So I have been building a free browser-based QR code generator for the past few months. It supports custom gradients, image overlays, and different dot shapes. The results look cool—think nebula images fading into purple gradients. I was happy... until I tried to actually use one. The "iPhone Failure" 📱 I tried scanning one of my cooler designs on my iPhone and it just did not scan. At all. WhatsApp failed. Some Android scanners worked, some didn't. I set the error correction to Level H (the max 30% recovery level). Still nothing. The Real Culprit: Contrast Detection I spent hours thinking it was a bug in my library. It wasn't. Phone cameras don't read QR codes like humans. They use contrast algorithms to find the boundary between dark modules and the light background. Your eyes: See two distinct colors. The camera algorithm: Sees gray noise. Error correction doesn't help because the modules aren't "missing"—they are just invisible to the scanner's logic.…