How Do I invert rgb or rgba colors in nuke?

#1

I have a pass that I think will look great as shadows if I simply invert it.
When I use an invert node, everything becomes white.

How do I simply invert the colors, and maybe the alpha too if needed?

#2

You’d use an Invert node, simple as that. Just tried with your image and it works as it should.

#3

Well for some reason it’s not working for me…everything just turns white.

#4

Ok, I think I found part of the problem.
I used the image above and it worked just fine.
However, for this project I’m trying to invert a channel from a multichannel .exr file, so I’m convinced somewhere therin lies the problem or solution…

#5

You’ll probably need a shuffle node to read the channel you need and invert that channel.

#6

That’s actually what I was doing :shrug:.

#7

OK, that’s going nowhere. How about you upload a frame?

#8

Thanks for the help, but I think the problem was that I had a few node, such as blur attached before the shufle node, so MAYBE that’s what messed it up.

I dunno.

I remedied it by simply creating another read node, then adding only the shufle node before the invert node, so it didn’t after compute anything additional.

Thanks again.

You can see the end result here, post #5.
http://forums.cgsociety.org/showthread.php?p=7802015&posted=1#post7802015