CMYK

CMYK represents colors by layering Cyan, Magenta, Yellow, and Black (Key) inks (subtractive color). All printed materials use CMYK. Standard black QR codes print best at K:100% only - 'rich black' (all inks at 100%) causes bleeding that can destroy fine modules.

For color QR codes, ensure sufficient CMYK contrast between dark and light areas. Higher K values in dark areas improve scanner accuracy. Always convert RGB designs to CMYK and verify scannability before printing.