Alfresco Transformer from PDF to OCRd PDF

This project includes a simple Transformer for Alfresco from PDF to OCRd PDF to be used with ACS Community 7.0+

OCR Transformation is performed by ocrmypdf, a wrapper of Tesseract that includes additional features in order to improve the accuracy of the process.

The Transformer ats-transformer-ocr uses the new Alfresco Local Transform API, that allows to register a Spring Boot Application as a local transformation service.

The folder embed-metadata-action includes an Alfresco Repository Addon that enables the action embed-metadata in Folder Rule feature.

ACS Community 7.4 or later requires modifying default configuration for HTTP requests timeouts. Increase default values (5000 ms / 5 s) to a larger value, like in the following sample that uses 500000 ms / 500 s

httpclient.config.transform.socketTimeout=500000
httpclient.config.transform.connectionRequestTimeout=500000
httpclient.config.transform.connectionTimeout=500000

Local testing

Build Docker Image for Alfresco OCR Transformer

Building the Alfresco OCR Transformer Docker Image is required before running the Docker Compose template provided.

$ cd ats-transformer-ocr

$ mvn clean package

Maven will create a Docker Image named alfresco/tengine-ocr:latest

Starting

$ docker run -p 8090:8090 alfresco/tengine-ocr:latest

Testing

A sample web page has been created in order to test the transformer is working:

http://localhost:8090

Deployment with ACS Stack

Obtaining Repository Addon to enable Embed Metadata Action

Before deploying Alfresco OCR Transformer, embed-metadata-action Repository Addon should be built.

$ cd embed-metadata-action

$ mvn clean package

$ ls target/embed-metadata-action-1.0.0.jar
target/embed-metadata-action-1.0.0.jar

Alternatively embed-metadata-action-1.0.0.jar can be download from Releases

Deploying Repository Addon to enable Embed Metadata Action

Use some of the available alternatives to deploy embed-metadata-action-1.0.0.jar in alfresco service, like adding the JAR to alfresco/modules/jar folder when using Alfresco Docker Installer tool.

Adding Alfresco OCR Transformer to Docker Compose (Local Transformer - HTTP) - Community Edition

Review that the following configuration is applied to docker-compose.yml file.

services:
    alfresco:
        environment:
            JAVA_OPTS : "
                -DlocalTransform.core-aio.url=http://transform-core-aio:8090/
                -DlocalTransform.ocr.url=http://transform-ocr:8090/
            "

    transform-core-aio:
        image: alfresco/alfresco-transform-core-aio:2.3.10
        mem_limit: 1536m
        environment:
            JAVA_OPTS: " -XX:MinRAMPercentage=50 -XX:MaxRAMPercentage=80"

    transform-ocr:
        image: alfresco/tengine-ocr:latest
        mem_limit: 1536m
        environment:
            JAVA_OPTS: " -XX:MinRAMPercentage=50 -XX:MaxRAMPercentage=80"

• Include the localTransform URL for OCR Transformer in alfresco Docker Container, http://transform-ocr:8090/ by default
• Declare the new transform-ocr Docker Container

Remember that you need to build Docker Image for alfresco/tengine-ocr before running this composition

Start ACS Stack from folder containing docker-compose.yml file.

$ docker-compose up --build --force-recreate

Sample deployment is available in docker folder.

Adding Alfresco OCR Transformer to Docker Compose (Async Transformer - ActiveMQ) - Enterprise Edition

Review that the following configuration is applied to docker-compose.yml file.

services:
    alfresco:
        environment:
            JAVA_OPTS : "
              -Dlocal.transform.service.enabled=true
              -Dtransform.service.enabled=true
              -Dtransform.service.url=http://transform-router:8095
              -Dsfs.url=http://shared-file-store:8099/
            "

    transform-router:
      image: quay.io/alfresco/alfresco-transform-router:${TRANSFORM_ROUTER_TAG}
      environment:
        JAVA_OPTS: " -XX:MinRAMPercentage=50 -XX:MaxRAMPercentage=80"
        ACTIVEMQ_URL: "nio://activemq:61616"
        CORE_AIO_URL: "http://transform-core-aio:8090"
        TRANSFORMER_URL_OCR: "http://transform-ocr:8090"
        TRANSFORMER_QUEUE_OCR: "ocr-engine-queue"
        FILE_STORE_URL: "http://shared-file-store:8099/alfresco/api/-default-/private/sfs/versions/1/file"

    transform-ocr:
      image: alfresco/tengine-ocr:latest
      mem_limit: 1536m
      environment:
        JAVA_OPTS: " -XX:MinRAMPercentage=50 -XX:MaxRAMPercentage=80 
		  -Docrmypdf.path=ocrmypdf -Docrmypdf.arguments=--skip-text -Dqueue.engineRequestQueue=ocr-engine-queue
		 "
        ACTIVEMQ_URL: "nio://activemq:61616"
        FILE_STORE_URL: "http://shared-file-store:8099/alfresco/api/-default-/private/sfs/versions/1/file"

• You can optionally disable local.transform service in alfresco Docker Container and enable transform service (asynchronous). Local Transform Service or Transform Service (supports only asynchronous requests) can be enabled or disabled independently of each other. Please keep in mind that when your deployment has Share and SOLR (think of full text indexing), or both then you'll need to have local.transform and transform service (asynchronous) enabled and running. The Repository will try to transform content using the Transform Service via the T-Router if possible and fall back to direct Local Transform Service. Share makes use of both, so functionality such as preview will be unavailable if local.transform service is disabled.
• Add OCR Transformer configuration to transform-router Docker Container: URL (http://transform-ocr:8090/ by default) and Queue Name (ocr-engine-queue as declared in ats-transformer-ocr/src/main/resources/application-default.yaml)
• Declare the new transform-ocr Docker Container using the ActiveMQ and Shared File services

Remember that you need to build Docker Image for alfresco/tengine-ocr before running this composition

Start ACS Stack from folder containing docker-compose.yml file.

$ docker-compose up --build --force-recreate

Sample deployment is available in docker-enterprise folder.

Defining the OCR Rule in Alfresco Share

Use your browser to access to Alfresco Share App (by default available in http://localhost:8080/share/)

Create a folder and add following rule (Manage Rules folder option):

• When: Items are created or enter this folder
• If all criteria are met: Mimetype is 'Adobe PDF Document'
• Perform Action: Embed properties as metadata in content

To limit the amount of parallel OCR processing threads, use the Run rule in background checkbox.

From that point, every PDF File uploaded to the folder will be OCRd. Original version for the PDF file will remain as 1.0 version, while the one with text layer on it will be labeled as 1.1 version.

Customizing ocrmypdf arguments

By default, Alfresco OCR Transformer is providing following ocrmypdf configuration.

# Executable command for ocrmypdf program
ocrmypdf.path=ocrmypdf

# Arguments for ocrmypdf invocation. This is the optimized option. 
# If --skip-text is issued, then no image processing or OCR will be performed on pages that already have text.
ocrmypdf.arguments=--skip-text

# To force OCR, use the following:
ocrmypdf.arguments=--force-ocr

Configuration can be changed by using Docker environment variables from command line.

$ docker run -p 8090:8090 -e OCRMYPDF_ARGUMENTS='--skip-text -l eng' alfresco/tengine-ocr:latest

Or with the equivalent notation in docker-compose.yml

transform-ocr:
    image: alfresco/tengine-ocr:latest
    mem_limit: 1536m
    environment:
      JAVA_OPTS: "-XX:MinRAMPercentage=50 -XX:MaxRAMPercentage=80 -Dqueue.engineRequestQueue=ocr-engine-queue"
      OCRMYPDF_ARGUMENTS: "--skip-text -l eng"

Additional contributors

• Thanks to dgradecak for the embed-metadata action approach: #2