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Okay. I'm going to reset Nuke one more time in order to show you the garbage matting
and grain suppression techniques. For this segment, we're going to need a couple
of different pictures. So, let's go to the Read node, our WORKSHOPS,
Lesson_5_Media, select bluescreen_film and film_BG.
These have a little more grain, so I can show you some grain stuff.
Select the bluescreen Read node, go to your Keyer tab and add your Primatte node
and hook it up to the background. A little more screen space for our picture.
First up, I'd like to show you how to do a Garbage matte with the Primatte node.
I'm going to move the Viewer over here and hook it up directly to the bluescreen.
If we look at the alpha channel, we can see that this is a three-channel film scan.
There's no alpha channel, which is what you would expect.
So, let's add a Bezier node to this bluescreen. Select the bluescreen Read node and type B
on the keyboard. So, we're going to draw a little garbage matte
around the lady, Alt+Cmd+Click.
And the Bezier node will turn off the red, green, and blue channels.
Now if we switch the Viewer to the alpha channel, we now have a
four-channel image. See here, there's an alpha channel here now
from the Bezier node. So, coming into Primatte now is a four -channel
image with the garbage matte in the alpha channel.
We'll switch back to RGB and hook the Viewer up to the Primatte node.
We don't need the Bezier anymore, so I'm going to fold that up to hide it.
To use the garbage matte all we have to do is come down here to mask and tell it
to look in the alpha channel. Ta-da! If you'd like to toggle it on and off,
you can do that right here. If you need to invert it, you can do it right
there. So, the bottom line is if you want a garbage
matte for Primatte, you have to put it in the alpha channel.
There's no mask input to the Primatte node. Now let's take a look at the Degrain features
in Primatte. First of all, we're going to need to pull
a key. So, I'm going to go to my Select BG Color.
I select my background color. Check the alpha channel.
I'll clean it up a little bit, clean the background noise, sample,
sample, sample, okay. So, I've got some grain.
This is a film scan. This is actually a 2K film scan that's been
scaled down to 1K. So, there's still a lot of grain in it.
So, we can turn on the Degrain feature here. Right now, the Degrain is none.
We'll go to the type pop-up and select small, medium, or large.
In our case, the graining is rather small. So, I'm going to select that one and then
we can dial it in. We don't want to hit it too hard, because
degraining removes edge detail. So, I'm going to show you that right here.
So, I'll adjust the tolerance here. We'll come back to our RGB and look at our
composite. I want to scoot in here to look at the fine
hair detail. So, if I change the Degrain to none, you can
see I get come hair detail back. Put it back to small. It goes away.
Id I go to medium and large, I lose even more hair detail, because it's
a more aggressive degrain operation. Now let's re-home the Viewer, because I wanted
to show you down here the output modes. There are actually three different output
modes. The default is composite, but you'll rarely
get to use that, because very few keys can actually be pulled with one Keyer
setting. You're normally going to pull multiple keys
and combine them, but the other two output modes are a premultiplied output and
an unpremultiplied output. I'll set it back to the default.
In this movie, we took a close look at the implementation of Primatte in Nuke.
First of all, we did a little theory of operation to understand how it's a
three-dimensional chroma keyer and it produces those multiple concentric shells
that you then deform with your selections from the screen.
We also went down the entire list of Primatte operations to see the effect of
each operation on the matte or the spill suppression. And finally, we saw how you apply a garbage
matte to Primatte, because it has no mask input, as well as how to do some grain
suppression operations.