Pre-scan lines to identify "isolated" ones — short lines (1-6 words)
with paragraph breaks both before AND after. These are heading
candidates even at body font size, common in academic papers
("Acknowledgements", "Limitations", "B.3 Prompt Engineering").
Inspired by opendataloader's HeadingProcessor which passes prevNode
and nextNode context to the heading probability scorer.
The isolated signal (+0.3) combines with rarity/bold/standalone
signals. A per-page density guard prevents false positives on
multi-column pages where many lines appear isolated. Continuation
word detection (ending in "the", "and", etc.) filters wrapped
paragraph lines.
MHS=0 docs: 18→13. MHS-S +0.004. No regressions.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Reverts commits 937311c, 1dcb0c6, 0300e96, 999f9a2. The thin-rect-to-line
synthesis and stacked table splitting improved extraction for specific
government PDFs but caused -0.05 TEDS regression on the benchmark by
preempting the heuristic detector with worse line-based grids.
These features need more targeted guards before re-enabling.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Rows with 3+ short-valued cells (avg ≤10 chars) and an empty first cell
are column headers (e.g. "UR | SC | ST | OBC | EWS"), not text overflow
from the previous row. Prevents them from being merged into the
preceding section title row.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Three fixes for better table extraction from spreadsheet-exported PDFs:
1. Convert thin filled rects (< 2pt) to PdfLine objects before line-based
table detection. Many PDFs draw table borders as narrow filled rectangles
instead of stroked paths — these were invisible to the line detector.
2. Relax uniform row spacing rejection (CV 0.05 → 0.02). Spreadsheet
exports have very even row heights that were being rejected as "chart
grids".
3. Fix continuation row merging: don't merge rows where the only non-first
cell content is a long label (section headers like "Category No. 03").
Don't merge first-cell-only rows with long text ("Note: ...").
Also adds multi-Y row splitting in line-based detection and column-aware
table detection skipping for multi-column pages.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Replace ad-hoc bold/ratio heading checks with a unified scoring system
based on font size rarity. For each line, compute:
score = font_rarity * 0.5 + bold * 0.3 + standalone * 0.2
Font rarity measures how infrequently a font size appears across the
document — heading fonts are rare while body text is common. This
approach (from opendataloader's ModeWeightStatistics) naturally adapts
to each document's font distribution instead of relying on fixed
thresholds.
Guards: require font_size >= 0.95 * base_size (no small-font headings),
word_count >= 3, and standalone (paragraph break before).
Benchmark improvement: MHS 0.56→0.58, MHS-S 0.66→0.70, overall +0.003.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Lines with font size 1.10-1.20x body text that are standalone and short
(1-8 words) are promoted to headings. This catches academic paper
headings where the font is only ~10% larger than body text, below the
previous 1.2x threshold.
Also syncs the simpler to_markdown_from_lines path to match the
table-aware path (removes stale colon exclusion).
Benchmark improvement: MHS 0.54→0.56, overall 0.761→0.766.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Lower minimum item count for body-font table candidates from 9 to 6,
allowing small 2-3 row tables to be detected.
- Allow 2-column body-font tables with short cells (avg ≤25 chars) to
bypass the "table-like content" validation. This catches text-only
definition/category tables (e.g., species lists) without false-positiving
on 2-column paragraph text (which has longer cells).
Benchmark improvement: TEDS 0.498→0.519, overall 0.750→0.754.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* feat(tables): improve heuristic detection for borderless wrapped-cell tables
Three changes to the body-font heuristic detector:
1. Adaptive Y-gap in find_table_regions_strict: use median qualifying-row
spacing × 3 instead of fixed 25pt. Tables with wrapped cells have
larger gaps between qualifying rows (those with 3+ X-clusters).
2. Y-only region filtering: use full X range when collecting region items.
The strict X bounds from qualifying rows excluded continuation lines
in wrapped cells, starving find_column_boundaries of items.
3. Merged-band retry: when split_side_by_side splits a page into bands
but no band produces a table, retry heuristic detection on all items
merged as a single band.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* feat(tables): gap-histogram column detection for small tables + lower avg_cells
Two changes to fix PDF 045 (borderless table with narrow "No." column):
1. Extend gap-histogram column threshold to small tables: when the gap
between within-column jitter and between-column spacing is >10pt
(unambiguous bimodal signal), use the detected threshold even with
fewer than 500 items. Previously only triggered for dense tables.
2. Lower BodyFont avg_cells_per_row minimum from 2.5 to 2.0 to handle
tables with wrapped multi-line cells where continuation lines have
only 1 filled cell.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(tables): trim empty outer columns + relax partial H-line validation
- Rect detection: trim empty first/last columns instead of rejecting
the whole table. Rect edges often extend beyond text boundaries.
- Line detection: accept tables with 6+ partial horizontal lines
(>15% width) when <3 full-spanning lines exist. Handles tables
with column-level separators instead of full-width rules.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* feat(tables): cell-rect fallback for tables with variable-width backgrounds
When rect clustering produces a grid that fails validation (empty
interior columns from variable-width cell backgrounds), fall through
to a new strategy: use rect Y-edges for row boundaries and text
X-position clustering for columns. This handles tables like the
opendataloader-bench 088-090 comparison tables where each cell has
its own background rect at different widths.
Also widen failed-cluster hint width cap for large clusters (≥30 rects)
to allow page-spanning table regions.
TEDS score on opendataloader-bench: 0.300 → 0.353.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(tables): relax vertical line spanning validation for partial borders
Accept tables with 4+ partial vertical lines (>10% table height) when
fewer than 2 span >30%. Handles tables like opendataloader-bench 053
with column-level vertical separators that don't extend the full height.
TEDS: 0.353 → 0.377 on opendataloader-bench.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(tables): lower cell-rect density threshold + add validation logging
- Lower cell-rect density minimum from 25% to 15% to accept sparser
tables with decorative backgrounds (fixes 147).
- Add debug logging to all heuristic validation paths for diagnosability.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* feat(tables): relax body-font validations for text-only and 2-column tables
Four fixes closing 71% of the TEDS gap vs opendataloader:
1. Validation 7 (table-like content): bypass numeric content requirement
for tables with 3+ columns that passed all structural checks. Text-only
tables (category lists, program descriptions) are legitimate.
2. Qualifying row threshold: lower from 3+ to 2+ X-clusters per row.
Enables 2-column body-font table detection (fixes 166).
3. Row-stripe max cell length: raise from 500 to 2000 for 3+ column
tables. Tables with paragraph descriptions in one column are valid
(fixes 121).
4. Row-stripe empty-column trimming: apply the same outer-column trim
as grid detection (fixes 121 column-0 rejection).
TEDS: 0.377 → 0.438 on opendataloader-bench (gap: -0.056 vs odl).
TEDS=0 docs: 14 → 9.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* feat(tables): enable 2-column body-font tables + lower all minimums
- Lower BodyFont minimum columns from 3 to 2 in detect_table_in_region
- Lower BodyFont minimum rows from 3 to 2
- Lower avg_cells_per_row minimum from 2.0 to 1.5 (handles wrapped cells
in 2-column tables)
- Apply empty-outer-column trimming to row-stripe detection (not just grid)
TEDS: 0.438 → 0.468 on opendataloader-bench (gap: -0.027 vs odl).
TEDS=0 docs: 9 → 8. 86% of original gap closed.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* feat(tables): text-based row fallback + fix 120 flow-chart and 188 leaderboard
Three changes that push TEDS past opendataloader:
1. Cell-rect Y-edge fallback: when rects have too few Y-edges for row
structure, derive rows from text Y-position clustering within the
rect bounding box. Fixes flow-chart tables (120) and column-header-
only rects (188).
2. Lower cell-rect minimum from 20 to 6 rects to catch smaller tables.
3. Relax validation 1 (first-column presence) from 50% to 25% of rows.
Tables with wrapped model names have continuation lines without first
column content.
TEDS: 0.468 → 0.508 on opendataloader-bench.
Now BEATS opendataloader (0.508 vs 0.494, gap=+0.014).
TEDS=0 docs: 8 → 5.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* feat(tables): wrapped-cell continuation row merging
Merge rows that have fewer filled cells than the header row into the
previous row. Handles wrapped multi-line cells where text overflow
creates extra rows (e.g., "Direct" + "communications" → "Direct
communications").
Conditions: fewer filled cells than header, more than previous row had,
not a data row (numeric), not a short subheader label.
TEDS: 0.508 → 0.522 on opendataloader-bench (now +0.028 vs odl).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(tables): tighten cell-rect validation + fix continuation-row merging
Cell-rect false positives:
- Raise density threshold back to 25% (from 15%)
- Add max cell length check (500 chars) to reject paragraph content
- Reject disproportionate grids (>20 rows, <4 cols)
Continuation-row merging:
- Wide tables (5+ cols): only merge rows with ≤50% header cells
- Narrow tables (2-4 cols): merge rows with fewer cells than header
- Prevents merging normal data rows in large tables (6_KE_Chart)
while keeping wrapped-cell merging for narrow tables (178)
TEDS: 0.498 on opendataloader-bench (still +0.004 vs odl).
pdf-evals: 191/192 passed, 0 regressions.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* fix(fonts): CID-as-Unicode passthrough and subscript/superscript merging
Add smart CID-as-Unicode passthrough for Identity-H fonts without
ToUnicode maps. Uses /W array median CID heuristic to distinguish
Unicode-CID PDFs (Chromium-generated) from GID-based subsets.
Add merge_subscript_items() pass that merges small-font items (<75%
of dominant font size, ≤4 chars, tightly adjacent) into parent items.
Fixes chemical formulas (NH3, H2O, KClO3), footnote references, and
subscript notation (vf, Hfg, m3/kg) that were previously orphaned
as separate text items.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* fix(subscripts): restrict merge to purely numeric text only
Tighten subscript merging to only merge items containing ASCII digits
(0-9). This avoids false positives with ordinal indicators (º), letter
subscripts (sol, vf), and small bullet characters (▶) that caused
table restructuring regressions.
Numeric-only keeps the primary wins: chemical formulas (NH3, H2O),
footnote references, and unit notation (m2, m3).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* fix(subscripts): restrict merge to parent text ending with a letter
Only merge numeric subscripts when the parent item's text ends with
an alphabetic character. Prevents false merges like "33" + "1" in
fractions (33 1/3%), table credit numbers after spaces, and footnote
refs after punctuation (land.1 → land. 1). Chemical formulas (NH3,
H2O, KClO3) still merge correctly since parent ends with a letter.
Reduces pdf-eval regressions from 13 to 2 (both are correct reversions
of over-aggressive footnote merging from the prior commit).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
OCR text layers and some PDF producers emit trailing spaces on each
text item, which combine with gap-based joining to produce double
spaces ("Vice President"). Now collapses runs of 2+ spaces to single
space within lines, preserving leading indentation.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Drop column-width padding from table output. Saves ~37% bytes on
table-heavy PDFs. Markdown renders identically — padding was purely
cosmetic. Optimizes token efficiency for AI agent consumers.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Only skip text with rendering mode 3 (truly invisible). Removes
fill color tracking that was incorrectly hiding white-on-dark text
in presentations and brochures.
Add 5 stripped public-domain PDF fixtures and golden markdown snapshots
for CI regression testing. Fix non-deterministic output caused by
HashMap iteration order in font stats, table heuristics, and rect
clustering by adding deterministic tie-breaking.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
