replace the BG with other BG

[TIMOTHY]

hallo chris , a simple question , but i still did not figer it out .

like , i rotoscope a person talking ,

than i want to key out the person , and merge with other BG (constand )

which tool i need to make it ?

i think a merge tool i can do it , but i do not know which the operation is get it works.

[chrisg]

Hi TIMOTHY,

There are a few ways to do this. One method is to plug your RotoPaint node into a Merge B pipe and plug your constant into Merge A. On the RotoPaint node, set it to output no channels, but output a mask into either rgba.alpha, mask.a, or any other channel you want. On the Merge, set it to Copy, then use whichever channel you plugged the mask into as a mask, and check the invert box. This technique saves your mask for use later on.

Another method is to create a Merge node (M) and pipe A into your original person talking clip, B into your constant, and the mask port on the right side of the Merge node into your RotoPaint node. On the RotoPaint node, check ON output mask, and set it to rgba.alpha.