What is the working principle of two-dimensional code

Do not know from when, our life suddenly full of two-dimensional code.Scan the QR code to browse the web page, add a friend to scan the QR code, Now even sell strawberry uncle all support sweep a code to pay.So have you ever wondered where does QR code came from? what exactly is it’s working principle?

Before we introduced how QR codes work, you probably already know that they convert information into small black and white squares and then fill in the large squares.

It's a bit like the answer sheet used in high school exams, where you turn the information into a pattern that can be scanned by a machine and you know in a second how many points you've scored.Of course, QR codes work differently than answer sheets, which we'll talk about later.

Let's first introduce the QR code brother bar code, which is the supermarket cashier to sweep the black and white bar.The computer identifies uneven black and white bars horizontally and finds the number information hidden in them.Instead of a barcode that carries information in one dimension, the QR code carries information in both horizontal and vertical dimensions, resulting in the square shape.

Bar codes and QR codes are like good brothers.They dress numbers, letters, symbols and other characters into black and white strips or blocks that can be recognized by a mobile phone, camera.So, the key question is, how do these characters become this two-dimensional code pattern?This brings us to one of mankind's epoch-making inventions: the binary system.We use numbers, letters, Chinese characters and other characters in a completely different style, but intelligent human beings have invented a method that allows them to be uniformly converted into a binary sequence of numbers consisting of 0 and 1.

This process of transformation is called coding.There are several universal coding rules in the world, and today we will explain what is coding with an example (ISO18004, the universal coding rule for subtitle QR codes).For example, AB is a two-letter character.According to coding rules, each individual English letter has a unique decimal number corresponding to it .Strings like AB, on the other hand, have to be evaluated on top of the corresponding number.And that translates back into binary, which is this string of numbers.

The entire computer and Internet civilization is built on this binary code.The video you're watching on your phone right now is really just a sequence of zeros and ones.After the characters become a sequence of numbers consisting only of 0's and 1's, a series of optimization algorithms are applied to obtain the final binary code.In the last series of codes, a 0 corresponds to a small white square, and a 1 corresponds to a small black square. We put these small squares into a group of 8 into a large square, which is a complete two-dimensional code pattern that can be recognized by the mobile phone camera.This is the basic principle of two-dimensional code.