<P> In colorimetry and color theory, lightness, also known as value or tone, is a representation of variation in the perception of a color or color space's brightness . It is one of the color appearance parameters of any color appearance model . </P> <P> Various color models have an explicit term for this property . The Munsell color model uses the term value, while the HSL color model, HCL color space and Lab color space use the term lightness . The HSV model uses the term value a little differently: a color with a low value is nearly black, but one with a high value is the pure, fully saturated color . </P>

The relative lightness or darkness of a color is a property of color known as