QR code Introduction

Two-dimen1_code records the data symbol information in a black/white image with a specific ry distributed in a plane (two-dimensional direction) according to a certain pattern. In real life, QR codes are common around us, for example: product anti-counterfeiting/tracing, advertising push, website links, data downloads, product transactions, positioning/navigation, electronic creden。, vehicle management, information transmission, business card communication, and WiFi sharing.

The concept of "0" and "1" bit streams that constitute the internal logic of computers is cleverly used in code compilation, A number of ry corresponding to the binary are used to represent the numerical value of the text. The input device of the image or the photoelectric scanning device can automatically read and read the text for automatic information processing. In many types of two-dimensional bar codes, commonly used code systems include data matrix, maxicode, Aztec, QR code, QR code, vericode 417, ultracode, Code 49, and code 16 K. Each code system has its own character set, each character occupies a certain width, and has a certain verification function. At the same time, it also has the ability to automatically identify different rows of information and handle graphics rotation changes. A QR code is a more advanced bar code format than a QR code. A one-dimensional code can only express information in one direction (generally horizontal), while a two-dimensional code can store information in both the horizontal and vertical directions. A QR code can only consist of numbers and letters, while a QR code can store Chinese characters, numbers, images, and other information. Therefore, the application of a QR code is much wider.

 

 

 

The QR code can be roughly divided into two types: matrix and row layout:

(1) Matrix

In a rectangle space, black and white pixels are encoded in different distributions in the matrix.

In the position of a matrix element, the square, Dot, or other shape points indicate the binary "1", and the dots represent the binary "0 ", the arrangement and combination of points determine the meaning of the matrix QR code. The matrix QR code is a new type of automatic reading and processing code system based on computer image processing technology and the principle of combined encoding. Representative matrix QR codes include code one, Maxi code, QR code, and data matrix.

In the matrix of Figure 21*21, black and white areas are specified as fixed locations in the QR code specification, known as the finder pattern and the timingpattern ). Image Search and positioning graphics are used to help the decoder determine the coordinates of specific symbols in the image. The yellow area is used to save the encoded data content and error correction information code. The blue area is used to identify the error correction level (that is, Level L to level H) and the so-called "mask pattern". This area is called "format information ).

 

(2) Row Layout

Line-based QR code (also known as stacKed QR code or layer-based QR code) is based on a one-dimensional code and stacked into two or more lines as needed. It inherits some of the features of one-dimensional code in coding design, Verification Principle, and recognition and reading method. The recognition and reading equipment is compatible with the one-dimensional code technology. However, due to the increase in the number of lines, it is necessary to determine the line, and its decoding algorithm and software are not exactly the same as the one-dimensional code. Typical row-specific QR codes include code49, code 16 K, and limit 417.