Onion skinning
The ghosts of neighbouring frames, what the colours mean, and how to tune them.
Onion skinning shows the frames around the one you are drawing, faintly, in colour, underneath your work. It is named after the translucent paper animators used to stack on a lightbox, and it is the single most useful thing in the workshop.
Without it you are drawing frame 5 from memory. With it you can see exactly where frame 4 left off and put frame 5 the right distance away.
Turning it on
The onion skin button sits in the timeline. O toggles it. It is on by default, and it is hidden automatically during playback.
What the colours mean
| Colour | Meaning |
|---|---|
| Red | Frames before the current one. Where the motion came from. |
| Green | Frames after the current one. Where it is going. |
Colour is what makes a stack of ghosts readable. Without it you cannot tell whether the shape behind your drawing is the past or the future, and that is the only thing you actually need to know.
Settings
The chevron next to the onion skin button opens its settings.
Before and after
How many frames to ghost on each side, from 0 to 3. They are set separately, which matters more than it sounds.
Most of the time you want 1 before and 0 after. You are drawing forward, and the frame you just made is the only reference you need. Reach for more when:
- 2 or 3 before for checking the arc of a movement across several frames, rather than just the last step.
- 1 after when you are drawing an in-between, filling a gap between two drawings that already exist.
- 0 on both when the drawing gets busy and the ghosts turn into noise. This is a real setting and you should use it.
Opacity
How strongly the nearest ghost shows, from 5 to 80 percent. The default of 30 is a reasonable place to sit.
Ghosts further away fade off from there, each one at 55 percent of the brightness of the one before it. So with opacity at 30 percent and 3 frames ghosted, the nearest sits at 30, the next at about 17, and the furthest at about 9. The falloff is what stops three ghosts from reading as one grey smear: distance in time looks like distance in contrast.
Using it well
The habit beginners fall into is turning everything up. Three frames each side at maximum opacity gives you seven overlapping drawings and no idea which is which.
Experienced animators use far less than you would expect, at far lower opacity. The ghost is a reference, not a tracing guide. If you can see it clearly enough to trace it, you will trace it, and your animation will not move.
Two things worth trying:
- Turn it off and check. If the drawing only reads with the ghosts behind it, it does not read.
- Turn it up briefly, then back down. A quick look at three frames of arc is useful. Drawing with three frames of arc up permanently is not.