PDF Parsing Supported File Types
PDF is not one format — the variants a serious parser must actually handle.
PDF parsing supported file types is a checklist worth making explicit, because "we support PDF" understates the format's real variety by a wide margin. Text-layer PDFs carry extractable glyphs directly — the easy case, though even here quality varies (properly tagged text versus vector-outlined "text" that's actually untagged shapes, invisible to naive extraction). Image-only PDFs are scans wrapped in PDF containers — no text layer at all, requiring OCR regardless of the file extension. Hybrid PDFs mix both within one document, or carry a corrupted text layer from a prior bad OCR pass masquerading as ground truth — the trap this glossary's text-extraction entry warns about, where trusting the embedded layer blindly is worse than ignoring it.
Beyond that baseline, real-world PDF intake includes: fillable forms (AcroForm/XFA field data, per the fillable-PDF entry, present, flattened, or partially both); password-protected and encrypted files (requiring credentials or exemption workflows before any parsing runs); malformed and non-conformant PDFs (produced by buggy generators, requiring repair libraries or graceful degradation rather than pipeline crashes); PDF/A archival variants (embedding fonts and color profiles for long-term fidelity — generally parse cleanly but with format quirks); linearized and object-stream-compressed files (fine for rendering, sometimes awkward for direct text-layer extraction depending on the library); and portfolios (PDFs containing other PDFs as attachments — a nesting case the splitting and bundle-classification machinery must recognize).
The practical implication is architectural: a parsing pipeline needs a detection step before processing — classifying which variant each incoming PDF actually is — and a routing table matching variant to treatment, because a pipeline hard-coded to "extract text layer" silently fails on image-only PDFs, and one hard-coded to "always OCR" wastes compute and accuracy on clean digital text. Robust intake also budgets for the format's edge tail: the corrupted file that needs repair, the portfolio that needs unpacking, the encrypted file that needs a human — each accounted for rather than silently dropped, per the ingestion-pipeline entry's defensive posture.
The text layer is data, not narrative — reconstructing paragraphs from positioned glyphs.
The form has fields with names and values — read them as data, not as pixels, when they're actually there.
Getting the words out — from the PDF's text layer or the scan's pixels — as the raw material for everything else.
Proof Perimeter runs document AI inside your own perimeter — with a provenance record on every field.
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