// Research series
Biometrics in 2D Barcodes
What survives when biometric information is compressed, printed, scanned and recovered from two-dimensional symbols.
3-part series · Read in order
// Reading path
From first question to final consequence.
- Part 1A face fits in 960 bytes.A signed QR can carry an offline face credential, but signature, encoding and card geometry leave roughly one kilobyte for the image.
- Part 2What survives the print, the scan and the phone.Error correction can recover exact codewords from a damaged symbol. It cannot recover biometric detail removed before the credential was printed.
- Part 3Colour buys capacity in exchange for illumination.Polychrome barcodes can multiply payload density, but they exchange binary contrast for dependence on inks, cameras and uncontrolled light.
What survives the print, the scan and the phone.
PHYSICAL CHANNEL Why error correction and biometric degradation are separate failure surfaces, and why treating them as one produces the wrong card. The first part of this series established the byte budget: roughly one kilobyte for a face, once the signature,...