Each QR Code symbol shall be built of square modules arranged in a regular square array and shall consist of function patterns and encoding region. And the whole symbol shall be surrounded on all four sides by a quiet zone border.
Function patterns are the shapes that must be placed in specific areas of the QR code to ensure that QR code scanners can correctly identify and the code for decoding. There are 4 types of function patterns; they are finder pattern, separator, timing patterns, and alignment patterns.
Encoding region contains data, which represents version information, format information, data and error correction codewords.
Finder Pattern
Finder patterns are the special position-detection patterns located in three corners (upper left, upper right, and lower left) of each symbol.
It consists of an outer dark square that is 7 × 7 modules, an inner light square that is 5 × 5 modules, and a solid dark square in the center that is 3 × 3 modules. The ratio of module widths in each position detection pattern is 1:1:3:1:1.
The finder pattern is designed to be a pattern that is unlikely to appear within the other sections of the QR code so that QR code scanners can search for this ratio of light to dark modules to detect the finder patterns and correctly orient the QR code for decoding.
Separators
Separators are the one-module wide areas of whitespace between each finder pattern and encoding region.
Timing Patterns
There are 2 timing patterns, i.e. horizontal timing pattern and vertical timing pattern. They are consisting of alternating dark and light modules. The horizontal timing pattern is placed in the 6th row of the QR code between the separators. The vertical timing pattern is located in the 6th column of the QR code between the separators. These patterns are helpful in determining the symbol density, module coordinates and version information area.
Alignment Patterns
An alignment pattern is constructed of 5 × 5 dark modules, 3 × 3 light modules and a single dark module in the center. QR codes that are version 2 and larger must have alignment patterns and the number of alignment patterns depends on the symbol version.
Encoding Region
Encoding region contains format information, version information, data and error correction codes. For format information, one-module array must be reserved near the top-left, top-right, bottom-left finder pattern and version information, an area of a 6 × 3 block above the bottom-left finder pattern and a 3 × 6 block to the left of the top-right finder pattern is reserved.
Quiet Zone
It is a 4-module wide area containing no data, and it used to ensure that the surrounding text or markings should not misguide the QR code data.
