At its core, a QR code encodes data by representing information using patterns of dots and blanks within a square grid.
QR codes are a popular method for storing and transmitting information quickly. Their power lies in their ability to encode various types of data into a compact, scannable image.
The Binary Basis of QR Code Encoding
The fundamental principle behind how QR codes encode data is the use of binary code. As stated in the reference:
- The data in a QR code is a series of dots in a square grid.
- Each dot represents a one and each blank a zero in binary code.
- These patterns encode sets of numbers, letters or both, including URLs.
Think of the grid as a canvas where each small square (or module) can either be filled in (a dot) or left empty (a blank). This simple on/off state corresponds directly to the binary digits 1 and 0, respectively.
Mapping Data to the Grid
- Data Conversion: The information you want to encode (e.g., a website URL, a contact number, a text message) is first converted into a binary sequence (a string of 1s and 0s).
- Grid Mapping: This binary sequence is then mapped onto the QR code grid. A '1' corresponds to a dark module (dot), and a '0' corresponds to a light module (blank).
- Pattern Formation: Specific arrangements and patterns of these dots and blanks represent the encoded data. The QR code standard includes predefined rules for how different characters and data types are translated into these binary patterns and arranged within the grid.
| Module State | Binary Value | Representation |
|---|---|---|
| Dot (Filled) | 1 | Dark Module |
| Blank (Empty) | 0 | Light Module |
Grid Size and Data Capacity
The amount of data a QR code can hold depends on its size, which is determined by the number of rows and columns in its grid.
- At its smallest, the grid is 21 rows by 21 columns.
- At its largest, this grid is 177 rows by 177 columns.
Larger grids contain more modules (dots/blanks), allowing for the encoding of more binary information and thus more complex data.
In addition to the data modules, QR codes contain essential structural patterns (like the large squares at the corners) that help scanners identify the code's orientation and size, but the actual data is primarily held within the binary patterns of dots and blanks in the main grid area.
