## 3 Methods
### Manual Corrections  
Input: images and their corresponding PageXML files  
Output: corrected PageXML files  
As emphasized during the Introduction, a fully automated workflow is often not reasonable or at least cannot be expected to yield sufficient (depending on the use case) or even perfect results, especially when dealing with early printings. Consequently, a potent, flexible, comprehensible, and easy-to-use option for manual correction is a must-have for every OCR workflow tool that relies on user intervention. In OCR4 all, this core task is covered by LAREX, whose functionality has been considerably extended since its original release as a region segmentation tool and will be explained in the following.  
LAREX works directly on PageXML files and the corresponding images. After loading a page, the information is displayed using additional layers over the image in three different views, which are all interconnected with each other:  
* Regions: LAREX offers a wide variety of tools and procedures to create new and edit existing regions, including the adding and deletion of regions, as well as changing their (sub-)type and sophisticated polygon manipulation operations.
* Lines: From an editing point of view, lines are treated exactly like regions and therefore allow the same comprehensive set of operations with minor adaptions.
* Text: The text view (see Figure 6) is divided into two further sub-views. In the first one, the page image is still presented to the user with all text lines color-coded, indicating the availability of corresponding GT. While this view is a suitable solution for users that aim for a perfect text and consequently have to take a thorough look at each line anyway, it is not optimal for use cases where users just want to scan the pages and lines quickly for obvious mistakes. For this use case, we introduced a second sub-view, which optimizes the correction process by providing a synoptic view where an editable text field is placed directly under each line image, allowing the user to get a quick overview.  
Figure 6: Two text correction views in LAREX: page based view with a virtual keyboard where a selection of lines can be corrected (left and center) and the corresponding line based view (right).  
Configurations  
To be able to deal with the wide variety of printings and the distinct challenges proposed by them, as well as to satisfy the individual needs of each user, OCR4 all offers plenty of ways to influence not only the workflow in itself, but also the parameters of the single submodules. All configurations are entirely accessible from the web GUI in an intuitive way and do not require any kind of knowledge regarding the usage of the command line.  
In order to not overwhelm inexperienced users by confronting them with a plethora of confusing options, settings, and parameters, but also to provide more experienced users to adapt selected settings to optimize the results, we carefully split the available options for each submodule into general and advanced settings. While the general settings usually only contain one or two parameters whose default settings normally completely suffice for the average user, the advanced settings comprise all remaining parameters and allow experienced users to maintain full control.  
In particular, the degree of automation can be influenced via the so-called process flow. By default, all modules from preprocessing to recognition are configured and executed at once. However, if, for example, a segmentation using LAREX is needed, which requires user intervention, the subsequent steps can still be run at once and fully automatically.