a value between 0.0 and 1.0, representing
from black to white.
The color of lightness value of 0 is always black regardless to
the hue and saturation, and the lightness value 1.0 is always white.
<EM>Saturation</EM> is a value between 0.0 and 1.0, and represents the
strength of the color. 
The greater the saturation value, the divider the color,
and small saturation values generate weak, dull tone colors.
<EM>Range</EM> limits the RGB values.
If you are using a color display which can assign 8bit value to e