Erwin Schrödinger, best known for putting a cat in a box and leaving it in a state of existential crisis, also had some thoughts about color. A century later, a team led by Los Alamos scientist Roxana Bujack has finally completed his unfinished color theory, using geometry to define how humans perceive hue, saturation, and lightness.
The researchers presented their findings at the Eurographics Conference on Visualization, formalizing Schrödinger's Riemannian model of color perception. Their key conclusion: those color qualities aren't just cultural baggage or learned behavior - they're baked right into the structure of color perception itself. "What we conclude is that these color qualities don't emerge from additional external constructs such as cultural or learned experiences but reflect the intrinsic properties of the color metric itself," Bujack said.
The big breakthrough? Schrödinger never formally defined the neutral axis - the line of grays from black to white - which is kind of like building a house and forgetting to include the foundation. The team found a way to define it using only the geometry of the color metric, which required moving beyond the traditional Riemannian model entirely. They also fixed the Bezold-Brücke effect (where changing light intensity makes colors shift hue) by using shortest paths in their geometric model, and addressed diminishing returns in color perception.
All of this could have practical applications in photography, video, visualization, and national security sciences - because apparently, even spy satellites need to know if that blob is olive or khaki.