Python implementation of QR code generator.

The module generates QR Code from text file or stdin. The output image can be saved, displayed or both.

Requirements:

Python 3

External libraries:

numpy, PIL

Usage examples:

• Create QR code from stdin and save the image.

There's only input message [-i] and output file name [-o] required and we are good to go. All the remaining parameters will be set automatically, based on the message length and its type (number, UTF-8, ASCII, etc.).

$ python3 qr_code.py -i "Hello world" -o "stdin_sample.png"

  [+] Latin-1 encoding applied.
  [+] QR version: 1 chosen.
  [+] Error Correction Level: Q chosen.
  [+] Best mask has been applied: [2]. With 342.0 penalty
  QR saved at: /absolute/path/to/the/stdin_sample.png

• Create QR code from a text file [-f] and display the image [-d]. We do not save it this time.
  Set the scale flag [-s] to control the output image size.

$ python3 qr_code.py -f samples/sample_text.txt -d -s 4

  [+] UTF-8 encoding applied.
  [+] QR version: 30 chosen.
  [+] Error Correction Level: Q chosen.
  [+] Best mask has been applied: [2]. With 12380.0 penalty

• Set QR code version and error correction level.

  If a message is too long to meet version [-v] and error correction level [-e] constraints, the following error will be raised.

  AssertionError: Message too long (7716) for a given version capacity (104)

  When we pass incorrect values, another error will be raised.

  qr_code.py: error: argument -v: Value out of range: 1111. Should be between 1 and 40.

  If these values are correct, then we should see the expected output image.

  $ python3 qr_code.py -i "Hello world" -d -s 5 -v 15 -e 2

  [+] Latin-1 encoding applied.
  [+] QR version: 15 chosen.
  [+] Error Correction Level: Q chosen.
  [+] Best mask has been applied: [4]. With 3546.0 penalty

• Setting QR code mask and quiet zone values.

It's not recommended to set a mask value [-m] if you want to be sure that the best one is chosen. It will however speed up generating QR codes noticeably. Quiet zone value [-z] determines width of white space around QR code.

  $ python3 qr_code.py -i "https://github.com/abcs-ab" -d -s 7 -v 8 -e 3 -m 3 -z 1

  [+] Latin-1 encoding applied.
  [+] QR version: 8 chosen.
  [+] Error Correction Level: H chosen.

• Last but not least, the [-h] flag.

  $ python3 qr_code.py -h

  usage: qr_code.py [-h] [-v VERSION] [-e EC LEVEL] [-m MASK] [-s SCALE IMAGE]
                    [-i INPUT TEXT | -f INPUT FILE NAME] [-o OUTPUT IMAGE NAME]
                    [-z QUIET ZONE] [-d]
  
  Create QR Code from text file [-f] or stdin [-i] and save as an image.
  When version is to be chosen automatically, then it's worth noting, 
  that keeping declared error correction level will be a priority.
  So, qr version will be increased first, before error correction level
  is lowered in order to fit a message.
  
  optional arguments:
    -h, --help            show this help message and exit
    -v VERSION            Valid values from 1 to 40. If omitted, version is computed automatically.
    -e EC LEVEL           Valid values from 0 to 3. Default 2.
                          0 - Level L (Low)         ~7% of codewords can be restored.
                          1 - Level M (Medium)      ~15% of codewords can be restored.
                          2 - Level Q (Quartile)    ~25% of codewords can be restored.
                          3 - Level H (High)        ~30% of codewords can be restored.
    -m MASK               Valid values from 0 to 7. Default None.
    -s SCALE IMAGE        Takes positive integer. Image is resized according to this value. Default 10.
    -i INPUT TEXT         Just write anything in "quotes" and the message will be processed.
    -f INPUT FILE NAME    Text file with a message to be encoded.
    -o OUTPUT IMAGE NAME  File name for QR code output image.
    -z QUIET ZONE         Takes positive integer. It's a width of white space around QR code.
    -d                    If the flag is present, QR code preview will be displayed, when done.
  
  

Appendix

• Kanji is handled by UTF-8 at the moment. However, straight kanji encoding would save fair number of bytes, thus longer messages would become available.

• Please, feel free to contact me if you find a bug, typo or have some questions.

Contact

abcs.luk@gmail.com

License

MIT