Masking & Cutouts

Masks let you control exactly which part of a clip is visible, opening up creative reveals, subject isolation, and clean compositing. This guide covers shape masks, track masks, and alpha channels — the core tools for cutting footage with precision.

1. What a mask does

A mask defines a visible area within your frame — everything inside the mask shape shows the clip, everything outside is hidden (or vice versa, depending on how it's set). This is different from cropping, since masks can be animated, moved, and shaped freely rather than being a fixed rectangular cut.

2. Adding a basic shape mask

In CapCut, select your clip, go to the Mask tool, and choose a shape — circle, rectangle, star, or a custom linear/mirror mask. Drag the shape's handles to resize and reposition it over the area of the frame you want visible. This is useful for spotlighting a specific subject while dimming or hiding the rest of the frame.

3. Animating a mask for a reveal effect

Combine a mask with keyframes to build a reveal — starting small and expanding to fill the frame, or wiping across the screen. Keyframe the mask's size or position at the start of the clip, then keyframe a different size/position later in the timeline. CapCut will animate the mask shape smoothly between the two points, creating a wipe or expanding-reveal transition.

4. Using track masks to combine two clips

A track mask uses one clip's shape or luminance to control the visibility of another clip layered above or below it — commonly used for text-shaped video fills, or using a shape as a "window" into a second clip. In CapCut, stack your two clips, select the top clip, and look for a masking or blend mode option that lets it reveal only through areas defined by the layer beneath it.

5. Working with alpha channel footage

Some effects and overlays (like transition packs or animated graphics) come as alpha channel files — footage with built-in transparency, rather than a solid background. When importing this type of overlay, CapCut typically auto-detects the alpha channel format (e.g. .mov with alpha), letting it composite directly over your footage without needing a green screen or manual masking.

6. Feathering mask edges for a natural blend

A hard-edged mask can look artificial, especially around organic shapes like a person's silhouette. Most CapCut mask tools include a "Feather" slider — increasing this softens the mask's edge, blending the transition between visible and hidden areas so cuts don't look like a sharp cutout. Use a small amount of feathering by default, and increase it further for stylistic soft-focus effects.

Common mistakes to avoid

• Hard mask edges: unfeathered masks often look pasted-on rather than integrated.
• Overcomplicating simple shots: masking effects work best when used purposefully — not every clip needs one.
• Ignoring mask animation timing: a reveal mask that moves too fast or too slow relative to the music can feel disconnected from the edit's rhythm.

Once masking feels intuitive, the next step is learning how to remove and replace backgrounds entirely using green screen and chroma key — covered in the next tutorial.