The CIE 1976 (L*, u*, v*) space is a color opponent space that aims to be perceptually uniform, so that one unit in the space corresponds to a just noticeable difference in color. The L* dimension corresponds to visual lightness, while the u* corresponds approximately to redness/greenness, while v* corresponds approximately to yellowness/blueness. It has much in common with the Yu'v' (CIE 1976 UCS) space, but is white point relative, uses a non-linear transform from Y to L*, and scales the u' and v' values to form the u* and v*. It is an alternative to the L*a*b*, and although previously very popular in some application areas such as displays, it has fallen out of use somewhat due to most modern delta E metrics being based on L*a*b* space.
It is a white relative space, where the reference white has the
L*u*v* value 100,0,0. The typical assumption is that an observer
is adapted to the white reference, so that the L*u*v* coordinates
correspond to the colors relative to that white.