h2-ml-ocr/ocr-fileformat

Validate and transform various OCR file formats (hOCR, ALTO, PAGE, FineReader)

ocr-fileformat

Validate and transform between OCR file formats (hOCR, ALTO, PAGE, FineReader)

• Installation
  • Docker
  • System-wide
• Usage
  • CLI
  • GUI
  • API
• Transformation
  • Transformation CLI
  • Transformation GUI
  • Transformation API
  • Supported Transformations
• Validation
  • Validation CLI
  • Validation GUI
  • Validation API
  • Supported Validation Formats
• License

Installation

Docker

You can run the command line scripts and web interface as a Docker container, you only need Docker installed.

To start the web interface on http://localhost:8080:

docker run --rm -it -p 8080:8080 ubma/ocr-fileformat

To run the command line scripts, mount the directory containing your input files into the container's /data directory:

docker run --rm -it -v "$PWD":/data ubma/ocr-fileformat ocr-transform alto2.0 hocr somefile.alto

System-wide

To install system-wide to /usr/local:

sudo make install

To install without sudo to your home directory:

make install PREFIX=$HOME/.local

If $HOME/.local/bin is not in your PATH, add this to your shell startup file (e.g. ~/.bashrc or ~/.zshrc):

export PATH="$HOME/.local/bin $PATH"

The web application has a PHP backed. You can deploy it on any PHP-capable server by copying the web folder somewhere below the document root of your server, e.g. /var/www/html for Apache on Debian/Ubuntu:

sudo -u www-data cp -r web /var/www/html/ocr-fileformat

In this example the GUI would be available under http://localhost/ocr-fileformat/.

Usage

The project offers two functionalities, which can be accessd via a command line script (CLI), using a web interface (GUI) or in you own tools (API)

CLI

• ocr-transform: Transformation of OCR output between OCR formats
• ocr-validate: Validation of OCR output against OCR format schemas

GUI

The web interface is for testing validation and transformations. You can upload a file or select an input file by URL.

API

• $PREFIX/share/ocr-fileformat/xslt - XSLT stylesheets
• $PREFIX/share/ocr-fileformat/xsd - XSD schemas
• $PREFIX/share/ocr-fileformat/script/transform - Transformation scripts
• $PREFIX/share/ocr-fileformat/script/validate - Validation scripts

Transformation

Transformation CLI

Usage: ocr-transform [-dl] <input-fmt> <output-fmt> [<input> [<output>]] [-- <saxon_opts>]

For example, you can transform an ALTO XML to a hOCR file with:

ocr-transform alto hocr sample.xml sample.hocr

Or convert from ALTO XML (version 2.1) to hOCR with:

ocr-transform alto2.1 hocr sample.alto sample.hocr

You can also pass arguments directly to the Saxon CLI by passing them after a double dash (--). For example, to set the foo parameter to bar:

ocr-transform alto hocr sample.xml sample.hocr -- foo=bar

Try ocr-transform -h to get an overview:

Usage: ocr-transform [-dhLv]   [ []] [-- ]

    Options:
        --help    -h     Show this help
        --version -v     Show version
        --debug   -d     Increase debug level by 1, can be repeated
        --list    -L     List transformations

    Transformations:
        abbyy hocr
        abbyy page
        alto2.0 alto3.0
        alto2.0 alto3.1
        alto2.0 hocr
        alto2.1 alto3.0
        alto2.1 alto3.1
        alto2.1 hocr
        alto page
        alto text
        gcv hocr
        gcv page
        hocr alto2.0
        hocr alto2.1
        hocr page
        hocr text
        page alto
        page hocr
        page page2019
        page text
        tei hocr

    Saxon options:
        Usage: see http://www.saxonica.com/documentation/index.html#!using-xsl/commandline
        Options available: -? -a -catalog -config -cr -diag -dtd -ea -expand -explain -export -ext -im -init -it -jit -l -lib -license -m -nogo -now -o -opt -or -outval -p -quit -r -relocate -repeat -s -sa -scmin -strip -t -T -target -threads -TJ -Tlevel -Tout -TP -traceout -tree -u -val -versionmsg -warnings -x -xi -xmlversion -xsd -xsdversion -xsiloc -xsl -y
        Use -XYZ:? for details of option XYZ
        Params:
          param=value           Set stylesheet string parameter
          +param=filename       Set stylesheet document parameter
          ?param=expression     Set stylesheet parameter using XPath
          !param=value          Set serialization parameter

Transformation GUI

Select the Transform menu option. Choose a URL, an input and an output format. Click Transform.

Transformation API

The stylesheets are installed in $PREFIX/share/ocr-fileformat/xslt and can be used directly in your scripts and software. You will need to use an XSLT 2.0 capable stylesheet transformer.

Supported Transformations

From ╲ To	hOCR	ALTO	PAGEXML
hOCR	=	✓	✓
ALTO	✓	=	✓
PAGEXML	✓	✓	=
FineReader	✓	-	✓
Google Cloud Vision	✓	-	✓
TEI	✓	-	-

Validation

Usage: ocr-validate [-dhL]   []

    Options:
        --help    -h     Show this help
        --version -v     Show version
        --debug   -d     Increase debug level by 1, can be repeated
        --list    -L     List available schemas

    Schemas:
        hocr
        alto-1-0 alto-1-1 alto-1-2 alto-1-3 alto-1-4 alto-2-0 alto-2-1 alto-2-2-draft alto-3-0 alto-3-1 alto-3-2-draft alto-4-0 alto-4-1
        abbyy-6-schema-v1 abbyy-8-schema-v2 abbyy-9-schema-v1 abbyy-10-schema-v1
        page-2009-03-16 page-2010-01-12 page-2010-03-19 page-2013-07-15 page-2016-07-15 page-2017-07-15 page-2018-07-15 page-2019-07-15

Validation CLI

For example, to validate an XML file againt the ALTO 3.1 schema:

ocr-validate alto-3-1 myFile.alto

Validation GUI

Select the Validate menu option. Choose a URL and an schema. Click Validate.

Validation API

The XSD files are installed under $PREFIX/share/ocr-fileformat/xsd

Supported Validation Formats

	hOCR	ALTO	PAGEXML	FineReader	Google Cloud Vision
Validation	✓	✓	✓	✓	-

License

This is free software. You may use it under the terms of the MIT License.

During the installation process several projects are included (in ./vendor). These projects have different licenses:

• Saxon HE 9.7, MPL.
• ALTOXML schema, "Open Source" for ALTO <= 3.1, CC BY SA 4.0 since ALTO 4.0
• PAGE schemas, ?
• xsd-validator by Adrian Mouat @amouat, Apache 2.0
• ABBYY FineReader XSD, ?
• hOCR-to-ALTO by Filip Kriz @filak, MIT
• hocr-spec by Konstantin Baierer @kba, MIT
• gcv2hocr by Endo Michiaki, CC BY 4.0
• format-converters by OCR-D, Apache 2.0
• prima-page-converter by PRImA Research Lab , Apache 2.0