Column detection:
- Raise MIN_COVERAGE_PRIMARY 20%→35% (prevents false columns in
flowing text where random gaps < 35% of rows)
- Raise MIN_COVERAGE_SECONDARY 12%→20%, MIN_DISTINCT_ROWS 2→3
- Vocabulary worksheets unaffected (columns appear in >80% of rows)
Graphic word filter:
- Only remove words with OCR confidence < 50 inside graphic regions
- High-confidence words are real text, not image artifacts
- Prevents legitimate colored text from being discarded
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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