After Effects CS6 Tutorial - 170 - Luma Keying Video Lecture | Adobe After Effects CS6: Complete Course from Novice to Pro - IT & Software

hey everybody how you doing buddy
Blackford here with another After
Effects cs6 tutorial and in this
tutorial I want to teach you about using
the luma key this time and luma key is
good for when you're trying to key out
luminance and it's pretty good and it's
pretty much the best for when you're
trying to key out black on white or
white on black and if you're trying to
use any other colors it doesn't really
work out that great and I'll show you
some examples real quick so we've got
this a fractal noise that I made and
it's just a bunch of white lines and if
you want to check out the settings up
home down here for you so there's the
settings and you can pause it on this on
this point in time and then look at my
settings and change them a few if you
would like and to get like about the
same thing I'm going to turn this all
the way down actually the sub scaling
there we go so that's what I've got
there and I just pretty much made a
bunch of white lines so I could
illustrate what's going on now when you
use something like fractal noise let
that affect on a solid you do not get an
alpha so if I come down here to alpha
it's just all white and when you have
all white that's not an alpha it's a
well that's not what I want I want these
white parts to not be in there so I'll
show you what I mean or I want the white
parts to stay or the black parts to move
out or whatever you want to do so to
create an alpha so what we're going to
do is add the luma key on here and we'll
go to keying and then luma key and we've
got it here and now we just have to mess
with the threshold and the tolerance now
as soon as I turn it up
the threshold it's going to like start
taking it out and now it's trying to
leave the all the white and take out the
black because I have it set to key out
darker up here no if I want to do the
opposite I can go on to key I'll
brighter and just keel the white so I'm
going to key out the white because it's
easier to see for us so if we mess with
the threshold here and decrease it or
increase it to what we want so something
like about there it looks like and then
we've got our tolerance that we can mess
with to actually like sometimes the
tolerance works better when you're using
Kyo similar and Kyo dissimilar and it
only has minimal effect when you're just
keying out the brighter or darker we've
got our edge stone which will work on
the edges for us here and it goes into
the negatives as you can see so I'm
going to keep mine as zero because I
feel like we've got a decent key and
then if you have like if your whole
entire thing had a bunch of this like
feather it off kind of stuff you could
mess with the edge feather if you wanted
to and make it
Maur feathery that depends on what
you're doing in your scene but I don't
need that so if we go ahead and check
out the alpha now we can see that there
is one now and now we have created an
alpha and we have achieved what we
wanted to achieve with our luma key so
that's how you use the luma key and
remember it's good for black on white or
white on black I'm going to show you how
the luma key doesn't work as well with
just like white with different color so
I'm going to bring in this a McChicken
picture and I'm just going to hide all
the rest of this stuff and we're turn it
back to RGB and we've got a picture of
our McChicken here now this is on a
white background so you might think that
the luma key will be able to take it out
pretty nicely well there's a couple
things that will probably mess up we've
got white mayonnaise in here that might
be affected some white spots on the
lettuce but we'll check out and see
what's going on and see how the luma key
can affect this so effect king luma key
now we've got key out darker which will
take out the dark stuff we want key out
brighter and then we want to increase
our threshold here to bring back our
chicken here so 255 is the greatest that
we can go on the luma key now let me
turn back on the transparency here you
can see that this is what we got going
on here so I'll go up to 255 real quick
it's going to bring in the white if I go
to 254 that's the next level it just
like snaps right to it which is not good
we got some stuff being taken out here
we got a pixel a couple pixels there
some pixels and
there and then of course all around the
outside it sucks
you can try to increase your tolerance
and all that stuff it doesn't work as
well you can try edge then but you still
have these pixels that are in the middle
that are all apt up and Plus around the
outside it does not look nice at all as
feather won't fix it so we need to find
what we need to use like a different
kind of method
I'll come out down to like key out
similar it's kind of like the same same
thing you can use your tolerance let me
bring the threshold down I take the edge
then off because that's what those great
things are so we're trying to Kio
whiskey out dissimilar and you try to do
pretty much the same thing in the same
pretty much the same thing exact same
thing happens doesn't work out too well
so you can see now that the luma key is
just good pretty much for black on white
and like the luminance kind of value
kind of stuff so if you really needed to
like get that McChicken pretty much
keyed out or whatever
try using auto trace and I made a
tutorial about auto trace a long time
ago probably I don't know check around
in the 30s or something like that
for my tutorial numbers and After
Effects cs6 and learn how to use the
auto trace to trace out something like
this it works pretty well actually so
that's all I got for you for luma keys
and they helped create alphas within
black and white images that don't
actually contain alphas so there you go
hopefully you guys learn something in
this tutorial and I'll see you guys in
the next one have a good day everybody