About
Chroma is a ratio parameter whereas colorfulness is an absolute property.
- Chromatic: Having hue
- Achromatic: Without hue
- Polychromatic: Having many hues
- Monochromatic: Having one hue only
Formula
The Chroma formula is the saturation (colorfulness) relative to the lightness.
$chroma = (1 - abs(2 * $lightness - 1)) * $saturation;
where lightness and saturation are values in the range 0 to 1 1)