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Track Mattes and Traveling Mattes

You set up a Track Matte when you want one layer to show through holes defined by another layer. 

A Track Matte can be a still image, a video, a graphic, text, or a shape. For example, you can use a text layer as a Track Matte for a video layer to allow the video to only show through the shapes defined by the text characters. The underlying layer (the fill layer) gets its transparency values from the values of certain channels in the Track Matte layer—either its alpha channel or the luminance of its pixels.

Defining the transparency of a layer based on the luminance of the Track Matte's pixels is useful when you want to create a Track Matte using a layer without an alpha channel or a layer imported from a program that can’t create an alpha channel. In both cases—using alpha channel mattes and luminance mattes—pixels with higher values are more transparent. Usually, you use a high-contrast matte so that areas are either completely transparent or opaque. Intermediate shades should appear only where you want partial or gradual transparency, such as along a soft edge.

If you animate the position or other transformations of the Track Matte layer, it’s called a traveling matte. If you want to animate the Track Matte and fill layers using identical settings, consider precomposing them.

Example of Track Matte

mask-mode-original-masks

 Track Matte layer set to Luma Matte.

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Fill layer with a pattern effect.

Result: The pattern is seen in the shape of the Track Matte. This is then composited over an additional image layer.

Convert a layer into a Track Matte

Any layer in your composition, no matter where it sits in the layer stack, can be used as a Track Matte source for any other layer. You can even have multiple layers all reference a single layer for their matte. You can also use the matte layer’s Alpha or Luma channels and invert them if necessary.

The Track Matte menu shares a column with the blending modes menu. To show the Track Matte menu, make sure that the Modes column is visible. Learn more Columns in After Effects.

Select Track Matte layer

  1. In the Timeline panel, identify the layer you want to use as the Track Matte layer.

  2. Select the layer you want to use the Track Matte on.

  3. In the Modes column, use the Layer List dropdown to pick which layer you use as a Track Matte, or use the pick whip to set which layer you use as a Track Matte source.

    Petua:

    If the Modes column isn't visible, right-click anywhere in the timeline header area >  Columns > Modes.

    The Layer List dropdown to pick which layer you use as a Track Matte.
    The Layer List dropdown to pick which layer you use as a Track Matte.

  4. Two toggle switches get enabled when a layer is selected as a Track Matte. You can use these switches to define transparency for the Track Matte:

    Alpha Matte

    Opaque when the alpha channel pixel value is 100%

    Luma Matte

    Opaque when the luminance value of a pixel is 100%

    Alpha Inverted Matte

    Opaque when the alpha channel pixel value is 0%

    Luma Inverted Matte

    Opaque when the luminance value of a pixel is 0%

    Track Matte Alpha / Luma toggle and Non-Inverted / Inverted toggle.
    Track Matte Alpha / Luma toggle and Non-Inverted / Inverted toggle.

    Nota:

    Although the video is turned off for the matte layer, you can select the layer to reposition, scale, or rotate it. Select the layer in the Timeline panel, and then drag the center (indicated by a circle with an X) of the layer in the Composition panel. By default, when a layer gets selected as a track matte, the visibility of the track matte layer gets off, but if you still want to use it in your composition, you can turn it back on.

    Using a Track Matte is similar to using the Preserve Underlying Transparency option, which causes a layer to get its transparency from the transparency of the composite of the layers below it in the layer stacking order. Learn more about the Preserve Underlying Transparency feature.

    • Use the Levels effect to increase the contrast between light and dark parts of the matte layer. This reduces the problem of having many mid-range values, which translates to partial transparency. (Usually, mattes are most useful when defining areas as entirely transparent or opaque, except at the edges.)
    • To use a channel other than the alpha channel of the matte layer as a matte, use one of the Channel effects (such as the Shift Channels effect) to route the desired channel's value into the alpha channel.
    • To animate a Track Matte to move with the layer that it's matting, make the Track Matte a child of the layer it's matting. Learn more about parent and child layers.

    Preserve underlying transparency during compositing

    The Preserve Underlying Transparency option causes a layer to get its transparency from the transparency of the composite of the layers below it in the layer stacking order. In other words, with this option selected, the opaque areas of the layer appear only when positioned over opaque areas in underlying layers. This option is useful for creating results such as glints or light reflecting off a polished surface.

    The behavior of a layer with the Preserve Underlying Transparency option selected is similar to the behavior of a clipping mask in Adobe Photoshop.

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