2D barcodes
by Chris Woodford. Last updated: September 13, 2011.
From buying groceries to tracking a UPS delivery,
barcodes make
our lives easier in all kinds of ways—but they've been 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 2D barcode—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 2D barcodes?
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—
a bit like mini crossword puzzles without any letters. They're
called two-dimensional (2D) barcodes
and, just like ordinary barcodes, they're
machine-readable so they can quickly pass on information about
a product in the blink of an electronic eye.
Where a barcode presents a string of information as a one-dimensional
line of black and white bars, a 2D barcode 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 2D barcode 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. This is an example of a data-matrix code made from four separate segments (see below).
What are the advantages of 2D barcodes?
If we already have barcodes, why do need something else as well?
2D barcodes are 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
2D barcode is a square of information running in two
directions so it can efficiently pack more information into the same
space. A typical 2D barcode can represent up to about 2000 characters of information.
- 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 2D barcodes 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: 2D barcodes can be read by the latest
cellphones (mobile phones) using their built-in digital cameras. No special reading
equipment is needed.
- Easy to transmit: 2D barcodes can be sent as SMS text
messages between cellphones.
- More secure: It's possible to encrypt the information in 2D barcodes to protect it.
What are the different kinds of 2D barcode technology?
To an untrained eye, 2D barcodes all 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 2D barcode, 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.
Data-matrix code is the name of the international (ISO) standards covering 2D barcodes, but not all 2D barcodes comply with them (Semacode does;
QR codes and Aztec codes are slightly different).
Photo: Two examples of 2D barcodes: 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 2D barcode technology used for?
You can put a 2D barcode anywhere you can put 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 2D barcode readers are leading to other,
more exciting applications. Advertisers who want you to find out more
about their products online simply print a 2D barcode 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 (website address) 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 2D barcode. 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 2D barcode applications 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: Everyday products are now starting to feature 2D barcodes, usually so people can find out more about them on websites. Look closely at this Fairy dish-washing detergent label and you'll see a data matrix code lurking in the center (just to the left of the words 'come true.')
Further reading
On this website
You might like these other articles on our site covering similar topics:
On other sites
- 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.
Books
