pylibdmtx

pylibdmtx

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Read and write Data Matrix barcodes from Python 2 and 3 using the libdmtx <http://libdmtx.sourceforge.net/>__ library.

• Pure python
• Works with PIL / Pillow images, OpenCV / imageio / numpy ndarray\ s, and raw bytes
• Decodes locations of barcodes
• No dependencies, other than the libdmtx library itself
• Tested on Python 2.7, and Python 3.5 to 3.10

The older pydmtx <https://sourceforge.net/p/libdmtx/dmtx-wrappers/ci/master/tree/python/>__ package is stuck in Python 2.x-land.

Installation

The libdmtx DLL\ s are included with the Windows Python wheels. On other operating systems, you will need to install the libdmtx shared library.

Mac OS X:

::

brew install libdmtx

Linux:

::

sudo apt-get install libdmtx0a

Install this Python wrapper; use the second form to install dependencies of the read_datamatrix and write_datamatrix command-line scripts:

::

pip install pylibdmtx pip install pylibdmtx[scripts]

Example usage

The decode function accepts instances of PIL.Image.

::

from pylibdmtx.pylibdmtx import decode from PIL import Image decode(Image.open('pylibdmtx/tests/datamatrix.png')) [Decoded(data='Stegosaurus', rect=Rect(left=5, top=6, width=96, height=95)), Decoded(data='Plesiosaurus', rect=Rect(left=298, top=6, width=95, height=95))]

It also accepts instances of numpy.ndarray, which might come from loading images using OpenCV <http://opencv.org/>__.

::

import cv2 decode(cv2.imread('pylibdmtx/tests/datamatrix.png')) [Decoded(data='Stegosaurus', rect=Rect(left=5, top=6, width=96, height=95)), Decoded(data='Plesiosaurus', rect=Rect(left=298, top=6, width=95, height=95))]

You can also provide a tuple (pixels, width, height)

::

image = cv2.imread('pylibdmtx/tests/datamatrix.png') height, width = image.shape[:2] decode((image.tobytes(), width, height)) [Decoded(data='Stegosaurus', rect=Rect(left=5, top=6, width=96, height=95)), Decoded(data='Plesiosaurus', rect=Rect(left=298, top=6, width=95, height=95))]

The encode function generates an image containing a Data Matrix barcode:

::

from pylibdmtx.pylibdmtx import encode encoded = encode('hello world'.encode('utf8')) img = Image.frombytes('RGB', (encoded.width, encoded.height), encoded.pixels) img.save('dmtx.png') print(decode(Image.open('dmtx.png'))) [Decoded(data=b'hello world', rect=Rect(left=9, top=10, width=80, height=79))]

Windows error message

If you see an ugly ImportError when importing pylibdmtx on Windows you will most likely need the Visual C++ Redistributable Packages for Visual Studio 2013 <https://www.microsoft.com/en-US/download/details.aspx?id=40784>__. Install vcredist_x64.exe if using 64-bit Python, vcredist_x86.exe if using 32-bit Python.

Limitations

Feel free to submit a PR to address any of these.

• I took the bone-headed approach of copying the logic in pydmtx\ ’s decode function (in pydmtxmodule.c <https://sourceforge.net/p/libdmtx/dmtx-wrappers/ci/master/tree/python/>__); there might be more of libdmtx\ ’s functionality that could usefully be exposed

• I exposed the bare minimum of functions, defines, enums and typedefs neede to reimplement pydmtx\ ’s decode function

Contributors

• Vinicius Kursancew (@kursancew) - first implementation of barcode writing
• Joseph Weston (@jbweston) - support for libdmtx 0.7.5

License

pylibdmtx is distributed under the MIT license (see LICENCE.txt). The libdmtx shared library is distributed under the Simplified BSD license (see libdmtx-LICENCE.txt).