A standard QR burns at the base of the column. The embers rising from it are a second code that spells the same text, and the glowing hotpoints are placed by the text's hash.
Different text in the embers
How the convention works
- QR: a standard QR at error correction H, which any phone can read. Dark modules are charred cells, coloured by distance from the flame.
- Embers: above the QR's quiet zone, a fixed plume of cells on the same grid. Each data cell holds one bit (ember or blank) of a Reed-Solomon-protected, whitened copy of the text, in a fixed shuffled order. Extra particles fill the gaps as decoys.
- Hotpoints: 5–8 dark modules chosen by SHA-256 of the text, with a glowing core. The scanner checks that they are hot.
Full spec: SPEC.md in the repository.