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OCR-D framework

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Python modules implementing OCR-D specs and related tools

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This repository contains the python packages that form the base for tools within the OCR-D ecosphere.

All packages are also published to PyPI.


NOTE Unless you want to contribute to OCR-D/core, we recommend installation as part of ocrd_all which installs a complete stack of OCR-D-related software.

The easiest way to install is via pip:

pip install ocrd

# or just the functionality you need, e.g.

pip install ocrd_modelfactory

All Python software released by OCR-D requires Python 3.8 or higher.

NOTE Some OCR-D-Tools (or even test cases) might reveal an unintended behavior if you have specific environment modifications, like:

  • using a custom build of ImageMagick, whose format delegates are different from what OCR-D supposes
  • custom Python logging configurations in your personal account

Command line tools

NOTE: All OCR-D CLI tools support a --help flag which shows usage and supported flags, options and arguments.

ocrd CLI

ocrd-dummy CLI

A minimal OCR-D processor that copies from -I/-input-file-grp to -O/-output-file-grp


Almost all behaviour of the OCR-D/core software is configured via CLI options and flags, which can be listed with the --help flag that all CLI support.

Some parts of the software are configured via environment variables:

  • OCRD_METS_CACHING: If set to true, access to the METS file is cached, speeding in-memory search and modification.

  • OCRD_PROFILE: This variable configures the built-in CPU and memory profiling. If empty, no profiling is done. Otherwise expected to contain any of the following tokens:

    • CPU: Enable CPU profiling of processor runs
    • RSS: Enable RSS memory profiling
    • PSS: Enable proportionate memory profiling
  • OCRD_PROFILE_FILE: If set, then the CPU profile is written to this file for later peruse with a analysis tools like snakeviz

  • PATH: Search path for processor executables (affects ocrd process and ocrd resmgr).

  • HOME: Directory to look for ocrd_logging.conf, fallback for unset XDG variables (see below).

  • XDG_CONFIG_HOME: Directory to look for ./ocrd/resources.yml (i.e. ocrd resmgr user database) – defaults to $HOME/.config.

  • XDG_DATA_HOME: Directory to look for ./ocrd-resources/* (i.e. ocrd resmgr data location) – defaults to $HOME/.local/share.

  • OCRD_DOWNLOAD_RETRIES: Number of times to retry failed attempts for downloads of workspace files.

  • OCRD_DOWNLOAD_TIMEOUT: Timeout in seconds for connecting or reading (comma-separated) when downloading.

  • OCRD_METS_CACHING: Whether to enable in-memory storage of OcrdMets data structures for speedup during processing or workspace operations.

  • OCRD_MAX_PROCESSOR_CACHE: Maximum number of processor instances (for each set of parameters) to be kept in memory (including loaded models) for processing workers or processor servers.

  • OCRD_NETWORK_SERVER_ADDR_PROCESSING: Default address of Processing Server to connect to (for ocrd network client processing).

  • OCRD_NETWORK_SERVER_ADDR_WORKFLOW: Default address of Workflow Server to connect to (for ocrd network client workflow).

  • OCRD_NETWORK_SERVER_ADDR_WORKSPACE: Default address of Workspace Server to connect to (for ocrd network client workspace).

  • OCRD_NETWORK_RABBITMQ_CLIENT_CONNECT_ATTEMPTS: Number of attempts for a worker to create its queue. Helpful if the rabbitmq-server needs time to be fully started.



Contains utilities and constants, e.g. for logging, path normalization, coordinate calculation etc.

See README for ocrd_utils for further information.


Contains file format wrappers for PAGE-XML, METS, EXIF metadata etc.

See README for ocrd_models for further information.


Code to instantiate models from existing data.

See README for ocrd_modelfactory for further information.


Schemas and routines for validating BagIt, ocrd-tool.json, workspaces, METS, page, CLI parameters etc.

See README for ocrd_validators for further information.


Components related to OCR-D Web API

See README for ocrd_network for further information.


Depends on all of the above, also contains decorators and classes for creating OCR-D processors and CLIs.

Also contains the command line tool ocrd.

See README for ocrd for further information.

bash library

Builds a bash script that can be sourced by other bash scripts to create OCRD-compliant CLI.

See README for bashlib for further information.


Download assets (make assets)

Test with local files: make test

  • Test with remote assets:
    • make test OCRD_BASEURL=''

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