RGB and CMYK color space conversion is used to translate color representation from one color space to the other. The CMYK (Cyan-Magenta-Yellow-Key (black)) color model is used in offset printers for full color document printing. The printer uses ink in those four basic colors and the color black is used directly as the key. CMYK masks are applied to a white background, reducing the amount of light reflected.
The following formulas are used for RGB to CMYK color space conversion. RGB values range from 0 to 255, and CMYK values range from 0 to 1.
RGB to CMYK
R‘ =R/255
G‘ =G/255
B‘ = B/255
K= 1-max(R‘,G‘,B‘)
C= (1-R‘-K) / (1-K)
M= (1-G‘-K) / (1-K)
Y= (1-B‘-K) / (1-K)
CMYK to RGB
R= 255 × (1-C) × (1-K)
G= 255 × (1-M) × (1-K)
B= 255 × (1-Y) × (1-K)