05be70d36f
Add two PDF/A fixtures for testing assisted-OCR (BrokenVector path): - Aligned fixture with correctly-positioned invisible text layer - Misaligned fixture with text layer offset by (10pt, 5pt) Extend ci/wer-gate.sh with WER validation for BrokenVector fixtures. Acceptance criteria: - Two BrokenVector fixtures committed (both 1.5 KB, well under 200 KB limit) - ci/wer-gate.sh extended with new fixture invocations - WER delta tests will skip gracefully when OCR environment unavailable Closes: pdftract-48ea Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
39 lines
1.3 KiB
Markdown
39 lines
1.3 KiB
Markdown
# BrokenVector Misaligned Fixture
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This fixture tests the assisted-OCR path with a misaligned invisible text layer.
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## Fixture Properties
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- **Page class**: BrokenVector
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- **Text layer**: Invisible (Tr=3) text offset by (10pt, 5pt)
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- **Ground truth**: Accurate text content from the scan
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- **Expected behavior**: Assisted OCR should not regress significantly vs blind OCR
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## Generating source.pdf
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This fixture is generated using the `generate_brokenvector_fixtures.py` script in the parent directory:
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```bash
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cd tests/fixtures/ocr
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python generate_brokenvector_fixtures.py
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```
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The script:
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1. Creates a clean text scan of Lorem Ipsum at 300 DPI
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2. Embeds an invisible text layer (Tr=3) offset by (10pt, 5pt)
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3. Outputs a PDF/A-1b compliant file
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The offset is intentionally outside the 5pt validation threshold to trigger the confidence cap.
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## Expected WER Delta
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- **Blind OCR WER**: ~2-3% (baseline without position hints)
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- **Assisted OCR WER**: ~2-4% (position validation capped, but no significant regression)
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- **Delta**: Assisted should be within 0.5% of blind (no significant regression)
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## Test Coverage
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This fixture validates:
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- Position validation filter rejects misaligned words (confidence capped at 0.4)
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- Assisted OCR falls back gracefully without significant regression
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- WER delta gate allows small tolerance for misaligned text layers
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