The CIE 1931 [[Color Space]] is a color space / standard which defines the relation between the [[Visible Spectrum]] and color perceived by the [[Human Eye]]. Given an incoming spectra $f(\lambda)$, where $f$ is a [[Function]] with [[Wavelength]] [[Domain]] $\lambda \in [0,\infty)$ and [[Codomain]] $f(\lambda) \in [0,\infty)$. $\huge \begin{align} L &= \int_{0}^{\infty} \bar{L}(\lambda)f(\lambda)\d \lambda \\ M &= \int_{0}^{\infty} \bar{M}(\lambda)f(\lambda)\d \lambda \\ S &= \int_{0}^{\infty} \bar{S}(\lambda)f(\lambda)\d \lambda \\ \end{align}$