Back-compatible Color QR Codes for colorimetric applications

•Color correction often relies on color charts that can accomodate limited colors (10 s).•QR Codes can be used to accomodate a large number of color samples (1000 s).•QR Code have compact form factor (a few inches) while chart have a wide factor form.•Our grayscale affinity to black and white during color mapping is fully back-compatible.•Grayscale method leads to much higher readability in adversarial opticial conditions.