Masking & Keying
Stackable masks, feathering, and a real GPU chroma keyer
Masks in ReelM stack. Draw an ellipse, subtract a rectangle from it, intersect the result with a polygon — each with its own feather, expansion, rotation, and opacity, all animatable.
- Shapes
- 5
- Combine modes
- add · subtract · intersect
- Coordinates
- Normalised (resize-safe)
- Keying
- GPU chroma
- Keyframes
- Supported
[How it works]
Masking & Keying in three moves
Draw the shape
Rectangle with corner radius, ellipse, freeform polygon, split, or filmstrip — placed in normalised coordinates so it survives a resize.
Combine and refine
Stack more masks and set each to add, subtract, or intersect. Feather the edge, expand or contract it, invert it, rotate it.
Key what's left
For green screen, the chroma keyer runs on the GPU with similarity, smoothness, and spill suppression you can tune per clip.
[Under the hood]
Built to be used, not just demoed
The details that separate a party trick from a tool you reach for daily.
Stacked, ordered masks
Masks are a list, not a single shape. Reorder, duplicate, and toggle each one independently.
Feather and expansion
Soften an edge in pixels, and grow or shrink the shape without redrawing it — the two controls a hard mask always needs.
Animatable
Mask properties are registered as keyframeable, so a mask can travel, open, or tighten over a shot.
Real colour keying
A GPU colour key, not a filter approximation — pick the key colour and tune similarity, smoothness, and spill suppression.
Blend into the stack
Combine masking with the eleven blend modes to composite over footage instead of just cutting a hole in it.
[The full inventory]
Everything in Masking & Keying
NO MARKETING ROUNDING. THESE ARE THE ACTUAL NAMES IN THE APP.
Mask shapes
Per-mask controls
Chroma key
- Key colour
- Any colour, picked per clip
- Similarity
- 0 – 1
- Smoothness
- 0 – 1
- Spill suppression
- 0 – 1
- Execution
- GPU, at preview and render
[ReelMy · agent surface]
Ask for it instead of clicking it
ReelMy can place and tune masks and keys directly — useful for "key out the green and feather the edge" in one turn.
All 79 tools[Questions]
Masking & Keying, answered
Not yet. Today's keyer is a real GPU chroma key, which is the right tool for a green screen. AI matting for arbitrary backgrounds is on the roadmap.
Yes. Mask geometry is stored in normalised coordinates, so switching a project from 16:9 to 9:16 doesn't scramble your shapes.
[Launching July 22, 2026]
Your next reel is one prompt away
Get early access before July 22, 2026 — no card, no watermark. The moment it lands, ReelMy cuts the first pass while you grab coffee, then you take the timeline as far as you want.