Print Contrast (PCS)
Print contrast — measured as PCS, the Percentage Contrast Signal — is the reflectance difference between the bars and the spaces of a barcode; decoders refuse symbols whose difference is too small.
What You Need to Know
Scanners see reflectance, not color: a barcode is "dark where bars are, light where spaces are" in near-infrared as well as visible light. PCS quantifies the gap (space reflectance minus bar reflectance, divided by space reflectance). The traditional minimum is 75% for retail scanning, and ISO/IEC 15416 grades contrast as one of its scan-quality parameters. Insufficient contrast — from colored barcodes, low toner, recycled kraft board, or black bars on dark-blue backgrounds — is the most common real-world scan failure after quiet-zone violations.
Color choice is therefore constrained by physics, not aesthetics. Red bars disappear to a red-laser scanner entirely (they reflect like the background); dark blue or green bars on white remain safe because they absorb the laser wavelength. GS1 recommends black bars on white spaces for anything scanned across an unknown installed base, and reserves colored or inverted symbols for controlled environments with matched imagers.
Where Print Contrast (PCS) Applies
The 13-digit retail point-of-sale barcode used on consumer products worldwide outside North America.
Generate EAN-13 →The original 12-digit retail barcode of the United States and Canada, and direct ancestor of EAN-13.
Generate UPC-A →A high-density, variable-length linear barcode that encodes all 128 ASCII characters, and the backbone symbology of modern logistics.
Generate Code 128 →The dominant 2D matrix barcode: up to 7,089 digits in a square symbol with selectable error correction.
Generate QR Code →A dense digits-only linear barcode that interleaves bar and space character pairs — logistics workhorse for numeric data.
Generate ITF (Interleaved 2 of 5) →