For surface-color applications, the specified white object is usually (though not always) a hypothetical material with unit reflectance that follows Lambert's law.
The resulting L will be scaled between 0 (black) and 100 (white); roughly ten times the Munsell value.
Note that a medium lightness of 50 is produced by a luminance of 25, due to the square root proportionality.
Hunter Associates Lab discovered[citation needed] that better agreement could be obtained with other color difference metrics, such as CIELAB (see above) by allowing these coefficients to depend upon the illuminants.
[4] If we take as the uniform lightness scale Priest's approximation to the Munsell Value scale, which would be written in modern notation as: and, as the uniform chromaticity coordinates: where ke is a tuning coefficient, we obtain the two chromatic axes: and which is identical to the Hunter Lab formulas given above if we select K = Ka/100 and ke = Kb/Ka.