All language subtitles for 3. Setting up Lighting for Green Screens

Hi and welcome to setting up lighting for greenscreens.

In this particular clip we're going to take a look at different backing colors,

or backdrop colors to film on.

In our first example we're going to take a look at a bluescreen.

Now some common thoughts about bluescreen is that it's best

for filming skin tones or characters on.

Now the reason for that is because the skin tones are primarily in the red

and green channel and not so much in the blue channel.

So the further you get away from the red and the green channel,

it should pull a better key overall.

Now that's not necessarily the case.

So long as you have really well-lit greenscreens,

or bluescreens, either one will work for skin tones.

Now the exception to that rule of course,

is blonde hair which we'll take a look at in a few minutes.

Now another thing to keep in mind of course is the luminosity so overall,

bluescreen does have less spill than greenscreen and we'll take a comparison,

or a look at that in a few minutes as well.

But bluescreens, one thing that we do want to keep in mind of course,

is the grain.

So let's take a look.

Here's the red channel, the green channel, and the blue channel.

Now most of the time,

the blue channel is the grainiest in traditional film stock,

but we're using digital footage here.

So it is grainier and things to keep in mind are the edge work,

and the key itself.

So it can cause issues, but we should be able to still work with it.

bluescreens are also well-suited for night scenes,

so long as they aren't lit too dark.

And the reason for that is the cool tones.

So now lets take a look at a greenscreen.

The greenscreen overall is much cleaner in the green channel.

So again: Red, green and blue.

And if we were to sample the colors in the skin tones, so here again 0.

23, 0.

13, 0.

11 and we go over top of here, we can see the greenscreen is almost 30% brighter.

So there is some contrast in that color which should

make it fine for pulling a key.

Now let's take a look at that hair.

It's that blonde hair we were talking about before.

So here we have some blonde hair.

We're going to crop into the blonde hair so we can take a look at it in detail.

And we're going to take a look at a Keylight.

So a Keylight does two things.

It can pull a key, so there's our alpha.

And it can despill the green.

Now I mentioned earlier that the bluescreen has a

lower limit than the greenscreen.

And when the greenscreen has a higher luminance value,

it will create more of a green spill.

When we despill the image, what happens is that introduces red.

So red will be introduced into things such as blonde hair.

Blonde hair tends to have more yellow tones in it,

so therefore that's why it will be kind of mixed up in the green.

It will also affect things such as lighter skin tones and light color clothing.

Another thing to keep in mind of course is we don't want

to put anything green on a greenscreen, it can create extra holes in our key.

So let's take a look at the luminosity issues that

we were talking about earlier.

So here are our two images, filmed in the exact same location,

the exact same lighting on set.

And we're going to take a look at the luminance.

So the greenscreen here has a luminant value of 0.

194 versus the bluescreen has 0.

08, so it is less than half of the luminosity.

So it doesn't need as much lighting to film that

element and still get a great key.

The other thing to keep in mind here of course, is how much spill there is.

So again, here's the greenscreen spill versus the bluescreen spill.

And you can see both.

But the green is more intense.

So pros and cons of both.

Of course, there's nothing wrong with filming with greenscreen,

just make sure that you keep that in mind when filming stuff like reflections,

that blonde hair, and light-colored clothing.

So let's take a look at some other backing colors.

So here we have a greenscreen.

And it was filmed on craft paper.

And we're going to pull a Keylight.

So a Keylight, here we go.

That is a really nice key actually.

It is a generic key.

There is nothing special about it.

We still have lots of refinement to do.

But if we look at the details, we can see that it's doing a pretty darn good job.

So this just proves once again that the greenscreen is

a great backing color to film on.

Let's look at some other backing colors.

Here we have a white backing color.

Now we would think because it has such high contrast that it

would that it would pull a fantastic key.

But unfortunately that isn't the case.

So let's take a look at a couple of different tools.

Our first tool here is our Keylight, that worked really well on the greenscreen.

But unfortunately not so well on the white backdrop.

So again, it's mostly suited for bluescreen and greenscreen,

so that's not going to work.

So we're going to take a look at the luminance keyer.

And the easiest way to describe this is that it will pull a

key based on the light versus dark values.

So this is nice and dark, contrasty in the leaves, and the white background.

So let's take a look.

So it is much better.

We do have a stronger alpha than we had before.

But again,

see here that it's still getting confused with some

of the highlights in the image.

So generally speaking, I would stay away from a white backing color.

You might recognize some of these issues from when

you try to pull a key with say, trees over a white sky,

or buildings over a white sky.

You're going to find these white edges, this white halo.

It can be treated.

You can fix those edges with varying different techniques.

But overall, I would stay away from that white backing color,

unless you absolutely have fantastic lighting equipment that you can work with.

So green and blue again, works best.

Next we're going to take a look at the opposite color, which is black.

So black craft paper and again, very contrasty.

Our luminance keyer worked very well previously,

so hopefully it will help us with our smudges and our

reflections and stuff like that.

So here's our luminance keyer and we're going to take a look at that alpha.

We have some issues.

So our candle, which should be opaque, is very much not opaque.

However, it's doing some nice things with our reflection.

So hopefully when we do our test, it will work.

So here's our checkerboard, and it's really fighting with those colors.

So again, as we suspected,

our candle is not opaque and it's really fighting with the

reflections and the smudges and so forth.

So again, this is going to take a lot of work.

Reflections are difficult,

but it's probably best suited for greenscreen or bluescreen backing colors.

So let's take a look at the bluescreen.

Here's an image that was filmed outside.

So very natural lighting, nothing too crazy.

Just a bluescreen backdrop.

And we're going pull again, a Keylight.

Keylight works best with this color.

And we sampled somewhere up here.

So towards the top of the plant,

and it's doing a pretty good job overall for just the initial key.

Nice edge work overall.

Let's take a look at the vase.

It's not bad.

We have some holes.

We would probably want to pull another key close to the vase.

So we'll do that, and we're retaining more detail.

So overall, what does this tell us?

It tells us that the Keylight is the best tool,

or one of the best tools to use for this particular image.

However, we might have to combine more than one key to get our final,

final alpha, but that's okay.

So this is a great tool to use and a great image.

Up next, we're going to take a look at that red backing color.

Again, we said earlier blonde hair on greenscreen doesn't work so well.

Green on green doesn't work so well.

Same goes for red on red.

So this skin tone, it does run heavy on the red side here.

So mostly in the red channel, followed by the green and the blue.

Of course our backing color is very, very red.

So let's try to pull a key.

We know the Keylight won't work.

In fact, we can see here we have some transparency in the fingers.

Our hand is actually be despilled so it's turning gray.

So this definitely is not a great tool to use for this backing color.

So let's try the luminance key or the keyer.

And so we can tell it to focus on the red backing color with a red screen.

We're going to modify it.

It's going to pull an alpha.

We're going to merge that onto our image and we can see here not so great.

So we're just going to refine that there.

It's better than it was before, so much better than that Keylight for sure.

But again, it's having problem with unevenly lit screen.

And it's just not quite where we need to get it.

So let's take a look at the Primatte,

which does like having different backing colors.

So much better of a solution.

Almost a perfect, little finger almost perfect,

not quite, some small details here which we can refine.

Let's take a look at that over top of our test backgrounds.

It's much better.

So red backing colors can be used.

It definitely wouldn't be my first choice.

I would stick to elements that are far, far from the red channel if possible.

But again, primarily stick to that green or bluescreen backing color.

So let's take a look at that hand on the greenscreen,

and a Keylight, and it's much better.

So the exact same hand, exact same environment,

but on a green backing color, and already we can see it's just better,

night and day.

A lot faster, a lot less work.

Despills working very nicely.

We're not losing the color, so it's not turning gray.

Definitely a better solution for this particular skin tone.

Next, let's look at that black backing color.

So it didn't work so well for us on the vase and the candle earlier,

but maybe it will work for some atmospheric elements.

So often you will find atmospherics in stock footage on black backing colors.

And so this was shot on black corrugated cardboard.

And we're going to pull the luminance keyer.

So here's our luminance keyer merged over top of our elements.

And it's working okay,

but look at the detail loss that we have in the center of the elements.

Looking a little bit crunchy.

And what I mean by that is that the falloff isn't as we like it.

We're losing some detail.

So an alternative to that, a quick solution,

not a final solution, is to do a plus operator.

So if I have to describe a plus operator,

visually speaking, it's going to take any color that's 100% black,

so here's 100% black, and it will drop it.

So it won't be visible at all.

As the numbers, as those values go up in color,

they become more and more visible.

So as it gets closer to 1.

0 or higher, it will be visible when merged over top with that background image.

So here we go, so we retain more detail.

Again, we're losing some of the core.

So if we merge the two of them together,

the plus with the premultiplied image, a lot better detail are gained.

And that filled in detail that we lost, but again, not quite final.

So well on our way,

but it will definitely need a lot more refinement to

use that as the final element.

One last thing that we're going to take a look at is of course smoke.

So here's smoke, a nice element shot on a black backdrop.

We're going to pull our luminance keyer and combine it with a plus.

You can see here again, not too bad for a first try.

Does not work so great for our candle holder here unfortunately.

That will need extra refinement if we did want to

retain that particular candle holder.

But for the smoke it works pretty good.

So again, just a start.

Just to show you what you can do with those different backing colors.

By no means final.

So definitely more refinement there.

So as a brief review of what we learned in this clip.

We looked at the greenscreens, the pros and cons of both.

And which backing colors and backdrop colors work best

for different subjects and/or objects.