Intro

Barcodes are being used in many documents or forms to enable machine reading capabilities and reduce manual processing effort. Simple 1D barcodes for example can mark a specific page on a form, or indicate a relevant document identification number. More complex 2D barcodes allow to encode even the full data of the document in a more structured form.

Docbarcodes extracts 1D and 2D barcodes from scanned PDF documents or images. It can be used to automate extraction and processing of all kind of documents.

Some working documents with barcodes are:

• Swiss tax statements (Zurich, other cantons can be added as well)
• Swiss salary statement
• US drivers licenses with MRZ (machine readable zone)
• Swiss QR Code Invoices, introduced by Six-group
• Swiss Covid Certificates

The approach works as follows:

1. Detect barcode regions on the document using opencv and image transformation heuristics
2. Extract the raw barcode data using zxing
3. Combine multiple barcodes and decode the data.

Quick start

Required:

• Java 8+

Install package

uv tool install docbarcodes

Download example pdf document

wget https://github.com/ArlindNocaj/document-barcodes/raw/master/data/salary_swissdec/SalarySinglePage.pdf 

CLI usage

Extract barcodes from salary statement document and format result json using jq.

docbarcodes ./SalarySinglePage.pdf | jq .

{
  "BarcodesRaw": [
    {
      "page": 0,
      "num_candidate": 2,
      "raw": "´cý¸z\u0000\u0002V\u0001\u0003\u0000\u0001\u0000\u0001PK\u0003\u0004\u0014\u0000\b\b\b\u0000év\u0003Q\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0004\u0000\u0000\u0000txabM�Ýnâ0\u0010�_Åò}b;¡!¬\u001cWá¯EbYÔÐjÕ;\u0013Ü\u00105±+Û,ð>û&ûb;\tÐö\"Îñ�\u0019Ïç�ùý©mÐ\u001fe]mt�YH1Rº4»ZW\u0019~ÞÌ�\u0014ß\u000b¾A�¦]�÷Þ\u007fü äx<�îX;·SeXî�+÷ª�ÄíHD#J£��B6Ò�§ª��ôpúæ��1*\u0016Ó\fS\nm�³{é$Ã�OLû!õ\u0019=/¦Áx^dxò8\u000bX\u0014�×\u000f£5 v�kyh$Z)ç\u001be1z|\n�&ÁJ¶\nj~ý\\/g¿Ñ¬QïÞ\u001a]¿£ü\u0001£×Å:ÃqÒµ�,3�o½ª��®PáÕAYPJ\u0003�·Jù\fÏêJÙ£ªP\u0002=�ó[s�±D\u0003(®ý9Ã�ý\u0001²×{£¡#�c\u0014Å)\u001a�Ð�a\"ø�r1EKé¼î©rµ1�×öÓÐZÞ¨è�ê\u000b`ùﯮ*é�ó\u0016V�¢ï$É\b\n�¦�MOs£\u001a+«Ñ\bvæ ½í\u0002�\u0017/A^\u0004++º\u0019\u000eî�a��(\u000b£��Ï\u0010'7bÁsÁ§¦\u0004Å8¹�î:µÙ\tþfM+\"Ê��Ñ�B¼78ôª�«Ï��rrqúSûÂ\u0005<¥V�AÊX\u001a\u000e!ájð\u0007k�»n�\u0014Æ\u0010R�~wùJù«¼KâAÜ'|y�\u0000/Ù�ÿPK\u0007\bK¦nJÎ\u0001\u0000\u0000Á\u0002\u0000\u0000PK\u0001\u0002\u0014\u0000\u0014\u0000\b\b\b\u0000év\u0003QK¦nJÎ\u0001\u0000\u0000Á\u0002\u0000\u0000\u0004\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000txabPK\u0005\u0006\u0000\u0000\u0000\u0000\u0001\u0000\u0001\u00002\u0000\u0000\u0000\u0000\u0002\u0000\u0000\u0000\u0000",
      "format": "PDF_417",
      "points": [
        [
          0.08509771986970684,
          0.2564102564102564
        ],
        [
          0.32166123778501626,
          0.2564102564102564
        ],
        [
          0.32166123778501626,
          0.35522904062229904
        ],
        [
          0.08509771986970684,
          0.35522904062229904
        ]
      ],
      "resultMetadata": {
        "ERROR_CORRECTION_LEVEL": "2",
        "PDF417_EXTRA_METADATA": {
          "addressee": "None",
          "checksum": -1,
          "fileId": "None",
          "fileName": "None",
          "fileSize": -1,
          "optionalData": "None",
          "segmentCount": -1,
          "segmentIndex": 0,
          "sender": "None",
          "timestamp": -1
        }
      }
    }
  ],
  "BarcodesCombined": [
    {
      "content": "<?xml version=\"1.0\" encoding=\"UTF-8\"?><T xmlns=\"http://www.swissdec.ch/schema/sd/20200220/SalaryDeclarationTxAB\" SID=\"000\" SysV=\"001\"><Company UID-BFS=\"CHE-123.123.123\" Person=\"Paula Nestler\" HR-RC-Name=\"COMPLEX Elektronik AG\" ZIP=\"3600\" CL=\"Abteilung Steuerungen\" Street=\"Eigerweg 6\" Postbox=\"124\" City=\"Thun\" Phone=\"033 238 49 71\"/><PersonID Lastname=\"Aebi\" Firstname=\"Anna\" ZIP=\"3000\" CL=\"\" Street=\"Länggassstrasse 26\" Postbox=\"690\" Locality=\"\" City=\"Bern 9\" Country=\"\"><SV-AS-Nr>123.4567.8901.28</SV-AS-Nr></PersonID><A><DocID>1</DocID><Period><from>2016-10-01</from><until>2016-11-30</until></Period><Income>48118.70</Income><GrossIncome>68000.00</GrossIncome><NetIncome>56343.00</NetIncome></A></T>",
      "format": "PDF_417",
      "sources": [
        0
      ]
    }
  ]
}

Code Usage

from docbarcodes.extract import process_document

barcodes_raw, barcodes_combined = process_document("./SalarySinglePage.pdf")

print(barcodes_raw)
print(barcodes_combined)

Development

Use uv for local development and testing:

uv sync --extra dev
uv run pytest

If jpype1 needs to build from source on your platform, install Apache Ant alongside Java before running uv sync.

FAQ

PDF rendering is handled by pypdfium2, which bundles its own PDFium binary — no external poppler installation is required.

Show package licenses

pip-licenses --with-urls --with-system --format=markdown

Improvements to be made:

• implement multithreading class for zxing in java which returns proper objects for python consumption
• extension mechanisms for other 2D barcode aggregations