"reverse" chroma key?

mtnmiller wrote on 11/20/2008, 10:03 AM

Hello,

Is it possible to do a "reverse" chroma key, where instead of picking one color to make transparent, that all colors are made transparent, except for one that is specifically chosen?

Case in point. I have general footage that includes bunch of pitch black shadows. I'd like to keep the shadows only and chroma-key out everything else in the frame.

Thanks for any insight.

Comments

bStro wrote on 11/20/2008, 10:22 AM

You could use the Color Corrector (Secondary) FX instead. It has an Invert Mask option.

Rob

johnmeyer wrote on 11/20/2008, 10:25 AM

Here are some threads which discuss how to turn a video frame into black and white, but leave one color. Apply the techniques discussed in these threads, but then do as bStro correctly suggests, namely use that color as a mask. Once you figure out which buttons to hit, it should be very straightforward.

Black & White with one just one colour?
----------------------------------------
removing color from all but a particular item

and

How to do this compositing effect...

also,

black and white and 1 selected colour

There is also this thread:

b&w video with colour flower

Color object over Black and White

richard-courtney wrote on 11/20/2008, 7:15 PM

If I get what you want is instead of common blue or green being replaced use
black as key color.

Then checkbox the show mask only on the chromakey fx. Render the video.

Use that video to key a background.
Did something like that for a sports intro where the player was solid color.