Original subtitles

In this clip we're going to review what is color spill.

So what exactly is color spill?

Well it occurs when the color reflects off of the back screen or off of the

backing region and casts a noticeable tint on your subject.

Certain areas of your model or, in this case,

the foreground subject, absorb or reflect that color,

which is typically blue or green.

It's kind of like throwing a ball against a wall and the

ball bouncing back off to hit another wall.

In this case, the light bounces off of the blue screen or the green screen,

and then throws its color onto the subject.

So this is a green screen that we're working with,

and let's take a look at what that spill looks like in more depth.

So I have pulled a really quick key over here,

and I'm going to look at it premultiplied against a non-despilled plate.

So here we can see the spill.

It's very obvious here on the edges, where there's transparency,

some over top of these areas which reflecting quite heavily against the

black chair and in the transparent bottle over here.

Let's take a look at what that looks like with a despill.

So again, it's causing some issues on these edges here,

that's where it's most noticeable.

It's working over here in the chair, so that's really great for the despill.

But we can see that it is, again,

the biggest problem with our transparent edges or anything that has motion blur,

reflections, and so forth.

So those are the things to really look out for.

Now there's one other thing that I do want to look at before

we get into just despill in more depth, and that is a spill matte.

So if we take the original image and we despill it,

so this is a temporary despill, and we do a minus operation,

this is what our spill is doing.

So here is an exaggeration of our spill.

I've just cranked up the gamma over here temporarily,

and this is what it looks like.

So we can see, again, this is where the spill's occurring,

on the bottom side of the chair, on the back of the chair,

and on the back of our subject.

And this matte really allows us to push the despill and the color correction of

the backing region and of the spilled regions even further.

So the spill matte, or in some cases it's called a spill map,

can be used to enhance that despill in more complex workflows.

So now that we have a brief overview of what spill is,

let's take a look at some basics of despills in our next clip.