QR code (2D barcode) coding and decoding algorithms?

Question

Looking for free/opensource code or description of algorithms to code (simple) and decode (hard) the 2D barcode QR code.

It doesn't seem like a trivial problem, but it's so popular in Japan that there must be something already available...

Solution 1

I have a colleague who worked on ZXing ("Zebra Crossing").

That's got a fair variety of platform support.

Solution 2

QR Code Demystified - Part 1
QR Code Demystified - Part 2
QR Code Demystified - Part 3
QR Code Demystified - Part 4
QR Code Demystified - Part 5
QR Code Demystified - Part 6

and

http://www.thonky.com/qr-code-tutorial/introduction/

To know the Mathematics theory behind it there is a discussion in Math Stackexchange

https://math.stackexchange.com/questions/76045/reed-solomon-polynomial-generator

Solution 3

http://www.swetake.com/qrcode/qr1_en.html

Just thought I'd mention this one which is explaining HOW they work.

Solution 4

(In response to those asking about QR codes in PHP)

The Google Charts QR chart type might work for you, if you don't expect a lot of traffic, or if you can cache the images. It's extremely easy to use- just put the text to encode in the URL.

Solution 5

Here's a good LGPL library for encoding QR code libqrencode

Libqrencode is a C library for encoding data in a QR Code symbol, a kind of 2D symbology that can be scanned by handy terminals such as a mobile phone with CCD. The capacity of QR Code is up to 7000 digits or 4000 characters, and is highly robust.

Here's a Google code project that decodes QR code - aimed at iPhone, but is LGPL and the source is available. Should be adaptable...

-Adam

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Comments

[helloworlder]

Apparently the Japanese specification of QR codes is free, but the International Standards Committee (ISO), decided to charge over 200 Swiss francs for the English version. If the English version is just a translation of the Japanese one then I'd say for that price, it's totally unethical.

[Dungeon Hunter]

To understand the reed solomon error code specififcation used in qr code refer math.stackexchange.com/questions/76045/…

[Adam Davis]

For those looking to encode and decode datamatrix codes (another common 2D barcode format) then libdmtx.sourceforge.net is a C library that encodes and decodes them.

[matbrgz]

ZXing looks really nice.

[Joe Hildebrand]

That link is dead.

[prakash]

Here's one (same?) pyqrcode.sourceforge.net

[mortalis]

The URL is broken, I guess the updated one is: swetake.com/qrcode/qr1_en.html. Cannot edit the post as there are too few characters changed...

[Mensch]

Thanks, fixed that.