OCR Ground Truth for Historical Commentaries

The dataset OCR ground truth for historical commentaries (GT4HistComment) was created from the public domain subset of scholarly commentaries on Sophocles' Ajax. Its main goal is to enable the evaluation of the OCR quality on printed materials that contain a mix of Latin and polytonic Greek scripts. It consists of five 19C commentaries written in German, English, and Latin, for a total of 3,356 GT lines.

Data

GT4HistComment are contained in data/, where each sub-folder corresponds to a different publication (i.e. commentary). For each each commentary we provide the following data:

• <commentary_id>/GT-pairs: pairs of image/text files for each GT line
• <commentary_id>/imgs: original images on which the OCR was performed
• <commentary_id>/<commentary_id>_olr.tsv: OLR annotations with image region coordinates and layout type ground truth label

The OCR output produced by the Kraken + Ciaconna pipeline was manually corrected by a pool of annotators using the Lace platform. In order to ensure the quality of the ground truth datasets, an additional verification of all transcriptions made in Lace was carried out by an annotator on line-by-line pairs of image and corresponding text.

Commentary overview

ID	Commentator	Year	Languages	Image source	Line example
bsb10234118	Lobeck [1]	1835	Greek, Latin	BSB
sophokle1v3soph	Schneidewin [2]	1853	Greek, German	Internet Archive
cu31924087948174	Campbell [3]	1881	Greek, English	Internet Archive
sophoclesplaysa05campgoog	Jebb [4]	1896	Greek, English	Internet Archive
Wecklein1894	Wecklein [5]	1894 [5]	Greek. German	internal

Stats

Line, word and char counts for each commentary are indicated in the following table. Detailled counts for each region can be found here.

ID	Commentator	Type	lines	words	all chars	greek chars
bsb10234118	Lobeck	training	574	2943	16081	5344
bsb10234118	Lobeck	groundtruth	202	1491	7917	2786
sophokle1v3soph	Schneidewin	training	583	2970	16112	3269
sophokle1v3soph	Schneidewin	groundtruth	382	1599	8436	2191
cu31924087948174	Campbell	groundtruth	464	2987	14291	3566
sophoclesplaysa05campgoog	Jebb	training	561	4102	19141	5314
sophoclesplaysa05campgoog	Jebb	groundtruth	324	2418	10986	2805
Wecklein1894	Wecklein	groundtruth	211	1912	9556	3268

Commentary editions used:

• [1] Lobeck, Christian August. 1835. Sophoclis Aiax. Leipzig: Weidmann.
• [2] Sophokles. 1853. Sophokles Erklaert von F. W. Schneidewin. Erstes Baendchen: Aias. Philoktetes. Edited by Friedrich Wilhelm Schneidewin. Leipzig: Weidmann.
• [3] Lewis Campbell. 1881. Sophocles. Oxford : Clarendon Press.
• [4] Wecklein, Nikolaus. 1894. Sophokleus Aias. München: Lindauer.
• [5] Jebb, Richard Claverhouse. 1896. Sophocles: The Plays and Fragments. London: Cambridge University Press.

Citation

If you use this dataset in your research, please cite the following publication:

@inproceedings{romanello_optical_2021,
  title = {Optical {{Character Recognition}} of 19th {{Century Classical Commentaries}}: The {{Current State}} of {{Affairs}}},
  booktitle = {The 6th {{International Workshop}} on {{Historical Document Imaging}} and {{Processing}} ({{HIP}} '21)},
  author = {Romanello, Matteo and Sven, Najem-Meyer and Robertson, Bruce},
  year = {2021},
  publisher = {{Association for Computing Machinery}},
  address = {{Lausanne}},
  doi = {10.1145/3476887.3476911}
}

Acknowledgements

Data in this repository were produced in the context of the Ajax Multi-Commentary project, funded by the Swiss National Science Foundation under an Ambizione grant PZ00P1_186033.

Contributors: Carla Amaya (UNIL), Sven Najem-Meyer (EPFL), Matteo Romanello (UNIL), Bruce Robertson (Mount Allison University).