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Chances are, if you have seen a print advertisement, you have seen a QR code. Although considered ‘old tech’ by some, this little black-and-white boxes seem to be going through a revival. About 1.3 billion mobile QR code coupons are estimated to have been redeemed last year, and that number is expected to rise to 5.3 billion by 2022 (source: Juniper Research).

Scan one with your phone, and the QR code will take you to a website or provide more information about the product or service being advertised. So, how exactly does it work?

QR stands for Quick Response. The code was developed in 1994 by Denso Wave, a subsidiary of Toyota Motor Corp. Denso Wave used the codes to track vehicles as they moved along the assembly line, and to quickly scan components used in the vehicles. Denso Wave actually holds a patent on the QR code, but the company has granted free license to it. There are now many sites which will generate QR codes for free, and they are very easy to use.

Before the QR code was developed, the most common product codes were one dimensional ‘zebra stripe’ barcodes. These are still found on almost every product. Barcodes are mechanically scanned – they are read by bouncing a narrow beam of light onto the code. The light reflects off the white gaps between the lines and this pattern is interpreted by the scanner. QR codes, however, are digitally scanned. The block of smaller black and white squares is read by a smart phone’s image sensor, and then interpreted by software.

Barcodes are said to be one-dimensional because they hold information only in the horizontal direction. QR codes, in contrast, are two-dimensional – they hold information in both the vertical and horizontal directions. This two-dimensionality means that QR codes can hold a lot more information than barcodes. In fact, today’s QR codes can hold around 350 times more information than a barcode.

The information in the QR code is contained in the black and white squares, called modules. It is this arrangement of modules that stores the data. The more modules, the more data. There are actually many parts to a QR code. For example, the large squares in three of the corners are a finder pattern. The finder pattern allows the decoder software to recognise the code as a QR code (as opposed to another type of code) and determine its correct orientation. The finder pattern squares are surrounded by white spaces, to separate them from the rest of the code. Next to the separators is the formation information section. This stores information that allows the software to correct errors in the code.

In the middle of the top third of the code are alternating black and white modules, called the timing pattern. This pattern enables the decoder software to determine the width of a single module. An alignment pattern ensures the code can be deciphered even if it’s distorted, for example, if viewed at an angle. The alignment pattern helps the decoder software to compensate for any distortions. Other parts of the code include empty bits of data called remainder bits, and the modules that make up the data itself.

Because QR codes were originally designed to withstand the wear and tear of the factory floor, they make use of an error correcting code called Reed Solomon code. This system adds redundant information to the data so that it can be recovered even if there are errors in transmission, storage and retrieval. It is similar to the system used on CDs and DVDs, which allows them to be read even if slightly scratched. This also allows small amounts of text or images to be incorporated into the QR code without affecting readablility.

Today, many smartphones a equipped with a QR code reader, and the codes are used for much more than shipping and logistics. There are also plenty of free apps available for both iPhones and Android smartphones. (Try scanning the code at the top of this article).

At Springwise, we have seen uses that include allowing cashless donations to the homeless, encouraging voter registration, dispensing medications, and the codes have even been incorporated into buildings. What innovative uses could QR codes be put to in the future?