## 3 Datasets
### Datasets Used  
As mentioned above, we used five datasets for our evaluation, covering different layout styles from the 15 th and 16 th Centuries, instead of one combined dataset with pages from many different books with different layouts and levels of difficulty. For each page in the datasets, the layout elements were annotated manually as the ground truth (GT) on the line level, since lines are the input for the subsequent OCR step. A general difficulty is the GT annotation of the height of a line, because in some layouts, letters from two adjacent lines touch each other. We used a complex algorithm to find the best polygon for line separation, but this is difficult to evaluate against a manual GT, because it would be too time-consuming to define these polygons manually. Therefore, the GT for lines allows any \"reasonable\" cut between adjacent lines. A different situation exists for the length of the line polygons, since cutting one letter or even half of a letter at the beginning or end of a text line would have a negative impact on the OCR, which is taken into account by the GT and the evaluation. The characteristics of the five datasets are as follows:  
The **CamStd** dataset is composed of images from two historical works from 1564 and 1565 with the same layout ([[http://kallimachos.uni-wuerzburg.de/camerarius/index.php/](http://kallimachos.uni-wuerzburg.de/camerarius/index.php/)]([http://kallimachos.uni-wuerzburg.de/camerarius/index.php/](http://kallimachos.uni-wuerzburg.de/camerarius/index.php/)) [PERSON]_[PERSON]_patris_[PERSON]_episcop_[PERSON]_orations_duae_1564 (accessed on 10 November 2022); [[http://kallimachos.uni-wuerzburg.de/camerarius/index.php/](http://kallimachos.uni-wuerzburg.de/camerarius/index.php/)]([http://kallimachos.uni-wuerzburg.de/camerarius/index.php/](http://kallimachos.uni-wuerzburg.de/camerarius/index.php/)) [PERSON]_[PERSON]_[PERSON]_in_patriam_coniuratio_1565 (accessed on 10 November 2022)). The dataset consists of 80 page images and contains no marginalia, no images, and only a single column of lines. It contains a header and a footer per page and a few dropped capitals. The **CamMarg** dataset was taken from one historical print from 1595 (http://kallimac hos.uni-wuerzburg.de/camerarius/index.php/ [PERSON]_Epistolae_families_1595 (accessed on 10 November 2022)) and is composed of 195 pages. It contains a few images and dropped capitals and many marginalia. Its headers and footers are composed of different components. The **GW5051** dataset is a subset of a print from 1497 digitized by the _Staatsbibliothek Berlin_ ([[https://digital.staatsbibliothek-berlin.de/werkansicht/?PPN=PPN799202126](https://digital.staatsbibliothek-berlin.de/werkansicht/?PPN=PPN799202126)]([https://digital.staatsbibliothek-berlin.de/werkansicht/?PPN=PPN799202126](https://digital.staatsbibliothek-berlin.de/werkansicht/?PPN=PPN799202126)) (accessed on 10 November 2022)) and consists of 142 page images. We selected it because of its two-column layout. Different from the above datasets, it does not have a justified print, but a ragged right side. It contains many images, but no marginalia. Its top line is composed of a headline (belonging to the reading order), a page number (a header element not belonging to the reading order), and a footer. The **GW5056** dataset is a subset of a print from 1497, made available by the _John Carter Brown Library_ ([[https://archive.org/details/stultiferanuain00](https://archive.org/details/stultiferanuain00) bran/mode/2 up]([https://archive.org/details/stultiferanuain00](https://archive.org/details/stultiferanuain00) bran/mode/2 up) (accessed on 10 November 2022)) and contains 150 page images. It is similar to the **GW5051** dataset, but has marginalia instead of a two-column layout and has a simpler header.