HSV
The hue, saturation, value (HSV) color system is similar to RGB in that you specify
a set of three numbers for each color. Each number represents a principal compo‑
nent: hue, saturation, or value. The hue (color) is a number between one and 360, the
saturation (amount of gray in the hue) is a number between one and 100, and value
(amount of white in the hue) is a number between one and 100. For the saturation,
the number represents a percentage of pure color where 100 is 100 percent pure color
and zero percent is gray. For the value, the number represents a percentage of bright‑
ness where 100 is 100 percent white and zero percent is black (Figure 5.5 shows a
few examples). This is a handy system to use when you want to keep the basic hue
while tweaking the saturation and value.