Adjustment layers

When you apply an effect to a layer, the effect applies only to that layer and no others. However, an effect can exist independently if you create an adjustment layer for it. Any effects applied to an adjustment layer affect all layers below it in the layer stacking order. An adjustment layer at the bottom of the layer stacking order has no visible result.

Because effects on adjustment layers apply to all layers beneath them, they are useful for applying effects to many layers at once. In other respects, an adjustment layer behaves like other layers; for example, you can use keyframes or expressions with any adjustment layer property.

Note: A more accurate description is that the adjustment layer applies the effect to the composite created from all layers below the adjustment layer in the layer stacking order. For this reason, applying an effect to an adjustment layer improves rendering performance compared with applying the same effect separately to each of the underlying layers.
If you want to apply an effect or transformation to a collection of layers, you can precompose the layers and then apply the effect or transformation to the precomposition layer. (See Precompose layers.)

Use masks on an adjustment layer to apply an effect to only parts of the underlying layers. You can animate masks to follow moving subjects in the underlying layers.

  • To create an adjustment layer, choose Layer > New > Adjustment Layer, or press Ctrl+Alt+Y (Windows) or Command+Option+Y (Mac OS).
  • To convert selected layers to adjustment layers, select the Adjustment Layer switch for the layers in the Timeline panel or choose Layer > Switches > Adjustment Layer.
Note: You can deselect the Adjustment Layer switch for a layer to convert it to a normal layer.

Andrew Kramer provides a video tutorial on his Video Copilot website in which he shows how to use an adjustment layer to apply an effect to only a short duration and to only specific portions of a movie.

Eran Stern provides a video tutorial on the Creative COW website that demonstrates the use of lights as adjustment layers, to precisely control which layers are affected by which lights.

Lloyd Alvarez provides a script on his After Effects Scripts website that creates an adjustment layer above each selected layer, with each new adjustment layer trimmed to the duration of the selected layer.