Roxo é uma “cor não espectral”, o que significa que existe apenas em nossas mentes: não há comprimento de onda de luz que corresponda a ela. Nosso cérebro percebe o roxo quando vê uma mistura de luz vermelha forte e luz azul forte, sem qualquer verde.

also theres [impossible colors](https://en.wikipedia.org/wiki/Impossible_color) like red-green, blue-yellow, stygian blue. the way the eye and optical cortex work are pretty amazing.

That depends on what you mean by “color”. If we go by “color you perceive” then all color is only in our minds. To us, purple, pink, and violet are all shades of each other.
If, on the other hand, we go by “color as wavelength”, then violet light is of a single wavelength while purple has two wavelengths, but our eyes have no way to differentiate between the two so purple and violet light are literally identical to our eyes.

So what’s with the V in ROYGBIV?

This is pretty cool to know that you can have a purple color as a mix and as a unique frequency — TWO very different wavelengths.

So it is EITHER an interpreted value or an actual value because our brain lacks another color or didn’t need one in order for us to understand what we were seeing.

If we could see X-Rays, what color would they be? Maybe your brain would make understand it with another sense like hearing. If our eyes had perfect detection, we would see a gradation of lower to higher frequencies, maybe we’d be seeing in black and white.

However, light is created by electrons dropping from higher to lower atomic orbitals and releasing energy in the process — so their are ONLY specific pulses that can occur based on atomic structure. Now of course, different atoms together, different surfaces, different speeds causing red-shift and such mean these specific bands are intermixed.

So, it’s likely the different cones were even more specialized at one time, and saw narrower bands important to acquiring food and avoiding predators.

Now if the I had a perfect single detector, we could differentiate these, but organically, it just worked out that it specialized into rods for luminescence three different cones as a primitive interferometer that and and Color is a concept.

If you scrape off the outer layer of the eye and reduce it’s UV coating, you might actually see ultraviolet. Most insects “see” in this range. But what color it is – no telling. We can’t really imagine another color because our brains aren’t wired for it. I can “feel” another color though as a way to imagine it. We have the capability to use one sense to describe something “out of range.” People losing a sense or who have synesthesia do this “trick.”

But the blue-red, and violet colors are where this trick was perfected and humans never noticed. I’d love to see an exact purple as red and blue, and also as the specific color source right next to each other to see if I can train myself to tell a difference.

It’s really cool to understand our blind spots and how our brains mask them.

I just found out I’m color blind. It came completely out of the purple!

So it’s just a pigment of my imagination?