I'd be curious to understand exactly how CRI equates to the charts in this post!

“I’ve thought about this for five minutes, and it seems so simple. It must be the tens of thousands of vision scientists and psychophysicists who have worked on this for the last century who have all missed how simple it is.”

Colors only exist in the human brain, they're qualia, interpreted from the mixture of wavelengths our eyes detect.

You could go a long way by specifying the reflectiveness over the visible light spectrum and then do the same for light sources. That way, you could do GDR style truly monochrome sodium vapor lamps, which makes telling colors apart impossible.

To do neon colors, you would need some sort of frequency redirect in your texture data as in "this pixel absorbs 80% infrared, but reemits it as visible red". Then you could have black light light sources and cool poster textures as well.

I think doing textures in this format would take too much space, but doing a 256 color palette that way might be fine.

> I sort of wonder is there a "true" way to represent color? Would an intensity over frequency curve do it?

There’s no single “true” way because color isn’t a fixed property of light itself, it’s the result of how a visual system interprets wavelengths.

Having said that, if you’re looking for an objective way that doesn’t depend on observer, you could use spectral power distribution.

That would be the mix of wavelengths present, plotted as intensity vs. wavelength.

That’s because a single wavelength (say 580nm) produces one specific color sensation, but many different combinations of wavelengths can produce that identical sensation (called metamers), so representing color by wavelength alone isn’t even uniquely “true” perceptually.

There are no objective "basic colors". What "white" means is "excites our different types of photoreceptors roughly equally". And the photoreceptors have the sensitivity curves that they do because of our sun’s surface temperature and a convenient "window" in the opacity of our atmosphere. Organisms evolved under a different star, within a different atmosphere would have a different idea of what a "neutral" color is.

(Because of additional processing done by our visual system, what looks "white" to us is very dependent on the color of the ambient light. But the 6500 K blackbody spectrum could be called the "most neutral" white to our eyes because that’s what they have evolved for.