How QR code and 2D barcode Works ?

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!

What are 2D barcodes?

You might 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.

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, there is no duplication of information to guard against a code being misprinted or damaged. 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 smartphones and tablet computers using their built-in digital cameras. No special reading equipment is needed. Even though they contain more information, they can be read accurately at high speeds.

• 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 barcodes, some available in the public domain and some that are still proprietary.

Here are some of the best known:

• QR Code® (pioneered in the 1990s by Japanese company Denso Wave), which has several variations, including Micro QR Code (a smaller version that carries less information), IQR Code (which can hold a lot more information), SQRC (which can carry secure, encrypted data), and FrameQR (like a traditional QR Code but with a recognizable image on top to make it easier for humans to use)
• 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)
• PDF417, which is more like a traditional barcode, but with data that extends vertically as well as horizontally
• Semacode

"Data matrix code" is the name of the international (ISO) standards covering 2D barcodes, but not all 2D barcodes comply with them.

What information does a QR code contain?

By their very nature, QR codes (and other data matrix codes) are meant to be read by machines, not humans, so there's only a certain amount we can tell just by looking at them. Although each code is different, they contain a few interesting, common features. Looking again at the gyamatech.blogspot.com QR code up above, we have:

1. Quiet zone: An empty white border that makes it possible to isolate the code from among other printed information (for example, on a dirty envelope, among the black and white print of a newspaper, or on smudged product packaging).

2. Finder patterns: Large black and white squares in three of the corners make it easy to confirm that this is a QR code (and not, say, an Aztec code). Since there are only three of them, it's immediately obvious which way up the code is and which angle it's pointing at (unless the code is partly obscured or damaged in some way).

3. Alignment pattern: This ensures the code can be deciphered even if it's distorted (viewed at an angle, printed on a curved surface, and so on).

4.Timing pattern: This runs horizontally and vertically between the three finder patterns and consists of alternate black and white squares. The timing pattern makes it easy to identify the individual data cells within a QR code and is especially useful when the code is damaged or distorted.

5. Version information: There are various different versions of the QR code standard; the version information (positioned near two of the finder patterns) simply identifies which one is being used in a particular code.

6. Data cells: Each individual black or white square that's not part of one of the standard features (the timing, alignment, and other patterns) contains some of the actual data in the code.

Further reading

There are a number of other features and complications that I won't go into here; if you'd like more detail, you'll find it by looking at these two excellent references:

• QR Code Tutorial: A very good explanation of how a QR code works, in theory, and practice. Includes detailed examples showing how QR codes encode actual binary data.
• QR Code by Tan Jin Soon, EPCglobal Singapore Council. Synthesis Journal, 2008. A longer explanation of QR codes and an excellent review of some typical applications.

What is 2D barcode technology used for?

The American space agency NASA was one of the earliest organizations to make widespread use of data matrix codes, in the mid-1980s: it engraved them onto parts from space rockets, such as the Space Shuttle, because they didn't come off, like paper labels, and could store so much more information.

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 sight of while you're on the move.

Transportation is another increasingly popular application. Numerous airline, railroad, and bus companies let you buy travel tickets online in advance through an easy to use the app and store them on your cellphone. Your phone displays the details on its screen as a 2D barcode code, which becomes your electronic ticket; at the check-in desk or onboard your bus or train, you just wave your phone past a scanner to validate your journey. The big drawback here is obviously the risk of your phone running out of power, so make sure you charge it up before you depart.

How can you make a QR code?

There are lots of online generators that will do it for you. The Bing search engine has a really neat one that shows you the QR code forming as you type, so you can get a sense of how a QR code is built from the information it contains, how adding more information changes the pattern, and how a code that contains more information generally leads to a more visually intricate pattern. Try it for yourself!

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