Looking at my lossy-compressed music library, the smallest album I have is 15MB and the largest (single disk) album is 70MB. Using LP-sized cards (12"x12"), a b

Looking at my lossy-compressed music library, the smallest album I have is 15MB and the largest (single disk) album is 70MB. Using LP-sized cards (12"x12"), a binary image would end up being about 1100-2500 DPI respectively for those two albums. Much too small to be scanned effectively. If you reduce the requirements to a single rather than an album, then you are looking at 1-10 MB per code, which is 300-900 DPI, still too dense. The camera would also be a limiting factor. The iPhone 12 has a 12 mega-pixel sensor, so even if you can get exact pixel-for-pixel alignment of the sensor and coded data, you would need to represent 10-50 bits of information in each pixel (eg via color/brightness), for an album, or 1-8 bits for a single song. In practice, you need several pixels per bit, so you would have to scan the code in sections - you couldn't image it at once. At that point, perhaps a tape would be more appropriate than a card. That is with fairly transparent compression though. You could be a lot more aggressive, and might get something that would work with a single photo.