• QR Code Basics: Invented in 1994 by DENSO Corporation, QR codes are the evolution of bar codes. They store data in two dimensions using an array of contrasting regions with higher information density. Use Reed–Solomon error correction.
• How QR Codes Work: Have square blocks on three corners for coarse identification and alignment. A "Quiet Region" around the edge helps disambiguate. Various elements like spacing gaps, format/versioning info, masks (applied via XOR), and alignment blocks exist. The payload is zig-zagged through the grid.
• Error Correction: Data is stored in 8-bit words with four configurable error correction levels (L: 7% restore, M: 15%, Q: 25%, H: 30%).
• Destruction Tests: Using the H version QR code, various distortions and deformations like shrinking, rotating, reducing contrast, losing corners/edges, adding noise, etc. were tested to see if it could still be read with a smartphone QR reader app.
• Quiz: A series of modified QR codes were presented, and viewers were asked to guess if they could be scanned.
• Test: Asked if the reader can scan a specific QR code.
• Update: Many people reported successfully scanning the wounded codes, noting various factors like monitor differences, lighting, scan conditions, app quality, etc. that can affect scanning. A complete list of articles is available here, and one can subscribe to email alerts here.