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Working with Masks in Adobe After Effects CS5

Article Description

This excerpt from Adobe After Effects CS5 Classroom in a Book shows you how to create a mask using the Pen tool, edit a mask, feather a mask edge, create a vignette, and more.

Creating a mask with the Pen tool

The computer screen currently contains a word-processing document. To replace it with the news promo, you need to mask the screen.

  1. Press the Home key, or move the current-time indicator to the beginning of the time ruler.
  2. Zoom in to the Composition panel until the monitor screen nearly fills the view. You may need to use the Hand tool (hand-tool.jpg) to reposition the view in the panel.
  3. Select the Pen tool (pen-tool.jpg) in the Tools panel. The Pen tool creates straight lines or curved segments. The monitor appears to be rectangular, so you’ll try using straight lines first.
  4. Click the upper-left corner of the monitor screen to place the first vertex.
  5. Click the upper-right corner of the monitor to place the second vertex. After Effects connects the two points with a segment.
  6. Click to place a third vertex in the lower-right corner of the monitor, and then click to place a fourth vertex in the lower-left corner of the monitor.
  7. Move the Pen tool over the first vertex (in the upper-left corner). When a circle appears next to the pointer (as in the middle image below), click to close the mask path.
4. Editing a mask | Next Section Previous Section