Isolating a person or object in video used to mean a green screen, or hours of manual rotoscoping. Final Cut Pro 11 changes that with Magnetic Mask, a machine learning feature that selects a subject with a click and then follows it through the clip during an analysis pass, with no green screen needed.
Watch the video above for the two-minute walkthrough, then read on for the exact steps, the refinement controls, and where the tool still needs help.
What Magnetic Mask is
According to Apple Support, the Magnetic Mask uses machine learning to isolate people, objects and shapes from the background, and it can then apply that mask to the rest of a clip automatically, without manual tracking or rotoscoping. Adding the effect on its own creates a matte, which removes the background and leaves transparency behind the subject, so it can be composited over a different background using connected clips.
The mask can also control another effect. Apple documents that almost any other video effect can be dragged from the Effects browser and paired with a Magnetic Mask, so the effect applies only where the mask is, rather than to the whole frame.
Step by step: adding and analyzing a mask
Step 1: Add a clip to the timeline, select it, and position the playhead on a frame that clearly shows the subject to be masked. Step 2: Open the Effects browser and find the Magnetic Mask effect; typing “magnetic” in the Effects browser search field is Apple’s suggested shortcut. Step 3: Apply it by dragging the effect into the viewer directly onto the subject, dragging it onto the timeline clip, or double-clicking it.
Step 4: If the subject was not already selected by dragging, click it in the viewer with the Add eyedropper; the mask controls appear at the top of the viewer and in the Video inspector. Step 5: Use the analysis buttons at the top of the viewer to extend the mask through time. Analyze applies it to the entire clip, Analyze Forward and Analyze Backward cover the parts after or before the current frame, and the Previous Frame and Next Frame buttons cover a single frame. Pressing Esc or Command-Period cancels an analysis in progress. Step 6: Play the analyzed section back, make any adjustments, and click Done in the upper-right corner of the viewer.
Refining the selection
A first click will not always catch everything. Clicking again with the Add eyedropper places a green control point and adds that area to the mask. To remove an area, click the Remove button at the top of the viewer and click with the Remove eyedropper, which places a red control point. Holding the Option key temporarily switches between the two eyedroppers. Apple notes that only a handful of control points is usually needed.
For areas that clicking handles poorly, the edit tools also include an Add brush and a Remove brush, brushed across an area to add or remove it, with a slider for brush size. For the edge itself, the Feather slider in the Video inspector softens the mask edge, outward with positive values and inward with negative values, helping a subject blend with a new background.
What it is good for
The most direct use is background work: removing a background, blurring it, or replacing it by compositing the isolated subject over another clip. Because a mask can also govern another video effect, a subject can be colour graded separately from the rest of the frame, and text can sit behind a moving subject. Apple also notes that multiple masks can be applied to one clip, for example one per person, so each can be isolated for colour correction.
Frequently asked questions
Where is Magnetic Mask in Final Cut Pro? In the Effects browser. Typing “magnetic” in the browser search field finds it quickly.
Does Magnetic Mask need a green screen? No. It selects people, objects and shapes in ordinary footage using machine learning, and removing the background leaves transparency that can be composited over another clip.
What does Analyze do? It extends the mask from the frame where the subject was selected to other frames. Analyze covers the entire clip, while Analyze Forward and Analyze Backward cover only one direction from the current frame.
How can a rough mask edge be softened? With the Feather slider in the Video inspector, which softens the edge outward with positive values or inward with negative values.
The bottom line
Magnetic Mask does not remove the need for judgement. Busy scenes, fine hair detail and subjects whose colours sit close to the background can still need extra control points, brush work or feather adjustments after analysis. Apple also advises applying retiming or stabilization before adding masks, and notes the best performance comes on a Mac with Apple silicon. Used within those limits, it turns a job that once took hours of rotoscoping into a click, an analysis pass and a short cleanup.
Editors cutting on the machine Pete edits on can see the MacBook Pro on Amazon to check the current configuration and pricing.