Keyers and hard masks struggle with hair, fur, smoke and glass because their edges are partly subject and partly background. A hard mask has no way to show a strand that is half in and half out. A keyer needs a clean colour to remove, and an ordinary background has none. WispFX predicts the alpha itself, so these edges stay soft, and it works on ordinary footage in After Effects and DaVinci Resolve.
Before you pull
- Pick the subject. Click the subject to add a keep point. Alt-click or right-click to leave something out. You can also type a short description, for example "the dog".
- Click again when the subject changes. If it changes shape or is covered, click it on that frame. Each clicked frame becomes a keyframe.
- Set Edge Room. The default is 4 percent (range 1 to 12). Raise it if wispy hair is cut off. Lower it if nearby objects leak in.
- Choose the preset. Quality needs 24 GB of video memory and is the preset used for the examples on this site. Draft and Balanced run on smaller cards.
Settings for each edge
| Edge or problem | Start with | Notes |
|---|---|---|
| Backlit hair | Quality, Edge Detail 60 to 80 percent, Choke 0 | Raise Edge Detail for backlit hair. Lower it if the plate’s grain shows in the matte. |
| Coloured glow on hair from the old background | Hair Cleanup at its default of 40 percent | Raise it if a glow remains. Set it to 0 to turn it off. |
| Fine fur | Default Edge Room, Feather 0 | Raise Edge Room if fine fur is cut off. |
| Smoke and motion blur | Choke 0, Feather 0 | WispFX keeps blur as soft alpha, and choking cuts it. |
| Glass | Quality, then check the Cutout view | Glass interiors keep faint alpha and the refracted background. Hair Cleanup does not clear them. |
| Liquid | Quality, then check the Cutout view | Liquid is kept on purpose. Check it over the new background. |
| Edges that flicker on a static shot | Stabilize 40 to 70 percent | Stabilize smooths chatter between frames. Real motion is left alone. |
| Dark haze around the subject | Clip Black, 0 to 50 percent | Values at or below the clip point become fully transparent. |
| Coloured spill on hair over a wall or sky | Despill: Edge unmix | Green and Blue screen modes are for real screens only. |
Check the edge
- Use the Alpha view to judge holes and chatter, and Overlay to spot missing hair.
- Use the Cutout view to judge edges, and Wipe to compare with the original plate.
- Judge the edge over the new background, not over black. Light Wrap brings the new background’s light onto the subject’s edge.
- Check a frame of fast motion blur and the fastest movement in the shot.
Limits
- Very sheer fabric can come out more transparent than it should.
- Glass interiors keep faint alpha and the refracted background.
- There is no per-frame spline editing. Click the subject again on a frame where it was lost, or raise Edge Room.
- Windows with an NVIDIA GPU only. There is no Mac build at launch.
When a keyer or Roto Brush is the better start
If the shot was filmed on an evenly lit green or blue screen, start with a keyer. If the subject has a clear edge, Roto Brush or a mask may be faster. The rotoscoping comparison explains how to choose.