or violet will form a "cool grey". When no color is added, the color is "neutral grey", "achromatic grey", or simply "grey". Images consisting wholly of black, white and greys are called monochrome, black-and-white, or greyscale.

; RGB model
: Grey values result when R = G = B, for the color (R, G, B) (0 < R, G, B < 1).
:; CMYK