How does a QR code work technically?

Basic knowledge of the QR code


Maybe you're holding my business card in your hand or leafing through an issue of WELT-KOMPAKT. Perhaps you've seen QR codes elsewhere and are wondering what you can do with them. QR stands for English: quick response. The idea behind it is that people can call up, save and process information in their everyday life with one click with their camera phone.
QR codes belong to the family of 2D barcodes which, in contrast to conventional barcodes, contain information both horizontally and vertically.

to scan

An example: In 2006 the world champion in SMS typing created 160 characters in approx. 42 seconds. A URL (Internet address) can be as long as 250 characters. Even the world champion at the time would need over a minute to type such an Internet address into his mobile phone browser. This is exactly where one of the advantages of QR codes lies: They replace typing in information and thus save time and nerves. Instead of typing in the information, you scan the QR code. All you need is a Java-enabled cell phone or smartphone with a camera. The code is photographed with the camera. A program in the cell phone analyzes the code and decodes the information.

Content of QR codes

The following forms of information are possible for conversion into a QR code:

  • Phone number
  • SMS
  • Link (url)
  • text
  • vCard (name, telephone number, email address)

Readers and Generators

So-called reader software is required to turn a camera phone into a QR code scanner. Readers are partly free. They are available from different manufacturers and for different cell phone models. The list of supported cell phones varies from reader to reader. With the N82, N93, N93i, N95, E66, E71 or E90 from Nokia, a barcode reader is preinstalled upon purchase. Whether a reader is available for your own cell phone model and how the reader is installed on the cell phone can be found on the manufacturer's website.

Available QR code readers:

(The lists are not exhaustive. The apps have not been tested.)

Many reader providers also offer the option of creating codes online. The codes created by the generators can be saved as an image and further processed as required. In this way you can easily create your own QR codes for any purpose.
There is also a Firefox extension that converts the current URL in the browser into a QR code with a click, and a web service that generates a QR code from an RSS feed.

List of available QR code generators:

(The list is not exhaustive. The generators have not been tested.)

Possible uses for analog QR codes

Examples of analog QR codes:
(External links on photos with examples)

  • Print products (magazines, posters, business cards, stickers, stamps, ...)
  • Textiles (T-shirts, bowls, ...)
  • Buildings (houses, walls, ...)
  • Jewelry (pendants, chains, ...)
  • Skin (tattoos, stamps, ...)
  • Packaging (boxes, bags, ...)
  • Food (chocolate, chips, ...)
  • Documents (ID cards, tickets, ...)

Digital processing

In addition to calling up an Internet address in the mobile phone browser, there are other processing options, depending on the type of information being coded.

  • Call with ...
  • Storage in ...
    • Bookmark / Bookmark
    • Contacts / phone book
    • Note (indirect, by means of copy & paste)
    • Course / history
  • Forwarding via ...
    • SMS
    • MMS
    • e-mail
    • Infrared
    • Bluetooth

Mobile tagging

Mobile tagging comes from English: tag = identification and describes the leaving of information that can be used mobile. Mobile tagging thus describes the spread of QR codes in general.
There are three main types of distribution:

  • Commercial tagging
  • Public tagging
  • Private tagging

While commercial tagging focuses on commercial interests, private tagging serves personal motives. Public tagging, on the other hand, serves charitable purposes. A detailed description of the different types of distribution can be found on the mobile tagging Wikipedia page.

Interface between analog and digital medium

Comparison between conventional and 2D code-based information transfer when changing media and the associated workflow (high, low effort):

Technical information

  • Any image format conceivable
  • Small file size because b / w
  • Scalable despite raster graphics without loss of quality or information (through pixel repetition)
  • Storage capacity of QR codes:
    • Numeric: maximum 7,089 characters
    • Alphanumeric: maximum 4,296 characters
    • Binary: maximum 2,953 bytes
  • Individual design options

2D codes and encryption (cipher / cryptography)

QR codes are mainly used to transfer information and not for encryption in the cryptographic sense. The data is therefore encrypted before it is encoded. 2D codes containing encrypted data can be found on Deutsche Bahn's online tickets or on envelopes franked with Stampit (Deutsche Post).

Mobile ticketing

With mobile ticketing it is possible to purchase a valid ticket at any time and anywhere. Current areas of application are admission tickets for cultural or business events as well as tickets for local and long-distance transport. The desired ticket can be purchased via the mobile phone browser (mobile e-commerce). You then receive an MMS with a 2D code. This is scanned by the organizer and thus the ticket is checked for validity.

Animated QR codes

Since QR codes displayed by monitors and displays can also be scanned, it is possible to animate the codes digitally. In digital, animated QR codes, you can save n times the amount of information in the same space by changing images n times. A picture change with shaky pictures is also possible in an analogue way.



Link list

The following links serve for further information and as suggestions for your own search.

On my own behalf

I get a lot of information from the Internet every day. With this basic information on the subject of QR codes, I would like to give something back to "the" Internet.

Yes, you are allowed to use parts of this page. But please always add a brief reference to the source. A link to this page ( is sufficient. Thanks!

In 2008 I was very fascinated by the QR code. Over time, the site grew in popularity. Unfortunately, I don't have as much time for this page as I did in 2008. I therefore ask for your understanding that there will be no more extensions or updates.

Imprint: Wilko Hartz, Hans-Sachs-Str. 30, D-40237 Düsseldorf, qr - code [at] wilkohartz. de,
Copyright: © 2008 - 2013 Wilko Hartz - all rights reserved
Creation: 03/03/2008, last update: 22/03/2013

QR Code ® is registered trademark of DENSO WAVE INCORPORATED in JAPAN and other countries.