Image occlusion flashcards, without the add-ons

What is image occlusion?

Image occlusion is a flashcard technique where regions of an image are covered with opaque boxes. You study by recalling what's hidden, then revealing it to check. It's the visual version of a fill-in-the-blank card — and for subjects where knowledge is spatial, it beats text cards by a wide margin.

Made for visual subjects

• Anatomy — hide muscle, bone, and nerve labels on figures
• Biology — cover organelles on cell diagrams, stages on cycle charts
• Geography — blank out countries, capitals, rivers on maps
• Chemistry — hide functional groups and reaction steps
• Medicine — imaging landmarks, histology slides, ECG features

How it works in FlashStacks

1. Add an image — create an image card and pick anything from your photo library
2. Draw your zones — drag rectangles over the areas to hide; add as many as you like
3. Tap to reveal — during study, recall first, then tap to uncover and grade yourself

The AI shortcut for diagram-heavy courses

Here's where it compounds: when you generate a deck from a PDF, FlashStacks automatically detects genuine diagrams among your lecture slides and queues them up for occlusion. You draw the boxes; the AI already did the finding. A 40-slide anatomy lecture becomes text cards and occlusion cards in one pass.

Image occlusion vs Anki's add-on

Anki's Image Occlusion Enhanced is powerful but desktop-only for card creation, with a dated editor. FlashStacks' version is native on iPhone — draw zones with your finger in seconds, no desktop round-trip, no add-on installation. If you're deciding between the two apps more broadly, see the full FlashStacks vs Anki comparison.