Motion Design – Masks, Mattes and Transparency

In After Effects there are many ways to mask. You can mask a layer with a path, or another layer or with transition effects. You also can use Lightness/Color/etc. to add transparency to other layers.

Layer Mask

  • directly applied to layer
  • moves, scales, rotates with layer
  • layers can have several masks that can be combined in an additive or subtractive way
  • defined by paths
  • mask path can be animated
  • edge can be feathered
  • it’s fixed to the layer and will transform with it

Track Matte

  • separate layer acts as matte/mask
  • does not move or scale with masked layer but can be parented
  • can use alpha OR luma
  • both also inverted
  • matte layer can be animated separately
  • only one matte per layer and vice versa

Set Matte effect

  • separate layer acts as matte/mask
  • can therefore be applied multiple times and to multiple layers
  • can use alpha, luma, color channels, etc. for matte
  • matte layer can not be animated separately
  • hard to understand because matte transforms with layer if applied to a Pre-Comp or Solid and collapse transformations is off and does not transform with layer if applied to a Shape Layer or if collapse transformations is on

Stencil Alpha

  • masks ALL layers underneath in a comp
  • layers above are not affected
  • to get a background you’ll need to precomp eveything

Preserve Underlying Transparency

  • layer will only be visible where anything is already in any layer underneath
  • only works in Comps without background layer