Implement header row detection for tables using two signals:
1. Bold font detection (fully implemented)
2. StructTree TH detection (stub pending MCID tracking)
Bold detection:
- is_bold_font(): detects bold fonts from PostScript name patterns
- is_cell_bold(): checks if all non-whitespace content in a cell is bold
- is_bold_header_row(): validates rows with >=2 bold cells
- count_header_rows(): counts contiguous bold headers from top
- Cell::mark_header_rows(): sets is_header_row flag on cells
TH detection (stub):
- is_th_header_row(): placeholder for StructTree TH detection
Requires MCID tracking on TableSpan (future work)
Will use ParentTree to map MCIDs to StructElems
Will verify TR > TH chain structure
Combined detection:
- is_header_row(): combines bold and TH signals
- Bold wins on conflict per body data design principle
Documentation:
- Updated table-structure-reconstruction.md with full header detection spec
- Documented implemented vs pending signals
- Added implementation notes for TH detection
Tests:
- 45 tests covering all bold detection scenarios
- Tests for multi-row headers (contiguous from top)
- Tests for single-cell row exclusion
- Tests for empty/whitespace cell handling
- Placeholder tests for TH detection
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
New research document covering parallel extraction architecture:
rayon page-level parallelism, Arc<> shared xref/font/object-stream
caches, RwLock font cache design, Tesseract thread-local OCR pool,
semaphore memory budget, ordered NDJSON streaming slot array, and
catch_unwind error isolation per page.
Also adds docs/research-index.md: a 622-line navigable index of all
83 research documents grouped into 9 thematic categories, with a
"Start Here" reading path, per-phase implementation reading tables,
and an alphabetical lookup table covering every document.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Two new research documents covering Japanese Ruby text and East Asian
typography (tagged/untagged furigana extraction, Kinsoku Shori spacing,
full-width normalization, tate-chu-yoko, CJK/Latin boundary detection,
ruby_text output field) and PDF/VT variable and transactional printing
(DPart hierarchy traversal, per-record extraction model, DPM metadata,
variable vs. static content classification, postal address extraction,
records array output schema).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Two new research documents covering Southeast Asian script extraction
(Thai/Khmer/Myanmar/Lao/Tibetan/Ethiopic — cluster structure, no-space
word boundary policy for Thai/Lao, Zawgyi vs Unicode detection for
Myanmar, USE shaping, Tesseract fallback) and OpenType MATH table
exploitation for formula extraction (MathConstants for fraction/
subscript/radical layout, TeX OML/OMS/OMX encoding tables, MathML
output generation, GlyphAssembly reconstruction, alternative text
and MathJax XMP source recovery).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Two new research documents covering the glyph-to-span-to-block assembly
pipeline (inter-operator merging, adaptive word gap threshold, column
detection, ligature bbox splitting, multi-granularity output) and
Unicode post-processing (NFC normalization, selective NFKC decomposition
for ligatures, PUA preservation, soft hyphen resolution, ZWJ/ZWNJ
handling, combining character reordering).
Also adds docs/plan/implementation-plan.md: the full 7-phase Rust
implementation roadmap covering core parser, font/encoding pipeline,
content stream processing, text assembly, OCR integration, API surface,
and advanced features — with crate selections, complexity ratings,
test strategy, and v0.1–v1.0 release milestones.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Four new extraction research documents covering PDF article thread
traversal for multi-flow magazine layouts, resource dictionary
inheritance and ResourceStack semantics for nested Form XObjects,
document catalog and page tree structure (UserUnit, Contents array,
page inheritance), and hyperlink/named destination extraction with
QuadPoints anchor text and link density classification.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Four new extraction research documents covering cross-reference table
and xref stream parsing with error recovery, PDF object model and lexer
correctness (all 8 types, string escapes, stream /Length recovery),
FontDescriptor fields and embedded font data (Type1/TrueType/CFF/OT),
and PDF/UA-2 / PDF 2.0 structure changes (MathML, NFC normalization,
new structure types, artifact classification improvements).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Four new extraction research documents covering ICC profile and color
space luminance estimation for text visibility, precise text state
tracking and bounding box computation (Tc/Tw/Tz/TL, font units, TJ
kerning, baseline clustering), PDF/X prepress handling (OutputIntent,
TrimBox, spot colors, article threading), and a complete content stream
operator reference (BT/ET, Tj/TJ/'/", BI/ID/EI, BX/EX, marked content).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Four new extraction research documents covering page label/PageLabels
number tree and outline/bookmark tree extraction, government form PDF
patterns (IRS, USCIS, court filings, classification markings), book and
publishing PDF structure (running heads, footnotes, index extraction),
and PDF stream filter pipeline (FlateDecode/LZW predictors, JBIG2 global
segments, CCITTFax, JPX, error boundaries).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Four new extraction research documents covering PDF portfolio and
attachment enumeration (ZUGFeRD, PDF/A-3 AFRelationship), incremental
update structure and xref chaining, PDF/UA tagged PDF deep dive with
all 36 structure types and MCID mechanics, and JavaScript/AcroForm/XFA
field extraction without script execution.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Four new extraction research documents covering color space and contrast
analysis for text visibility, medical/scientific document structure
(ICH E3, IMRaD, FDA labeling, eCTD), multilingual mixed-script extraction
with UBA bidi handling and CJK vertical text, and digital signature
metadata extraction with DocMDP integrity context.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Four new extraction research documents covering text rendering modes
(Tr 0-7 including invisible OCR layers), legal/financial document
extraction patterns, character-level confidence aggregation with output
schema, and PDF/E engineering document handling (CAD, GD&T, schematics).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Three new extraction research documents covering subset font Unicode
recovery, pdfLaTeX/XeLaTeX encoding tables and two-column layout, and
proper vs. improper redaction detection with output schema.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- word-boundary-reconstruction: expected position formula with Tc/Tw/Tz,
TJ kerning gap detection, Td/Tm jump analysis, four space-width threshold
strategies including adaptive histogram, multi-column gap discrimination
- scanned-vs-vector-page-classification: four-category taxonomy, fast
pre-checks, image coverage AABB computation, character density ratio,
validity rate, glyph bbox plausibility, region routing map, confidence
scoring with cost-aware OCR threshold
- pdfa-compliance-and-extraction: ISO 19005 part/level matrix, XMP
pdfaid detection, Level B/U/A guarantee implications for extraction,
font embedding requirements, artifact tagging, PDF/A-3 embedded files,
PdfaLevel enum with per-level fast-path branching
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Four research documents covering PDF spec fundamentals, font types and
encoding, glyph Unicode recovery, and tagged PDF structure/reading order.
SDK invocation notes with subprocess and HTTP examples for Python, Node.js,
Go, Ruby, Java, Rust, and Bash.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
