QR in a shop window that still scans
Street traffic is fast. The code must stay readable through reflections, tinted glass and evening light.
Size beats decoration
Aim for at least 8–10 cm on the short side for pavement scanning. Tiny ornate codes look nice and fail outdoors.
Contrast against the room behind
Put the print on a light board or matte vinyl. Dark shop interiors eating into dark modules kill scans at dusk.
Test from the curb
Scan from the pavement at lunch and after dark. If one phone fails, enlarge or move away from neon reflections.