Lightness
（重定向自Colour Value）
![](/Images/godic/202501/05/ColorValue.svg2630.png")
![Observe that the lightness is 50% for a luminance of around 18% relative to the reference white.](/Images/godic/202501/05/Lightness_approximations.svg2630.png")
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. Lightness is a relative term. Lightness means brightness of an area judged relative to the brightness of a similarly illuminated area that appears to be white or highly transmitting. Lightness should not be confused with brightness.