Image Occlusion

Last modified: 09/03/2026

What it does

Image Occlusion (IO) hides parts of an image so you recall the hidden label or structure during review.

Creating an IO card

Using the modal (recommended)

1. Right-click in a note → Add flashcard → Image Occlusion Card.
2. Choose an image from your vault or drag one into the modal.
3. The IO Editor opens with the image on a canvas.
4. Use the toolbar to draw mask regions over the areas you want to test.
5. Optional: click Auto-Mask to detect text regions and create masks automatically.
6. Review and adjust generated masks (move/resize/delete, update group keys).
7. Choose a save mode (Solo or All) and click Save.

Writing in Markdown

Add a card block with an IO field pointing to an image:

T | Anatomy — Bones of the hand |
IO | ![hand_diagram.png](./hand_diagram.png.md) |
G | Anatomy |

After sync, open the IO Editor from review or the Card Browser to add masks.

NOTE

The IO Editor is desktop-only. On mobile, a notice is shown.

IO Editor

The editor opens in a modal canvas.

Toolbar

Tool	Description
Occlusion	Draw new mask rectangles/circles over the image
Auto-Mask	Detect text-like regions with OCR and create masks automatically
Transform	Move or resize existing masks
Delete	Remove the selected mask
Reset	Revert all masks to their saved state

Shapes

Masks can be rectangles or circles.

Auto-Mask (OCR)

The editor includes an Auto-Mask action that uses OCR to detect likely text regions and create masks automatically.

• Works best on clear, high-contrast images.
• Generated masks are editable: you can move, resize, regroup, or delete them before saving.
• If no regions are detected, use manual mask drawing as usual.

Zoom & pan

Use Zoom In, Zoom Out, and Fit to navigate large images. Hold Spacebar and drag to pan across the image.

Groups (mask groups)

Each mask has a group key. Masks with the same group key are revealed together during review.

• Type a key in the group input to assign the selected mask to a group.
• Masks without a group key are treated as individual items.
• During review, grouped masks are hidden/revealed as a unit.

Hide all / Hide one / Group mode

When creating IO cards in the modal, you can choose how masks behave:

Mode	Behaviour
Hide All	All masks are hidden at once — you recall everything
Hide One	Only one mask (or group) is hidden per card — others remain visible
Group	Masks are grouped — each group becomes one review card

Save modes

When saving from the editor, choose one of two modes:

Mode	Button	Behaviour
Solo	Save Solo	Each mask (or group) becomes its own review card — only that region is hidden
All	Save All	All masks are hidden at once and revealed together

Reveal settings

In Settings → Cards, you can configure how IO cards are revealed during review:

Setting	Options	Description
Reveal mode	Reveal All / Reveal Group / Reveal One	Controls how many masks are shown when you reveal the answer

• Reveal All — All masks are removed at once.
• Reveal Group — Only masks in the same group are revealed.
• Reveal One — Only the target mask is revealed.

How cards are generated

• The original IO card block becomes a parent card (not reviewable itself).
• Sprout generates one child card per mask or group (depending on save mode).
• Children inherit the parent's title and info fields.

Review

During review the image is displayed with coloured mask overlays. After revealing, the masks are removed so you can check your recall.

• Click the image to zoom into a full-screen overlay.
• If the source image is missing, an error is shown and the card cannot render correctly.

Settings

Setting	Default	Description
Default IO attachment folder	Attachments/Image Occlusion/	Where IO images are stored
Delete orphaned IO images	On	Auto-delete images when their IO cards are removed

Configure these in Settings → Storage → Image Occlusion.