| type | knowledge | |||
|---|---|---|---|---|
| created | 2026-02-03 | |||
| tags |
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| status | active |
coOCR/HTR is a browser-based tool that helps domain experts verify, validate, and correct OCR/HTR results.
Standard OCR/HTR pipelines often produce erroneous results on historical documents:
- Unusual script forms (Kurrent, Fraktur, historical handwriting)
- Complex layouts (tables, marginalia, strikethroughs)
- Domain-specific vocabulary (technical terms, historical concepts)
These errors require human expertise to correct - but existing tools are often:
- Complex and difficult to use
- Not optimized for the correction workflow
- Without AI support for difficult passages
coOCR/HTR positions itself as an Editor-in-the-Loop tool:
┌─────────────────────────────────────────────────────────────────┐
│ WORKFLOW │
├─────────────────────────────────────────────────────────────────┤
│ │
│ [Image/PAGE-XML] ──► [coOCR/HTR] ──► [Correct OCR/HTR] │
│ │ │
│ ▼ │
│ ┌─────────────────┐ │
│ │ Expert │ │
│ │ - verifies │ │
│ │ - validates │ │
│ │ - corrects │ │
│ └─────────────────┘ │
│ │
└─────────────────────────────────────────────────────────────────┘
| Mode | Input | Use Case |
|---|---|---|
| Generate OCR | Upload image | Document has no transcription yet |
| Correct OCR | Upload PAGE-XML | Transcription exists (e.g., from Transkribus) |
- LLM Transcription: For difficult documents where standard OCR fails
- Hybrid Validation: Deterministic rules + LLM Review for quality assessment
- Visual Interface: Synchronized view of image, text, and validation
| User | Need |
|---|---|
| Digital Humanists | OCR correction for edition projects |
| Archivists | Fast transcription of holdings |
| Historians | Source access with AI support |
| Citizen Scientists | Accessible transcription work |
The product is complete when:
- Self-explanatory: Someone unfamiliar with the tool can use it without instructions
- Complete Workflow:
- Upload own documents (image OR PAGE-XML)
- Generate OCR or edit existing transcription
- Validate and correct
- Export in usable format (PAGE-XML, TXT, JSON)
- Workflow Integration: Output can be used in other processes
- Quality Assurance: "Good, correct OCR/HTR comes out the other side"
coOCR/HTR is positioned as an open-developed, community-driven tool. The development model follows an Open Development approach: the codebase is public, contributions are welcome, and institutional forks are explicitly encouraged.
| Institution | Context | Status |
|---|---|---|
| ZBZ (Zentralbibliothek Zürich) | Jeanne Hersch Edition, 289 documents | Fork planned (GitLab Uni Zürich, Podman) |
| ÖAW (Klugseder) | Medieval music manuscripts | Fork exists (reference implementation) |
The ZBZ plans to fork co-ocr-htr for their OCR/TEI pipeline (see zbz-ocr-tei). Their deployment uses Podman (daemonless Docker alternative) on institutional infrastructure with Azure-based LLM access. This validates the tool's architecture: browser-based, no backend dependencies, configurable API endpoints.
The Open Development vision positions domain experts (archivists, philologists, historians) as peer reviewers of LLM output — not just users, but co-developers of quality standards. Each institutional fork can contribute validation rules, prompts, and domain knowledge back to the main project.
- Not a replacement for specialized HTR models (Transkribus, eScriptorium)
- No training tool for custom models
| Phase | Status | Description |
|---|---|---|
| Phase 1: Core Application | [x] | LLM integration, Viewer, Editor, Validation |
| Phase 2: Multi-Page & Docs | [x] | Page navigation, Help/About Pages |
| Phase 3: Batch Processing | [x] | Transcribe/validate all pages automatically |
| Phase 4: Polish & Release | [x] | Tests, PAGE-XML Export, UI refinements |
Live Demo: dhcraft.org/co-ocr-htr
| Principle | Meaning |
|---|---|
| Expert-in-the-Loop | Machine assists, human decides |
| Categorical Confidence | confident/uncertain/problematic instead of 0-100% |
| Constructive UI | Helps with work, doesn't get in the way |
| Workflow Tool | Input in, correct output out |
| Zero Dependencies | Runs in browser, no installation |
References:
- METHODOLOGY - Scientific foundations
- IMPLEMENTATION-PLAN - Technical roadmap
- ARCHITECTURE - System architecture
Updated: 2026-02-14