Swedish Lion Libre
An HTR model for historical swedish developed by the Swedish National Archives in collaboration with the Stockholm City Archives, the Finnish National Archives and Jämtlands Fornskriftsällskap. The model is trained on Swedish handwriting dating from ca 1600-1900
Model Details
Model Description
- Developed by: The Swedish National Archives
- Model type: TrOCR base handwritten
- Language(s) (NLP): Historical Swedish handwriting
- License: {{ license | default("[More Information Needed]", true)}}
- Finetuned from model: trocr-base-handwritten
Uses
The model is trained on Swedish running-text handwriting dating from the start of the 17th century to the end of the 19th century. Like most current HTR-models it operates on a text-line level, so it's intended use is within an HTR-pipeline that segments the text into text-lines, which are transcribed by the model.
Direct Use
The model can be used without fine-tuning on all handwriting but performs best on the type of handwriting it was trained on, which is Swedish handwriting from 1600-1900. See below for detailed test and evaluation results.
Downstream Use
The model can be fine-tuned on other types of handwriting, or if you plan to use it to transcribe some specific material that is within it's domain but not included in the training data, for instance if you got a large letter collection dating from the 17th century, it can be fine-tuned on a small amount of manually transcribed in-domain data, say 20-50 letters, and then used to transcribe the entire collection.
Out-of-Scope Use
The model wont work well out-of-the-box for other languages than Swedish, and it wont work well for printed text.
How to Get Started with the Model
Use the code below to get started with the model, but bare in mind that the image has to be a single text-line.
from transformers import TrOCRProcessor, VisionEncoderDecoderModel
from PIL import Image
import requests
img_path = 'path/to/image'
image = Image.open(img_path)
processor = TrOCRProcessor.from_pretrained("microsoft/trocr-base-handwritten")
model = VisionEncoderDecoderModel.from_pretrained('Riksarkivet/trocr-base-handwritten-hist-swe-2')
pixel_values = processor(images=image, return_tensors="pt").pixel_values
generated_ids = model.generate(pixel_values)
generated_text = processor.batch_decode(generated_ids, skip_special_tokens=True)[0]
If you want to transcribe entire pages, consider using HTRflow, a package developed by The Swedish National Archives and intended for streamlining large and small scale HTR/OCR-projects. Install the package, write a pipeline config yaml, where you specify the models to use by their huggingface id, add preprocessing or post-processing steps, and then run the pipeline with htrflow pipeline <path/to/yaml> <path/to/image/images>
. A .yaml file for an entire pipeline, transcribing full pages, could look like this:
# Demo pipeline for running text
steps:
# Region segmentation
- step: Segmentation
settings:
model: yolo
model_settings:
model: Riksarkivet/yolov9-regions-1
generation_settings:
conf: 0.3
batch_size: 32
# Line segmentation
- step: Segmentation
settings:
model: yolo
model_settings:
model: Riksarkivet/yolov9-lines-within-regions-1
generation_settings:
conf: 0.3
batch_size: 16
- step: TextRecognition
settings:
model: WordLevelTrocr
model_settings:
model: Riksarkivet/trocr-base-handwritten-hist-swe-2
generation_settings:
batch_size: 16
num_beams: 1
- step: ReadingOrderMarginalia
settings:
two_page: always
- step: RemoveLowTextConfidencePages
settings:
threshold: 0.95
- step: RemoveLowTextConfidenceLines
settings:
threshold: 0.95
# Export to Alto and Page XML
- step: Export
settings:
dest: outputs/new_models/alto
format: alto
- step: Export
settings:
dest: outputs/new_models/page
format: page
# Sets label format to regionX_lineY_wordZ
labels:
level_labels:
- region
- line
- word
sep: _
template: "{label}{number}"
See the documentation for the HTRflow package for further instructions on specific steps and customizations
Training Details
Training Data
We cannot publically release all data the model was trained on, since we ourselves haven't created all the data, but below are links to the datasets we can release publically:
Göteborgs poliskammare 1850-1900
Krigshovrättens domböcker
Svea hovrätt
Bergskollegium
Frihetstidens utskottshandlingar
Carl-Fredrik PÃ¥hlmans resejournaler
Trolldomskommissionen
Göta hovrätt
Bergmästaren i Nora
Älvsborgs lösen
Jönköpings rådhusrätt magistrat
Training Procedure
Preprocessing
The text-line polygons were masked out and placed against a white backgroundy, with dimensions decided by the polygon's bounding box.
Training Hyperparameters
See config.json at model repo
training regime: bf16
learning rate: 5e-5
weight decay: 0.01
Evaluation
In-Domain Evaluation Data (Sorted by CER)
These are the character and word error rates on evaluation data taken from the same archives that was included in the training set. Of course the evaluation samples aren't part of the training data. The number of samples included in the training-set give an indication of how the model improves by fine-tuning it on some specific material within the model's range.
Dataset | WER | CER | Train Lines | Eval Lines |
---|---|---|---|---|
krigshovrattens_dombocker_lines | 0.0330 | 0.0075 | 16,887 | 1,877 |
stockholms_stadsarkiv_allmana_barnhuset_1700_lines | 0.0647 | 0.0120 | 565 | 142 |
stockholms_stadsarkiv_blandat_2_1700_lines | 0.0807 | 0.0170 | 25,024 | 2,781 |
goteborgs_poliskammare_fore_1900_lines | 0.0800 | 0.0187 | 339,297 | 17,858 |
stockholms_stadsarkiv_stockholms_domkapitel_1700_lines | 0.0948 | 0.0187 | 96,409 | 5,075 |
stockholms_stadsarkiv_politikollegiet_1700_lines | 0.1108 | 0.0225 | 120,238 | 6,329 |
bergskollegium_relationer_och_skrivelser_lines | 0.1056 | 0.0253 | 62,201 | 6,912 |
stockholms_stadsarkiv_stadens_kamnarsratt_1700_lines | 0.1252 | 0.0278 | 38,330 | 4,259 |
svea_hovratt_lines | 0.1484 | 0.0313 | 36,884 | 4,099 |
stockholms_stadsarkiv_stockholms_domkapitel_1800_lines | 0.1400 | 0.0324 | 2,070 | 230 |
stockholms_stadsarkiv_handelskollegiet_1600_1700_lines | 0.1785 | 0.0350 | 9,201 | 1,023 |
frihetstidens_utskottshandlingar_lines | 0.1481 | 0.0362 | 13,490 | 1,499 |
stockholms_stadsarkiv_kungliga_hovkonsistoriet_1700_lines | 0.1541 | 0.0364 | 5,753 | 640 |
national_archives_finland_court_records_lines | 0.1607 | 0.0368 | 147,456 | 7,761 |
stockholms_stadsarkiv_blandat_1600_1700_lines | 0.1505 | 0.0379 | 16,137 | 1,794 |
stockholms_stadsarkiv_blandat_3_1600_lines | 0.1633 | 0.0400 | 43,142 | 4,794 |
stockholms_stadsarkiv_norra_forstadens_kamnarsratt_1600_1700_lines | 0.1755 | 0.0463 | 18,474 | 2,053 |
carl_fredrik_pahlmans_resejournaler_lines | 0.1768 | 0.0482 | 7,081 | 787 |
stockholms_stadsarkiv_sollentuna_haradsratt_1700_1800_lines | 0.1921 | 0.0505 | 19,096 | 2,122 |
stockholms_stadsarkiv_byggningskollegium_1600_lines | 0.2262 | 0.0514 | 3,104 | 345 |
ra_enstaka_sidor_lines | 0.1991 | 0.0538 | 5,078 | 565 |
trolldomskommissionen_lines | 0.2321 | 0.0600 | 33,498 | 3,722 |
stockholms_stadsarkiv_stockholms_domkapitel_1600_lines | 0.2170 | 0.0607 | 11,619 | 1,292 |
stockholms_stadsarkiv_botkyrka_kyrkoarkiv_1600_1800_lines | 0.2548 | 0.0627 | 3,617 | 402 |
gota_hovratt_lines | 0.2450 | 0.0630 | 2,421 | 269 |
bergmastaren_i_nora_htr_lines | 0.2558 | 0.0709 | 7,916 | 880 |
bergskollegium_advokatfiskalkontoret_lines | 0.2906 | 0.0722 | 2,411 | 268 |
jl_fornsallskap_jamtlands_domsaga_lines | 0.2585 | 0.0732 | 60,544 | 6,728 |
alvsborgs_losen_lines | 0.1896 | 0.0806 | 5,632 | 626 |
jonkopings_radhusratt_och_magistrat_lines | 0.2864 | 0.0853 | 1,179 | 131 |
national_archives_finland_letters_recipes_lines | 0.3857 | 0.1360 | 651 | 163 |
Testing Data
Out-of-Domain Test Data (Sorted by CER)
These are all test-sets taken from archives that we're not at all included in the training data. So these are the results one would expect if one uses this model out-of-the-box on just any running text document within the models time-span. The entire test-suite is available here: test-suite for htr
Dataset | WER | CER | Eval Lines |
---|---|---|---|
1792_R0002231_eval_lines | 0.1190 | 0.0250 | 501 |
1794-1795_A0068546_eval_lines | 0.1503 | 0.0303 | 510 |
1775-1786_A0068551_eval_lines | 0.2203 | 0.0543 | 525 |
1841_Z0000017_eval_lines | 0.2247 | 0.0555 | 470 |
1690_A0066756_eval_lines | 0.2571 | 0.0611 | 249 |
1716_A0017151_eval_lines | 0.2517 | 0.0650 | 558 |
1824_H0000743_eval_lines | 0.2684 | 0.0674 | 260 |
1699-1700_C0113233_eval_lines | 0.2713 | 0.0691 | 394 |
1845-1857_B0000011_eval_lines | 0.2546 | 0.0706 | 153 |
1812_A0069332_eval_lines | 0.2868 | 0.0793 | 69 |
1659-1674_R0000568_eval_lines | 0.3278 | 0.0886 | 304 |
1755-1756_C0112394_eval_lines | 0.3440 | 0.0918 | 248 |
1723_H0000374_eval_lines | 0.3105 | 0.1140 | 378 |
1887-1892_A0002409_eval_lines | 0.3670 | 0.1297 | 784 |
1679_R0002397_eval_lines | 0.4768 | 0.1422 | 88 |
1800_C0101725_eval_lines | 0.4459 | 0.1767 | 37 |
1871_K0017448_eval_lines | 0.4504 | 0.1945 | 331 |
1654_R0001308_eval_lines | 0.5200 | 0.2179 | 199 |
Metrics
Character Error Rate (CER)
Character Error Rate (CER) is a metric used to evaluate the performance of a Handwritten Text Recognition (HTR) system by comparing the recognized text to the reference (ground truth) text at the character level.
The CER is calculated using the following formula:
Where:
- ( S ) = Number of substitutions (incorrect characters)
- ( D ) = Number of deletions (missing characters)
- ( I ) = Number of insertions (extra characters)
- ( N ) = Total number of characters in the reference text
A lower CER indicates better recognition accuracy.
Word Error Rate (WER)
Word Error Rate (WER) is a metric used to assess the accuracy of an HTR system at the word level by comparing the recognized text to the reference text.
The WER is calculated using the following formula:
Where:
- ( S ) = Number of substitutions (incorrect words)
- ( D ) = Number of deletions (missing words)
- ( I ) = Number of insertions (extra words)
- ( N ) = Total number of words in the reference text
Similar to CER, a lower WER indicates better word-level accuracy.
Technical Specifications
Model Architecture
See config.json at model repo
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Model tree for Riksarkivet/trocr-base-handwritten-hist-swe-2
Base model
microsoft/trocr-base-handwritten