| --- |
| license: cc-by-4.0 |
| language: |
| - sv |
| tags: |
| - kraken |
| - htr |
| - ocr |
| - fraktur |
| - swedish |
| - historical |
| pipeline_tag: image-to-text |
| --- |
| |
| # Swedish Fraktur — Kraken OCR/HTR model |
|
|
| A [Kraken](https://kraken.re) recognition model (`.mlmodel`) for **OCR of older |
| Swedish text printed in Fraktur (blackletter)**. It produces a diplomatic |
| transcription that keeps historical orthography, the long s (ſ) and period |
| spelling, and works on scanned page images. |
|
|
| - **File:** `svensk_fraktur.mlmodel` |
| - **Type:** Kraken recognition model (baseline/HTR pipeline) |
| - **DOI:** [10.5281/zenodo.20702142](https://doi.org/10.5281/zenodo.20702142) |
| - **Best validation accuracy:** 0.9880 (≈ 1.2 % CER) on a held-out split |
| - **Base model:** `german_print` (fine-tuned from it) |
| - **Training data:** Språkbanken, *Svensk fraktur 1626–1816* |
|
|
| ## Usage |
|
|
| Fetch the model directly from Zenodo: `kraken get 10.5281/zenodo.20702142` |
|
|
| **Kraken (CLI):** |
|
|
| ```bash |
| kraken -i page.jpg out.txt segment -bl ocr -m svensk_fraktur.mlmodel |
| ``` |
|
|
| For multi-page PDFs, render pages to images first (e.g. ~300 DPI) and pass them |
| to Kraken. **eScriptorium:** import the `.mlmodel` under *Models*. |
|
|
| ## How it was trained |
|
|
| Fine-tuned from `german_print` on the Språkbanken corpus *Svensk fraktur |
| 1626–1816* (199 page images with line-level diplomatic transcriptions). The page |
| images were OCR-bootstrapped and the recognized lines aligned to the ground-truth |
| line text (≈98 % coverage), producing PageXML for `ketos train`. A low learning |
| rate (`-r 0.0001`) was decisive — it let the model improve steadily past epoch 0 |
| instead of drifting away from the strong starting point. See [`training/`](training/) |
| for the scripts and exact commands. |
|
|
| The validation accuracy is measured on a held-out split of the same corpus and is |
| therefore optimistic relative to entirely new documents; on a real volume |
| (1600s Swedish Fraktur) it produced a near-flawless body-text transcription with |
| preserved long-s and period spelling and no systematic substitution errors. |
|
|
| ## Limitations |
|
|
| - Trained on Swedish Fraktur print; not intended for handwriting or modern |
| (antiqua/roman) type. |
| - Ornate/decorated title-page initials are read less reliably than body text. |
| - Output is **diplomatic** (verbatim): historical spelling, long-s and printed |
| line-break hyphens are preserved. Modernisation/normalisation should happen in |
| a downstream step, not here. |
|
|
| ## Provenance, rights and attribution |
|
|
| This is a derivative model. Full chain: |
|
|
| | Layer | Resource | By | DOI | License | |
| |-------|----------|----|-----|---------| |
| | Base model | german_print (OCR model for German prints) | S. Weil, J. Kamlah, T. Schmidt (2023) | [10.5281/zenodo.10519596](https://doi.org/10.5281/zenodo.10519596) | **CC0-1.0** | |
| | Training data | Svensk fraktur 1626–1816 | Språkbanken Text, University of Gothenburg | [10.23695/5sme-7437](https://doi.org/10.23695/5sme-7437) | **CC-BY-4.0** | |
| |
| The base model is **CC0** (no attribution legally required; cited as courtesy). |
| The training data is **CC-BY-4.0**, which requires **attribution**. When you use |
| or redistribute this model, please keep the following attribution: |
| |
| > Trained on *Svensk fraktur 1626–1816*, Språkbanken Text, University of |
| > Gothenburg (digitisation: Gothenburg University Library; transcription: |
| > GREPECT), [doi.org/10.23695/5sme-7437](https://doi.org/10.23695/5sme-7437), |
| > licensed CC-BY-4.0. |
| |
| This model is released under **CC-BY-4.0** (see [`LICENSE`](LICENSE)). |
| |
| ## Citation |
| |
| See [`CITATION.cff`](CITATION.cff). |
| |
