General

QR code

QR Code (Quick Response Code) is two dimensional code which is categorized in matrix code. The code consists of black modules arranged in a square pattern on a white background. The information encoded can be made up of four standardized kinds of data (numeric, alphanumeric, byte/binary, Kanji). The QR Code was designed for high speed reading, high capacity, high density, error correcting, structured append and high speed decoding.

 

Standards

  • October 1997 – AIM (Association for Automatic Identification and Mobility) International
  • January 1999 – JIS X 0510
  • June 2000 – ISO/IEC 18004:2000 Information technology – Automatic identification and data capture techniques – Bar code symbology – QR code
  • 1 September 2006 – ISO/IEC 18004:2006 Information technology – Automatic identification and data capture techniques – QR Code 2005 bar code symbology specification

 

Storage

The amount of data that can be stored in the QR Code symbol depends on the datatype and error correction level. The maximum storage capacities are as follows:

Numeric only Max. 7,089 characters (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
Alphanumeric Max. 4,296 characters (0–9, A–Z [upper-case only], space, $, %, *, +, -, ., /, 🙂
Binary/byte Max. 2,953 characters (8-bit bytes) (23624 bits)
Kanji/Kana Max. 1,817 characters

 

Encryption

There are a few implementations. An Android app manages encryption and decryption of QR codes using DES algorithm. Japanese immigration use encrypted QR Codes when placing visas in passports.

 

Error Correction

Level L 7% of codewords can be restored.
Level M 15% of codewords can be restored.
Level Q 25% of codewords can be restored.
Level H 30% of codewords can be restored.

 

License

The use of QR Codes is free of any license. The QR Code is clearly defined and published as an ISO standard.

Image is from wikipedia.