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title: Picarones
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sdk: docker
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Picarones
Heritage OCR / HTR / VLM and post-correction benchmarking tool
Outil de comparaison d'OCR / HTR / VLM et de post-correction pour documents patrimoniaux
Status (May 2026) — version 1.x, scientific prototype under
consolidation. The core (corpus, runner, metrics, HTML report) is
usable to compare transcription pipelines on a ground-truth corpus.
A targeted rewrite (see
docs/roadmap/rewrite-2026.md)
rebuilds the orchestration layer and evaluation views for a stable
2.0 release by the end of 2026.
What is Picarones?
Picarones is an open-source comparison tool for OCR, HTR, VLM and post-correction pipelines on heritage documents (manuscripts, early printed books, archives).
The input is a folder of (image, ground truth) pairs — ground truth
in plain text, ALTO XML, or PAGE XML. Picarones runs the AIs you plug
in (OCR engines, VLMs, OCR+LLM pipelines, ALTO mappers, ensembles…) on
every page, compares each output to the ground truth, and produces an
HTML report with the numerical results.
Without ground truth, no benchmark — Picarones measures how well an AI matches a known reference, not how it transcribes an arbitrary document.
Limits to keep in mind. Picarones is a tool, not a verdict machine. CER/WER and the philological metrics measure agreement with a single reference; the choice of reference, normalization profile and metric is an editorial decision the user must own.
Version française ci-dessous.
Use case
A digital library plans to OCR a production corpus — say, several thousand 17th-century parish registers, 19th-century newspapers, or medieval glossed manuscripts. Several pipelines are on the table (alternative OCR, LLM correction, ALTO mappers, ensembles); the question is which one to deploy.
The candidates cannot be benchmarked on the production corpus itself (no ground truth). A small golden dataset matching the target profile is assembled; Picarones runs each candidate on it and reports CER, recovered fuzzy searchability, preserved numerical sequences, errors introduced by post-correctors, and statistical significance. The numbers inform the deployment decision.
En français
Picarones est une plateforme open-source de banc d'essai pour des IA d'OCR, HTR, VLM et des pipelines de post-correction sur documents patrimoniaux.
L'entrée est un dossier de paires (image, vérité terrain) — VT en
texte brut, ALTO XML ou PAGE XML. Picarones exécute les IA que vous
branchez sur chaque page, compare la sortie à la VT à tous les
niveaux pertinents et produit un rapport HTML autonome avec chiffres
factuels, tests statistiques et snapshot de reproductibilité. Sans
vérité terrain, pas de benchmark.
Features
Heritage-specific metrics
Three families of metrics calibrated for historical documents:
- Classical OCR/HTR — CER (raw, NFC, caseless, diplomatic), WER, MER, WIL via jiwer; 10-class error taxonomy; bootstrap 95% CIs; line-level Gini distribution.
- Philological — MUFI coverage, abbreviation expansion (Capelli), early-modern typography (long-s, ligatures, tilde nasals), modern archives markers, Roman numerals, Unicode block accuracy, NER precision (HIPE), reading-order F1 (ICDAR 2015), layout F1.
- Comparison & decision — Friedman + Nemenyi + Critical Difference Diagram (Demšar 2006); cross-engine taxonomic divergence + oracle complementarity; cost / speed / CO₂ Pareto front; multi-run stability (Cohen κ, Krippendorff α); longitudinal trend with change-point detection; controlled per-slot ANOVA-like comparison.
For the full list with definitions, see docs/views.md
and the contextual glossary embedded in every report (25 bilingual
entries).
OCR+LLM pipelines
Composable chains: tesseract -> gpt-4o, pero_ocr -> claude-sonnet,
zero-shot VLM, etc. Three pipeline modes: text-only post-correction,
image+text post-correction, and zero-shot. Over-normalisation
detection flags LLMs that silently modernise historical spellings.
A composed-pipeline benchmarking layer (Sprint 63+) runs N candidate
pipelines on the same corpus and ranks them by a chosen metric.
Corpus import
| Source | Method |
|---|---|
| Local folder | picarones run --corpus ./corpus/ |
| IIIF manifests (any institutional repository) | picarones import iiif <manifest-url> |
| Gallica API (BnF SRU + IIIF) | GallicaClient / picarones import iiif |
| HuggingFace Datasets | Web UI: POST /api/huggingface/import |
| HTR-United catalogue | Web UI: POST /api/htr-united/import |
| eScriptorium | EScriptoriumClient |
| ZIP upload (browser) | Web upload endpoint |
Supported corpus formats: plain text pairs, ALTO XML, PAGE XML.
Interactive HTML report
A single self-contained HTML file (or with --lazy-images for large
corpora). Five views:
- Ranking — sortable table of all engines and metrics.
- Gallery — color-coded CER badges per document.
- Document — synchronized N-way diff, triple diff for OCR+LLM.
- Analyses — distribution charts, Pareto, calibration, robustness projection, philological profile, longitudinal trends, levers.
- Characters — Unicode confusion matrix, ligature analysis.
Above the views: factual narrative synthesis (20+ deterministic detectors, every number traceable to the input — anti-hallucination proven by tests), Critical Difference Diagram, Pareto front. Side panels for contextual glossary and Advanced mode (visible columns, strata filters, opt-in personal composite score).
Web interface
FastAPI application with real-time SSE progress streaming, ZIP
upload from the browser, dynamic engine and normalization profile
selectors, browse and re-download generated reports, bilingual
French/English UI. Deployable on HuggingFace Spaces (Docker, port
7860) and on institutional infrastructure (see
docs/operations/deployment-institutional.md).
Longitudinal tracking & robustness
Optional SQLite database recording benchmark history across runs. CER evolution curves per engine, automatic regression detection between consecutive runs (Pettitt change-point analysis, Sprint 92). Robustness analysis measures engine resilience to noise, blur, rotation, resolution and binarization, projected on the real corpus quality profile (Sprint 81).
Quick start
# Install
pip install -e ".[dev,web]"
# Tesseract (system binary, required for the Tesseract engine)
sudo apt install tesseract-ocr tesseract-ocr-fra tesseract-ocr-lat # Debian/Ubuntu
brew install tesseract tesseract-lang # macOS
# Generate a demo report (no engine needed)
picarones demo --output demo_report.html
# Run a benchmark
picarones run --corpus ./corpus/ --engines tesseract --output results.json
picarones report --results results.json --output report.html
# Web UI
picarones serve --port 8080
For Docker, institutional deployment, or HuggingFace Spaces, see
INSTALL.md and
docs/operations/deployment-institutional.md.
Supported engines
| Engine | Type | Installation |
|---|---|---|
| Azure Doc Intelligence | Cloud API | AZURE_DOC_INTEL_ENDPOINT + AZURE_DOC_INTEL_KEY |
| Google Vision | Cloud API | GOOGLE_APPLICATION_CREDENTIALS env var |
| Mistral OCR | Cloud API | MISTRAL_API_KEY env var |
| Pero OCR | Local Python | pip install -e .[pero] |
| Tesseract 5 | Local CLI | pip install pytesseract + system binary |
LLM/VLM adapters (used through pipelines, not as standalone OCR
engines): GPT-4o, Claude, Mistral Large, Ollama (local). See
docs/cli-workflows.md.
The Engine table is regenerated automatically by
scripts/gen_readme_tables.py — adding a new adapter under
picarones/engines/ makes the next CI run update this table or
fail.
CLI commands
| Command | Description |
|---|---|
picarones compare |
Compare two benchmark JSON runs and flag regressions (Sprint 28) |
picarones demo |
Generate a demo report with synthetic data (no engine required) |
picarones diagnose |
Pre-wired workflow: bench + improvement levers + factual recommendations |
picarones economics |
Pre-wired workflow: bench + effective throughput + cost projection |
picarones edition |
Pre-wired workflow: bench + philological metrics for critical editing |
picarones engines |
List available OCR engines and LLM adapters |
picarones history |
Query longitudinal benchmark history (SQLite) |
picarones import |
Import a corpus from a remote source (IIIF, HF, HTR-United) |
picarones info |
Display version and system information |
picarones metrics |
Compute CER/WER between two text files |
picarones pipeline |
Run / compare composed pipelines from a YAML spec (Sprint 70) |
picarones report |
Generate an HTML report from JSON results |
picarones robustness |
Run robustness analysis with degraded images |
picarones run |
Run a full benchmark on a corpus |
picarones serve |
Launch the FastAPI web interface |
Each command supports --help for full options. See
docs/cli-workflows.md for end-to-end
examples.
Web API endpoints
The web app exposes a documented OpenAPI spec at /docs (Swagger UI)
when running. Summary:
| Method | Endpoint | Summary |
|---|---|---|
GET |
/ |
Index |
POST |
/api/benchmark/run |
Api Benchmark Run |
POST |
/api/benchmark/start |
Api Benchmark Start |
POST |
/api/benchmark/{job_id}/cancel |
Api Benchmark Cancel |
GET |
/api/benchmark/{job_id}/status |
Api Benchmark Status |
GET |
/api/benchmark/{job_id}/stream |
Api Benchmark Stream |
GET |
/api/benchmark/{job_id}/synthesis_preview |
Api Benchmark Synthesis Preview |
POST |
/api/config/load |
Api Config Load |
POST |
/api/config/save |
Api Config Save |
GET |
/api/corpus/browse |
Api Corpus Browse |
GET |
/api/corpus/image/{upload_id}/{filename} |
Api Corpus Image |
POST |
/api/corpus/upload |
Api Corpus Upload |
GET |
/api/corpus/uploads |
Api Corpus Uploads |
DELETE |
/api/corpus/uploads/{corpus_id} |
Api Corpus Delete |
GET |
/api/csrf/token |
Api Csrf Token |
GET |
/api/engines |
Api Engines |
GET |
/api/history/regressions |
Api History Regressions |
GET |
/api/htr-united/catalogue |
Api Htr United Catalogue |
POST |
/api/htr-united/import |
Api Htr United Import |
POST |
/api/huggingface/import |
Api Huggingface Import |
GET |
/api/huggingface/search |
Api Huggingface Search |
GET |
/api/lang |
Api Get Lang |
POST |
/api/lang/{lang_code} |
Api Set Lang |
GET |
/api/models/{provider} |
Api Models |
GET |
/api/normalization/profiles |
Api Normalization Profiles |
GET |
/api/reports |
Api Reports |
GET |
/api/status |
Api Status |
GET |
/health |
Health |
GET |
/reports/{filename} |
Serve Report |
The complete OpenAPI JSON is also exposed at /openapi.json for
client generation.
Normalization profiles
Picarones ships 11 built-in normalization profiles for historical
text comparison (defined in
picarones/measurements/normalization.py,
exposed via /api/normalization/profiles):
nfc, caseless, minimal, medieval_french,
early_modern_french, medieval_latin, medieval_english,
early_modern_english, secretary_hand, sans_ponctuation,
sans_apostrophes.
Custom profiles can be loaded from YAML files with user-defined
diplomatic tables and exclude_chars sets. See
docs/profiles.md.
A traceability table mapping each profile to its source standard (MUFI v4.0, TEI P5, DEAF) will ship in Sprint A12 (B-6).
Project structure
picarones/
├── core/ Cercle 1 — pure abstractions (7 modules)
├── measurements/ Cercle 2 — official metrics (~70 modules + narrative engine)
├── engines/ Cercle 2 — 5 OCR adapters
├── llm/ Cercle 2 — 4 LLM adapters
├── pipelines/ Cercle 2 — OCR+LLM pipelines
├── modules/ Cercle 2 — official BaseModule modules
├── extras/ Cercle 3 — plugins (importers, historical)
├── report/ Cercle 3 — HTML rendering
├── cli/ Cercle 3 — Click CLI (15 commands)
├── web/ Cercle 3 — FastAPI app + 11 routers
├── prompts/ 8 versioned prompt templates
└── data/ Indicative tables (pricing.yaml)
Strict 3-circle architecture: imports flow only from outer to inner.
Enforced by tests/core/test_circle_dependencies.py (Sprint A3).
See docs/architecture.md for the full
manifesto.
Environment variables
See .env.example for the complete list. Key
variables:
# Security & mode (cf. SECURITY.md)
PICARONES_PUBLIC_MODE= # 1/true/yes for HF Space (no cloud OCR)
PICARONES_CSRF_REQUIRED= # 1 for institutional deployment
PICARONES_BROWSE_ROOTS= # restrict browse to specific paths
# Cloud API keys (optional)
MISTRAL_API_KEY=
OPENAI_API_KEY=
ANTHROPIC_API_KEY=
GOOGLE_APPLICATION_CREDENTIALS=
AZURE_DOC_INTEL_ENDPOINT=
AZURE_DOC_INTEL_KEY=
# RGPD retention (Sprint A11)
PICARONES_UPLOAD_RETENTION_DAYS=7
For HuggingFace Spaces, set these in Settings → Variables and secrets.
CI/CD
GitHub Actions: .github/workflows/
ci.yml— tests on Python 3.11/3.12/3.13 × Linux/macOS/Windows, ruff, mypy strict on core/, security scanners (bandit + pip-audit- trivy), coverage gate
--cov-fail-under=85, pytest-timeout 300s.
- trivy), coverage gate
precommit.yml— replays pre-commit hooks (catches--no-verifybypass).release.yml— on tagv*.*.*: PyPI + ghcr.io multi-arch + GitHub Release with notes from CHANGELOG.perf_regression.yml— weekly cron + PR-triggered: CER anti-regression on a synthetic reference corpus.sync_to_huggingface.yml— auto-syncsmainto the HF Space.
Development
pip install -e ".[dev,web]"
pre-commit install
pytest tests/ -q
ruff check picarones/ tests/
python -m mypy picarones/core/
Test suite: ~3900 tests, ~3 min on a modern laptop. Coverage
floor at 85% (currently ~87%). The network marker excludes tests
requiring live HTTP. A handful of tests depend on optional engines
(pero-ocr, pytesseract) and are skipped/fail gracefully when
those binaries are not installed in the local environment — the CI
matrix runs them in a fully provisioned image.
For end-to-end developer guides, see
docs/developer/index.md (FR) /
docs/developer/index.en.md (EN).
Conventions
- Never
except Exception: pass— uselogger.warning("[module] degraded feature: %s", e). - One canonical home per module — circle dependency direction enforced by tests.
- Engines declare
execution_mode("io"or"cpu") so the runner picksThreadPoolExecutorvsProcessPoolExecutorappropriately. - Hardcoded UI strings forbidden — always go through i18n
(cf.
docs/developer/extending-i18n.md).
Roadmap
Detailed history and current direction live in:
CHANGELOG.md— Keep a Changelog format, one entry per sprint up to the latest release.docs/roadmap/evolution-2026.md— technical evolution roadmap (axes A and B for 2026+).docs/roadmap/rewrite-2026.md— targeted rewrite plan (S1–S26) restructuring orchestration aroundPipeline → Artifacts → Projection → EvaluationView. Target: end of 2026.docs/audits/— internal audit notes ;BACKLOG_POST_LIVRAISON.md— promises not in scope.
Honest status (May 2026). Several items historically presented as "institutional readiness complete" are not at the level the README previously claimed and remain on the post-delivery backlog:
- RGPD documentation is a draft, not a validated policy.
- Governance / COI policies are documented but not exercised by an external review.
CITATION.cff+ Zenodo DOI + JOSS submission are planned, not done.- Accessibility (WCAG 2.1 AA) and security pentest are scoped but not externally audited.
The rewrite-2026 plan (S1–S26) prioritises stabilising the benchmark core and the security boundary of the web layer over adding new features. Until S26 ships, treat the web app as an experimental demonstrator and the CLI as the supported interface.
Documentation
| Audience | Entry point |
|---|---|
| End user | docs/user/reading-a-report.md (EN) |
| Developer | docs/developer/index.md (EN) |
| Operations / DSI | docs/operations/deployment-institutional.md, docs/operations/data-retention-rgpd.md, docs/operations/release-process.md |
| Architect | docs/architecture.md, docs/api-stable.md |
| Researcher | docs/case-studies/, docs/reproducibility-snapshots.md |
| Contributor | CONTRIBUTING.md, GOVERNANCE.md, CODE_OF_CONDUCT.md |
| Security | SECURITY.md |
| Accessibility | ACCESSIBILITY.md |
The complete functional specification is in
SPECS.md (full refresh planned in Sprint A14).
Citation
A CITATION.cff file and a Zenodo DOI are planned, not yet
shipped (see BACKLOG_POST_LIVRAISON.md).
Cite the GitHub repository with the commit SHA used in your benchmark.
Every Picarones report embeds the commit hash and a snapshot of the
parameters used (cf.
docs/reproducibility-snapshots.md)
so the cited commit is sufficient to attribute the result.
Contributing
See CONTRIBUTING.md (FR) /
CONTRIBUTING.en.md (EN).
Code of conduct: CODE_OF_CONDUCT.md
(Contributor Covenant 2.1).
Governance & maintainership: GOVERNANCE.md.
License
Copyright 2024–2026 Picarones contributors.