Two-dimensional code ui is a kind of two-dimensional code, which is different from the traditional one-dimensional code (such as bar code on goods). Two-dimensional code stores information in both horizontal and vertical directions, so the information capacity is greatly improved. QR code? It is a registered trademark of Denso Wave Company.
What are QR codes and mobile phone QR codes?
Two-dimensional bar code is a kind of black and white figure distributed on a plane (two-dimensional direction) according to certain rules, which is used to record data symbol information. In coding, the concepts of "0" and "1" bit streams, which constitute the internal logic foundation of the computer, are skillfully used, and several geometric figures corresponding to binary are used to represent the numerical information of characters, which can be automatically read by image input equipment or photoelectric scanning equipment to realize the automatic processing of information: it has some characteristics of barcode technology: each code system has its own specific character set; Each character occupies a certain width; It has certain verification function. At the same time, it also has the characteristics of automatically identifying different lines of information and dealing with the rotation and change of graphics. Two-dimensional code/two-dimensional code can express information in both horizontal and vertical directions at the same time, so it can express a lot of information in a small area.
The cooperation of QR code and mobile phone camera will produce many applications. For example, in the future, we can print the QR code on our business card, and others only need to take a photo with a camera phone with QR code recognition software, and all the information on the business card will be input into the phone; If the goods in the supermarket are also printed with QR codes, we can get a lot of detailed information about the goods on the mobile phone. At present, the QR code has been widely used in Japan and South Korea, and it has also been popularized in Taiwan Province and Chinese mainland. In the future, we can use QR code to buy coke, pay bills and shop online in vending machines.
Classification of 2D Barcode/QR Code
2D barcode/QR code can be divided into stacked 2D barcode and matrix 2D barcode. The stacked/row-arranged two-dimensional bar code is formed by stacking a plurality of rows of chopped one-dimensional bar codes; Matrix two-dimensional bar code consists of a matrix, where binary "1" is represented by dots, binary "0" is represented by spaces, and the coding consists of dots and spaces.
? Two-dimensional bar code with stacked/row arrangement
Stacked/line 2D barcode (also called stacked 2D barcode or layered 2D barcode), its coding principle is based on one-dimensional barcode and stacked into two or more lines as required. It inherits some characteristics of one-dimensional bar code in coding design, checking principle and reading mode, and the reading equipment is compatible with bar code printing and one-dimensional bar code technology. However, due to the increase of the number of lines, it is necessary to judge the number of lines, and its decoding algorithm and software are not exactly the same as those of one-dimensional bar code. Representative two-dimensional bar codes are: Code 16K, Code 49, PDF4 17, etc.
? Matrix QR code
Short array two-dimensional bar code (also called chessboard two-dimensional bar code) is coded in rectangular space by the different distribution of black and white pixels in the matrix. In the position of the corresponding element in the matrix, the binary "1" is represented by the appearance of points (squares, points or other shapes), and the binary "0" is represented by the absence of points. The arrangement and combination of points determine the meaning represented by matrix two-dimensional bar code. Matrix two-dimensional bar code is a new coding system based on computer image processing technology and combined coding principle, which can automatically read and process graphic symbols. Representative matrix two-dimensional codes include: code one, Maxi code, two-dimensional code, data matrix and so on.
At present, among dozens of QR codes, the commonly used code systems are: PDF4 17 QR code, Datamatrix QR code, Maxicode QR code, Code 49, Code 16K, Code One and so on. In addition to these common two-dimensional barcodes, there are Vericode barcode, CP barcode, Codablock F barcode, Tian Zi barcode and Ultracode. ...& gt& gt
Question 2: What is the principle of QR code? Two-dimensional code uses several geometric shapes corresponding to binary to represent alphanumeric information, converts the information into binary geometric shapes, and generates a matrix diagram. After the QR code is generated, it needs to be decoded by a special decoder. At present, infrared probes are used to capture graphics, which are generally divided into hard decoding and soft decoding. Hard decoding refers to direct decoding with software after the probe captures the graphics, while soft decoding refers to comparative decoding by capturing the graphics and sending them to the QR code library.
Question 3: How does a QR code work? Two-dimensional code uses several geometric shapes corresponding to binary to represent the numerical information of characters, and converts the information into binary geometric shapes to generate a matrix diagram. After the QR code is generated, it needs to be decoded by a special decoder. At present, infrared probes are used to capture graphics, which are generally divided into hard decoding and soft decoding. Hard decoding refers to direct decoding with software after the probe captures the graphics, while soft decoding refers to comparative decoding by capturing the graphics and sending them to the QR code library.
Question 4: What is the recognition principle of QR code? Can you fake it? QR code QR code
[Edit this paragraph] What is a 2D barcode/QR code?
Two-dimensional bar code is a kind of black and white figure distributed on a plane (two-dimensional direction) according to certain rules, which is used to record data symbol information. In coding, the concepts of "0" and "1" bit streams, which constitute the internal logic foundation of the computer, are skillfully used, and several geometric figures corresponding to binary are used to represent the numerical information of characters, which can be automatically read by image input equipment or photoelectric scanning equipment to realize the automatic processing of information: it has some characteristics of barcode technology: each code system has its own specific character set; Each character occupies a certain width; It has certain verification function. At the same time, it also has the characteristics of automatically identifying different lines of information and dealing with the rotation and change of graphics.
Two-dimensional code/two-dimensional code can express information in both horizontal and vertical directions at the same time, so it can express a lot of information in a small area.
[Edit this paragraph] Classification of 2D barcode/QR code
2D barcode/QR code can be divided into stacked 2D barcode and matrix 2D barcode. The stacked/row-arranged two-dimensional bar code is formed by stacking a plurality of rows of chopped one-dimensional bar codes; Matrix two-dimensional bar code consists of a matrix, where binary "1" is represented by dots, binary "0" is represented by spaces, and the coding consists of dots and spaces.
1. Stacked/progressive 2D barcode
Stacked/line 2D barcode is also called stacked 2D barcode or layered 2D barcode), and its coding principle is based on one-dimensional barcode and stacked into two or more lines as required. It inherits some characteristics of one-dimensional bar code in coding design, checking principle and reading mode, and the reading equipment is compatible with bar code printing and one-dimensional bar code technology. However, due to the increase of the number of lines, it is necessary to judge the number of lines, and its decoding algorithm and software are not exactly the same as those of one-dimensional bar code. Representative two-dimensional bar codes are: Code 16K, Code 49, PDF4 17, etc.
2. Matrix QR code
Short array two-dimensional bar code (also known as chessboard two-dimensional bar code) is coded in rectangular space by the different distribution of black and white pixels in the matrix. In the position of the corresponding element in the matrix, the binary "1" is represented by the appearance of points (squares, points or other shapes), and the binary "0" is represented by the absence of points. The arrangement and combination of points determine the meaning represented by matrix two-dimensional bar code. Matrix two-dimensional bar code is a new coding system based on computer image processing technology and combined coding principle, which can automatically read and process graphic symbols. Representative matrix two-dimensional codes include: code one, Maxi code, two-dimensional code, data matrix and so on.
At present, among dozens of QR codes, the commonly used code systems are: PDF4 17 QR code, Datamatrix QR code, Maxicode QR code, Code 49, Code 16K, Code One and so on. In addition to these common two-dimensional barcodes, there are Vericode barcode, CP barcode, Codablock F barcode, Tian Zi barcode and Ultracode barcode.
[Edit this paragraph] Features of 2D barcode/QR code
1. high-density coding, large information capacity: it can accommodate up to 1850 capital letters or 27 10 numbers or10/08 bytes, or more than 500 Chinese characters, which is several times higher than ordinary bar codes.
2. Wide coding range: Barcodes can encode digitized information, such as pictures, sounds, characters, signatures, fingerprints, etc. , and represented by bar code; Can represent multiple languages; Can represent image data.
3. Strong fault tolerance and error correction function: This enables the QR code to be read correctly when it is partially damaged due to perforation, fouling, etc. When the damaged area reaches 50%, the information can still be recovered.
4. High decoding reliability: far lower than the decoding error rate of two millionths of ordinary bar codes, and the error rate does not exceed one millionth.
5. Encryption measures can be introduced: good confidentiality and strong anti-counterfeiting.
6. Low cost, easy to manufacture and durable.
7. The shape, size and proportion of bar code symbols are variable.
8. Two-dimensional bar codes can ... >>
Question 5: What is the core principle of QR code anti-counterfeiting? Two-dimensional code anti-counterfeiting means that two-dimensional code can be changed. Each QR code has its own independent digital information, and each product has an independent QR code. After the enterprise builds its own network platform, consumers can obtain the information of product authenticity by scanning the QR code. If the information in the background of the enterprise cannot be scanned, it proves that the product is a fake. However, if counterfeiters forge a QR code in batches, enterprises can immediately obtain information on their own platforms, and how many times a product of their own has been scanned in a certain area, they can immediately have anti-counterfeiting actions. However, the QR code cannot completely prevent counterfeiting, and it can only increase the difficulty of counterfeiting. Enterprises can receive counterfeit information at the first time through the platform to improve the efficiency of counterfeiting.
Question 6: What is the principle of QR code sign-in? Using digital technology, communication technology and cryptography principles, the login IP address or website of the sign-in system is expressed in the form of two-dimensional code, which supports online input or import of user information, and realizes the functions of query and statistical analysis of all input information, and then the two-dimensional code is labeled or printed in the form of two-dimensional code. When operating, you can use your mobile phone (or proprietary scanning equipment) to scan the QR code, log in to the designated official website, and input relevant information. At the same time, you can log in to the enterprise website or WeChat platform through the extended function of the login platform, learn more about the brand introduction and product information of the enterprise, and realize online ordering, mobile payment and other functions through the online mall.
Question 7: The principle of scanning code login The general idea of scanning code login is that the WeChat mobile phone client obtains some information from the QR code of the webpage, and then sends it to the webpage WeChat server, which verifies the information and responds.
1. Every time you open the WeChat web version, a QR code with a unique uid will be generated, which will change after each refresh. This can ensure that a uid can only bind one account and password, and ensure the uniqueness of the logged-in user. You can view the information in the QR code through the code scanning function provided by UC browser on your mobile phone, but it will not automatically open the address. I refreshed it three times, and the scanning results are as follows, in which the last string of numbers is uid:
By looking at the source code of the webpage, many related resources needed after login have been preloaded when loading the webpage, so the login user can quickly display the user information after confirmation.
2. In addition to returning a unique uid, when you actually open this page, the browser will also create a long connection with the server to request a scan record of the uid. If not, a status code 408 (request timeout) will be received after a certain period of time (currently about 27 seconds), indicating that the next request should continue; If the status code 20 1 is received (the server successfully created a new resource), it means that the client scanned the QR code.
Question 8: Find the working principle of mobile phone scanning QR code 50 points. Now the common QR code is QR code, which is encoded in a rectangular space through the different distribution of black and white pixels in the matrix. We know that computers use binary (0 and 1) numbers to store and process data, while in two-dimensional codes, black and white rectangles are used to represent binary data. The black we can see with the naked eye stands for binary "1" and the white stands for binary "0". The arrangement and combination of black and white determines the content of matrix two-dimensional code, which is convenient for computer to encode and analyze two-dimensional code symbols. Using black and white to represent 0 and 1 is convenient for computer to read, which is why the QR code is black and white.
Two-dimensional code scanning positioning process
But the photos taken by mobile phones are all in color, so is scanning QR codes. It is also colored by default, but the colors are deep and light, so the recognition software relies on the depth of color to complete the first step of QR code recognition. This step is called ashing, which means treating the dark color as dark gray and the light color as light gray.
It is not enough to recognize only the gray level, because there will be noise when scanning due to the influence of the surrounding environment. The so-called noise here is actually equivalent to the noise generated when the mobile phone takes pictures. Perhaps the noise in the picture will not have much influence on the picture, but the noise during scanning is easy to cause the analysis error of scanning, so the second step is denoising.
After completing the above two steps, we will enter the crucial binarization process. As mentioned above, the computer uses binary, and the task of binarization is to convert dark gray and light gray patterns into only black or white colors. In binarization, QR codes will first be interpreted as black and white bar codes. Then it is converted into binary information according to analytical formula and threshold operation. Perhaps most people can't understand the formula, but you should know that binarization is a very complicated and accurate step.
After the above three steps, the next step is to find the detection mode. What is the detection mode?
Friends who often read QR codes know that there are three squares on the QR code. What are the functions of these three squares? What does this mean? In fact, its exact name is position detection map. With these three points, you can identify information no matter which direction you read the QR code. The QR code can be recognized even if it is rotated.
Each position detection pattern can be regarded as consisting of three overlapping concentric squares, which are 7×7 dark module, 5×5 shallow module and 3×3 dark module respectively. The module width ratio of the position detection pattern is1:1:3:1:1. This aspect ratio feature of1:1:3:1:1is unlikely to appear in other positions of the image, so it is used as the scanning feature of the position detection pattern. Based on this feature, when a straight line (that is, the red line seen during scanning) is alternately cut into1:1:3:1:1,it can be considered that the straight line has passed the position detection graph.
In addition, some graphics on the QR code are mixed with geometric graphics, which are invisible to the naked eye, such as positioning graphics and separators. The positioning figure is two "lines" connecting three position detection figures in the figure, and its function is to determine the coordinates of the module in the two-dimensional code symbol, while the separator is used to separate the position detection figure from the rest of the symbol. That is to say, the position of data information in the two-dimensional code that can be read by scanning is determined by the positioning figure and separator. So there are three small squares on the QR code, whose main function is to identify and determine the coordinates of the modules in the QR code symbol.
Two-dimensional code decoding and error correction
After obtaining the recognizable QR code, the next work is to decode and correct the error. Decoding is to decode and compare the format information, version information, data and error-correcting code information contained in the QR code, and to correct errors at the same time. In fact, a two-dimensional code includes all kinds of decoding information in addition to the detection graphics mentioned above. We can have a general understanding of the information elements contained in a two-dimensional code through the schematic diagram of the information contained in the two-dimensional code.
After decoding, the work from the identification of the QR code to the decoding on the mobile phone is completed, and the remaining work is to transmit data through the network to obtain the relevant content of the QR code. Maybe you never thought that the seemingly simple operation of QR code recognition would involve so many steps and formula calculations, and this is only for ordinary QR codes. If it is an encrypted QR code, the work behind it can be ... >>
Question 9: What is the principle of QR code scanning gun? Recognition by 2d laser head is actually image analysis or fixed in hardware.
Question 10: What is the principle of QR code and why is it called 2D? What is two-dimensional? A floor plan can contain information? Who invented it? The principle of QR code can be described from the principle of matrix QR code and the principle of determinant QR code.
Matrix principle
Matrix two-dimensional code (also called chessboard two-dimensional code) uses the different distribution of black and white pixels in the matrix to encode in rectangular space.
In the position of matrix elements, square points, dots or other shaped points represent binary "1", and the missing points represent binary "0". The arrangement and combination of points determine the meaning represented by the matrix QR code. Matrix QR code is a new coding system based on computer image processing technology and combined coding principle, which realizes automatic recognition and reading of graphic symbols. Representative matrix two-dimensional codes include: code one, Maxi code, two-dimensional code, data matrix and so on.
In the matrix of figure 2 1*2 1, black and white areas are designated as fixed positions in the two-dimensional code specification, which are called finder pattern and timingpattern. Image search graphics and positioning graphics are used to help the decoding program determine the coordinates of specific symbols in the graphics. The yellow area is used to store coded data content and error correction information codes. The blue area is used to identify the level of error correction (that is, L level to H level) and the so-called mask pattern. This area is called "format information".