“A QR code is really just a way of encoding a few bytes of data in a way that can be easily read froma photo by a smartphone or similar device.”

andrewt.net article · Dithered QR Codes: Embedding Images While Maintaining Scannability

“They're designed to be very robust to bad focus, bad printing, funny angles, and missing areas.”

andrewt.net article · Dithered QR Codes: Embedding Images While Maintaining Scannability

“The idea is that once we've thresholded the entire picture, every part of the image will be, on average, closer to the correct brightness than more regular dithering.”

andrewt.net article · Dithered QR Codes: Embedding Images While Maintaining Scannability

“The other advantage of this irregular dithering is that the salt-and-pepper noise caused by the QR code data modules is much harder to spot.”

andrewt.net article · Dithered QR Codes: Embedding Images While Maintaining Scannability