cfe65158a3
- Enable PP-StructureV3's use_doc_orientation_classify feature - Detect rotation angle from doc_preprocessor_res.angle - Swap page dimensions (width <-> height) for 90°/270° rotations - Output PDF now correctly displays landscape-scanned content Also includes: - Archive completed openspec proposals - Add simplify-frontend-ocr-config proposal (pending) - Code cleanup and frontend simplification 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
57 lines
2.1 KiB
Markdown
57 lines
2.1 KiB
Markdown
# Change: Fix Table Column Alignment with Header-Anchor Correction
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## Why
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PP-Structure's table structure recognition frequently outputs cells with incorrect column indices, causing "column shift" where content appears in the wrong column. This happens because:
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1. **Semantic over Geometric**: The model infers row/col from semantic patterns rather than physical coordinates
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2. **Vertical text fragmentation**: Chinese vertical text (e.g., "报价内容") gets split into fragments
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3. **Missing left boundary**: When table's left border is unclear, cells shift left incorrectly
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The result: A cell with X-coordinate 213 gets assigned to column 0 (range 96-162) instead of column 1 (range 204-313).
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## What Changes
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- **Add Header-Anchor Alignment**: Use the first row (header) X-coordinates as column reference points
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- **Add Coordinate-Based Column Correction**: Validate and correct cell column assignments based on X-coordinate overlap with header columns
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- **Add Vertical Fragment Merging**: Detect and merge vertically stacked narrow text blocks that represent vertical text
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- **Add Configuration Options**: Enable/disable correction features independently
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## Impact
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- Affected specs: `document-processing`
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- Affected code:
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- `backend/app/services/table_column_corrector.py` (new)
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- `backend/app/services/pdf_generator_service.py`
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- `backend/app/core/config.py`
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## Problem Analysis
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### Example: scan.pdf Table 7
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**Raw PP-Structure Output:**
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```
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Row 5: "3、適應產品..." at X=213
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Model says: col=0
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Header Row 0:
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- Column 0 (序號): X range [96, 162]
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- Column 1 (產品名稱): X range [204, 313]
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```
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**Problem:** X=213 is far outside column 0's range (max 162), but perfectly within column 1's range (starts at 204).
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**Solution:** Force-correct col=0 → col=1 based on X-coordinate alignment with header.
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### Vertical Text Issue
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**Raw OCR:**
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```
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Block A: "报价内" at X≈100, Y=[100, 200]
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Block B: "容--" at X≈102, Y=[200, 300]
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```
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**Problem:** These should be one cell spanning multiple rows, but appear as separate fragments.
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**Solution:** Merge vertically aligned narrow blocks before structure recognition.
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