- [Announcer] The new Chroma Keyer node is GPU powered
stripped down version of Key Light.
It's not designed for difficult and complex keys,
but more of a quickie keyer for real time use
in Nuke's Studio timeline but still useful
in regular node even without GPU's.
Here we'll take a look at the basic set ups
for the new Nuke Chroma-keyer node.
Starting with my green screen read node,
we go up to the keyer tab,
and here is our new Chroma-Keyer node.
The first thing we want to do is to set the screen color.
And if you take a look at some of the controls here,
you can see these are really very, very Key Light.
So this is Key Light lite as it were.
So we'll turn on our screen sampler.
Over here on the green screen,
Shift, Alt, Cmd or Ctrl and sample our green screen color.
Let's take a look at the alpha channel.
I'm going to clear my sampling box there.
And let's dial in screen gain
to clear out most of the background noise.
There we go.
Next, let's take a look at the white point.
For that I'm going to gamma way down,
and to reveal any soft spots in my key, lookie here.
So we'll use the white point to pull that up like so,
until it's just disappears, no more.
Then, restoring your gamma, we can clear more of this out.
Again, when we're doing fine work on the background plain,
we want to set our gamma up very high.
That'll reveal all the noise.
Okay, now we'll go to the black point.
Pull up on that to pull it away from our character edges.
There we go. Restore viewer gamma.
Okay, let's switch back to the RGB.
So now we have a four channel pre-multiplied image.
You'll notice that there is no BG input on this node.
In fact, there are no inputs of any kind.
Just the original green screen.
So, again, a very stripped down node.
So, to do a composite now we'll add a merge node
by selecting this and typing M on the keyboard.
Hook that up to our background plate.
And now I an instant comp.
Okay, the last thing we want to do for a basic setup
is where do we do our color correction?
So we'll select the Chroma-Keyer node,
and type G on the keyboard, add a grade node.
Now, I'm grading it before it goes to the merge node.
So I can, you know, gain it up or down,
have all kinds of fun.
Now the important thing here is for you to realize
that this is in fact hooking up to the grade node,
a pre-multiplied image, as I said before.
So, as a consequence of that you are absolutely required
to set the (un)pre-multiply option here to alpha.
And I'll show you, we'll push in,
take a look at some fine detail here.
Watch what happens, I'm going to blast the gamma up silly here.
If I don't do that, I'm going to turn it off right here.
Boom. You see the edges? Okay?
So this is having a profound effect on all your edges.
So make sure you always set the (un)pre-multiply correctly.
And if you'd like to see a really good tutorial
on (un)pre-multiplying operations,
go to my Nuke Nuggets course and look at episodes 10 and 11.
This entire subject is discussed in great detail.
Okay. Viewer back to normal.
As you can see, the Chroma-Key node
is designed to pull a quick key to get things going.
Then you'll probably want to replace it later
with a full up keyer setup using your favorite keyer.