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What is half black/white though? I don’t see any gray. Only black and white Did he subdivide the qr code cell into four sub pixels and make the left two one co
by hammock 2y ago
What is half black/white though? I don’t see any gray. Only black and white
Did he subdivide the qr code cell into four sub pixels and make the left two one color and the right two another? That’s what I would have guessed for the “lenticular” effect at different angles. But the subpixels I see are more checkerboard ish
- layer8 2y agoQR code decoders usually work by sampling the values from a dot grid overlayed on the camera image (or something along those lines). If a QR square isn’t actually uniform, the sampled value for that square will change if you move the camera a bit. When you hold a QR code in front of the camera, the picture is continuously sampled, yielding different bit values all the time because you don’t hold the camera a 100% still (in addition to sensor noise and the like). The QR decoder is however satisfied as soon as the result passes the QR checksum verification. The image recognition that outputs the bit pattern of the QR code is inherently heuristic in nature, and only the checksum verification is what decides if the recognition worked successfully. The trick in TFA is to produce an image where two different results of the heuristics can both pass the checksum verification, so which one you get depends on circumstantial factors.
- hammock 2y agoMore non-deterministic than I would have thought. Your explanation makes sense tho thanks