50 lines
2.5 KiB
Markdown
50 lines
2.5 KiB
Markdown
# pdftract
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A PDF text extraction library that gets the hard parts right.
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## What it does
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- **Correct reading order** — layout regions are segmented and sequenced before text is emitted, handling multi-column pages, sidebars, footnotes, and mixed-layout documents without relying on PDF operator order
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- **Font encoding recovery** — when `ToUnicode` CMaps are absent, wrong, or incomplete, pdftract works through a layered recovery pipeline: glyph name lookup via the Adobe Glyph List, font fingerprinting against known metrics and embedded checksums, and glyph outline shape matching
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- **Structure tree extraction** — PDF/UA and PDF/A documents encode their logical structure (headings, paragraphs, lists, tables, reading order) in a `StructTree`; pdftract reads this directly when present, producing accurate semantic output at no extra cost
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- **Per-page hybrid routing** — each page is independently classified and routed to the appropriate pipeline: vector text extraction, full OCR, or assisted OCR where vector hints improve raster accuracy
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- **Structured output with provenance** — the primary output is JSON carrying per-span bounding boxes, font name, size, and confidence score alongside the extracted text, not a flat string dump
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## Output
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```json
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{
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"pages": [
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{
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"page": 1,
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"blocks": [
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{ "kind": "heading", "text": "Introduction", "bbox": [72, 680, 400, 700] },
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{ "kind": "paragraph", "text": "...", "bbox": [72, 640, 540, 670] }
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],
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"spans": [
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{ "text": "Introduction", "bbox": [72, 680, 400, 700], "font": "Times-Bold", "size": 14.0, "confidence": 0.99 }
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]
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}
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],
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"metadata": { "title": "...", "author": "...", "page_count": 10 }
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}
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```
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## Usage
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```
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pdftract extract invoice.pdf # structured JSON to stdout
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pdftract extract invoice.pdf --text # plain text to stdout
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pdftract extract invoice.pdf --output out.json
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pdftract serve --port 8080 # HTTP service: POST /extract
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```
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## Architecture
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Rust core with PyO3 Python bindings and a CLI binary. The same binary runs as a command-line tool or as an HTTP microservice — the container deployment is just `pdftract serve`.
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See `docs/research/` for technical deep-dives into the PDF specification, font encoding, glyph Unicode recovery, and tagged PDF structure. See `docs/notes/` for SDK invocation examples in Python, Node.js, Go, Ruby, Java, Rust, and Bash.
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## Status
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Early development. See `docs/plan/` for the implementation roadmap.
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