How a QR code works

Everything you need to know about the QR code: what they are, how they work and how mobile devices are able to read them in seconds.

The QR codes were born in Japan in 1994, and eventually their creators probably could not have imagined the impact that today. Both in advertising campaigns and in the inventory management of a warehouse, QR codes have greatly facilitated the task of accessing any type of information through a simple drawing.

But, before knowing how QR codes work, let's first know the origin of these curious images created based on lines, points and blank spaces.

Who created the QR codes

The acronym QR has its origin in English, and does not mean anything other than "Quick Response", which translates as "Quick Response" in Spanish. If we go back to the true origin of this technology, we will see that the first two-dimensional bar code was created by the Japanese firm Denso Wave back in 1994.

At the time, its creators had enough doubts as to whether the QR would be able to displace the traditional barcodes. Finally, they got the big companies to start using this technology to, for example, identify the parts of the cars in an assembly line.

Of course, in order to ensure that they can work on any mobile, these codes are subject to standards for worldwide distribution. The Japanese standard is JIS X 0510, and it was published in 1998. After two years, in the rest of the world an even more universal standard was made through the ISO (International Organization for Standardization), which guaranteed its expansion throughout the planet.

How much information does a QR code store?

QR codes, let's not forget, are nothing more than black and white squares , and they are still a text file encoded in a somewhat 'weird' way. We are talking about a file that, of course, can contain a large number of characters. To give you an idea:

Only numbers - Max. 7,089 characters

Alphanumeric - Max. 4,296 characters

Binary - Max. 2,953 bytes

Kanji / Kana - Max. 1,817 characters

QRs can have a minimum size of 21 x 21 or a maximum of 177 x 177 square . This is denoted by the version, ranging from 1 to 40. As a curiosity, the V version is N x N, with N = 17 x 4V . Depending on the version chosen, you will have more or less pictures.

But they also have the ability to correct errors in scanning. By adding and removing pixels, data can be recovered due to a lack of sharpness.

Level L- 7% of the keys can be restored

Level M - 15% of the keys can be restored

Level Q - 25% of the keys can be restored

Level H - 30% of the keys can be restored

In this way an almost immediate reading speed is achieved. At the moment that the reader detects the position and alignment squares, the extraction of the information is almost immediate.

How QR codes are read, here comes the important thing

We will explain how a QR code is formed and how it could be interpreted without an Android device (and with time).

To do this, it will need five parts into which a QR code is divided: Position symbols, alignment symbol, dimension lines, variable information, and the body. Here you can know more clicking on Qr scanner.

Positioning and alignment symbols, the base

What can be seen without problems are the position and alignment symbols? Thanks to the position symbols, the QR reader is located and can continue with the data scan. Of course, once you determine the position you are in because these codes can be read backwards.