Edit a Magnetic Mask in Motion

After you apply a Magnetic Mask to a clip, you can make detailed adjustments using tools in the Inspector or canvas. You can also use the Timeline to view, navigate, or delete reference frames indicating points in the clip where the mask was edited.

Refine a Magnetic Mask selection

In the Layers list or Timeline in Motion, select an applied Magnetic Mask, then position the playhead at a point within the clip that shows the area to be masked.
In the Magnetic Mask Inspector, click the Select Objects button .
Do any of the following:
- Add or remove areas from the mask with selection tools: Click the Add or Remove button in the Selection Tools row, then click an area in the canvas to add to or remove from the mask.
  In the canvas, additional control points are shown to indicate areas added or removed from the mask, and a reference frame is added to the Timeline.
- Add or remove areas from the mask with touch-up brushes: Click the Add or Remove button in the Touch-up Brush Tools row, then drag across an area in the canvas to add or remove it. To adjust the size of the brush, drag the Brush Size slider in the Inspector.
  Areas are added or removed from the mask based on the size of the brush and the brush strokes, and a brush tool edit (a white dot) is added to the Timeline.
  Tip: To switch between eyedroppers or brushes temporarily, press and hold the Option key as you click or drag in the canvas. When you release the Option key, the tool reverts to the previously active eyedropper or brush.
  Tip: To see the size of the brush tool while you resize it, hold down the Shift key and drag in the viewer.
- Soften the edge of the entire mask: Drag the Feather slider.
  Positive feathering values soften the mask from its edge outward; negative values soften the mask from its edge inward. Feathering the edge of a mask can make the isolated object blend more easily with the background.
  To specify whether the touch-up brush affects the mask before or after feathering, click the Apply Brushes pop-up menu, then choose Before Feather or After Feather.
Optional: To remove a mask (including any control points, brushstrokes, and analysis data) for a frame, click the Reset Frame button .

When you add control points, new reference frames are created. To navigate between reference frames, click or in the Inspector. To view reference frames in the timeline, see Edit Magnetic Masks in the Timeline.

Invert a Magnetic Mask

By default, a Magnetic Mask isolates people or objects from the background. You can quickly invert a mask—swapping its solid and transparent areas, to remove people or objects from the background rather than isolate them.

In the Layers list or Timeline in Motion, select an applied Magnetic Mask, then position the playhead at a point within the clip that shows the masked area.
In the Magnetic Mask Inspector, click the Show Result button , then select the Invert Mask checkbox.

Change the blend mode of a Magnetic Mask

In the Layers list or Timeline in Motion, select an applied Magnetic Mask, then position the playhead at a point within the clip that shows the masked area.
In the Magnetic Mask Inspector, click the Show Result button .
Click the Mask Blend Mode pop-up menu, then choose Add, Subtract, Replace, or Intersect.
Mask blend modes determine how a mask interacts with the clip’s alpha channel. See Mask controls in the Inspector.

Edit Magnetic Masks in the Timeline

When you add a Magnetic Mask to a clip, the Motion Timeline shows rendered analysis ranges, reference or analysis frames containing control points, and frames containing edits made with the touch-up brushes.

In the Motion Timeline, do any of the following:

Choose a mask to display in the canvas and Magnetic Mask Inspector: Click an analyzed frame range (the light gray bar below a Magnetic Mask timebar).
Remove a mask (including any control points, brushstrokes, and analysis data) for a single frame: Double-click a reference frame indicator, then click Reset Frame.

See Intro to the Timeline.

See alsoMask a layer in Motion

Download this guide: PDF

Helpful?

Motion User Guide

Edit a Magnetic Mask in Motion

Refine a Magnetic Mask selection

Invert a Magnetic Mask

Change the blend mode of a Magnetic Mask

Edit Magnetic Masks in the Timeline