All language subtitles for 4. Primatte Fundamentals

In this clip we are going to be talking about Primatte keying fundamentals.

So, how exactly does the Primatte tool work?

Well, the Primatte tool is a three-dimensional chroma keyer.

It isolates the image into four different segments which can be

also called the polyhedral slicing algorithm.

The polyhedral slicing algorithm operates in a

three-dimensional RGB color space by arranging each of the

individual RGB color components into the X,

Y or Z axis.

A color then can be represented by a point locating

within the virtual XYZ space.

So,

now that we understand the math or at least the

description of the Primatte tool, let's take a look at it in detail.

Back to our scratch and we're going to take a look at a

overlay that I have already created and that is this one over

here and compare it to our image.

So,

if I bring down the dissolve just a little bit for this

overlay we can see it in relation to our plate.

The first one is color sample and that's A,

or I call it A and that is the exact pixel that we're going

to select for the initial greenscreen key.

So,

because this exact pixel is being selected we have zero alpha here

and because we have no alpha that means that we don't need any

despill because no RGB image is visible.

The second sample is B.

B has light colors to A but they're not exactly the same so because of

that we do have some values in our alpha and because we have some

values in our alpha we require a despill.

C.

C basically allows us to have a solid alpha.

We can see here this is the inside of our character so we do want

to have a solid matte and because we have spill,

let's just take a look at that very quick.

We have some spill here,

we have to do a despill operation so spill on the cup or mug here,

on the watch reflection over there and over here on the cup.

Back to our overlay.

So, here we have a solid alpha but a despill.

On this section of our character you will notice that there's no

need for a despill so because of that there is no despill

operation but we do have a solid alpha.

So this is a recap.

Section A is our initial sample area.

It has no alpha and no despill because there is no RGB image.

Area segment B is going to be similar colors to A.

It has some alpha below one and has a despill.

C,

this type of area has a despill and a solid alpha of one and D

requires no despill and has a solid alpha of one as well.

So now that we understand the different segments of the Primatte tool,

let's see how to pull a key.

So down to our example down here and we are starting on frame one.

Now,

in these examples they are set up in the following way and that is that I

have a starting point and then I have a reference of something that has

been pulled previously for us to review so each different section here that

we have will build upon the last one.

Let's pull a Primatte key.

Here we go,

we're going to toggle down to our tool and down here we're going to see Actions,

operation, Smart Select BG Color.

That's the initial sample that we're going to take.

Make sure that this little eyedropper is select and

we're going to zoom in to our character.

Make sure not to select any portion of him but as close as we can to his edges.

So Ctrl+shift+left mouse button and drag and we're

going to take a look at the result.

So looking pretty good overall, that's our initial key.

We're going to deselect that little red sample so Ctrl+shift+click

and it gets rid of it and turn off our eyedropper.

Take a look at the alpha.

So our alpha, it's working a little bit for now.

We see some information in the backing region.

We also have some holes inside of our matte so it will need to be revised.

Now you can sample different locations for this tool

so if I sample here it changes, here again,

here again so it is because the greenscreen is unevenly lit to a certain degree.

I find that it pulls the best key up here by the character's head.

So let's see how we can go and refine this key a little bit further and so

we turn off that eyedropper and go to our next tool.

So again,

this is a tool that's been pulled in advance but

let's take a look at our next step.

Here, we have multiple different steps,

we're going to move on to our next one so Clean BG Noise.

BG noise is considered to be in the backing region of our image,

so where the greenscreen was,

and we want to clean it up so we are going to select the Primatte

tool make sure that eyedropper is selected and hold down

Ctrl+shift+left mouse button and drag and continue to remove it until

the majority of it is no longer visible.

So it's looking pretty good there.

I'm going to turn down that LUT again and see it hasn't done anything for our

core or our inside of our image here so that will have to be revised but in

our backing region it's looking pretty clean.

So, deselect, Ctrl+shift+click,

turn off our eyedropper and move on to the next step.

There are two options for the following step and this is the first

one of the two we will review in a few moments what the benefit

and the downfalls of this method are.

So here is our start image again and we are going to look

to fill in the inside of our matte.

So, selecting your Primatte,

go down to the third option which is clean the foreground noise,

make sure your eyedropper is selected and Ctrl+shift+left mouse

button click and we're going to fill in these gaps.

I'm going to turn down my LUT just so I can make sure that

there's no extra details that were missing.

And that's looking pretty good for us so turn off the eyedropper,

turn off the red box and we have a really nice,

solid matte but look what happens when we go back to RGB,

back to regular LUT,

we've reintroduced all of this green so this was in our

previous step and this is it at our current step.

So we have a really nice alpha which is great except

for we have the green reintroduced.

So we definitely don't want that which brings us to option B.

So going back to where we were before,

here we've completed the Clean BG Noise step.

Let's go into the alpha to be sure, there we go.

And we can replace the Clean FG Noise with the Matte(+) and the Spill(+).

The first one is the Matte(+) and the Matte(+) is an alternative to cleaning

the foreground noise where it doesn't affect the despill.

So I'm going to select Matte(+),

make sure it's selected here and I'm going to fill in my matte.

So we just box select a number of different times,

adjust the LUT so we can see those details,

make sure we're not missing anything.

It's looking pretty darn good so turn off the eyedropper,

back up to the regular LUT and let's take a look at the RGB.

So here, this is great unlike before again where we lost the despill.

Now we have the despill staying the same and a solid alpha.

So what if this is too much magenta?

What if we need to reintroduce a little bit more color back into our image?

Well that's where the Spill(+) comes back into play.

So let's take a look at that Primatte again and we're

going to go back up to Spill(+).

So Spill(+) will re-add a little bit of the green,

Spill(-) will subtract it so we will start with Spill(+).

I'm going to add just a little bit, make sure the eyedropper is selected.

Ctrl+shift+left mouse button and drag.

We've added a little bit be careful 'cause it's a little bit

steppy down here so it's a good happy medium.

Oh, it looks like we've added too much back to our character so Spill(-).

Just a little bit, get rid of that up in there.

Going to get rid of just a little bit more, let's just double check in there.

There we go.

It's a happy medium between the two so we have no green.

This is it again, previously all green.

This it revised and this was it before we revised it so it's a great way to

retain our alpha while also modifying the despill separately.

Let's just turn those off in all of our examples and take a look.

And it's retained our alpha.

It's great despill mix in with retaining the alpha channel.

Now that we've gone through each one of those steps,

or at least the major steps,

let's take a look at a way that we can automate some of these

particular steps in the workflow to work ahead.

So over to our last example,

I am going to view my regular image and view this Primatte tool.

We've already gone through Actions operation,

now we're going to go up a little bit further in the

property bin and go to Initialize algorithm,

Auto-Compute.

There are three different options here.

There's the Primatte, Primatte RT+ and RT.

Now the Primatte is the heaviest of the three and it has the most flexibility.

Primatte RT+ is the second best.

It's a little bit faster than the Primatte RT but it has a little bit less

features so it struggles with backing colors with little saturation and it

doesn't support complementary colored despill so it's not as great as the

Primatte but still better than the Primatte RT.

So, what is a complementary color?

Let's take a look at an example here.

So,

here's your grade tool and I'm going to open up the

color wheel here so Ctrl+shift+click, we have our color wheel.

You will see here is our greenscreen kind of area or range and the

opposite of it is the complementary color which is magenta.

That's why our despill was turning a little bit more magenta.

The more magenta you add, the more it will basically, neutralize the green.

So back to our image here.

Deselect our grade tool.

Here is our Primatte, let's take a look at the result of the Auto-Compute.

And there we go there.

It's doing something funny so let's take a look at a brand new one from scratch.

Here's our Primatte tool, pull a brand new key.

We're going to say, view it here and say Auto-Compute.

That's a little bit more what we're looking for.

It is keeping some information in the backing region as well in our alpha.

Now you will notice that it goes down to the third option.

We can go back an option and clean up that BG noise and so forth so it's

really meant to be a starting point with our tool.

Now the next one is we've pulled a key with the Primatte

RT so let's take a look at that one.

So Primatte RT and it's rid of all the information the backing region

and it's created a nice and solid alpha down here.

99.

99% solid alpha.

The last example here is the Primatte RT so that is the fastest of

the three and let's take a look at those results.

It's having some problems with this here.

It's adding some alpha back to where our despill was

really intense so it does work.

I would say that probably the second one in this example,

for going through simple keys at least,

is the best option of the three but sometimes you will

find that a mixture or just try different settings and you

may get better results so try, try again.

If you don't get the right key the first time add another keyer,

try a slightly different order of operation and you should

be able to get a good mixture between the despill and

creating a really great alpha.