eli5: Why is it impossible to imagine new colors?


eli5: Why is it impossible to imagine new colors?

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Colors basically correspond to a specific point (wavelength) within the visible spectrum of light. It’s a dot along a path – and every possible dot is already mapped out so nothing new can be found.

Our brains kind of imagine non-existing colors all the time. Pink and brown don’t exist in the way we think of them. We can’t see a mix of green and red, so it comes out brown in our brains. Pink is a mix of red and purple light.

“Light consists of electromagnetic waves, and colour depends on the wavelength. If colours were simply a naming scheme for wavelengths then pink is not one, because it is made up of more than one wavelength (it’s actually a mix of red and purple light). If you took a laser and tuned it across the visible wavelengths, from infrared through to ultraviolet, you would not pass pink on the way.”


Everything you “just know” about color, you learned by having human eyeballs. And human eyeballs turn out to have some weird biases.

Your eyeballs detect color with three kinds of color sensors (cone cells). Each kind responds to different frequencies of light. [But they’re not evenly spaced on the spectrum.](https://en.wikipedia.org/wiki/Cone_cell#/media/File:Cone-fundamentals-with-srgb-spectrum.svg) Two kinds of cone cell (M and L, in the picture) mostly detect red-green light, overlapping with one another, but with slightly different strengths. The other one (S) detects blue and purple.

And which color you *perceive* depends on the *differences* between these cells’ response, in what’s called an “opponent process”. The M and L signals, *taken together,* tell you how red or green something is. The S signal tells you how blue or purple it is. That’s why the most common kind of colorblindness is *red-green* colorblindness. That’s what happens when someone’s M cells or their L cells don’t work.

The color signals from your cone cells, plus the brightness signal from your rod cells, are combined in your brain to make your sense of color vision. Those signals are all your brain has ever learned about what it is like to perceive color. That’s the whole space of color that you can ever see with the kind of eyeballs that you’ve always had.

This is an amazingly inaccurate question. There are many designers who work with mixing colors to create new ones. They are frequently issued to the public in color palettes.

I had a dream once where the sky was a mixture of bright blue and violet-brown but I have no way to describe the color of violet-brown to anyone. And in this dream many flowers that shouldn’t have had spots in patterns on them like daffodils in the a bit more shimmery and “darker” violet-brown somewhat like spots on a banana.

So I can imagine the color but I don’t have words to convey it and have no way to show it to people.