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[object Object] BOOKSCANNER

OCR engines

Aglaïa runs OCR through a pluggable engine abstraction: every backend implements the same recognize(image, languages) contract, so you can switch engines per document without changing anything else. Several ship in the box, you can install another from the plugin store, and you can write your own.

Background

No single OCR engine wins everywhere. Apple Vision is fast and on-device but weaker on non-Latin scripts; vision-language models (Surya 2, GLM-OCR) are far more accurate on hard pages but slower and heavier; a cloud service reads anything but sends your page over the wire. Aglaïa exposes all of them behind one interface and lets you choose, even mixing a fast primary with a slow complement that only re-reads the low-confidence lines.

Use cases

  • Clean Latin text → Apple Vision (or Apple Document), near-instant.
  • Mixed or non-Latin scripts → a VLM engine for accuracy.
  • Tricky historical type → Mistral Document AI in the cloud.
  • Bulk, offline → keep everything on-device; nothing leaves the machine.

Comparison of OCR engines

EngineWhereSpeedAccuracyNotes
Apple Documenton-devicefastgold (mixed script)recovers page (headings, blocks, reading order) — the choice for Markdown
Apple Visionon-devicefastgoodline-based, Latin-first, no page — for the searchable-PDF text layer, not Markdown; default
Surya 2on-device (local VLM)slowgoldQwen3.5-VL via the shared VLM backend — MLX on Apple Silicon, vLLM on CUDA
GLM-OCRon-device (local VLM)slowhighsame backend; a second opinion on hard pages
Mistral Document AIcloudnetwork-boundgoldreads any script; key in the OS keychain; runs synchronously or as a cheaper batch job

A unified OCR DPI knob downsamples the page to a sweet spot (≈150 dpi) before inference, regardless of engine.

Choosing an engine

In the GUI, pick the engine in the OCR tab. From the headless CLI, pass --ocr to aglaia run — --ocr auto for the default (Apple Vision → Surya), or a named engine with options, e.g. --ocr apple:lang=fr-FR or --ocr surya. Add --ocr-lang fr-FR+en-US to set languages. List what’s available with aglaia list ocr.