Fascinating, thanks a lot for these. Scandit and Cognex have iOS apps, and Aspose has a web recognizer demo. I tried all three with a 2D QR code (my vax card!

Fascinating, thanks a lot for these. Scandit and Cognex have iOS apps, and Aspose has a web recognizer demo. I tried all three with a 2D QR code (my vax card!) from which I truncated ~2-3 bit-"rows" from the bottom. None of the apps/site detected the code. This is truly not a thorough test -- the 2D rows may be more information-dense than I think i.e. they are not recoverable using the built-in error correction (basically I'm removing too much information -- the equivalent of a long/deep scratch on a CD). -- I'm just trying to get an intuitive sense of how much damage a QR code can sustain and ... I guess if there's such a thing as QR code forensics (there must be...??) for decoding partial codes versus not detecting "anything". Thanks again for the links. Super interesting space