Remove a background

Select a video or image clip on the timeline and open the Inspector’s Video tab, Basic section. Scroll to Remove background. It has three modes.

Auto removal

1. Open Remove background and pick Auto removal.
2. Set Subject to Auto, Person or Object. Person uses a model trained on people; Object keeps the one thing the picture is of.
3. The row reads “Fetching the model… N%” the first time (15 MB for Person, 179 MB for Object; see the AI models), then “Finding the subject… N%”.
4. Adjust Feather to soften the edge.

Auto removal keeps what the model finds and drops the rest. If nothing is found the clip shows as shot and the panel says so: try another subject, or custom removal.

Custom removal

Custom removal starts from the same mask and takes corrections you paint on the monitor:

• Smart brush adds the thing under your stroke, Smart eraser removes it. Both are model-aware, so a loose stroke is enough. The first use fetches the brush model (about 40 MB).
• Brush and Eraser paint the mask directly, pixel by pixel, for the places the smart tools miss.
• Size and Feather set the stroke. The panel counts your strokes.
• Click Apply to end painting.

Strokes draw on the stage in blue (keep) and red (erase) while you paint.

Chroma key

Shot on a real green or blue screen? Pick Chroma key, click the Color swatch and pick the screen colour from the picture, then tune Similarity, Softness and Spill (spill suppression cleans the green fringe off hair and edges). Green Screen and Blue Screen on the Effects page are the same thing pre-keyed to that colour.

What goes behind

The cut-out clip has nothing behind it, so put the new background on a lane below it. Any picture or video works; so does a shape from the Stickers page, or nothing, for a title card.

If Concat closed during a removal

The smart brush and the automatic cutout start by themselves whenever a clip’s mask is still to be worked out, including when a project opens. In 0.2.7, a removal that closed the app part way through started again on every open and closed it again, so the project could not be opened. From 0.2.8 the project opens: that stroke or cutout is skipped and a notice says so once. To retry, turn the cutout off and on again, or undo the stroke and paint it again.

0.2.8 also fixes two Windows crashes: an automatic cutout that fell from the person model to the object model, or a timeline using both, could close the app on its second removal. And a stroke painted on a stabilized clip lands where the brush was.

Enhance

Next to Basic, the Enhance section restores and enlarges a clip’s picture with a small model (5 MB). See Enhance.