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

There are a lot more QR code libraries available, and while they're conceptually very similar, the open source DataMatrix libraries are much less developed and are far less reliable.

I tried libdmtx, but it was extremely slow, and also it had problems with most of my barcodes, even after I cleaned up the images as much as I could.