Core Workflows

Everything on this page works without an API key or internet connection. Niobium uses local OCR to detect text regions and creates image occlusion flashcards automatically.

From a directory of images¶

The most common workflow. Point Niobium at a folder of screenshots, slides, or diagrams.

Push to Anki directly¶

Requires Anki to be open with AnkiConnect installed.

niobium -dir /path/to/images -deck "Anatomy 2025"

Niobium creates the deck if it does not exist.

Export as .apkg (no Anki needed)¶

niobium -dir /path/to/images -apkg ./output

Import the .apkg into Anki with File -> Import. See APKG Export for details.

From a single image¶

# Push to Anki
niobium -i /path/to/diagram.png -deck "Anatomy 2025"

# Export as .apkg
niobium -i /path/to/diagram.png -apkg ./output

From a PDF¶

Niobium extracts embedded images from the PDF and processes each one.

# Push to Anki
niobium -pin /path/to/lecture.pdf -deck "Lecture 3"

# Export as .apkg
niobium -pin /path/to/lecture.pdf -apkg ./output

# Process only specific pages
niobium -pin /path/to/lecture.pdf --page 5-10 -apkg ./output

See PDF Processing for more details.

Extract images from a PDF (without creating cards)¶

Useful for reviewing what’s inside a PDF before making cards.

niobium -pin /path/to/lecture.pdf -pout /path/to/images

Images are saved as numbered files in a timestamped subdirectory.

Two-step PDF workflow¶

For large PDFs, extract first, review, then process:

# Step 1: extract all images
niobium -pin /path/to/lecture.pdf -pout /path/to/images

# Step 2: delete unwanted images (title slides, blank pages, etc.)
# ... manually review the folder ...

# Step 3: create cards from the curated set
niobium -dir /path/to/images -apkg ./output

This gives you full control over which images become flashcards.

Create basic front/back cards¶

Each image becomes a single card with the image as the front and an empty back. Useful for quick visual review decks.

niobium -dir /path/to/images -deck "Quick Review" -basic True

Tune OCR behavior¶

Change languages¶

niobium -dir /path/to/images -deck "My Deck" --langs en,fr

Adjust box merging¶

If OCR creates too many fragmented boxes:

niobium -dir /path/to/images -deck "My Deck" --merge-lim-x 20 --merge-lim-y 20

GPU acceleration¶

niobium -dir /path/to/images -deck "My Deck" --gpu 0

All of these can also be set persistently in your config file.

Re-running on the same directory¶

Niobium tracks processed images via a local cache. If you add new images to a directory and re-run, only the new images are processed. See Caching.

Default output directory¶

When no output flag is given, Niobium saves .apkg files to {work_dir}/outputs (default: ~/niobium_work/outputs). The filename is derived from your input (e.g., lecture.apkg for lecture.pdf).

# These all save to ~/niobium_work/outputs/
niobium -dir ./slides
niobium -pin lecture.pdf
niobium -i diagram.png