Two-dimensional code has fault-tolerant function, when a part of the two-dimensional code picture is blocked, it can still be scanned.
The fault tolerance rate of two-dimensional code refers to the ability of scanning the two-dimensional code icon after it is blocked. The higher the fault tolerance rate, the more parts of the QR code image can be blocked.
The fault tolerance rate of two-dimensional code is expressed by letters, and the fault tolerance level is divided into four levels: L, M, Q and H:
l:7%； m: 15%； Q: 25%; High: 30%
The density of two-dimensional code is different according to the number of characters to be encoded and the level of fault tolerance. Obviously, the fewer characters, the lower the fault tolerance rate and the lower the density of the QR code; On the contrary, the more characters, the higher the fault tolerance rate and the higher the density of the QR code.
The principle of fault tolerance is that the QR code is redundant in the encoding process, just as 123 is encoded as 123 123, so that the contents of the QR code can still be read completely as long as a part of the QR code picture is scanned.
Extended data:
We printed the QR code on the book. In principle, the lower the density, the smaller the area. Therefore, when making two-dimensional code, the number of coded characters should be reduced as much as possible, which can appropriately reduce the fault tolerance rate without affecting the scanning effect. Generally speaking, no more than 29×29 lines is an ideal two-dimensional code size.
How to reduce the number of characters to be encoded? Of course, reduce the length of the website as much as possible. Web pages can be easily generated by using self-media platforms such as WeChat and Weibo, but the URL is relatively long; A short URL can be generated by using the publisher's own domain name. QR code service providers generally provide ultra-short URLs.