The Roto Brush is a tool designed to help you quickly isolate elements and cut them out from their background.

In this example, we're going to cut out this yellow flower with a bee on top from its background and superimpose it over top of this title animated background that I've already created.

So, I'll start by making sure Layer 1 is visible in the Timeline and I'll move my Current Time Indicator to frame 0.

Then I want to make sure I'm working at full resolution, so I'll click on my dropdown here and make sure I'm set for Full resolution here and then I'll click on this dropdown on the right to make sure that its setting is Off (Final Quality).

Then I'll double click on Layer 1 to open it up in the Layer panel.

Now just so I can see the entire video file.

I'll go ahead and click on the magnification dropdown and tell it to fit to 100%.

Now we can grab the Roto Brush tool up here out of the tool part and rather than clicking and trying to select the edges, I'm just going to click and draw inside the flower and once I've done that, you'll see a pink purple selection around the edge of my flower, and it's selected too much of the image down here.

So, I'm going to hold down Alt on Windows or Option on the Mac and I'll click outside the selected area with my red cursor and I'll click and drag over top of the areas I want to deselect and then I'll let go and you can see it's done a pretty good job selecting the flower here.

Now once you've drawn the initial Roto Brush selection, you want to pay attention to this area here.

This is the span, and this is the span of frames where it's going to apply the Roto Brush which is currently only 20 frames.

Now, even though this clip is 5 seconds long I'll just focus on the first 2 seconds for this video example.

If you want to do the full 5 seconds yourself, you can.

But I think you'll understand the it just pretty quickly when we do the first 2 seconds here.

So, I'm going to hover over the right side of my span and click and drag until it crosses over the 2 second area.

Then I'll press the Spacebar and watch the selection actually be generated over multiple frames.

Now I'll press the Spacebar to stop playback and I want to tell you if you're ever noticing problems with the selection you can step through frames by using the number 2 to move one frame at a time down the Timeline or 1 to move back up the Timeline.

I'm seeing an issue right here so I'm going to go back to the beginning which is frame 0 and I'll start this process over again, but I need to fix this one area so I'm going to zoom in by pressing the . key and then I'll hold down Alt on Windows or Option on the Mac and I'll just go over this one little area here and now it's properly selected the petals.

If you need to change the size of the brush you can hold down Control on Windows or Command on the Mac and click and drag up or down to make the brush larger or smaller.

Now I'll zoom back out again just by pressing the , key and then I'll go ahead and press the Spacebar to analyze the full 2 seconds.

Notice as the analysis is happening it's doing a really good job of isolating the selected area.

Once it gets through my span I'll go ahead and press the Spacebar to stop playback.

Now just to make sure my work area is set to 2 seconds I'll move my Current Time Indicator to 2 seconds in the Timeline and press N to set the end of my work area.

Now let's go back to the Composition panel and you can see we've successfully isolated the flower. to make adjustments, I'll go to my Effect Controls panel here and I want to shift the edge in, so I'll click and drag on the Shift Edge parameter and I'll just have it crop in all the way around the edges just a little bit and then I want to position this flower to the left.

So, I'll select Layer 1 and press P to open the Position and I'll scrub on the X parameter to position this off the left-hand side.

Now when we go ahead and preview our animation you can see I've got my animated title underneath my isolated flower.

Now to make the flower pop off the background a little bit more, I'll press the Spacebar to stop playback.

Select Layer 1, go to my Effects and go to Perspective and choose Drop Shadow.

Then I can increase the Softness of my shadow and add a little bit of distance.

Now when I scrub through not only do I have the isolated element, but I have a nice little drop shadow to add a little bit more pop.

And all of the selection and isolating was made possible by using the Roto Brush.