Using the Roto Brush in After Effects

In today’s post, Jeff, our Adobe certified lead instructor here, at, will show you how to use the Roto Bruh tool in After Effects.

Note: remember to watch the video tutorial Jeff prepared for you.

Let’s start!

That is what we are going to do next. And we will start at changing of the guard here.
This is an easy thing for the Roto Brush tool do. Because the Roto Brush tool works like the quick selection tool inside Photoshop that looks for the edges of something.

The edges can be defined by color differences, by contrast differences, brightness, that kind of stuff. Here at these two guys. That they are green, lime green, fluorescent green things are relatively easy to pick out because the color is so distinct relative to what is around them.

To do this, I am going to make a new comp. I go to my assets here. I’ve got the changing of the guard here and I drag that down to the new comp icon like so.

Create a new comp in AE

To work with the Roto Brush tool, again, because working with a paint tool, we just work on the layer panel, double-click on this layer panel.

Now, you can go to the paint workspace, which has the composition panel next to the layer panel. You can see how your work is going, which is fine. I like the bigger view here, for me, that I can do that as well. I can just make it myself.

I can take this panel, which is the composition panel and drag it out of this frame. Just clicking up here on the name. Just click it out like that to the left, that means it’s going to make a new frame and stir by itself.
That is another way to do this, just so you know.

Here’s the video tutorial:

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What we do work in the layer panel here. I am going to take this guy and put him back in here but it’s dragging this to the left, it puts it inside the same frame.

Now I want to go back to the layer panel. I drag it to the left, make sure my tabs are in the right order. Here we go. I like that order, like composition layer. It’s more comfortable. Now, I want to highlight these guys. I am going to zoom in on them to see them a little bit better.

Hold on to Z Key and zoom.

With the Roto Brush selected, I have this little green circle. That is my brush.
The Roto Brush brush is a green circle with that cross in the middle. That means that you are going to add something to the selection. The way you add something is simply by drawing inside it.

You don’t need to be exact. You just need to say

Find the edges for me.

It did. It found then edges like little pink line there, magenta line [00:02:18] edges. But it missed this part up here because it sees that it’s something different that the brighter color here.
I need the “add” to that. I just brush there. I am telling it

No, include that too.

But then I went a little bit too far there. I am going to zoom in a bit,

Control command plus.


I want to get rid of the bump there. To rid of something that is to take something out of the scene.

Hold on the Alt and the option key

and it changes the brush to an add to a minus. Red minus.

Red minus

Now, drag there and say

I don’t want that little bump.

Sometimes you want to further tell After Effects some other information.

I can  hold on the Alt and the option key and basically say

I don’t want any of this stuff.

And that just further give that additional information saying, “Okay, nothing like that should be in your selection” is what you are telling it, basically.

Someone saying that he worked days fixing things with Roto. It works well but it’s a total pain. Yes, so it’s like being a Disney animator frame by frame. Yes, like I say, the Roto Brush is going to be a fun tool for you to use and the results are not necessarily beautiful. But it’s your way to deal with things like this.
I want to select this guy as well. You can select more than one object in the sane scene. I am going to use the same process. I am going to draw inside him like that. Done it like that and see what happens. Okay.

It picked up this little oddity out there and it didn’t get the rest of the sleeve. I draw down the rest of the sleeve. Here we go. Made too much, I’ll show you that in a second.
The brush is too big, I think. So

hold on to Control command

and drag left to make it smaller and drag down here to have the arm, right? Now we’ve got a pretty good selection. But we don’t let that bump there.

Hold on the Alt and option key

and drag it to get rid of the bump, right?
Hold on the option key to get rid of that odd thing. Who knows how that happened. And then this person’s white, whatever it is there. Hold on the Alt and the option key and get rid of that. Now we have a pretty good selection. That little thing there, I’ll live with it, right? Because we are going to be zoom way out, anyways.
Alright. Now we have this base, this base frame. Let’s go this base frame here. If I pull back forward,

Shift, forward slash,

there they are. You can barely see them in your monitor. Two little maroon things are on those two guys.

When you do that, up here in layer panel, right down here you will see a little orange box

base frame

That is the base frame and to the right of it will be 20 frames that After Effects has already attempted to figure out how that selection is going to work, using some predictions.
If you go up to— You know the effects control panel. You know the Roto Brush and refine edge effect.

Roto Brush Pannel

Under the Roto Brush side of things, there is something called the Roto Brush propagation. This basically, it sets the rules of the propagation, which are way difficult to understand.  If you want to get into the fine details, the Roto Brush, be my guest.

The Help file or the Help, the part of the Help file that comes with After Effects does get with the detail about each of those little points there and you can certainly check into them. But for what we are doing here, most times, you just need to go with the defaults. That is what we are going to do here. Down below here, this refine edge, which we haven’t done yet and we are not going to do in this particular case.

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So to get this 20 frames here, they are based on how you tell it to propagate the frames here. That is what is going on here. What you are going to do is if you think that After Effects is going to get it. Like for four here, it’s going to now go through those frames one at a time. A little green line is showing up here. It is going through. It will show me that result and nothing changed. It’s Perfect. We got those guys perfectly selected.

If you think it’s not going to be a problem, you can take these little Vs. One side of the base frame the Vs go away from it and on the other side the Vs go in this direction. You can drag them all the way to the beginning and the end, depending on where you are starting.

I can take this guy here and drag it all the way at the end like a because I am sure that After Effects is going to get this right. Then I can take my current indicator and go to the end and have it go through the whole darn thing and work to create frames all the way there just to confirm that it’s working right and to save those frames.

I am going to stop it by taking my current indicator back here. I am letting this go into that point so I don’t take a lot of time doing that.

Once it selected the frames properly, which it’s going to do here. You can’t miss the green jackets there. You can then freeze them, which then saves them.

Because if you were to go to work on something else and come back with this, you need to go through the same process of playing through it again, to restore those frames.

If you freeze them and then it goes through a process of freezing them, which takes awhile saving every single darn frame and like a preview video file. I am going to click Stop and it takes awhile to do that. Then I’ll unfreeze it to go work on it again and that is how the process works. Now look it’s building it all over again.

This is the basic process to use Roto Brush on something that is really easy to select and how you can take those little- angled things, those little brackets and drag them one with the other to create the Roto Brush for the whole thing. Once you’ve done that, you can play it pretty easily and you have now removed those guys from the background. I go back to this composition panel will be these two things sitting there all by themselves over a transparent background.

Thank you for watching this video. My name is Jeff Sengstack, an Adobe Certified Expert and the Lead instructor here at If you want to watch this entire video lesson, as well as other live classes and After Effects Crash Courses. Then I invite you to check out the BlueFx After Effects Academy. Just click the link below this video to find out what we’ve prepared for you in the After Effects Academy.

Join The After Effects Academy And Get Acces To This Full Lesson + Weekly Live Classes And After Effects Templates

Remus Hosu

Remus Hosu

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