📱 Technical Standards of QR Codes & Principles of Error Correction
A QR Code (Quick Response Code) is a two-dimensional matrix barcode invented in 1994 by the Japanese company Denso Wave. While traditional one-dimensional barcodes store information along a single horizontal axis, limiting payloads to dozens of digits, QR codes encode data both vertically and horizontally. This matrix structure accommodates up to 7,000+ characters, making them an indispensable conduit in the mobile era.
🛡️ Finder Patterns and Reed-Solomon Error Correction
When scanning a QR code, the speed and angles of alignment do not prevent immediate recognition due to the three distinct square targets located at the corners. These are called Finder Patterns, enabling scanner cameras to determine the matrix's orientation, skew, and size instantly. Additionally, QR codes implement Reed-Solomon Error Correction, a mathematical coding system. If a printed code becomes muddy or scratched, this redundancy algorithm reconstructs the missing bits. Levels range from Low (L) to High (H), correcting between 7% and 30% of damaged data. Our "Insert Logo" feature leverages this High (H) error correction standard. By intentionally covering the center portion of the matrix with a visual graphic, scanners treat the logo area as "damage" and reconstruct the blocked bits using the surrounding Reed-Solomon blocks without scan errors.
💡 Privacy & Security Advantages of Local Processing
Q. Is it safe to convert private enterprise Wi-Fi passwords or personnel vCards into QR codes? A. Many free web tools require sending text strings containing Wi-Fi access tokens, emails, or directory profiles to remote databases, which are then compiled on their backend servers. This creates potential security concerns for private directories. On the other hand, EVEDAYS' QR Generator processes values 100% locally within your client browser RAM, compiling the matrix directly onto a canvas element. Because the payload never leaves your device, no third-party server keeps a copy of your WiFi password or contact details. Keep in mind that the QR code itself is readable by anyone who scans it, so you still control who you share it with.