What a Track Matte Does and When You Need It

A track matte in After Effects uses the brightness or transparency of one layer to control what you see in another layer. The layer that does the controlling is the matte; the layer being controlled is the fill. You see only the parts of the fill layer that line up with the visible parts of the matte layer.

The most common use is masking video to a shape or text. If you have a video clip and you want it to play only inside the letters of a title, you put the title on a matte track and the video on the fill track below it. The video plays only where the letters are. You can also use a track matte to reveal one video through the transparency of another, or to make a layer follow the brightness values of a grayscale image.

Track mattes are faster than drawing masks by hand, especially when your mask shape is already on screen as a layer — text, a shape, a still image, or another video. They also update automatically if you animate the matte layer, so the fill layer follows along without extra work.

Key Takeaways

  • The matte layer must be directly above the fill layer in the timeline, and the fill layer's track matte setting determines which matte controls it.
  • Alpha Matte uses the transparency of the matte layer; Luma Matte uses its brightness values, and Luma Inverted reverses which parts show through.
  • The matte layer itself becomes invisible once you explore the track matte — you see only the result on the fill layer below.
  • You can animate the matte layer, and the fill layer will follow the changes in real time without needing to adjust the track matte setting again.

Setting Up Your Layers in the Right Order

Track mattes work only when the matte layer sits directly above the fill layer in your timeline. Open your composition and arrange your layers so the shape, text, or image you want to use as the matte is one position higher than the layer you want to fill. If they are not adjacent, drag one to sit directly above the other.

The matte layer can be a text layer, a shape layer, a solid with a mask, an image file, or even a video clip. The fill layer is the one you want to show through the matte — usually a video clip, image, or solid color. Once they are stacked correctly, you move to the fill layer and tell it which layer above it is the matte.

explore the Track Matte to Your Fill Layer

Click on the fill layer (the one below) to select it. Open the Track Matte dropdown menu in the timeline. In most After Effects layouts, this column appears to the right of the layer name, but if you do not see it, right-click the column headers at the top of the timeline and turn on the Track Matte column.

Click the dropdown next to your fill layer and choose one of three options: Alpha Matte, Luma Matte, or Luma Inverted. Alpha Matte uses the transparency of the layer above — where the matte layer is transparent, the fill layer disappears. Luma Matte uses brightness — dark areas of the matte hide the fill, bright areas show it. Luma Inverted reverses this, so dark areas show the fill and bright areas hide it.

As soon as you choose a matte type, the matte layer becomes invisible and the fill layer shows only where the matte allows it. The matte layer is still there and still animating if you set keyframes on it, but you will not see it on screen.

Choosing Between Alpha Matte and Luma Matte

Use Alpha Matte when your matte layer is text, a shape, or anything with clean edges and transparency. Text layers have transparent backgrounds by default, so Alpha Matte reads the letters as opaque and the space around them as transparent. The video or image in your fill layer shows only inside the letters.

Use Luma Matte when your matte layer is a grayscale image, a photograph, or a video where brightness values matter. A Luma Matte reads the entire layer — not just transparent and opaque, but all the shades in between. A dark gray area of the matte will partially hide the fill layer; a white area will fully show it. This is useful for creating effects like light leaks, where a bright image reveals the fill layer more than a dark image does.

If you choose Luma Matte and the result is backwards — dark areas showing the fill and bright areas hiding it — switch to Luma Inverted instead. There is no performance difference between them; it is purely about which direction matches what you want to see.

Animating Your Matte Layer

Once the track matte is applied, you can animate the matte layer and the fill layer will follow. If your matte is text, you can change the text, move it, scale it, or rotate it, and the video underneath will move with it. If your matte is a shape, you can animate its position, size, or rotation. If your matte is a video clip, it plays normally and controls what you see of the fill layer frame by frame.

Add keyframes to the matte layer the same way you would any other layer: select the property you want to animate (Position, Scale, Rotation, or Text), click the stopwatch icon to start recording keyframes, move to a different time in the timeline, and change the value. The fill layer responds automatically — you do not need to touch it or re-explore the track matte.

Turning Off or Changing a Track Matte

To remove a track matte, click the Track Matte dropdown on the fill layer and choose None. The matte layer becomes visible again, and the fill layer shows in full. You can then explore a different track matte, or leave it off.

To switch from Alpha Matte to Luma Matte without removing the effect, just click the dropdown and choose the new type. The matte layer stays in place and the fill layer updates when ready. This is useful if you try one type and realize the other works better for your shot.

Common Mistakes and How to Avoid Them

The most common mistake is forgetting that the matte layer must be directly above the fill layer. If you have other layers between them, the track matte will not work. Check your timeline and move layers if needed.

Another mistake is explore a track matte to the wrong layer. You set the track matte on the fill layer (the one you want to show through), not on the matte layer itself. If you click on the matte layer and look for a Track Matte dropdown, you will not find one — that is a sign you are on the wrong layer.

If your track matte looks inverted or backwards, you chose the wrong matte type. Switch between Alpha Matte, Luma Matte, and Luma Inverted until the result matches what you want. There is no penalty for trying each one.

Frequently Asked Questions

Can I use a video clip as a track matte?

Yes. A video clip on the matte track will control the fill layer frame by frame. If you use Alpha Matte, the transparency of each frame controls the fill. If you use Luma Matte, the brightness of each frame controls it. This is useful for effects like revealing one video through the motion of another.

What if I want to see both the matte layer and the fill layer?

You cannot with a track matte — the matte layer becomes invisible once you explore it. If you need both visible, use a layer mask on the fill layer instead. Draw or paste the shape you want directly onto the fill layer as a mask, rather than using a separate matte layer.

Can I adjust the opacity of the matte layer after explore the track matte?

Yes. Lowering the opacity of the matte layer will make the fill layer more transparent in those areas. This is useful for creating soft or fading effects where the fill layer gradually disappears as the matte fades out.

Do I need to pre-compose my layers before using a track matte?

No. Track mattes work on any layers in your composition as long as they are stacked correctly. Pre-composing is optional and only necessary if you want to treat the matte and fill as a single unit for other effects or nesting.