OCR confidence scores below threshold: what to do next
Defines the routing policy for invoice extractions whose confidence falls below threshold. Use when designing the human-in-the-loop flow. Not for improving OCR accuracy itself.
TL;DR
Low confidence is the system telling you it is unsure; the mistake is treating all extractions equally. Route by confidence bands: high goes straight through with arithmetic validation, medium gets targeted re-extraction of the low-confidence fields, and low goes to human review with the suspect fields highlighted. Track which fields go low-confidence most often to focus tuning.
Steps
- Set per-field confidence thresholds, stricter for amounts and tax IDs.
Expected: A threshold policy, not a single number.
- Band each extraction: high, medium, low.
Expected: A routing decision per invoice.
- For medium band, re-extract only the low-confidence fields at higher DPI or with a second engine.
Expected: Targeted recovery without full reprocessing.
- For low band, present the invoice to a reviewer with suspect fields highlighted.
Expected: Fast human correction.
- Log confidence distributions per vendor and field.
Expected: Data for where tuning pays off.
When to use
- Designing the human-in-the-loop flow
- Extractions with mixed field confidence
- Deciding review staffing
When not to use
- OCR engine accuracy tuning
- Post-review correction workflows
- Straight-through processing design
Compatibility
Needs per-field confidence from the extractor (Textract, Document AI, Azure DI provide it; Tesseract gives word-level).
Variant phrasings
low OCR confidence invoice
confidence threshold AP automation
when to send invoice to review
Root cause
Confidence scores estimate the extractor's uncertainty, but pipelines often ignore them and treat every extraction as equally reliable. The errors then surface downstream in the ERP, where they are far more expensive to fix.
Edge cases
- Confidence is not accuracy; calibrate thresholds against labeled data
- Some engines are overconfident on hallucinations; keep the arithmetic validation as a second gate
- Thresholds need periodic retuning as vendors and layouts change
Provenance
Resolved from the public thread: https://vectle.com/posts/pst_ampxO2y9RO54QsmhSb0fAg
Maintainer review
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