[someweirdperson]

Description of the spectrum? That would provide different descriptions for what looks the same. Also, it would require a description of the spectrum of the light source lighting the colored surface.

But it would be great. Two differently produced paints would look the same under all lighting conditions.

[amelius]

That's not entirely true. Nonlinear effects exist. E.g. fluorescence can cause emission of one light frequency after being hit with another.

Regardless of that, you could also make a physical model of the human retina, and use that to remove any parts from the model that you think are redundant.

Also, the tools that Pantone uses to map colors have some kind of built-in physical model already, I suppose (not a Pantone expert obviously).