QR Basics

QR Codes are matrix-type, two-dimensional codes that accomplish three primary goals:

  1. meet the needs oftoday’s advanced information society for information diversification,
  2. achieve high-capacity storage, and
  3. record product management information in the smallest amount of space possible.

Small Space, BIG Heart

Conventional bar codes contain up to 20 numerals of information. However, QR codes can contain up to 7,089 numerals in a single code. In addition, QR codes can manage letters including Chinese characters, symbols,and control codes. Further, the amount of data contained in a bar code (20 numerals) can be stored in a QR code in approximately 1/30th the amount of space.

2D

Bar codes combine both bars of varying thicknesses, and spaces to hold data in the horizontal direction. On the other hand, QR codes hold data two-dimensionally in both the horizontal and vertical directions, drastically increasing the volume of recordable data. QR codes consist of cell groupings, function patterns to improve reading performance, and data areas to express numerals and Roman characters, all arranged within a square. Function patterns include the cut-out symbols, alignment patterns, the timing pattern, and margin.

360° Multidirectional High-Speed Reading

Code searching for conventional matrix type codes took a considerable amount of time. Code searching was performed by reading the code symbol position (X, Y) and the code periphery (size: L, angle: θ, contour) from an uploaded image.
With QR codes, the cut-out symbols representing the code position can be searched 360°, in any direction based on the ratio of black and white scan lines (1:1:3:1:1). And since the cut-out symbols are located in three of the four corners, the code periphery can be searched based on this positional relationship. Subsequently, lengthy code searching is no longer necessary with QR codes, enabling reading speeds 20 times higher than that of conventional matrix codes.
Moreover, cut-out symbol searching can be performed by the hardware. Using the hardware further increases overall speed by enabling image reading and processing to be conducted simultaneously.

Error Correction

QR Code has error correction capability to restore data if the code is dirty or damaged. Four error correction levels are available for users to choose according to the operating environment. Raising this level improves error correction capability but also increases the amount of data QR Code size.
To select error correction level, various factors such as the operating environment and QR Code size need to be considered. Level Q or H may be selected for factory environment where QR Code get dirty, whereas Level L may be selected for clean environment with the large amount of data. Typically, Level M (15%) is most frequently selected.

 

Warp Resistance

There are cases when the image may be read in a warped state due to the curvature of the attachment surface, or the angle of the reader. To compensate for warping, QR codes contain internal alignment patterns positioned at fixed intervals. First, the error between the assumed center position based on the contour of the code and actual center position of the alignment pattern are solved. Warping compensation is then performed based on this error, enabling codes that are warped both linearly and non-linearly to be read.

Linking Function

QR codes having a linking function that can divide and display a single code in several pieces (maximum 16). The divided code contains indicators to determine the number of divisions and which piece of the code is to be displayed. The data can then be arranged and read as single code, regardless of the order in which the codes are scanned by the reading device. As a result, code printing is possible, even in long, narrow spaces.

 

QR Code Size Decision Factor

The size of QR Code is decided by determining a symbol version, based on data capacity, character type and error correction level, and by setting a module size, based on the performance of the printer for printing or the scanner for reading.