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Hebrew OCR Pipeline

Zero-hallucination OCR pipeline processing thousands of multi-column historical Hebrew texts at 96% accuracy.

Hebrew OCR Pipeline screenshot 1

Project Overview

A zero-hallucination Hebrew OCR pipeline built at Introva, processing thousands of multi-column historical texts at 96% accuracy. Combines Google Vision API with custom layout-detection algorithms, an advanced post-processing engine backed by a 23,000+ word lexical database, and Sefaria API integration for citation normalisation.

Key Features

  • 96% accuracy on multi-column historical Hebrew texts
  • Custom layout-detection algorithms for columns, footnotes, and marginal notes
  • 23,000+ word lexical database for word-level correction and disambiguation
  • Zero-hallucination design — surfaces low-confidence tokens rather than inventing text
  • Sefaria API integration for citation validation and normalisation

Case Study

Context

Built at Introva for a corpus of thousands of multi-column historical Hebrew texts with pre-modern orthography, mixed scripts, and variable scan quality.

Pipeline

1. Image preprocessing — deskew, binarise, denoise, consistent DPI 2. Layout detection — custom logic for columns, footnotes, and marginal notes before OCR 3. Raw OCR — Google Vision API for character recognition 4. Lexical post-processing — 23,000+ word database for correction, context-aware disambiguation, abbreviation expansion, and Sefaria API citation normalisation

Results

  • ~78% raw Google Vision accuracy → 96% with layout detection and lexical post-processing
  • Zero-hallucination constraint: the post-processor never invents text unsupported by the raw OCR signal
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