5.5

855Motion User Guide
• Add: Removes all pixels from areas outside the mask shape. Each new mask adds
more transparency, letting more of the underlying image show through. The Add
blend mode (the default for new masks) is useful for adding back regions of an
image that other masks are cutting out or when masking multiple areas that do
not intersect in a single image. In the following example, both the rectangle and
circle masks remove areas outside of the mask shapes, revealing the underlying
black canvas.
If the layer contains an alpha channel, a mask set to Add mode reveals only the
masked section of the original alpha channel.
Note: To display the rest of a masked layer so you can trace it to create a second
mask, turn off the first mask in the Layers list or Timeline. The outline of the first
mask remains visible, even though it’s no longer affecting the layer’s transparency.
• Subtract: Removes all pixels from the area inside the mask shape, effectively
punching a hole in the image. In the following example, the rectangle and circle
masks punch a hole through the blue gradient object, revealing the underlying
black canvas.