The colour orange occurs between red and yellow in the visible spectrum at a wavelength of about 585–620 nm, and has a hue of 30° in HSV colour space. It is numerically halfway between red and yellow in a gamma-compressed RGB colour space, the expression of which is the RGB colour wheel. The complementary colour of orange is azure. Orange pigments are largely in the ochre or cadmium families, and absorb mostly blue light.