The $XYZ$ [[Color Space]] is a [[Linear Transformation]] of the [[CIE 1931 Colorspace]]. $\large \begin{align} \mat{X\\Y\\Z} &= \mat{1.9102 & -1.11212 & 0.20191\\ 0.37095 & 0.62905 & 0 \\ 0 &0&1 } \mat{L\\M\\S}_{\text{HPE}} \end{align}$