Combine Alpha-Channels in Combustion

#1

Hi!
I`m searching a simple way to combine 3 to 4 Alpha-Channels like with the Key-Mix node in Shake.
Is anybody in here, who can help me with this problem?

Greetz,
Marco

#2

If I understand you well wants to use an image as alpha xchannel for another one. For this you can use operators as setx matte or use Stencil Layers

#3

Hmm… we mean not exactly the same thing :wink:
I have 3 Images, each of them with an Alpha Channel and I will add these channels to one.
This new alpha-channel will be used for a matte.

#4

You can use “Compound Alpha Arithmetic Control Operator” to compine alphas.
If you want to combine 3 alphas, you have to use 3 of that operator.

Just change operator modes of them. First ones mode should be SET and others SUBTRACT.

I hope it helped.

#5

Hi Marc…

As far as i’ve learnt from ur query is it like…

For example ur 3 images have an alpha of a circle, a square & a rectanlge respectively…
Then u wanna combine these 3 images into one single alpha image (ie the circle,square & rectangle in one image).

If that is the case then try nesting the 3 images & use that as a single layer & then stencil it…

#6

Thanks guys! :thumbsup:

#7

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