There are lots of issues with using a QR code that I’m only just realising. For example, the Kaywa gernerator lets you choose a size of QR Code – I think the dimensions are the same between similar codes but the pixels in the image produced are different. It looks like the information is sometimes truncated for me with smaller size images. This suggests that (obviously) the code reader is very resolution dependant; my camera is low-quality and there is a chip in the lens which I think is contributing to this issue. A slightly better camera would probably be more effective.
I’m still trying to work out how exactly the QR code works. Initial dives into the class has been spent rummaging through pages and pages of two-dimensional array declarations – that suggests that these codes may not be that complex.