I don’t understand the conclusion that magenta doesn’t exist because it doesn’t fall on the ROYGBIV color spectrum. Like how can we say a color that is naturally occurring in nature, that we can see does not exist because it is not on a man-made color spectrum? Why is it not that the ROYGBIV color spectrum flawed instead?
Some say our eyes are tricked into seeing it because it doesn’t exist…why is it a trick if it is how we would naturally see it?
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Your premise is wrong. There is no such conclusion. No one is saying a particular color doesn’t exist, what’s true is that it doesn’t exist *as a single wavelength of light.* The wavelengths of visible light range from 380 to 750 nanometers. On the visible light spectrum, each wavelength will produce a different color, but there’s no single wavelength that is magenta or purple or brown or many other colors.
Our eyes have 3 types of cells called cones that detect color. We have cones that are most sensitive to red light, cones that are most sensitive to green light, and cones that are most sensitive to blue light. Magenta is simply what we see when there’s a combination of red and blue light that stimulates our red and blue cones.
Magenta exists, however it isn’t part of the “visible spectra” by itself.
Things that look magenta reflects/radiates (long wavelength) red and (short wave length) blue light, whilst not really giving of light from in between on the spectra.
There are other [extra-spectral colors](https://en.m.wikipedia.org/wiki/Spectral_color#Extra-spectral_colors) too.
One thing that I’d like to add to the other comments is that the visible spectrum is a small subset of all radiation (with infrared being “redder than red” and ultraviolet being “more violet than violet”; so much so that our eyes can’t detect it).
This means that we have a line, where on one end we have red, and on the other we have violet. However, our color spectrum can be recognized as a circle as well; as you said, it’s the ROYGBV rainbow. So if we take our line of colors, and bend it into a circle, how to we get red and violet to blend into one another?
So, our brain has to interpolate between the colors to make magenta, since it doesn’t have a wavelength associated with it. This is called an [extra-spectral color](https://en.wikipedia.org/wiki/Spectral_color?wprov=sfla1) if you’d like to know more.
Magenta is the glue our brains use to roll the light spectrum into a color wheel.
Try imagining it in terms of sound. There’s something it feels like to hear a low noise, and something it feels like to hear a high one. If you hear both at once, nothing special happens – you just hear ‘high and low at the same time’.
‘Magenta’ in sound space would be if there was a totally different sound for this combination of low and high pitches, which didn’t really sound like either of those two elements.
So you’re right that ROYGBIV are just cultural labels that we’ve assigned to different percepts. For example in Russian, ‘light blue’ is a unique color just as ‘light red’ is in English (we call it ‘pink’).
But underneath these labels, the physical nature of light spans an axis. It goes from tiny wavelengths (violet) to long wavelengths (red). This is a linear thing, with two ends – just like sound pitches.
Unlike sound though, the two ends don’t appear opposite and irreconcilable to us. Instead, the two ends of this space combine to create something that feels new.
The reason for this is probably that single sources of sound don’t tend to create extremely different pitches at once, while it’s pretty common for single surfaces to reflect extremely different wavelengths of light.
That’s why, as you note, we see magenta occurring naturally. It’s a somewhat common and useful pattern of light to pick up on that we’ve evolved to see as a unique thing – unlike ‘super low- and also super high-pitched’ noises.
Perception is weird, but useful!
Check out the [Line of Purples](https://en.wikipedia.org/wiki/File:Line_of_purples.png). On this graph, all the spectral colours are shown on the curved border with the wavelengths marked in blue letters. But the straight part of the border is the Line of Purples. Our eyes see these as fully saturated colours but they’re not spectral colours because no one wavelength of light can create these colours.
Our eyes have long (L), medium (M) and short (S) wavelength cells (roughly, red, green and blue). Light which stimulates just L and M cells can be matched with just a single wavelength, because the L and M wavelengths are next to each other. The same with M and S. But L and S are far apart, separated by M, so the only way to make colours involving just L and S cells is with at least two separate wavelengths. Using a wavelength between L and S will stimulate the M cells and look green.
It might help to think about how we see yellow. You can make a pure yellow with just a single wavelength, around 580 nm. But you can also make yellow by mixing a red and a green wavelength, like 540 nm and 620 nm. The second yellow is just as much a real colour as the spectral version; they’ll look almost exactly the same.
Color is complicated.
A very simplified understanding of color is that light comes in different wavelengths, and that our eyes and brain translate those different wavelengths to color. Prisms or raindrops can split white light into its different wavelengths, forming a rainbow. The rainbow starts at red, which has the longest wavelength, and progresses gradually to violet, which has the shortest wavelength.
The thing is, while it is true that different wavelengths of light correspond to different colors, that’s *far* from the whole story. Not every color can be traced back to a nice, pure, single wavelength of light. In fact, in nature, it’s very rare that we encounter such pure wavelengths. Instead, almost every surface or light source that we see reflects or emits light that is a mixture of different wavelengths.
This is certainly true for the light that you’re looking at right now: the light coming off your screen. The pixels on your screen mix red, green and blue light to make a bunch of different colors. For instance, if some pixels on your screen are yellow, then actually that’s a mixture of red and green light. So the simplified explanation of “yellow equals some wavelength of light” is obviously not right, because here you are looking at red and green wavelengths of light, and you’re seeing yellow. And it’s not like those red and green wavelengths *physically* combine to make an intermediate, yellow wavelength. Physically, they are still separate: there is both red and green light there. It’s your eyes and brain that make it look yellow.
The reason for this is that you only have three different color-sensitive cells in your eyes. Each of these is sensitive to a different part of the visible light spectrum, although there is also significant overlap between them. Pure yellow wavelengths of light activate both the “green” and “red” cells, but you can achieve the same effect by shining both red and green light on them at the same time. Your eyes cannot tell the difference.
So, really what color is, is the relative activation of your three color cell types. Each of the *spectral colors,* i.e. the colors of the rainbow that are pure wavelengths of light, leads to a different pattern of color-cell-activity, and so we can distinguish them as different colors. But it doesn’t stop there. There are more colors that we can discern. For instance, we can discern darker and lighter colors, and we can discern colors that are more saturated versus those that are more muted. Because these properties of lightness and saturation also lead to different activity patterns of your three color cells.
This means we can see far more different colors than just the spectral colors of the rainbow. Which is funny, because it means that “all the colors of the rainbow” is actually not that many colors. Take brown, for instance, or pink, or grey. They’re not in the rainbow either, but it doesn’t mean they don’t “exist”. They just don’t correspond to a single wavelength of light.
So what does this mean for magenta? Well, magenta is another color that you cannot encounter as a pure wavelength of light. You can only get it by mixing wavelengths that are on the short side (blues and violets) with those that are on the long side (reds) of the spectrum. This ends up activating the red and blue color cells in your eyes. So this is a color that is “in between” red and blue, but it’s not in-between in the same way that e.g. green is, because green wavelengths would activate the green color cells, and magenta does not. And so this wavelength mixture gets interpreted as its own distinct shade of color.
In summary, this is a paradox that only arises from an over-simplified understanding of color. To suggest that a color doesn’t “exist” implies that it has no objective basis. Which would be true if colors always corresponded to pure wavelengths, since there is no magenta wavelength of light. But in fact, the objective basis of color is formed by complex reflectance (and emission) *spectra* of light, and there certainly are such spectra (wavelength mixtures) that correspond to magenta colors.
Our eyes create colour when the receptors are stimulated in a certain way. The colour spectrum is wavelengths of light. Red has a wavelengths, also blue or yellow or violet. However we have interpretations for colours that doesn’t have one corresponding wavelength. Magenta is like this. Magenta happens when we get a lot of red and blue at the same time. As it turns out using the combinations of red, green and blue can trigger our receptors any kind of way. We can add green and red which triggers our receptors like yellow. All RGB at the same time triggers everything so we see white.
And we can put together combinations that doesn’t happen with wavelengths only. Like magenta, our eyes just happens to interpret red and blue that way.
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