Add OCR Languages

By default the Papermerge DMS docker image includes English and German OCR languages.

You can install extra languages in couple of steps described in the following guide.

Note

All languages are specified in three letters code as per ISO 639-2T standard - second column in the table.

Step 1 - Create your custom OCR docker image

First, you need to create your own OCR worker image to include the necessary languages. Create a Dockerfile based on the existing papermerge/ocrworker:0.3.1 image and install the required OCR language packages:

FROM papermerge/ocrworker:0.3.1
# Add the required languages here
RUN apt update && apt install -y tesseract-ocr-kaz tesseract-ocr-rus

Step 2 - Verify the languages in the OCR worker

Once the docker image is built and the ocr worker is running verify that the languages are installed:

docker exec -it <ocr_worker_docker_container_id> tesseract --list-langs

Step 3 - Add the language support in the Papermerge codebase:

a. Update OCR task schema: In the papermerge/core/features/tasks/schema.py file, add the new language codes to the LangCode type:

LangCode = Literal[
    "ces",
    "dan",
    "deu",
    "ell",
    "eng",
    "fas",
    "fin",
    "fra",
    "guj",
    "heb",
    "hin",
    "ita",
    "jpn",
    "kor",
    "lit",
    "nld",
    "nor",
    "pol",
    "por",
    "ron",
    "san",
    "spa",
    # add additional languages here
    "kaz",
    "rus",
]

b. Update UI Constants:

In the ui2/src/cconstants.ts file, add required language names:

export const OCR_LANG: OCRLangType = {
    ces: "Čeština",
    dan: "Dansk",
    deu: "Deutsch",
    ell: "Ελληνικά",
    eng: "English",
    fin: "Suomi",
    fra: "Français",
    guj: "ગુજરાતી",
    heb: "עברית",
    hin: "हिंदी",
    ita: "Italiano",
    jpn: "日本語",
    kor: "한국어",
    lit: "Lietuvių",
    nld: "Nederlands",
    nor: "Norsk",
    osd: "Osd",
    pol: "Polski",
    por: "Português",
    ron: "Română",
    san: "संस्कृत",
    spa: "Español",
    // Add additional languages here
    kaz: "Қазақша",
    rus: "Русский",
};

c. Update OCRCode Type: In the ui2/src/types.ts and ui2/src/types/ocr.ts files, extend the OCRCode type:

export type OCRCode =
    | "ces" | "dan" | "deu" | "ell" | "eng" | "fin" | "fra" | "guj" | "heb"
    | "hin" | "ita" | "jpn" | "kor" | "lit" | "nld" | "nor" | "osd" | "pol"
    | "por" | "ron" | "san" | "spa"
    // Add additional languages here
    | "kaz" | "rus";

Step 4 - Build custom Papermerge image

docker buildx build --platform linux/amd64 -t myimage:0.0.1 -f docker/standard/Dockerfile .