All language subtitles for 6. Evening out the Green Screen

In this clip,

we're going to take a look at the last step in the preprocessing workflow,

and that his evening out of the green screen.

Now you're going to recognize a few of the different

items from the other clips and modules,

and those are things such as denoising the plate,

doing some color corrections to the plate,

potentially some different keyers and so forth.

So if you need a refresher,

please be sure to go back to those previous clips and modules.

So let's get started.

So here we have a character on a green screen in the green screen room,

but also on a green screen blanket.

Now unfortunately,

the two of them don't combine very well and we are

going to have to treat them separately.

So let's take a look at the luminance, the y for luminance,

and we're going to color slab them down so we can see the details.

So again, some evenness in the backing region here,

but definitely some issues with the wrinkles in the

fabric that we will have to address.

Go back to full color, A, A, and let's get started.

So the first thing that we want to do is denoise the plate.

So if you haven't done so already,

please be sure to denoise the plate just to get the

best details with our edge work.

Next, we're going to pull a really quick key.

So I pulled a keylight here first for reference,

and we'll take a look at the alpha.

Now you will notice that as suspected, we have some issues in the backing region.

So if we mouse over top of those numbers,

it is around seven to 10 percent, so close,

but not quite the rage that we're looking for.

Where we really have issues is of course is where the green blanket is,

and that's between 45 percent and 50 percent opacity.

So we will look at that and refine it so we can get a really nice key.

Okay, next step.

We're going to create a clean plate.

So back to full color.

So one,

and we're looking at the full clean plate before we revise the backing region.

And what we want to do is remove just the character.

So we don't want to change any of the backing region.

We are going to remove the character and the blanket.

So sometimes you will only remove the character,

but in this case, character and the blanket through the IBK color node.

So we've revised those.

We have one here for reference.

And if we look at the two of them,

again it hasn't changed a whole lot since before.

This is after,

and hopefully we're going to get a really nice

difference keyer out of those two tools.

So that is our next step.

On to the IBKGizmo.

So we take the IBK color and we're going to hook up an IBKGizmo nodek.

Here is a default one set to green,

and we're going to look at a more refined one that's

set up a little bit better for us.

So here is C, and we're going to hook up the input and look at the results.

So here's a much refined one.

We have a nice alpha to start with.

Not 100 percent black and white, but it should do for this particular workflow.

So again, revise the tools to optimize them.

Here I have taken the IBKGizmo, I have worked with the red weight,

with the blue/green weight and with the luminance match.

And again, with the IBK color,

just modifying some of the darks and the lights and eroding

away at the appropriate number of pixels.

So now that we have our clean plate and our solid alpha,

or somewhat of a solid alpha,

we're going to look at sampling the overall green screen color.

So why would we do this?

Well,

in order to get the green screen or the backing region to have

a solid uniform color for keying purpose,

we're going to take an average of all those colors so hopefully

we get a good color somewhere in between.

So we're using a constant, and with the constant,

we're going to go back and view our original image.

Select our constants and go into the picker portion of

the constant in the properties bin.

And zoom in and take an overall sampling.

Now I'm not going to sample the shadows.

We're going to avoid that area because it's pretty dark,

but sample the rest of the area.

So Control + Shift and drag,

and it gives us a nice overall sampling of the green.

So this is the color green that we're going to be aiming

towards changing our backing region to.

So Control + Shift + click to get rid of that red box.

Moving on.

So now what we want to do is we want to figure out what the difference

is between our clean plate and that sampled green.

So to do so, we use what is called the minus operator.

So we are going to add a merge tool with a default of over to

the IBK color and attach that to the B input,

B subtracts from A, and attach A to our constant.

We're going to change this to minus,

so let's just find the minus and take a look at the outcome.

So there we go.

So we can see that is determine the difference between the original clean

plate and what we have up here as our overall sample.

we're going to use this to re-introduce information

and even out the green screen, which we will take a look at in a few minutes.

The next step is that we want to invert the matte.

So let's take a look at that matte one more time.

So here's our matte.

And we don't want to change the color of our character,

but rather just even out the green screen.

So in order to do that, we need to invert the matte,

invert all, in order for this to work correctly.

So invert all.

There is some issues within the sword, we can address that after.

I'm not too worried about it.

But we're going to have to treat again this blanket separately in another step,

and that's fine as well.

We can get that evened out very, very nicely for us.

So we've inverted all, and that's after the matte.

And after that, we are going to add a shuffle.

So we are going to shuffle the alpha.

So let's take a look, this is our alpha,

and we're going to shuffle it to the red,

blue or RGB, so red, green, blue and the alpha.

So let's just cycle through there quickly.

So here is RGBA, and they're all the same.

So we'll shuffle it, because we are going to be using the multiplier right away.

So on to the next one.

So this one's a little bit more complicated,

but we will go through how it works.

So we have our clean plate.

We have our alpha matte, which we have since inverted.

And we have moved that alpha to all four channels.

We also have our reference image or our overall sampling of the green screen.

So let's take a look at how the multiplier works,

which is how we're going to add together our alpha or

our matte with the solid green color.

So when we go back to the minus,

you're going to notice a couple of different things.

And you're going to notice that the values are kind of funny.

So these are all positive.

There's some negative in there,

but they're going to change when we change this to the multiply operator.

So let's change this to multiply, multiply, and take a look at these values.

So here we can see already that it has subtracted the center of our character,

our character from this previous step,

which was the difference between our clean plate and our overall green color.

So we don't want to color correct or change the color of our character.

Remember, multiply multiplies the alpha against the RGB.

So there is nothing in our alpha.

So therefore, it's going to not reveal the RGB in that area.

So it's exactly what we want.

So what will this do?

It will take the negative values that we have over here that

were created from the multiply operator,

and they're going to use them to darken the lighter backing region.

So right now it's too bright relative to our sample colors.

So we want to darken it.

We have the opposite over here.

So we're going to sample these colors over here.

We can see that they're all positive.

So the positive values are used to lighten the dark backing

region relative to the green screen samples.

So let's take a look at that.

So here is our clean plates,. 41.

And here it is.

44.

So we can tell that it's a little bit darker than our overall green sample.

So we want to lighten it so that it matches the same color range.

And doing so, in darkening and lightning these various regions,

it's going to allow us to have the overall solid

even lighting in the background.

So let's see how that is applied.

So we have the multiply, we have the plus,

minus values in our image, and we've cut out our character.

A plus adds values together.

So we're going to change this new tool.

So we've hooked up a new tool, new merge to the multiply.

So that is the A input to the multiply,

and the B input is going to our original plate.

So that's the one with all of the information that was uneven.

we're going to change that to plus because plus is

going to even out the green screen.

Look at that, look how even it is now.

So remember,

it is lightning the darker regions and it is darkening the ones that were too

bright before to give us a nice even background color here.

So let's take a look at what it's doing to our edges and make sure that we

keep those edges because that's what's most important.

So here's our original image, and here's the corrected one.

So very, very subtle.

But we're keeping those edges.

So we can pull a key from this after and still have great edges and get rid

of all that extra artifacting that we had in our alpha.

So let's take a look at one last step.

We'll skip the edge blur for now and take a look at that in a few minutes,

but let's compare our original against our new ones.

So that's our original,

and this is what it looks like now that we've revised that even green screen.

So much better than it was before.

Again, this is before, this is after.

Still retaining those edges.

Before and after.

And so already, it's getting so much better than it was before.

Now unfortunately,

we're still having issues with this blanket down here at the

bottom so we're going to jump into that right now.

So let's take a look at the example that we have down here.

So this is almost identical to what we had before,

only we're adding to it to fix the blanket.

So let's take a look.

So this region in here is what we just completed.

It's nicely labeled so that you can see what's going on.

So this is part one.

And down here is going to be part two.

So this is incorrectly labeled, let's just fix that really, really quick.

That should be part one, and I'll explain that in a minute.

So this is the same step that we just took with the

exception of one modification, the modification being the IBK color step.

So the original IBK color that we did, let's just toggle over here for a second,

is that we removed the entire image.

So the blanket and the character.

This time, we're going to remove just the character.

And the reason for that is our target is this silly blanket

that doesn't seem to want to go away.

Now we do have part of the sword up here that's still remaining.

I'm going to leave it because we're just going to isolate

the bottom portion of the plate down here.

So all the same steps, let's just see what this looks like down here.

So part two complete, and wow.

What a difference this has made.

So we'll step through a couple of the steps really quickly.

So again we have our clean plate, we've retained the blanket down here.

We pulled a key, we've isolated our character, no green blanket so far.

Inverted it, so there is just isolating our blankets.

We've removed our character.

And of course, plussed it over top so that we've evened out the green screen.

Now unfortunately,

it's done something funny with our sword up here and we kind of

knew that was going to happen because we saw it in the alpha

and the various different images.

So we can fix that.

We're going to fix that by combining the best parts of each one of these images.

So we have part, where we focused on the bottom part of the blanket,

and part one where we focused on the top portion of our character.

We're going to combine them using what's called a keymix.

Now the keymix will be reviewed in more detail in future modules and clips,

but we will look at it very, very quickly.

So here we have placed into the A input,

that is our bottom portion down here that we have looked at.

So that's for the blanket.

And the B input is going to be for the top portion of our character.

It is isolated with a roto shape.

So just a garbage matte, and the garbage matte will isolate that A input.

So only reveal the A input.

So let's take a look.

And it's refined the top part of our swords.

So let's take a look at A versus B.

So this is before when the sword was not working so well,

and B, when it has been revised.

So let's take a look at where we started from And where we got to.

So if we look at the very, very top, this is where we started.

Very uneven.

We got that silly blanket again at the bottom.

And our revised image.

So it's not perfectly gone,

but the great news is we've retained the details in our character's legs.

Now one thing to revise it of course is going to be the blur.

So we did blur our character, and sometimes that will really help.

So if I go down to here,

and we will notice that there is artifacting that can occur in our legs,

so if we add a little bit of an edge blur,

it can soften that artifacting.

So where is that happening?

So where we inverted our matte, remember that?

So here's our inverted matte.

We've shuffle it to all the channels.

It's occurring over here when we pulled that keyer.

And so blurring the edge will just soften that transition between the two.

So it's not always needed, but it is a great option.

So before we wrap, let's take a look at the different steps that we've done.

So here is the original image when we pulled the original keylight

that wasn't working so well and that uneven lighting and of course

the green blanket down at the bottom.

Next one is the evened out green screen image where we focused

primarily on the background and not the blanket.

The next one is where we focused on just a blanket

and not so much on the background.

And of course, revise where we've combined the two of them together.

Now you'll notice that some of these values are quite high.

We can refine them, so we went into the keylight,

modified some of those sliders.

So we played around with things such as the clip white and the clip black,

and that really helped to even out this keyer,

so much better than it was before.

And so let's go to full color.

There we go, so we got a really good key compared to where we started with,

and we're well on our way to completing a fantastic composite.

So as a brief recap of this particular clip,

we reviewed how to even out the green screen in order to refine our key.