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James R. Barlow
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% SPDX-FileCopyrightText: 2022 James R. Barlow
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% SPDX-License-Identifier: CC-BY-SA-4.0
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(lang-packs)=
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# Installing additional language packs
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OCRmyPDF uses Tesseract for OCR, and relies on its language packs for all languages.
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On most platforms, English is installed with Tesseract by default, but not always.
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Tesseract supports [most
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languages](https://github.com/tesseract-ocr/tesseract/blob/main/doc/tesseract.1.asc#languages).
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Languages are identified by standardized three-letter codes (called ISO 639-2 Alpha-3).
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Tesseract's documentation also lists the three-letter code for your language.
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Some are anglicized, e.g. Spanish is `spa` rather than `esp`, while others
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are not, e.g. German is `deu` and French is `fra`.
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Language packs (strictly speaking, Tesseract "traineddata" files) generally correspond
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to the language in question, but different language packs are used in certain
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situations. For German, the "Fraktur" language pack can assist with reading older
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materials in the Fraktur typeface family (`deu_frak`). Some communities have changed
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their script from Cyrillic to Latin; the Cyrillic version of Uzbek is available
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as `uzb_cyrl` and the Latin version is `uzb`.
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After you have installed a language pack, you can use it with `ocrmypdf -l <language>`,
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for example `ocrmypdf -l spa`. For multilingual documents, you can specify
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all languages to be expected, e.g. `ocrmypdf -l eng+fra` for English and French.
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English is assumed by default unless other language(s) are specified.
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For Linux users, you can often find packages that provide language
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packs.
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## Platform install steps
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### Debian and Ubuntu (apt)
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```bash
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# Display a list of all Tesseract language packs
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apt-cache search tesseract-ocr
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# Install Chinese Simplified language pack
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apt-get install tesseract-ocr-chi-sim
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```
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You can then pass the `-l LANG` argument to OCRmyPDF to give a hint as
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to what languages it should search for. Multiple languages can be
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requested using either `-l eng+fra` (English and French) or
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`-l eng -l fra`.
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### Fedora
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```bash
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# Display a list of all Tesseract language packs
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dnf search tesseract
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# Install Chinese Simplified language pack
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dnf install tesseract-langpack-chi_sim
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```
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You can then pass the `-l LANG` argument to OCRmyPDF to give a hint as
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to what languages it should search for. Multiple languages can be
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requested using either `-l eng+fra` (English and French) or
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`-l eng -l fra`.
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### Arch Linux
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```bash
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# Display a list of all Tesseract language packs
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pacman -Ss tesseract-data
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# Install German language pack
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pacman -S tesseract-data-deu
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```
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You can then pass the `-l LANG` argument to OCRmyPDF to give a hint as
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to what languages it should search for. Multiple languages can be
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requested using either `-l eng+fra` (English and French) or
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`-l eng -l fra`.
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### Gentoo
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On Gentoo the package `app-text/tessdata_fast`, which `app-text/tesseract` depends on, handles Tesseract languages.
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It accepts USE flags to select what languages should be installed, these can be set in `/etc/portage/package.use`.
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Alternatively one can globally set the [L10N use extension](https://wiki.gentoo.org/wiki/Localization/Guide#L10N) in `/etc/portage/make.conf`.
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This enables these languages for all packages (e.g. including aspell).
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```bash
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# Display a list of all Tesseract language packs
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equery uses app-text/tessdata_fast
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# Add English and German language support for Tesseract only
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echo 'app-text/tessdata_fast l10n_de l10n_en' >> /etc/portage/package.use
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# Add global English and German language support (the `l10n_` from equery has to be omitted)
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echo L10N="de en" >> /etc/portage/make.conf
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# update system to reflect changed USE flags
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emerge --update --deep --newuse @world
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```
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You can then pass the `-l LANG` argument to OCRmyPDF to give a hint as
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to what languages it should search for. Multiple languages can be
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requested using either `-l eng+fra` (English and French) or
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`-l eng -l fra`.
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### macOS
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You can install additional language packs by
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{ref}`installing Tesseract using Homebrew with all language packs <macos-all-languages>`.
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### Docker
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Users of the OCRmyPDF Docker image should install language packs into a
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derived Docker image as
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{ref}`described in that section <docker-lang-packs>`.
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### Windows
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The Tesseract installer provided by Chocolatey currently includes only English language.
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To install other languages, download the respective language pack (`.traineddata` file)
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from <https://github.com/tesseract-ocr/tessdata/> and place it in
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`C:\\Program Files\\Tesseract-OCR\\tessdata` (or wherever Tesseract OCR is installed).
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## Custom language packs
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If you have fine-tuned or trained Tesseract and generated custom trained data, you can
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copy your `customlang.traineddata` file into your Tesseract "tessdata" folder, and
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then use the `-l customlang` argument to tell OCRmyPDF to pass that language on to
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Tesseract.
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