How QR Codes Work?

QR codes may look like a random assortment of black squares over a white background, but their intricate structure is what essentially allows them to store the information and be decodable by a scanner.

Scanning QR dog

Table of Contents

What is a QR code?

QR codes are a type of two-dimensional barcode that were created in 1994 by the Japanese company Denso Wave to allow high-speed component scanning in the automotive industry. Humble beginnings…

20-plus years later, QR codes have outgrown their initial use thanks to their “Quick Response” to access digital content in the physical world, becoming a powerful mobile marketing tool. From contact, product or service information to how-to videos on YouTube, directions in Google Maps or Wi-Fi access, QR codes offer endless possibilities to interact and engage with a target audience.

How QR codes work

QR codes may look like a random assortment of black squares over a white background, but their intricate structure is what essentially allows them to store the information and be decodable by a scanner.

The structure of a QR code

  • Version information: These patterns specify the version of the QR code. Currently there are 40, ranging from version 1 that has 21×21 dots, to version 40 with 177×177 dots. Versions 1 to 7 are the most used for mobile marketing.
  • Format information: These patterns store information about error correction and data mask. The error correction aspect ensures that the QR code can be decoded even if it is partially covered or damaged.
  • Data and error correction keys: These patterns store the actual information of the QR code.
  • Position pattern: These patterns indicate the correct direction of the QR code.
  • Alignment pattern: This pattern allows the QR code to be decoded in 360º.
  • Timing pattern: These patterns allow the decoder to determine the width of the data matrix.
  • Quiet zone: This crucial space allows the decoder to identify the QR code from its surroundings.

QR Code Structure Wikipedia

The version of a QR code

QR codes are differentiable by their version, which is no more than the number of modules (the small black squares) they are composed of.

As mentioned before, there is a total of 40 different versions of QR codes. These versions are defined by the number of modules they have; the more modules inside a QR code, the more storage capacity it will have.

Version number 1 has 21 modules. The following versions increase by 4 modules until they reach the version 40 with 177 modules total.

The error correction level of a QR code

QR codes are processed with the use of a Reed-Solomon code, originally developed to help in the music industry since it can measure communication noise from artificial satellites.

The Reed-Solomon code works by adapting the QR code when readable errors come up. There are up to four levels of error correction that can restore the data of the code if it is partially obscured or slightly damaged:

  • Level L: Approximately 7%
  • Level M: Approximately 15%
  • Level Q: Approximately 25%
  • Level H: Approximately 30%

These percentages indicate the capability of the restoration of each codeword inside the QR code.

By using a strong algorithm, the Reed-Solomon code can convert the original data into a polynomial sequence to help restore the code if damaged. In other words, the Reed-Solomon code creates a backup of the QR code to restore it and go back to it in case of reading errors.

The storage capacity of a QR code

The amount of data a QR code can store depends on its version, its error correction level and its datatype, of which there are four:

  • Alphanumeric: it can store up to 4,296 characters.
  • Numeric: it can store up to 7,089 characters.
  • Binary: it can store up to 2,953 bytes
  • Kanji: it can store up to 1,817 characters

How Dynamic QR codes work

There are two main types of QR codes: static and dynamic. Static ones encode the content within the QR code itself, meaning that once set it cannot be changed. Dynamic QR codes, on the other hand, are linked to a short URL which redirects to the chosen content, making them recyclable; you can update or change their content as many times as you want without having to reprint them.

How to scan a QR code

You need two things to scan a QR code; a device with a camera, such as your smartphone, and a scanner app. Most of these can be downloaded for free from the app stores. If you have an Android or iPhone device, you can use their respective pre installed scanners. Upon opening the app, hover over the QR code with your smartphone’s camera to scan it and access its content.

QR code insights

Knowing how a QR code works and how to scan one can give you a different perspective on how to approach your QR code campaign, basically putting you in the shoes of your target audience. Keep in mind the following things and you will most definitely have an opportunity to attract their attention:

  • A clear and concise call-to-action: ask yourself why someone would scan your QR code. Then proceed with the implementation of your campaign. This is arguably the most important part of the entire process.
  • The placement of the QR code: not only where but how. Understanding how a QR code works will help you avoid or solve issues that may arise during the printing stage.
  • Teach your audience: provide information at least on a basic level on how to scan your QR code to ensure that no one misses out on the experience that you are offering.

How to create a QR code

In order to create QR code you first have to search for a QR code generator, like uQR.me. With our platform you will be able to create dynamic QR codes which can be reused, customized and tracked. Upon registering to a plan that suits your needs, create a project and then you will be able to create your QR code and set its content. Once that is done, download it as a vector or raster image to start using it.