Data-matrix codes

Last updated: June 30, 2010.

From buying groceries to tracking a UPS delivery, barcodes make our lives easier in all kinds of ways—but they've doing so now for decades. Originally patented in the 1940s, barcodes were commercially tested in the 1960s and gradually became ubiquitous in the 1980s. The basic idea has barely changed in all that time: just like in the 1960s, a barcode is still a zebra pattern of stripes with numbers written underneath that needs a special scanning device to decode it. But all that could change soon as the data-matrix code—a kind of second-generation barcode technology—slowly takes over. Let's take a closer look at how it works!

Photo: Are these the world's geekiest cakes? Montreal's Clever Cupcakes baked this cunning QR Code cupcake (left) and Twitter cake (right) for a festival in March 2010. The QR Code takes you to the website of Concern Worldwide, an organization working to relieve poverty, hunger, and disaster in developing countries. Photo courtesy of Clever Cupcakes published on Flickr in 2010 under a Creative Commons Licence.

What are data-matrix codes?

You may have already noticed odd black-and-white squares appearing on your parcels, letters, utility bills, T-shirts, product packaging, and in all kinds of other places. Those are data-matrix codes. Just like barcodes, they're machine-readable so they can quickly pass on information about a product in the blink of an electronic eye. Looking like mini crossword puzzles without any letters, data-matrix codes are sometimes called two-dimensional (2D) barcodes. Where a barcode presents a string of information as a one-dimensional line of black and white bars, a data-matrix code packs a lot more information into a grid of black and white, square-shaped dots.

Photo: Do-it-yourself postal systems, such as Royal Mail's SmartStamp® (in the UK) and Deutsche Post's Stampit (in Germany), let you print your own franking labels on parcels without the bother of going to a post office. They print a data matrix code on the postage label to validate it and protect against fraud. The code is read and checked when the mail passes through automated sorting equipment.

What are the advantages of data-matrix?

If we already have barcodes, why do need something else as well? Data-matrix is a step further, with lots of advantages:

• More information: A barcode is just a short line of black and white bars so it can't contain much information: typically just a dozen digits or so—enough to identify a box of cornflakes to a grocery store checkout, but not much more. You can't add extra information to a barcode without making it longer and more unwieldy. By contrast, a data-matrix code is a square of information running in two directions so it can efficiently pack many times more information into the same space.
• Fewer errors: Barcodes hold so little information that there is very little redundancy. Apart from the length of the bars (which effectively repeat the barcode's information in the vertical direction), there is no duplication of information to guard against a code being misprinted or damaged (such as when a grocery box becomes torn in the store or a parcel label smudges in the rain). But the higher capacity of data-matrix codes means they can hold the same information in different ways with sophisticated, built-in error checking systems. If a code is damaged, that's easy to detect—and it may still be possible to read some or all of the code.
• Easier to read: Data-matrix codes can be read by the latest cellphones (mobile phones) using their built-in digital cameras. No special reading equipment is needed.
• Easy to transmit: Data-matrix codes can be sent as SMS text messages between cellphones.
• More secure: It's possible to encrypt the information in data matrix codes to protect it.

What are the different kinds of data-matrix technology?

To an untrained eye, all data-matrix codes look much the same. Look more closely, though, and you'll see they do vary quite a bit. There are actually several different types of data-matrix codes, some available in the public domain and some that are still proprietary. The best known include QR Code® (pioneered in the 1990s by Japanese company Denso-Wave), Aztec code (developed by Welch Allyn and recognizable by a distinctive square "bulls-eye" pattern in the center), MaxiCode (used by the US postal service, and featuring a round "bulls-eye" center), and Semacode—though there are literally dozens of others.

Photo: Two examples of data-matrix codes: A QR Code on the left and an Aztec code on the right. Both contain the address of this website (www.explainthatstuff.com). At least, they're supposed to!

What is data-matrix technology used for?

You can print a data-matrix code anywhere you can print a barcode (software for generating codes is easy to find online) and use it in very similar ways for tracking and tracing all kinds of objects. Cellphones with built-in data-matrix readers are leading to other, more exciting applications. Advertisers who want you to find out more about their products online simply print a data-matrix code in the corner of their ads. Just point your cellphone at the code, scan it in, and your phone browser will automatically read the code, decode the Web address of the advertiser's site, and take you there instantly—no need to type in a tedious URL or anything like that. It's especially convenient for billboards, posters, and other ads you catch site of while you're on the move.

Airline boarding is another increasingly popular application. Your airline sends your boarding details to your cellphone in the form of an SMS text message containing a data-matrix code. Your phone displays the code on its screen and you can then use it as an electronic ticket and boarding pass. (German airline Lufthansa's Mobile Boarding Pass is an example.) Expect to see lots more data-matrix applications like this appearing very soon!

Photo: Left: Using an iPhone as a Swiss air mobile boarding pass. This airline uses Aztec codes; others (including Lufthansa) use QR Codes. Photo by Simon Aughton published on Flickr in 2009 under a Creative Commons Licence. (The personal flight details have been blurred.)

Photo: Right: An advertisement featuring a QR code®: the idea is that you point your phone at the ad, the phone interprets the code as a URL, and the browser in your phone loads the appropriate website automatically so you can find out more information about whatever is being advertised. Photo by courtesy of Gaku, published on Flickr in 2007 under a Creative Commons Licence.

Further reading

• QR Codes in the wild: A Flickr photo album where people share pictures of codes they've spotted cropping up in all kinds of everyday places.