Aztec Code is a high density two-dimensional matrix style bar code symbology that can encode up to 3832 digits, 3067 alphanumeric characters, or 1914 bytes of data. The symbol is built on a square grid with a bulls-eye pattern at its center. Aztec Code uses less space than other matrix barcodes due to its lack of a quiet zone. With a unique finder pattern that resembles an Aztec pyramid in the middle of the symbol, Aztec Code are easily recognizable.
The symbol is built on a square grid with a bulls-eye pattern at its centre for locating the code. Data is encoded in concentric square rings around the bulls-eye pattern. The central bulls-eye is 9×9 or 13×13 pixels, and one row of pixels around that encodes basic coding parameters, producing a "core" of 11×11 or 15×15 squares. Data is added in "layers", each one containing two rings of pixels, giving total sizes of 15×15, 19×19, 23×23, etc.
The corners of the core include orientation marks, allowing the code to be read if rotated or reflected. Decoding begins at the corner with three black pixels, and proceeds clockwise to the corners with two, one, and zero black pixels. The variable pixels in the central core encode the size, so it is not necessary to mark the boundary of the code with a blank quiet zone.
