Finder Pattern

Finder patterns (position detection patterns) are concentric square shapes placed at the top-left, top-right, and bottom-left corners of a QR code. Their three-layer black-white-black structure is designed to be detected at a 1:1:3:1:1 ratio from any scanning direction.

Scanners first locate these three finder patterns to determine the QR code's position, size, and tilt. Having patterns at only three corners allows the bottom-right position to be inferred, enabling orientation detection. This finder pattern design is the primary reason QR codes can be read at high speed.