Graphics Programs Reference
In-Depth Information
Now what you have in front of you is a hard matte, or
crunchy
matte, and you can use it
fortwothings:agarbagematteandacorematte.Youdon'tneedacorematte,becausethe
coreoftheIBKisfine.YoudoneedagarbagemattebecausetheoutsideoftheIBKmatte
is a big mess of gray noise. However, if you use the matte as it is now, you will lose a lot
ofthe fine detail the IBK produced. Youneed to make the matte youhave here bigger and
then you can use it to make the outside area black. For that you will need to use one of
three tools: Erode, Dilate, and Erode (yes, really, keep reading).
Erode, Dilate, and Erode
There are three tools in Nuke that can both
dilate
(expand) or
erode
(contract) a matte.
Their names are confusing and, since they all have two sets of names, it gets even more
confusing. They are called one thing in the Filter toolbox, where you can find them, but
once you create them they are called something else in the interface. Yes, it is that crazy. I
do wish they would simplify this little source of confusion. Here's the rundown:
•
Erode(Fast):
Asimplealgorithmthatallowsonlyforintegerdilatesorerodes.By
integer
I mean it can dilate or erode by whole pixel values. It can do 1, 2, 3, and
similar sizes, but it can't do 1.5 pixel width, for example. This makes it very fast,
butifyouanimateityouseeitjumpingfromonesizetoanother.Oncecreated,the
control name becomes Dilate.
•
Erode(Filter):
Amorecomplexalgorithmthatusesoneoffourfiltertypestogive
more precise control over the width of the Dilate or Erode operation. This allows
for
subinteger
(orsubpixel) widths.Itsname changes toFilterErode whencreated.
•
Erode (Blur):
Another type of erode algorithm. This one creates a harsh black-
and-white matte and then gives control over blurring. Called Erode when created.
Right now you will use the Erode (Fast) node.
1. Select Keylight1 and insert an Erode (Fast) from the Filter toolbox after it
Figure 7.35. The node is named Erode (Fast) in the Filter toolbox.
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