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

I found a new and effective way, just using cv2. The code below will decode a QR code.

import cv2
# Name of the QR Code Image file
filename = "attandence_Record_QR_code.png"
# read the QRCODE image
image = cv2.imread(filename)
# initialize the cv2 QRCode detector
detector = cv2.QRCodeDetector()
# detect and decode
data, vertices_array, binary_qrcode = detector.detectAndDecode(image)
# if there is a QR code
# print the data
if vertices_array is not None:
  print("QRCode data:")
  print(data)
else:
  print("There was some error") 

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
  

The following code works fine with me:

brew install zbar
pip install pyqrcode
pip install pyzbar

For QR code image creation:

import pyqrcode
qr = pyqrcode.create("test1")
qr.png("test1.png", scale=6)

For QR code decoding:

from PIL import Image
from pyzbar.pyzbar import decode
data = decode(Image.open('test1.png'))
print(data)

that prints the result:

[Decoded(data=b'test1', type='QRCODE', rect=Rect(left=24, top=24, width=126, height=126), polygon=[Point(x=24, y=24), Point(x=24, y=150), Point(x=150, y=150), Point(x=150, y=24)])]