Document Understanding with LayoutLM

Build a document understanding system using LayoutLM models.

Document details:
- Document types: [INVOICES/FORMS/RECEIPTS/etc.]
- Tasks: [CLASSIFICATION/NER/QA]
- Languages: [LANGUAGE(S)]
- OCR needed: [YES/NO]

LayoutLM implementation:
1. Document processing:
   - OCR with coordinates
   - Text and layout extraction
   - Image preprocessing
2. Model selection:
   - LayoutLM v1/v2/v3
   - LayoutXLM for multilingual
   - Donut for end-to-end
3. Data preparation:
   - Token-bbox alignment
   - Label encoding
   - Dataset format
4. Fine-tuning:
   - Token classification
   - Document classification
   - Document QA
5. Post-processing:
   - Entity grouping
   - Confidence thresholds
   - Output formatting
6. Evaluation:
   - Entity-level F1
   - Document-level accuracy
   - Field extraction accuracy
7. Production:
   - Pipeline orchestration
   - Batch processing
   - Error handling

Handle multi-page documents and tables.