Hmm, that's an interesting concept to think about, but my grey card example was an analogy, not a solution. To the degree that using a physical object of a known color value along with an adjustment of white balance to adjust the resulting image, photographers are able to create colour-accurate images. It sounds like you're getting at what I was guessing at, which is a higher degree of accuracy, though.

Uh, it's an approach specifically designed to take lighting into account. It can only appear as the correct gray if you adjust for the type of lighting. The idea that different light has different colour temperatures is not a new thing to photographers lol

Some of the others touch on this approach, and photographers have been doing it for quite some time: a gray card.

In order to calibrate both lighting and color balance, you basically take a gray card of known value and you place it next to the subject. Now in post-processing, you can know what an 18% gray value should look like, and this will help you achieve an accurate depiction of what was there.

It's not super scientific, but I imagine it would be just a more accurate version of that. Similar to how science defines time based on the vibration of a specific caesium isotope. You have one agreed-upon reference, and everything else derives from that.

The title and article both make it seem like being sociable leads to better gut biomes, when the study just shows that they're correlated.