This colour model is user-oriented, being based on the intuitive appeal of the artist's tint, shade and tone. The coordinate system is cylindrical and the HSV model is defined as a cone within this cylinder. Hue (H) is measured by the angle around the vertical axis, with red at 0 degree, green at 120 degree and so on. The height of the cone represents value (V) in a range from 0 (black) at the apex to 1.0 (white) at the base of the cone. Saturation (S) is a ratio ranging from 0 on the center line (V axis) to 1 on the triangular sides of the cone.