How to Create a Mask Layer in After Effects

Introduction

Mask layers in After Effects allow you to control the visibility of elements by cutting out specific areas of a video, image, or shape. This technique is useful for creating reveals, transitions, and blending effects. In this guide, you’ll learn how to create a mask using shape layers and track mattes.

Step 1: Open Your Project

Launch After Effects and open your existing project or create a new one. Make sure you have the video, image, or shape layer you want to mask in your timeline.Step 2: Create a Shape Layer

Select the Shape Tool (Q) and draw a shape over the area you want to use as a mask. Ensure the shape layer is above the layer you want to mask in the timeline.Step 3: Apply Track Matte to the Layer

Click Toggle Switches/Modes at the bottom of the timeline. In the Track Matte column of the video or image layer, select Alpha Matte (if you want to use the shape’s transparency) or Luma Matte (if you want to use brightness values for masking). This will make your shape layer act as a mask. Step 4: Pre-Compose for Better Organization

To keep your layers organized, select both the masked layer and the shape mask layer, then go to Layer > Pre-compose. Name the pre-comp and select Move All Attributes into the New Composition to keep the mask effect intact.

Step 5: Import and Add a Background

If you want to add a new background, import a video or image and place it below the pre-composed layer in the timeline. This will ensure the mask reveals the foreground while the background remains visible.Step 6: Experiment with Blend Modes

To enhance the effect, select the pre-comp layer and try different Blend Modes like Overlay, Screen, Multiply, or Hard Light from the Modes dropdown. This will help blend the layers more naturally.Step 7: Preview the Animation

Press Spacebar to preview the animation. Adjust the mask shape, feathering, or opacity if needed to achieve the desired effect.Step 8: Render the Final Output

Once satisfied, go to Composition > Add to Render Queue, set your preferred render settings, and export your final animation.

Conclusion

By using shape layers and track mattes, you can easily create custom masks in After Effects. This technique is useful for transitions, text reveals, and dynamic visual effects.