RGB

RGB is a method of representing colors by mixing light of three colors: red, green, and blue. It is called "additive color mixing", and setting all three colors to their maximum produces white. Every display that emits light, such as smartphones, computer monitors, and televisions, represents colors in RGB. Each color is specified in 256 steps from 0 to 255, and about 16.77 million colors can be represented.

When a QR code is displayed on a smartphone screen or monitor, the RGB color space is used. A standard QR code consists of two colors, black (R:0, G:0, B:0) and white (R:255, G:255, B:255), and this combination produces the maximum contrast. When creating a color QR code, if you do not secure a sufficient difference in RGB values between the dark modules and the light background (the contrast ratio), scanners will be unable to read it.

Printed materials use CMYK (cyan, magenta, yellow, black) rather than RGB. When printing a QR code created in RGB, a color conversion from RGB to CMYK takes place, and the printed result may differ from the colors seen on screen. Vivid colors in particular are hard to reproduce in CMYK, so for QR codes meant for print, specifying the colors in CMYK from the start is the reliable approach.