From ChatGPT. I checked it and it looks right to me.   The Luther–Ives criterion states: A three-channel camera is exactly colorimetric if and only if its spectral sensitivity functions span the same three-dimensional function space as the human color-matching functions. 1. Spectral responses Let \(s(\lambda)\) be the spectral power distribution reaching the camera. For... [Read More] The post The math behind the Luther-Ives criterion first appeared on the last word.