Advance!!
Vmusic

Comments

Rory Cooper wrote on 10/12/2009, 10:06 PM

Multiply for white and add for black

I assume your blacks are solid, but preferably check that your clip might contain alpha info

Otherwise add mask gen and click invert
This you will use as a mask layer with your original clip

Chethu wrote on 10/13/2009, 4:32 AM

USe Sony Chroma Keyer Video effects , that solves your issue in few steps.

-Chethu

Rory Cooper wrote on 10/13/2009, 4:52 AM

It’s good that you are thinking about different options Chethu, but if you use Chroma key to choke the black you will also choke the shadows and greys which you need in the footage

farss wrote on 10/13/2009, 6:02 AM

When using Add make certain the blacks in what you're adding are superblack. If not the blacks in the background get shifted towards grey. Best to watch what's happening with the waveform monitor.

Bob.