It's not only the glossiness, it's also about the original size. Barcodes work because they are at a fixed size, and a picture on screen can seldom reproduce th

It's not only the glossiness, it's also about the original size. Barcodes work because they are at a fixed size, and a picture on screen can seldom reproduce the exact same size. This is also why QR Codes have reference points (those three corner blocks or the big centre block)