pre/un-premultiply nodes?

#1

bit of a noob question here im afraid (I’m new to fusion) but i cant find the answer anywhere, I tried the manual as well as google.

Im searching for nodes that can pre and unpremultiply, I know the color correction nodes has an option to do this automatically but I need to do it manually at some point in my tree.

I could do this manually I guess but I can’t even find a node that divides two inputs so I’m a bit stuck.

Most comp applications simply has nodes to do this sort of thing, it should be straightforward but I can’t for the life of me find these nodes in fusion.

#2

The ChannelBooleans - Node does exactly what you need. You can use two inputs and apply several different mathematical operations. Such as dividing your background rgb channels by the alpha of a foreground image, for example.

Hope that helps!

#3

hey

cool, that seems to do the trick

I would have thought there would be a dedicated node to do it as it’s so common, but oh well, this works fine too.

#4

Well, the ChannelBooleans-Node is pretty powerful and supports all kind of operations. People keep looking for an invert-node in Fusion, since it is a pretty common taks too. Again, you can do all this stuff with the ChannelBooleans, although I have to admit, it’s not that obvious at first :wink:

#5

You can always set up the Channel Boolean tool to the operation you desire, and save it as a setting, macro, or default. You can then add that setting to your toolbar, access the macro from the tool menu, or as the default operation anytime you add a boolean.

#6

HI, i´m not so god on English but i believe that a boolean node can do the trick, also you can try using a matte control node setting to active the “post multiply image”.
Hope it helps.

#7

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