You couldn't even name a paint by a short number (like a hex code) if you wanted to. That only works because we get to think of colors in terms of three channels, a mix of red/green/blue. Cherry (brand a) and Cherry (brand b) paint could look identical under daylight but totally different under incandescent.
To define an actual reflective color of an object, you need a spectral reflectance distribution. This measures what percent of light is reflected at any given wavelength.
Then the actual color you see depends on the spectral power distribution of the light source. For every wavelength, you multiply the amount of light of that wavelength by the percent of light reflected at that wavelength, and you end up with a new spectral power distribution for light coming off the object.
That goes into your eye, hits the retina, activates three types of cones in some proportion, and your brain turns it into a perceived color.
Incidentally, the image linked above includes a tomato. “#FF6347” doesn't cut it.
Pantone works because it's a lookup table that maps short names to a set of predefined reflectance distributions. In the real world, that's as close to hex colors as we can get.
For a bit more detail in that step at the retina, here are the relative responses of the different cones to various wavelengths (normalized to max = 1):
Once you account for how much light comes off the object at each wavelength, these curves determine how strongly they impact your color perception. S/M/L stand for short, medium, and long, and are the names we give to the different cone types based on the relative length of waves that stimulate them.
As you can see, we don't have a very balanced view of the "visible spectrum." Butter, for example, is about 1.5x as reflective at 400nm as 450nm. But your eyes are something like 20x as sensitive to the light at 450nm (near peak sensitivity of short wavelength cones), so that light has a bigger impact on activating the short cones. 450nm is also picked up by medium and long cones, while 400 is pretty much below their range.
To define an actual reflective color of an object, you need a spectral reflectance distribution. This measures what percent of light is reflected at any given wavelength.
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/imgvis/spd...
Then the actual color you see depends on the spectral power distribution of the light source. For every wavelength, you multiply the amount of light of that wavelength by the percent of light reflected at that wavelength, and you end up with a new spectral power distribution for light coming off the object.
That goes into your eye, hits the retina, activates three types of cones in some proportion, and your brain turns it into a perceived color.
Incidentally, the image linked above includes a tomato. “#FF6347” doesn't cut it.
More info (and image source) here: http://hyperphysics.phy-astr.gsu.edu/hbase/vision/spd.html
Pantone works because it's a lookup table that maps short names to a set of predefined reflectance distributions. In the real world, that's as close to hex colors as we can get.