How to decode a QR-code image in (preferably pure) Python?

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You can try the following steps and code using qrtools:

  • Create a qrcode file, if not already existing

    • I used pyqrcode for doing this, which can be installed using pip install pyqrcode

    • And then use the code:

      >>> import pyqrcode
>>> qr = pyqrcode.create("HORN O.K. PLEASE.")
>>> qr.png("horn.png", scale=6)

  • Decode an existing qrcode file using qrtools

    • Install qrtools using sudo apt-get install python-qrtools

    • Now use the following code within your python prompt

      >>> import qrtools
>>> qr = qrtools.QR()
>>> qr.decode("horn.png")
>>> print qr.data
u'HORN O.K. PLEASE.'

Here is the complete code in a single run:

In [2]: import pyqrcode
In [3]: qr = pyqrcode.create("HORN O.K. PLEASE.")
In [4]: qr.png("horn.png", scale=6)
In [5]: import qrtools
In [6]: qr = qrtools.QR()
In [7]: qr.decode("horn.png")
Out[7]: True
In [8]: print qr.data
HORN O.K. PLEASE.

Caveats

  • You might need to install PyPNG using pip install pypng for using pyqrcode

  • In case you have PIL installed, you might get IOError: decoder zip not available. In that case, try uninstalling and reinstalling PIL using: 

    pip uninstall PIL
pip install PIL

  • If that doesn’t work, try using Pillow instead

    pip uninstall PIL
pip install pillow

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