Shades of gray
Achromatic grays
Achromatic grays are colors in which the RGB (red, green, and blue) values are exactly equal. Since achromatic grays have no hue, the hue code (the h in the hsv values of the color) is indicated with a dash. Achromatic grays are the axis of the color sphere, with white at the north pole and black at the south pole of the color sphere. The various tones of achromatic gray are along the axis of the color sphere from white at the top of the axis to black at the bottom of the axis.
Shades of gray-7