NUKE | Adding Alpha

In this Danswers, we learn how to add an external alpha channel to an image stream that was rendered as only RGB.

[CodeCreativityCommerce]

Thank you for that simple but yet effective explanation. It would have taken me days to figure it out lol

[Tom_CGI_Effects]

I have had this problem for about 1-2 days on a moving black and white mask which I didn't want to roto. This fixed it immediately. Thank you very much.

[mjparent]

you can also in the read node check auto alpha.
I think after a copy node you need to add a premult node.

[MWard-kpdk]

What if the video/image does not have an alpha aov? Would you be able to create one with a shuffle node and copy that onto itself?

[BakaNimate]

Thank you for this. I just stumbled on such issue. Strange I have never encountered it before. I render on Arnold, passes to merged EXR. Do you have an idea what might have caused this problem? Just so I try to avoid it next time.

[peshangahmed]

how can i write the file that has alpha as transparent in nuke?

[i]

How did it work for you without adding a pre-multiply node after the copy alpha? thanks

[thehippo]

Will this work with Red Alpha channels?

[davidswift]

Nice tutorial. I'm a real newbe to Nuke though. I saved a layer with transparency in Photoshop. It appears as a black element on white, but it needs to be white on black. All I want to do is to invert the alpha. People will laugh at me. So simple but still don't know how...cmd + I in Photoshop. That's why I hate Nuke. Nothing is intuitive. Because I don't know how, I'll have to go back to Photoshop and invert everything. For anyone who laughs at me, you didn't know shit until you learned it.

[LivPoxleitner]

does your plate also need an alpha channel?

[bluestaxks]

when I connect Copy1 to Merge, Copy node gets ERROR why??

[ArdanaMAX]

this isnt work i got error input copy1