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imixs/tika

The Docker Image 'imixs/tika' provides a Tika Server. This server can be used for OCR via a Rest API provided by the Apache Tika Project

Features

  • inherit form official openJDK
  • runs tika and tesseract with OpenJDK 10
  • supported languages: de, en

The Rest API

The Rest API is provided by the Apache Tika Project. You will find details about the API here.

Get the Text of a Document

$ curl -X PUT --data-binary @GeoSPARQL.pdf http://localhost:9998/tika --header "Content-type: application/pdf"
$ curl -T price.xls http://localhost:9998/tika --header "Accept: text/html"
$ curl -T price.xls http://localhost:9998/tika --header "Accept: text/plain"

Examples:

$ curl -T test/IMG_20190421_132434.jpg http://localhost:9998/tika
$ curl -T test/imixs-workflow.pdf http://localhost:9998/tika
$ curl -T test/zugferd_invoice.pdf http://localhost:9998/tika
$ curl -T test/IMG_20190421_133732.jpg http://localhost:9998/tika

PDF File with embedded image

$ curl -T test/Dokument01.pdf http://localhost:9998/tika --header "X-Tika-PDFOcrStrategy: ocr_only"

Running and stopping a container

You can start an instance of the postgres service with the Docker run command:

docker run -it --rm --name="tika" \
    -p 9998:9998 \
    imixs/tika

To run tika in a docker-compose or docker swarm environment just use the following setup:

  tika: 
    image: imixs/tika
    ports:
      - "9998:9998"

Docker Swarm and Kubernetes

The imixs/tiker image can perfectly be used in a docker swarm environment or in a kubernetes cluster. So you have a single service providing OCR functionallity via a Rest API.

Imixs-Archive

The Imixs-Archive Project provides a Imixs-Workflow plugin to be used for OCR.

Configuration

Out of the box, Apache Tika will start with the default configuration. Setting the environment Variable TIKA_CONFIG you can specify a custom tika configuration file to be used by the tika server.

Through a custom Tika Config xml file, it is possible to have a high degree of control over which detectors are or aren't used, in what order of preferences etc. It is also possible to override just certain parts, to (for example) have "default except for no POIFS Container Detction". You will find more about the configuration details here.

This is an example how you can set a custom tika-config.xml file in a docker-compose.yaml defintion:

  tika: 
    image: imixs/tika
    environment:
      TIKA_CONFIG: "/tika-config.xml"
    ...
    volumes:
      - ~/my-config/tika-config.xml:/tika-config.xml
    ....
  ...

This is an example for a tika configuration with higher OCR resolution:

<?xml version="1.0" encoding="UTF-8"?>
<properties>
  <parsers>
    <parser class="org.apache.tika.parser.DefaultParser"></parser>
    <parser class="org.apache.tika.parser.pdf.PDFParser">
            <params>
            	<!-- OCR_ONLY  |  OCR_AND_TEXT_EXTRACTION  -->
                <param name="ocrStrategy" type="string">OCR_AND_TEXT_EXTRACTION</param>
                <!-- GRAY | RGB  -->
                <param name="ocrImageType" type="string">RGB</param>
                <param name="ocrDPI" type="int">400</param>
            </params>
    </parser>
  </parsers>
</properties>

Using Header Parameters

During a HTTP request it is also possible to pass through header parameters to the Tika Server. These header parameters are prafixed with X-Tika-OCR and X-Tika-PDF.

$ curl -T test/Dokument01.pdf http://localhost:9998/tika --header "X-Tika-PDFOcrStrategy: ocr_only"

The code that handles the X-Tika-OCR and X-Tika-PDF headers is the class TikaResource.processHeaderConfig.

Those header suffixes and values are mapped by the TesseractOCRConfig and PDFParserConfig configuration objects via reflection. In this way you can set any config option with a corresponding header parameter.

To see what X-Tika headers you can set, look up the options on the config class you want to tweak things on (Tesseract or PDF), then build the name, then set the header. If you are not sure what the option does, or what values it takes, look at the JavaDocs for the underlying setter method that will get called.

For example the config method setExtractInlineImages on PDF, maps to the header parameter

X-Tika-PDFextractInlineImages

Note: Header parameters are case sensitive!

OCR Tesseract

You can also configure the OCR feature based on Tesseract. Find details here.

Contribute

The source is available on Github. Please report any issues.

Checkout the sources from GitHub:

git clone https://github.com/imixs/imixs-docker.git 
git checkout -b master origin/master

To build the image from the Dockerfile run:

$ docker build --tag=imixs/tika ./tika

Push manually to Docker repo (Docker-Hub)

To push the image to a docker repo:

$ docker build -t imixs/tika:X.X.X .
$ docker push imixs/tika:X.X.X