Original subtitles

In this clip we are going to take a look at the IBK keying fundamentals.

So let's take a look at the initial setup.

Down here you will notice that we have two different tools.

We have the IBKColour and the IBKGizmo.

The two of them work together to pull a final alpha.

The IBKColour is hooked up to our original source plate with the one input.

The IBKGizmo is attached to the IBKColour through the C input.

The IBKGizmo is also hooked up to the original

image through the foreground input.

Together, the final output is a premultiplied image and a final alpha.

The IBKColour creates a clean plate so it removes that

foreground image from our original source plate.

It then takes that clean plate and compares it against the source plate

and the result is a premultiplied image with an alpha.

Now that we know the basic setup of the IBK keyer,

let's go down to the little details so that we can modify it.

Again,

here is our setup and you will notice one extra thing and that is the BG input.

Now we won't look at the BG input for this particular clip but the BG

input is usually used to refine our edges so just to integrate those

edges better into the background image in post.

Before we start to modify all of the sliders we're going to set the screen type.

In the IBK Keyer the screen type is green because of

course we are using a green screen.

If it was blue, we would use blue and so the IBKGizmo is a little bit different.

The input screen type coming from the IBKColour node is green.

So, C-green because the input is C.

C-blue, again, if it's a bluescreen and then we have the pick.

Now we already know that we have slight variation in our greenscreen here.

Down here it's around.

6 and up here it's around.

47 so just over a 10% difference between the greenscreen backing colors.

If it was completely even then we can use the picker and

pick the color overall but since it isn't,

we're going to stick with the C-green.

Let's move on to our next step and that is the size slider.

Double clicking on the IBKColour, we're going to change the size.

Now the size type generally defaults to a value of 10

and I like to keep it in around 10.

Well, let's take a look at why.

Let's take a look at our output of our IBKGizmo and

take a look at our edge work.

So if we decrease this value you can see that it started to erode away

at our alpha edges and it produces a hard matte.

If we increase it it continues to grow the edges of our image.

If we keep it in around 10, which is a really good value,

let's keep it around 10, give or take.

We're going to take a look at our RGB image.

Here's our RGB image and let's take a look at it against our original.

We can see here it's keeping our edge detail really nicely.

Let's decrease the value so it's eroding and it's adding that hard edge an

increasing will give us more detail but it's pretty subtle.

We're going to leave it at 10.

We can see here it also starts to eat away at our core so

we're starting to lose our alpha in the core.

We can see the endless color changing so we're going to leave

it around 10 and not increase it anymore.

The next step is the darks and the lights.

This allows us to continue to refine our details in our alpha.

Let's take a look.

So back to the IBKColour and we want to,

also in this step, look at the IBKGizmo.

Now you're going to notice that there is a black color in here.

That's okay, it will be filled in in a few steps.

So the IBKGizmo, again,

is our final alpha and already this alpha is pretty contrasty

so if we stop down we can see there's not a lot of

information in the backing area at all,

a little bit here but again it is pretty small.

Again, some minor holes in our core,

a little bit of information in the backing region but for the most part

it's working pretty good for the initial settings.

Now,

this is usually set to zero and we're going to take a look

why changing that value is going to help.

Right now the backing region is okay.

If we decrease this value, I usually start with a very small value of negative.

001 which starts to fill in my core in this particular case.

Notice it will start to clean this backing area.

I'm going to increase it, one five, and it fills it in more.

Start at one and that's looking pretty good there.

So around negative.

1, negative.

15 for this example should do a good job.

So again, only modify it if need be.

Don't modify if it isn't needed.

These numbers will have to be played around with eventually we

can tweak them overall to get the best results.

On to the next value.

Again, we start with that negative.

15 and now we're going to take a look at our RGB in the IBKColour.

By default this value is at one and if we change the LUT it's going to be very

hard to see but you can see it around here that there is some gradient in our

greenscreen so it starts by the black portion,

again,

we're going to fill this in with green after but we can see that the

values are changing and then it sticks to about.

46,. 48 and again, changes.

So we want to even out this color here.

We're going to do this by dropping the light values so.

99.

It's not doing a whole lot so let's drastically change it and see what it does

and we can notice how that color pops so here is at one and.

9 and it's starting to fill in that color.

Now we can fix that even further in our next step,

and that is with the erode,

but so far this is looking good so we're going to leave that at.

9 and modify it later if need be.

So we're going to change the LUT back to the normal and go on to the erode.

Again, we're going to double click on that IBKColour.

It is exactly where we had it before except for we've

already started to erode away at our image,

so default value of zero.

Let's change our LUT again so that we can see those details that we had here.

We're going to slowly erode away and see that it start to disappear around.

2, two five, three.

So if we push this too far it might erode away too much.

Again, we only want to change it as much as need be.

The values are good around, I'd say, 2.

5 to 3.

5 so we'll leave this at about 3.

5, there,

and it is nice and even now in this particular region that surrounds

our character and then we're going to patch in the black areas here

so we can complete our clean plate.

On to our next example.

Again, our values are the same with the exception of the patch black.

So we want to patch the surrounding colors of green inwards into our character,

so patch black and you're going to notice that it slowly patches in the

black region and so that should take us in around... Oh,

it looks like we changed the wrong settings let's go back there for a moment.

So patch black,

I patched the green into the black region so in around five

for the patch black is a good setting.

Again, no need to change that drastically further.

It's not going to change, it's not going to help us any.

So we're going to leave it at around five.

Now, we have our clean plate.

We can notice that there's not a lot changing between the two which is great.

Now if I change this LUT again, the A B,

we are losing a little bit of detail over here but it's

producing a really good alpha so far and the reason why this

is being blurred is up to our size.

If we bring our size down you can see it's not changing a whole lot

but if we increase it too much it blurs our image.

So again, down to what it was, up to 10, not changing it drastically.

It does blur it a little bit but increasing it too much

completely blurs our greenscreen and evens it out which is not

going to help our difference keyers.

So change it to 10 which give us a really good alpha again,

evens it out a little bit.

Again,

that's the benefit of the IBK keyer or keying setup is that it

works very well with uneven greenscreens.

So we have our final output and let's compare A versus B,

so before versus after and we are retaining that

detail very nicely in our edges.

If we need to modify those settings we can always tweak these values in here.

Sometimes if the greenscreen isn't entirely green or

blue modifying these values will help.

In this case it doesn't do much, in fact, it almost makes it worse.

So here, if we change this to negative.

1 it's not really doing anything so we're going to leave that at zero.

It's not really helping us and again, negative.

1 not really doing anything so best just to leave with those values

at zero and only modify in the green channel.

The other thing to keep in mind is if your greenscreen or bluescreen is

slightly darker than usual sometimes increasing these values,

rather than decreasing them, will yield good or better results.

So our final alpha of course,

there is some holes in it so it's not quite 100% black or white however we

have a really nice RGB premultiplied image with nice,

soft edges.

So to fix the core or the hard matte inside of our final alpha we will

revise that inside of the IBKGizmo in our next clip.

A quick recap of what we learned here today in this particular clip.

We reviewed the basic setup of the IBKColour and IBKGizmo.

We reviewed the basic settings for the IBKColour tool

here and we outputted the basic alpha.

So now that we have a very good starting point we will look at

finalizing this using the IBK keying setup in our next clip.