• $\begin{array}{l}{W}^{*}=25Y^{1/3}-17\hfill \\ U^{*}=13W^{*}(u-u_{\text{n}})\hfill \\ V^{*}=13W^{*}(v-v_{\text{n}})\hfill \end{array}$

Note 1 to entry: Y, u, v describe the colour stimulus considered, and u_n, v_n describe a specified white achromatic stimulus, where $u=u^{\prime }$, $v=\frac{2}{3}{v}^{\prime }$; $u_{\text{n}}^{}=u_{\text{n}}^{\text{'}}$, ${\displaystyle v_{\text{n}}=\frac{2}{3}{v}_{\text{n}}^{\text{'}}}$.

See also "CIE 1976 uniform-chromaticity-scale diagram".

Note 2 to entry: The difference between two stimuli, ΔE*, is defined as the Euclidean distance between the points representing them in U*V*W* space and calculated as:

• $\Delta E_{}^{\text{*}}={\left[{\left(\Delta U_{}^{\text{*}}\right)}^2+{\left(\Delta V_{}^{\text{*}}\right)}^2+{\left(\Delta W_{}^{\text{*}}\right)}^2\right]}^{1/2}$.

Note 3 to entry: The CIE 1964 uniform colour space is obsolete (except that it is still used in the calculation of the colour rendering index). The currently recommended object colour spaces are the CIE 1976 L*a*b* colour space and the CIE 1976 L*u*v* colour space.