Counterpoint

It is almost incomprehensible at first to imagine that the rainbow is not viewed similarly by all people, that there might be more, or fewer, colors in the world than we thought, or that someone might not bother to give colors a name.

Different languages and cultural groups also carve up the colour spectrum differently.

We can argue that colors are not real.

Black
and
White are
All I see
In my infancy
Red and Yellow then came to be
Reaching out to me
Lets me see

Seriously though, while language does have an effect on how we perceive the world in the fine details, it's not like people who don't have the words can't tell the difference between a thing that's green and a thing that's blue. No one would mistake the color of a leaf for the color of the sky unless they had an actual physical defect, they would just have to use different vocabulary to state the difference. Perception of color is filtered through our anatomy but it does derive from measurable physical quantities. Color is real because light is real and frequency is real and abstract divisions of continuous phenomena are real.

It is not blue and green but shades between blue and green. When asked to put colored tiles in order, people lacking color vocabulary for that range don't perform as well as people who do have it.

Imagine a warm blue. It's a sort of sky blue, that's really a sea foam, meaning it's actually a shade of green even if we call it blue and don't see that it's a green at all. My walls are a bright, warm blue that we'd probably all say was blue even though it's green. It isn't just that it's closer to blue so we call it that (a blue-green), it's that if I said it was green or blue-green most people would look at me like I'm gravely mistaken.

The most interesting part in this is how we see magenta even though it doesn't exist in the spectrum.

Also, I've never heard anyone call magenta purple.

Red, yellow, green, cyan, and blue also don't exist in the spectrum in exactly the same way that magenta doesn't. Colors are a qualia, a model in our minds, not frequencies of light.

Right. Other than our general interpretation of reflected wavelengths as color, the video covers this with yellow. Our red and green cones fire, so we decide that it must be a wavelength between red and green: yellow. The issue with magenta is that our red and blue cones fire so we decide this is a color between red and blue... but not green because our green cones didn't fire. Regardless of our qualia, this is illogical. This idea that there is a circle instead of a spectrum, a color wheel, that there is something between red and blue other than green, that's what makes magenta more imaginary than other colors.

No, it's not more imaginary. The perception that there must be a color between blue and red that isn't green is exactly the same perception that there must be a color between red and green that isn't blue. There is no difference in the imaginariness of yellow and magenta since color itself is imaginary, and that imaginary model is circular (at least for trichromats).

Color isn't electromagnetic frequencies. The perception of color is only triggered by those frequencies, but not in a simple one-to-one fashion -- there's an effectively infinite number of ways to combine different frequencies of light that can result in the perception of any one given color. Magenta is only unique in that it has infinity-1 ways to make it happen.

this is not true.

Pure wavelengths do exist for most colours.

Generally speaking in the real world pure wavelengths are rare and most light is a mixture of many wavelengths.
With that said, if we generate pure wavelengths within the range that humans can see they produce a set of colours.

However, because of the way vision works, the actual wavelength per se is not what's important so much as the relative level of activity it produces in our different cone types.

For the the pure wavelengths as you can imagine, depending on their location in the spectrum they will tend to illicit a large response from first the Short-wavelength cones, then gradually more of the Medium-wavelength ones, until for a time they dominate, before fading in to stronger Long-wavelength cone activation.

However as we already noted, in the real world most stuff is mixtures and you can in fact have light sources that strongly stimulate both the Long-wavelength cones & the Short-wavelength cones without stimulate the Medium-wavelength cones.That is Magenta and that is why it cannot be produced with a pure wavelength.

The colours you mention are all ones we would recognize in the spectrum of pure wavelengths (e.g., a rainbow).

You're missing my point. Color isn't wavelengths of light. Color is a mental phenomenon that's produced by the relative signals from the cones. The existence or nonexistence of a pure frequency of light that can elicit a perceived color doesn't make that color any more or less real or imaginary.

Magenta is as real or imaginary as yellow as they are both directly produced in the exact same way: from a balance of signals from two different cone types with a lesser or no signal from the remaining third cone type. That is the physical phenomena that color sight directly relates to, not the wavelength of light. You can't actually see wavelengths. That's why you can't tell the difference between yellow and red/green.

It's confusing because we say things like "yellow light" (or just "yellow" like I did above as a shorthand) when we mean either "light of a single wavelength that elicits a perception of yellow" or "some mixture of wavelengths that elicit yellow". Those are two different physical phenomena that produce the exact same mental phenomenon of yellow. Yellow, as a thing itself, is independent of the laws that govern electromagnetism. Magenta is no different. Color is its own thing.

I'm not saying Magenta isn't real or that it's imaginary.

You are the one saying "Red, yellow, green, cyan, and blue also don't exist in the spectrum in exactly the same way that magenta doesn't." and I disagree.

All of these exist, magenta too. The difference (and it is a real difference) is that of the ones you named, magenta is THE ONLY ONE which we cannot be made to perceive via stimulation with a light source of a single wavelength. "Red, yellow, green, cyan, and blue" are literally part of the spectrum, while magenta is not.

Yes, most light is a mixture of wavelengths, yes colour is in our brains rather than the world per se, & yes metamers (different mixtures of light that are perceptually indistinguishable) exist and there are an infinite number of patterns of light that are indistinguishable to us... so what? All perceivable colours are equally real (or unreal depending on your perspective) but Magenta is nonetheless different in nature from the colours of the spectrum in my opinion.

Try hanging out in a room lit by a light source of a single wavelength and very quickly you will see that our direct perception of light is far from its only important properties.

But red, etc. aren't *literally* part of the spectrum. If eyes and brains like ours didn't exist, there would be no redness to a certain wavelength of light that we call red light. Color is not an inherent property of light, but of our visual system. Colors don't exist on a spectrum, they exist on a circle (for trichromats).

Magenta isn't different from the other colors. The way it is triggered may be more limited, but the actual phenomenon of magenta is indistinguishable from that of the other colors, and thus is not different in nature (the nature in this case is not the nature of electromagnetism, but if how our brains work).

Also, "[magenta] is not real" is literally in the thumbnail, which is the argument i'm objecting to.

Ah well, I disagree with her there too... at least to the extent that any colour is "real".

Your point is well taken, colour is a product of a perceptual system, where as the spectral power distribution of a light source is something out there in the world.

Wavelengths exist on a spectrum and pure wavelengths produce a characteristic phenomenon which is also commonly referred to as the colour spectrum, and yes "red" or the percept of it (or whatever linguistic game we need to play to make this notion clear), is a part of that spectrum.

To represent the perception of colour, you actually need a 3-dimensional space.

I'm not suggesting that the perception of Magenta is qualitatively different from other colours, merely that it's not a part of the rainbow and that it cannot typically be induce by a pure light source.

I think that although the end result is in-effect the same, this is still a notable and important difference that sets Magenta apart from those colours that are part of the spectrum.

Theory of knowledge has no practical use when discussing color theory. I mean, if we're going down that road, everything is imaginary. There is no need to postulate whether you are a brain in a jar; if reality is exactly as we perceive it, then you are a brain in a jar called your skull and your filthy lying eyes and ears send you signals that you maybe extrapolate into something halfway reasonable.

This video isn't really about blowing your mind, it's a promise to blow your mind to trick you into watching an art education video. And you fell for it.

Even in college, I wasn't taught this, yet I was graded on my ability to mix paints to match a given swatch. The problem is so bad that the paints they had us buy didn't include the colors named in the second video. That set of paints is a standard set for oil painting and is missing cyan and magenta. Understanding CMYK is really fundamental but somehow often gets skipped over.