Rectangle Mask Node

The Rectangle Mask is the third basic primitive mask. Simple to set up, it covers every need for fixed or animated rectangular areas.

Common use cases: letterbox (black bars), isolating a screen, UI frame masks, rectangular wipe transitions. Corner Radius lets you go from a sharp square to a rounded rectangle, or even a circle (Width = Height + Corner Radius 1.0).

• Effects Library: Tools > Mask > Rectangle
• Quick add: right-click in the Node Editor → Add Tool > Mask > Rectangle

• Effect Mask (blue) - optional. A mask to combine through the Paint Mode.

2.35 cinema letterbox:
MediaIn → Color Corrector (Gain 0) ← Rectangle Mask (Height 0.17, Center Y top)
       + Rectangle Mask (Height 0.17, Center Y bottom, Paint Mode Add)
       → MediaOut

Isolating a TV screen:
MediaIn → Color Corrector ← Rectangle Mask (matching Angle, low Soft Edge)
(localized grading on the screen area)

Rectangular wipe transition:
Clip A → Merge ← Clip B
        Rectangle Mask (Width animated 0 → 1 over 24 frames) as Effect Mask
        → progressive wipe

Center X / Y

Position of the rectangle's center.

Width / Height

Independent dimensions. Equal = a square. Different = a rectangle.

Corner Radius

Corner rounding. 0.0 = sharp corners, 1.0 = fully rounded corners (a pill or a circle depending on Width/Height).

Angle

Rotation of the rectangle around its center.

Level

Mask opacity (0-1).

Soft Edge

Feathers the edges. Selectable filter (Box, Bartlett, Multi-box, Gaussian). Gaussian for quality.

Solid

Filled or outline only.

Border Width

Outline thickness when not Solid.

Invert

Inverts the mask.

Paint Mode

See the dedicated section.

When an Effect Mask is connected, the Paint Mode controls how they combine:

Merge

Standard alpha-based blend.

Add

Adds the two masks together (combined areas become more opaque).

Subtract

Removes the incoming mask from the rectangle.

Minimum / Maximum

Takes the lower / higher value of the two masks, pixel by pixel.

Average

Average of the two masks.

Multiply

Multiplies the two masks (intersection).

Replace

The incoming mask fully replaces the rectangle.

Invert

Inverts the combined mask.

Copy / Ignore

Copy just passes the incoming mask through. Ignore uses only the rectangle.

• Cinema letterbox - two Rectangle Masks (top/bottom) combined to create 2.35 or 2.39 cinema black bars.
• Isolating a screen / monitor - a Rectangle with an adjusted Angle to match a screen shot at an angle. Localized grading on the screen content.
• Animated rectangular wipe - Width animated from 0 to 1 = a reveal bar sweeping across the screen. A classic motion graphics transition.
• UI card / button masks - Corner Radius + Rectangle Mask = a UI card mask to apply effects (background blur, color tint) only inside the card.
• Localized grading area - isolate a rectangular zone (architectural window, sign, painting) for targeted grading.
• Safe area overlay - a Rectangle Mask with Invert to show the broadcast safe areas over a shot (monitoring).
• Mask for a corner pin target - a Rectangle used as the source area for a Planar Tracker or Corner Positioner.

• Corner Radius for a modern UI - 0.1-0.2 gives a contemporary UI look (Material, iOS). Corner Radius 1.0 = stadium/pill.
• Low Soft Edge for precision, high for soft rectangular vignettes.
• Angle for tilted shots - if you mask a screen shot at an angle, Angle lets you align the rectangle without switching to a Polygon.
• Animated Center Y for a descending bar - a wide Rectangle Width + a thin Height + an animated Center Y = a horizontal bar sweeping vertically.
• Add Paint Mode for a letterbox - two Rectangle Masks combined with Add (top + bottom) give you a letterbox in one clean chain.
• Invert to reveal only the rectangle - when you want the effect only inside the rectangular area (and not the rest), depending on the use case.
• For very complex rectangles (multiple corners, custom cutouts), prefer a Polygon Mask or several combined Rectangle Masks.