Module for Omeka S to extract OCR text in XML and TSV from PDF files, allowing instant fulltext searching within any IIIF viewer like Universal Viewer or Mirador with IIIF-Search module).

The xml format is the simple pdf2xml or the most common standard alto. The tsv format is a simple two columns with the words and the list of positions by page.

The tsv format is recommended as it is a lot quicker, in particular for items with many pages.

• This module needs pdftohtml command-line tool on your server, from the poppler utilities:

# Debian and derivatives
sudo apt install poppler-utils
# Red Hat and derivatives
sudo dnf install poppler-utils

• Before Omeka S version 3.1, the module requires to set the base uri in the config file of Omeka config/local.config.php in order to upload the file in background:

    'file_store' => [
        'local' => [
            'base_path' => null, // Or the full path on the server if needed.
            'base_uri' => 'https://example.org/files', // To be removed in Omeka S v3.1.
        ],
    ],

• Upload and unzip the Extract OCR module folder into your modules folder on the server, or you can install the module via github:

cd omeka-s/modules
git clone [email protected]:bubdxm/Omeka-S-module-ExtractOcr.git "ExtractOcr"

• Take care to rename the folder "ExtractOcr".
• Install it from the admin → Modules → Extract Ocr -> install
• Extract OCR automaticaly allows the upload of XML files.

• Create an item
• Save this Item
• After save, add PDF file(s) to this item
• To locate extracted OCR xml or tsv file, select the item to which the PDF is attached. Normally, you should see an XML or a tsv file attached to the record with the same filename than the pdf file.

• IIIF-Server: Module for Omeka S that adds the IIIF specifications to serve any images and medias.
• IIIF-Search: Module for Omeka S that adds IIIF Search Api for fulltext searching on universal viewer.
• Universal Viewer: Module for Omeka S that includes UniversalViewer, a unified online player for any file. It can display books, images, maps, audio, movies, pdf, 3D views, and anything else as long as the appropriate extensions are installed.
• Mirador
• Or any other IIIF viewers, like Diva.

• Extract strings with pdftotext with arg -tsv and store them in a file or in database for simpler and quicker search.
• Extract strings by word, but with one position by row, allowing to search with "AND", not only "OR".

See online Extract OCR issues.

This module is published under GNU/GPL.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

• Copyright Syvain Machefert, Université Bordeaux 3 (see symac)
• Copyright Daniel Berthereau, 2020-2024 (see Daniel-KM on GitLab)