This article refers to the address: http://
On the common QR code, there are squares on the three corners.
This is the three anchor points, and the graphic rotation does not affect the recognition.
To understand the principle of QR code, we must first come to know it. The most common QR code now is the QR code (QR is a code system), let's take it as an example.
Let's look at a QR code. The first thing we see is geometry. In these figures, there are many important "parts" hidden. Huang Haiping, an associate professor at the School of Computer Science, Nanjing University of Posts and Telecommunications, gave us a detailed analysis (below).
First, there are three squares on the three "corners" of the QR code. Don't underestimate this block. It is called a position detection pattern. With these three points, no matter which direction the QR code is read, the information can be identified. Even if the QR code pattern is rotated, it can be recognized. Maybe you will ask, why are there not squares in the four corners? In fact, more points can be set, but the geometric knowledge tells us that 3 points can determine a plane, and a saved corner can be embedded more. information.
In addition, there are some graphics on the QR code mixed in the geometry, which are invisible to the naked eye, such as positioning graphics and separators. The positioning graph is the two "lines" between the three position detection patterns in the figure. Its function is to determine the coordinates of the module in the two-dimensional code symbol, and the separator is used to separate the position detection pattern from the rest of the symbol. . That is to say, the position of the data information that can be read by scanning in the two-dimensional code is determined by the positioning pattern and the separator.
There are also two figures that are hard to find with the naked eye. The top left corner position detection pattern is "version information". Each QR code has a version number. We often say that V1.0 and V2.0 are versions; The detection of the periphery of the graphic at three locations is "format information", which refers to the encoding format used by the two-dimensional code.
Why is the QR code black and white?
Black means binary "1" and white means binary "0"
"The reason why we scan the QR code can read so much information is because the information is encoded into the QR code." Huang Haiping said, "The information input by the QR code can be divided into three categories, text information. Such as business card information; character information, such as web address, phone number; and picture information, and even a short video."
How is the data information compiled? After the information is entered, the code system of the information encoding must first be selected. The common two-dimensional codes are code systems with QR code as the code.
The QR code is a matrix two-dimensional code, which is coded in a rectangular space by different distributions 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 represent binary data. The black that we can see with the naked eye is binary "1", white for binary " 0", the arrangement of black and white determines the content of the matrix two-dimensional bar code, so that the computer can encode and analyze the two-dimensional code symbols.
In order to make us more vividly understand, Huang Haiping QR coded the information "bcde" (at the same time, in order to prevent the leakage of the key "a", this is to protect the information), so after encoding, there is a total of 0 And 1 form a rectangular arrangement. A QR code is generated from this information.
As for the position of the data information in the black and white rectangle, non-professionals cannot know. "This is all work in the background. The QR code has automatic rules, and the information is arranged in the corresponding position of the QR code." Huang Haiping said.
The error correction code information is also mixed into the two-dimensional code together with the data information. This is because when we scan the QR code, we cannot guarantee that every bit of the information is correct, which depends on the error correction code information.
In addition, very important correction patterns are hidden in the QR code. When the QR code is contaminated or destroyed, the correction pattern ensures that unbroken information can still be identified. In other words, the information we scanned and read back a lot of copies in the QR code. “Even if the damage area of ​​the QR code is as high as 50%, the information can still be read.†This means that when we scan a QR code, we don’t need to scan only the entire image, but only a certain part of the graphic. The reason why the information may be successfully obtained. Do not believe you can try!
Having said that, it is easy to understand why the QR code can read the information. "When we scan with the scanning software of the photoelectric scanner or the intelligent terminal of the mobile phone, it is actually a decoding process, and the decoding is precisely the inverse process of the encoding. Specifically, it is the area where the position detection pattern locates the two-dimensional code, according to The encoding format information and error correction code of the dimension code are used to interpret the data. If the encoding is encrypted, the encryption key information is required for decoding."
Maybe you have a question. Previously, barcodes have been used in many applications in life. For example, there are barcodes on the shelves of supermarkets. What are the advantages of QR codes compared to barcodes?
Huang Haiping said that the barcode is one-dimensional, and the two-dimensional code is encoded in the horizontal and horizontal directions, and the amount of information stored is much larger. Data shows that up to 1,850 uppercase letters, 2710 numbers or more than 500 Chinese characters can be recorded. In addition, the space utilization rate of the two-dimensional code is high; the two-dimensional code can be encoded by other code systems in addition to the common OR code. Also, the error correction capability and correction capability mentioned above, as well as the encryption function, are advantages of the two-dimensional code.
Why can I see the information in part of the QR code?
The calibration graphic is hidden in the QR code and has multiple data information backups.
Power X (Qingdao) Energy Technology Co., Ltd. , https://www.qdpowerxsolar.com