Export

Aglaïa exports a project to a searchable PDF or Markdown. Both read the chosen stage of each visible page from the project DB.

PDF (lib/workers/pdf_export.py)

A page is encoded by colour type:

• Bitonal (BW) → build_bitonal_pdf(rows, out, engine=...):
  • "jbig2" (default, smallest) — lossless JBIG2 via the in-tree aglaia_jbig2 PyO3 wrapper (encode_page_lossless), embedded as a /JBIG2Decode image XObject.
  • "g4" — CCITT Group 4 fallback. Used when JBIG2 is unavailable; the encoder probe (from aglaia_jbig2 import encode_page_lossless) degrades gracefully to G4 if the native extension isn’t built.
• Colour / gray → JPEG (/DCTDecode).

Compression mode (PDFprocessor.create_pdf_from_db): "jbig2" / "g4" / "native" / "auto". auto uses the bitonal path (JBIG2 if installed, else G4) when every page is BW, and otherwise falls back to native (all pages as JPEG). jbig2 / g4 skip non-BW rows; native embeds every row as a JPEG regardless of type.

An invisible OCR text layer (Helvetica, WinAnsi, render mode 3) is overlaid per page when OCR results exist, so the PDF is selectable / searchable while showing the scanned image. PDF object assembly + the text layer go through pikepdf (qpdf); page rendering for previews uses pypdfium2 (PDFium).

JBIG2 ships only when the build env was synced with --extra jbig2 (it compiles the Rust crate). See distribution.md; the encoder is credited in ../ABOUT.md.

Markdown

write_markdown turns OCR text into free-flowing Markdown (headings, paragraphs, dehyphenation, footnotes, lists, cross-page merge). Full heuristics in markdown_export.md.

What gets exported

Only visible pages of non-deleted scans: queries filter scans.deleted_at IS NULL AND branches.trashed_at IS NULL. Per-page visibility is the eye toggle (see gui.md); each page exports its currently-chosen stage.