Read and write Data Matrix barcodes from Python 2 and 3.
Project description
Read and write Data Matrix barcodes from Python 2 and 3 using the libdmtx library.
- Pure python
- Works with PIL / Pillow images, OpenCV / imageio / numpy ndarrays, 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 package is stuck in Python 2.x-land.
Installation
The libdmtx DLLs 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.
>>> 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. 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); 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).
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