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I am working on a Stop-Motion Project and am using Blender 2.8 to add green-screening effects via masking using the nodes. In the image, the green screen has a similar shade of green to Doc-Ock, and have created a mask to prevent the shades from clashing. The top mask been successfully combined with a powerpoint image, however I am have trouble adding the inverse of the mask to the image. I am using Alpha Over, and the line that was used to create the mask is showing/cutting-out. Is there a way to seamlessly combine the two masks? I have tried using Add and Subtract via the Mix Node to no avail. Any suggestions are appreciated! enter image description here

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Masks can be combined as images. Use a color mix node and add (or subract) different masks. In this example a couple of garbage mattes have been combined to be used by a single keying node.

enter image description here

Or you can combine the resulting image with others that have an alpha channel already using alpha over.

enter image description here

Or combine the alpha channels separately and associate them later using the set alpha node.

enter image description here

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  • $\begingroup$ Is there a way to include the invert node? I attempted this trick, but an invert is needed to include the part of the scene that does not require a mask, ie the inverse of the mask. $\endgroup$ – velocipede1895 May 24 at 19:09
  • $\begingroup$ Don't use the answers section to add information to the queston. There is an edit link for that on the original post. Invert is not needed if you use the right operation. Think of the masks as black and white layers. You either add or subtract. If you absolutely need to invert then use an invert node. $\endgroup$ – no-can-do May 24 at 19:16
  • $\begingroup$ For some reason the add or subtract do not work when Invert is added between the mask and add nodes. What I did to resolved the issue was create another mask overlapping the outline of the first mask and plug that into the CoreMatte of the Keying Node, which seems to be working for now. Thank you for your help! $\endgroup$ – velocipede1895 May 24 at 21:09
  • $\begingroup$ Please post an answer detailing your solution. Maybe some user in the post-pandemic world might find it useful. $\endgroup$ – no-can-do May 24 at 21:11

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