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.
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.
In subtractive color (e.g., paints) value changes through various tints and shades can be achieved by adding black or white, respectively, to the color. However, this also reduces saturation. Chiaroscuro and Tenebrism both take advantage of dramatic contrasts of value to heighten drama in art. Artists may also employ shading, subtle manipulation of value.