In image occlusion, you generate flashcards from an image by hiding parts of it behind an opaque box on the front side, then revealing the hidden portion on the back side. It's like cloze deletion, but for images.
Image occlusion can be useful for any subject, but is especially helpful for visual-heavy topics like anatomy, chemistry, data science, or geography.
Image occlusion is a Pro feature. You can create image occlusion flashcards from up to 5 images on a free plan, so you can try it out before committing to the Pro plan.
Creating Image Occlusion flashcards
Before creating an image occlusion flashcard, you'll need to add an image to your notes. Or, if you have the URL of the image handy, you can use /ioc (insert image occlusion) to add the image and start an image occlusion in one step.
Otherwise, Ctrl+click on the image you'd like to create cards for (Cmd+click on a Mac), or click the image flashcards button that appears in the upper-right corner of the image when you hover your mouse over it. (On a mobile device, tap once to show these options.)
This opens the image in a window where you can begin selecting what parts of the image you want to occlude (hide from the front of the flashcard). Click and drag to cover the area you want to test yourself on. You can occlude any rectangular area you want, and add as many different occlusions as you want.
Creating occlusions with AI
If you want to hide all the labels in a diagram, RemNote can try to automatically create the occlusions for you – click the “Generate Cards with AI” button on the upper-right toolbar.
If the boxes aren't quite perfect, you can edit or merge them (see next section) after creation.
There are two AI models available for image occlusion, a basic one and an advanced one. Both models use AI credits; the advanced one places the occlusions more reliably, but costs about 10 times as much (~3 AI credits per use compared to ~0.3). Choose between them with the Advanced AI Image Occlusion option in Settings > AI.
The models are run automatically when you launch the image occlusion editor – this allows RemNote to automatically recognize all text within the image so you can search for it. If you don't want to use AI credits on this, you can turn off the Extract Text from Image Occlusions option (see above screenshot).
Merging and splitting
By default, each occluded area generates its own card, but you can merge occlusions so that multiple areas will be hidden on the same card. The letters on each occlusion indicate which ones go together; each letter corresponds to a single card that will be generated.
To merge, hold Shift or Ctrl and click on multiple sections (or use the checkboxes that appear next to the items when you start selecting them), then press the Merge button on the toolbar.
If you change your mind, you can split merged occlusions back into their own cards by selecting them and pressing the Split button on the toolbar.
Previewing
To double-check that you've created cards the way you want to, select the preview button at the top. This will show the front of each card the way it will appear when you practice it in the flashcard queue.
Hide All, Test One
You can either show everything on the front side of each card except the current occlusion (the default behavior), or hide all occluded portions on every card (showing the item(s) you are supposed to answer in this particular card in blue and the others in gray).
In the screenshots above, Hide All, Test One mode is used. If you turn it off, the flashcards will instead look like this:
RemNote will save your choice here and use it for the next card you create, so if you create many cards in a row that belong in one mode or the other, you don't have to keep changing it on every card.
Labels
You can add additional details to image occlusion cards as labels. To add a label, click on the occlusion you want to label, then the … button, then Label Front of Card or Label Back of Card, depending on whether you want the label to appear on the front or the back of your card. Front-side labels are useful for providing prompts or hints; back-side labels are useful for reminding yourself of mnemonics or additional context.
In this example, we show the first letter of the nucleotide being tested so we can remember which one it's asking for without memorizing the colors in the diagram.
Rotating occlusions
Sometimes the part of the image you want to hide isn't at right angles to the image. You can draw an occlusion and then rotate and move it to neatly cover the appropriate area using the circular rotation point at the top of the occlusion.
Additional options
There are several more options on the settings menu (gear icon) in the upper-right corner of the image occlusion interface.
Auto Zoom in Queue: When an image occlusion card generated from this image appears in your flashcard queue, RemNote will automatically zoom in to it, as if you had clicked on the image. This is useful for very large images that would otherwise be difficult to read.
Type in Labels in Queue: If you have a back-side label (see the Labels section above) for an occlusion, show a type-answer box asking you to fill in that label. If there is no back-side label but you used Generate Cards with AI, RemNote will read the text under the occlusion and use that as a back-side label for purposes of this option. (A back-side label, if any exists, will override the automatically determined text.)
Enable Test In Sequence Card: Create a single card that asks you to answer all of the occlusions in a specific order, like a list-answer card.
This card is generated in addition to the individual cards for each occlusion (or set of occlusions, if merged), not instead of them. In many cases, this is a great way to get extra practice and improve your memory. In cases where you want only a sequence card, additionally choose the Disable All Cards option; the sequence card will still be generated.
When this option is enabled, small numbers will appear above each occlusion in the editor. You can click on these to change the order in which the occlusions appear (they start in the order in which you created them).
Disable All Cards: Don't show any of these cards (except any test-in-sequence card, as explained in the bullet point above) in the queue. You can also disable or enable cards selectively by clicking on the card's occlusion and moving the toggle switch.
Delete All Cards: Remove all of the occlusions and their review history, keeping the image. You might choose this if you draw the occlusions poorly and want to try again, for instance.
Example uses
Charts, graphs, and diagrams
Charts, graphs, models, diagrams, and flow charts make excellent image occlusion material. If you don't have the right one, consider making your own and uploading it to RemNote!
Tables
Image occlusion cards are also a fast way to test yourself on the contents of tables you might find in a textbook or on a website: grab a screenshot of the table, paste it into RemNote, and then generate image occlusion cards.
Equations
Image occlusion is an easy way to study important equations in subjects like chemistry, physics, or math. Snip the equation you need, upload it as an image, and start occluding!
(Note that you can also type equations directly in RemNote. But the image occlusion method can come in handy if you don't want to retype a long, complex equation whose LaTeX source you lack.)