Onion Skinning in Animation: Read the Ghost Frames

What is onion skinning in animation?

Onion skinning displays neighboring drawings or frames as faint overlays around the image you are editing. It helps you compare positions, proportions and changes without repeatedly switching images. The overlays are references, not automatically created in-between drawings. Check which layer, time range and frame-or-drawing mode your software is showing, then review the actual animation in playback. A convincing stack of ghost images is not proof that the movement works.

The name sounds more culinary than the job. In practice, onion skinning is a way to keep several moments visible while working on one.

This guide concentrates on digital drawn animation. It uses current official documentation, including the Krita manual labelled 5.3.0 and Toon Boom's July 2026 explanation of onion-skin modes. Interface details vary by application and version; the numerical example below is an original planning worksheet, not a claimed software test.

What should you look for in the overlays?

Choose one question before enabling a large range of ghosts. Are you checking the distance between poses, keeping a head the same size, or making sure a hand follows the intended path? Different questions need different references.

For a proportion check, compare identifiable landmarks: top of the head, chin, elbow or the corners of a simple shape. For a position check, make sure the references are being shown in their actual locations rather than temporarily shifted for tracing.

Our timing and spacing guide explains the movement decisions. Onion skinning is a way to inspect those decisions, not a replacement for making them. It cannot decide whether a character should hesitate before reaching or move immediately.

Try limiting the display to the nearest useful earlier and later drawing. Add more only when you can say what information the extra outline supplies. Too many overlapping contours can make the current drawing harder to identify.

How is an onion skin different from an in-between?

An onion skin lets you see a reference. An in-between is an actual drawing or generated pose that belongs in the sequence. Turning on the overlay does not do the drawing work for you.

Krita's animation guide describes a frame-by-frame raster workflow: artists create important poses and draw intervening frames. It identifies the Onion Skin Docker as a viewing aid within that process. Krita: Animation.

Imagine a closed hand in one drawing and an open hand in another. Overlaying them helps you compare the starting and ending shapes. It does not tell you which finger moves first, how the hand turns, or how many intermediate drawings communicate the action.

That distinction also prevents a software misunderstanding. Seeing two faint poses at once does not mean both poses have been combined into the current artwork. Before correcting anything, hide the overlays and inspect the active drawing by itself.

For the larger distinction between drawn and rigged workflows, see 2D versus 3D animation. Here, the immediate task is simpler: identify which visible lines are editable artwork and which are references.

Why do frames and drawings give different results?

A frame is a position in time. A drawing is artwork that can remain visible across several frame positions. An exposure describes how long that drawing is shown.

Toon Boom distinguishes two onion-skin modes. Its By Frames mode examines the animation across frame times, including exposure and interpolated movement. Its By Drawings mode shows individual drawings and omits the intervening keyframe/interpolation states described in its guide. The publisher recommends different modes for different workflows; the word "previous" therefore needs a unit. Toon Boom: frames versus drawings.

If you ask for the previous frame during a held pose, the previous frame may contain the same drawing. If you ask for the previous distinct drawing, the reference can be farther back in time.

This is why a seemingly empty overlay is not always a broken tool. The referenced image may be identical to, and directly under, the current image. Inspect the timeline before changing the artwork.

Can a short timeline make the distinction clearer?

Use this original, hypothetical plan for a small rectangle moving across a canvas. Each drawing has a different horizontal position. The values are chosen for explanation, not copied from a production or measured in an application.

Each drawing occupies four frame positions. The sequence contains twelve displayed frames but only three different drawings. At an assumed playback rate of 24 frames per second, those twelve frames occupy half a second: 12 divided by 24 equals 0.5.

Now inspect frame 5, which displays drawing B:

• One frame earlier is frame 4, also B.
• One frame later is frame 6, also B.
• The previous different drawing is A.
• The next different drawing is C.

The frame-based neighbors in this example do not reveal a change of position because both contain B. The distinct-drawing neighbors do. Their horizontal gaps are 88 minus 40, or 48 pixels, and 160 minus 88, or 72 pixels.

This does not prove the resulting animation is smooth, appealing or correctly timed. It tells you why two range settings can expose different information. The plan intentionally uses holds; it does not include drawings between those three positions.

If you recreate it, write the frame numbers beside your notes and check your application's range rules. Do not assume that every program counts offsets or repeated drawings identically. The arithmetic describes this worksheet, not a universal software-output promise.

How do you keep the current drawing readable?

Use opacity, tint and range to make the reference subordinate to the drawing you are editing. Start with a modest number of references, then adjust visibility until the current image is unambiguous.

The Krita Onion Skin Docker documentation explains separate controls for overall visibility and opacity, opacity at individual offsets, tint strength and previous/next colors. It also identifies the animated-layer lightbulb control. Krita: Onion Skin Docker.

Treat color as a label, not an artistic instruction. If earlier drawings are tinted one color and later drawings another, that helps identify time direction; it does not mean the character changes color in the animation.

Our practical suggestion is to check one side at a time when the image becomes confusing: earlier reference, current drawing alone, later reference. Then restore the combined view. Choose settings you can distinguish comfortably rather than following someone else's preferred color combination.

If you need to compare several poses, first write what you are checking. "Keep the rectangle's height consistent" is actionable. "Make the ghosts look nicer" is not much of an animation brief.

Why might onion skins not appear in Krita?

The Krita manual notes that the layer must be animated and warns that white pixels are not transparency. It also describes restrictions on layers with fully opaque default pixels. A white-filled animation layer can therefore be the wrong starting point for the intended overlay workflow. Krita's layer and transparency guidance.

Before repainting or erasing anything, save a separate working copy. Check that the intended animated layer has frames, its onion-skin control is enabled, and the selected range actually contains useful references. Preserve the original drawing while you investigate.

Also verify what you are editing. Krita's timeline documentation says painting affects the active keyframe, which is not necessarily every selected timeline cell. It distinguishes duplicate frames, which contain separate image data, from clones, which share image data. Editing a clone can therefore affect linked instances. Krita: Animation Timeline Docker.

If several apparent "frames" change together, inspect the active keyframe, held exposure and clone relationship before assuming an onion-skin defect. This is an editing-state question, not a reason to delete a sequence.

Can a ghost image be in a different place from the artwork?

Yes, some applications provide a temporary reference-offset tool. ToonSquid calls its version Out-of-Pegs, also known as Shift-and-Trace. Its handbook explains that this shifts surrounding onion-skin references for comparison without changing the drawings' actual positions in the timeline or export. ToonSquid: Out-of-Pegs.

That is useful for comparing proportions when an object has moved across the screen. It also means you should not measure its real travel from a deliberately shifted ghost.

Before judging spacing, reset or disable temporary reference offsets using the application's documented controls. Then compare the unshifted positions and actual frames. Keep a note if a screenshot was captured with reference offsets active; otherwise another person may mistake a working aid for the animation's geometry.

What should you review after turning the overlays off?

Inspect the current artwork alone, then step through the actual sequence and play it at the intended rate. These are different checks: the single drawing shows its own shape; sequential review shows changes; playback reveals whether those changes communicate in time.

Use a short review note with three headings: what the overlay helped you compare, what you changed in the actual artwork, and what still needs checking in playback. That prevents an elaborate reference setup from becoming the achievement you evaluate.

Watch the shot in context as well. An overlay cannot show whether the preceding cut leaves enough time to understand the action. The animatic guide explains that larger timing test.

For a first exercise, keep the subject to your own simple shape and save the project before making structural edits. No character likeness, studio footage or elaborate scene is needed to learn what the tool is showing. Once the references answer your question, hide them and let the actual drawings do the work.

Sources

• Krita Manual 5.3.0: Animation
• Toon Boom: Frames versus drawings in Onion Skin
• Krita Manual 5.3.0: Onion Skin Docker
• Krita Manual 5.3.0: Animation Timeline Docker
• ToonSquid: Onion Skinning and Out-of-Pegs