LAREX
LAREX is a semi-automatic open-source tool for layout analysis on early printed books. It uses a rule based connected components approach which is very fast, easily comprehensible for the user and allows an intuitive manual correction if necessary. The PageXML format is used to support integration into existing OCR workflows. Evaluations showed that LAREX provides an efficient and flexible way to segment pages of early printed books.
Please feel free to visit the tool homepage and the web application. A short user manual is available here.
Table of Contents
Additional information about developing for LAREX see here
Installation
Linux
This guide uses tomcat 8 and Ubuntu (please adjust accordingly for your setup)
- Install required packages:
apt-get install tomcat8 maven openjdk-8-jdk - Clone Repository:
git clone https://github.com/OCR4all/LAREX.git - Compile:
mvn clean install -f LAREX/pom.xml. - Copy or link the created war file to tomcat:
- Copy
cp LAREX/target/Larex.war /var/lib/tomcat8/webapps/Larex.war - Link:
sudo ln -s $PWD/LAREX/target/Larex.war /var/lib/tomcat8/webapps/Larex.war
- Copy
- Start Tomcat:
systemctl start tomcat8- (Restart Tomcat via
systemctl restart tomcat8) - (To start Tomcat automatically at system boot
systemctl enable tomcat8)
- (Restart Tomcat via
Windows
This guide uses eclipse to simplify the setup on Windows
- Install Eclipse IDE for Enterprise Java Developers from the official website
- Download tomcat 8 or up from the official website
- Create a tomcat server in eclipse:
- Open
Window->Show View->Other...->Server->Servers - Click prompt to add a new server, select
Apache->Tomcat <version> Server->Next-> set your Tomcat installation directory ->Finish.
- Open
- Clone Repository:
File->Import->Git->Projects from Git->Clone URI-> SetURI: https://github.com/OCR4all/LAREX.git->[✓] master->Next >->Next >->Import as gernal project->Finish
- Set as Maven Project:
- Import Project
- Right click on
Larex->Configure->Convert to Maven Project->Finish
- Right click on
- Update maven project (if not updated automatically)
- Rightclick on
Larex->Maven->Update Project...->OK
- Rightclick on
- Start Larex
- Right click on
Larex->Run As->Run on Server.
- Right click on
Mac OS X
This guid uses homebrew (please adjust accordingly for your setup)
- Install Homebrew (see https://brew.sh/).
- Install required packages:
brew cask install javabrew install tomcat git maven
- (Verify tomcat installation):
brew services listtomcat should be listed in the output of this command
- Clone Repository:
git clone https://github.com/OCR4all/LAREX.git
- Compile:
- run
mvn clean install -f LAREX/pom.xml.
- run
- Copy or link the created war file to tomcat
- Copy:
cp LAREX/target/Larex.war /usr/local/Cellar/tomcat/[version]/libexec/webapps/Larex.war - Link:
ln -s $PWD/LAREX/target/Larex.war /usr/local/Cellar/tomcat/[version]/libexec/webapps/Larex.war
- Copy:
- Start Tomcat:
brew services start tomcat- (Restart Tomcat via
brew services restart tomcat)
Usage
Access in browser
Go to localhost:8080/Larex.
Using your own images and books
You can add your own books by copying them to src/webapp/resources/books
(Or an alternative direction set in the config file. See section Configuration for more information).
Book directories must have the following structure:
bookDir/
├── <book_name>/
│ ├── <page_name>.png
│ └── <page_name>.xml
└── <book2_name>/
└── …
More information
Detailed information about the usage of LAREX can be found in the OCR4all getting started guides.
See sections and chapters about Segmentation, Ground Truth Correction and Post Correction.
Configuration
Larex contains a configuration file (src/webapp/WEB-INF/larex.config) with a few settings that can be set before running the application.
bookpath
The setting bookpath sets the file path of the books folder.
e.g. bookpath:/home/user/books (Linux)
e.g. bookpath:C:\Users\user\Documents\books (Windows)
Larex will load the books from this folder.
[default /src/main/webapp/resources/books]
localsave
The setting localsave tells the application how to handle results locally when saved.
<mode>=[bookpath|savedir|none]
bookpath: save the result in the bookpath
savedir: save the result in a defined savedir
none: do not save the result locally [default]
e.g. localsave:bookpath
savedir
The setting savedir is needed if localsave mode is set to "savedir".
e.g. savedir:/home/user/save (Linux)
e.g. savedir:C:\Users\user\Documents\save (Windows)
websave
The setting websave tells the application how to handle results on the browser side when saved.
<value>=[true|false]
true: download the result after saving [default]
false: no action after saving
e.g. websave:true
modes
Set the accessible modes in the Larex gui <value>=[[segment][edit][lines][text]] A combination of the modes "segment", "edit", "lines" and "text" can be set as a space separated string. e.g. modes:segment lines
The order of those modes in the string also determines which mode is opened on startup, with the first in the list being opened as main mode. The mode "segment" can be replaced with "edit" in order to hide all auto segmentation features. ("edit" will be ignored if both are present)
[Default]modes:segment lines text
directrequest
This setting enables or disables the direct open feature.
<value>=[enable|disable]
This feature allows users to load a book from everywhere on the servers drive aswell as to alter the options websave, localsave and savedir.
enable: enable direct request
disable: disable direct request [default]
e.g. directrequest:enable
This feature should be used with caution but is very useful when using Larex in a workflow with other web applications. (e.g. in docker)
The easiest direct request would be via a html form with the values bookpath, bookname, websave (optional), localsave (optional) and savedir (optional).
<form action="http://localhost:8080/Larex/direct" method="POST">
bookpath: <input type="text" name="bookpath"/><br>
bookname: <input type="text" name="bookname"/><br>
websave: <input type="text" name="websave"/><br>
localsave: <input type="text" name="localsave"/><br>
savedir: <input type="text" name="savedir"/><br>
modes: <input type="text" name="modes"/><br>
<input type="submit"/>
</form>
OCR4all UI mode
This setting enables or disables OCR4all UI mode.
<value>=[enable|disable]
This setting allows displaying and/or hiding certain UI elements when LAREX is used in combination with OCR4all.
enable: enable OCR4all UI mode
disable: disable OCR4all UI mode [default]
e.g. ocr4all:enable
Related Publications:
Reul, Christian; Springmann, Uwe; Puppe, Frank: LAREX – A semi-automatic open-source Tool for Layout Analysis and Region Extraction on Early Printed Books. In Proceedings of the 2nd International Conference on Digital Access to Textual Cultural Heritage (2017). ACM. Draft available at arXiv.
Reul, Christian; Dittrich, Marco; Gruner, Martin: Case Study of a highly automated Layout Analysis and OCR of an incunabulum: ‘Der Heiligen Leben’ (1488). In Proceedings of the 2nd International Conference on Digital Access to Textual Cultural Heritage (2017). ACM. Draft available at arXiv.
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