Colour Mixing: The Mystery of Magenta

Colour Mixing: The Mystery of Magenta

Purple is a weird colour. The formal name for purple is
magenta, and the weird thing about magenta is that you won’t ever see it in a rainbow. And the rainbow is supposed
to be the full spectrum of colours. So why doesn’t purple,
why doesn’t magenta appear in the rainbow? And the answer is to do
with colour mixing. I’ve always had a problem with
colour mixing, because I know that you can’t mix
photons together. So you can’t take a blue photon
and a green photon and mix them together to get
some other photon. That just doesn’t happen. And yet, you can mix paints
together in art. Color mixing is definitely
something you can do. So what’s the answer? Well actually, you can’t mix
colors together in physics, but you can do it in biology. It’s to do with how
your eyes work. For example, if I shine red
light and green light into your eyes at the same time, if
I cross these over, you will see yellow. So when you mix red and green
together, you get yellow. And if you look at the spectrum,
yellow is in between red and green. So maybe that’s the rule for
mixing colours together. You mix two colors together, you
get the colour in between on the colour spectrum. And we can test that again,
so I’ll look at green and blue together. So if I mix green and blue
together, I get cyan. And cyan is in between blue
and green on the spectrum. So that’s great, you mix two
colours together, you get the colour in between. But why, why is that? Well, your eyes can’t
measure the wavelength of light directly. So it’s not like a photon comes
in, and you know, it’s 200 nanometers or whatever,
and it detects that. Instead, you have these cone
cells at the back of your eyes that are sensitive to different parts of the spectrum. So when red light comes into
your eyes, there’s a set of cones that fire and tell your
brain you’re looking at something red. So we’d call those
the red cones. There’s another set of cones
that are more sensitive to green, so when there’s green
light going into your eyes, they fire and they send a
message to your brain. And there’s blue
cones, as well. So you’ve got red cones, green
cones, and blue cones. So what about yellow? What about when you’re looking
at yellow light, like that? Well in that situation, you
don’t have a yellow cone. So what do you do? Well, yellow is quite close
to red, so your red cone fires a bit. And yellow is quite close to
green as well, so your green cone fires a bit. So your brain is getting a
message from your red cone and your green cone at the same
time, and it’s deciding, OK well, I must be looking at
something in between those two colours, then. And that’s brilliant, because
your brain is perceiving something about the world
that it isn’t able to measure directly. It isn’t directly sensitive
to yellow light. It does mean that you
can be tricked. And so if I make red light and
green light go into your eyes, but no yellow light, you
will see yellow. Anyway. So, go red torch and a green
torch, and there’s no yellow light, here. But when I combine them, you
will see yellow, anyway. And TVs do this all the time. So if you look up close
at TV, you’ll see the individual pixels. And there are red pixels, green
pixels, and blue pixels. Those are the only colours being
produced by your TV. And yet, they can produce all
the other colors with this trick of colour mixing. So what about purple? What about magenta? Well, what should your brain do
if your red cone fires at one end of the spectrum and your
blue cone fires at the other end of the spectrum, but
your green cone doesn’t fire? Does it do the same trick? Does is think I must be looking
at colour in between red and blue? When the colour between red and
blue is green, and you’re definitely not looking at
something green, because your green cone isn’t firing. So in that situation, your
brain invents a colour. It makes up a color, and that
colour, is magenta. And I can show you that with
my red and blue torches. So when they’re combined
together there, you see magenta– absolutely beautiful. And that’s why you don’t see
magenta in the spectrum. You don’t see magenta in the
rainbow, because it doesn’t have a wavelength. It’s just the absence of
green, if you like. Just to show you the full
palette of colours that you can see on a TV screen– so you get red and blue mixed
together makes magenta. Green and red makes yellow. Green and blue make cyan. When you mix them all together,
you get white. So when your red cone, your
green cone, and your blue cone are firing together, you
get white light.

39 thoughts on “Colour Mixing: The Mystery of Magenta

  1. We don't know what to say. With the addition of Greek, this video is now officially our most translated one ever! We now have subtitles in Arabic, Chinese, Dutch, Danish, French, German, Greek, Indonesian, Italian, Polish, Portuguese, Serbian, Spanish, Swedish, and Turkish. We can't thank you enough! We appreciate each and every one of you who has donated their time and skills.


  3. So there is no purple paint with purple coloured particles, only purple paint with a mixture of blue and red coloured particles?

  4. Anytime I need to see your face I just close my eyes
    And I am taken to a place
    Where your crystal minds and MAGENTA feelings
    Take up shelter in the base of my spine
    Sweet like a chica cherry cola

  5. I always thought red and green combined would get you black…..I thought any 2 complimentary colors combined made black.

  6. During the 1960s I lived in the UK in a Universe where Magenta was one of the primary colors used in the first color TV sets. I think Cyan was one of the other primary colors. Sometimes I wonder what happened to that Universe – Where did it go?

  7. Purple exists but the problem is that I called it the purple but in fact its called VIOLET and its on the end of spectrum and Im able to see that colour on rainbow its looks bit fade but its definitely there
    Near blue at the edge

  8. Now i understand why yellow made me feel worse when i was carsick as a child…(the car sickness could have been avoides had i known to look at a distant stable object.)the colour spectrum is circular actually, the rainbow has red to blue with purple at its base in opposition to yellow…we just dont see it complete.

  9. YOU ARE WRONG! I DO SEE PURPLE IN A RAINBOW! I THOUGHT EVERYBODY DID TOO! WHAT'S WRONG WITH YOUR EYES? I also see two different colors of blue for each eye when I look at the sky

  10. It is amazing to me how smart people are after the fact. Post your U tube to refute. All information an all ideas are accepted in my brain. Thank you sir.

  11. See the book "Mauve: How One Man Invented A Color That Changed The World", by Simon Garfield (978-0-393-32313-9 51895; $7 or so on Amazon). Mauve was invented 1856 and historically bridged then-philosophical science to practical applied sciences. Fun vid. Exciting science.

  12. Purple, Magenta and Scarlet are distinct non-spectral colors. Magenta is half red and half blue. Purple is mostly blue, and Scarlet is mostly red.

  13. I'm a colorist I understand color theory very well and u are right on about the eye not being able to detect certain tones,but your talking strictly about light not actual pigments. It's pretty simple if you understand the basic color wheel it explains what colors make another color and why opposite colors cancel each other out

  14. Are our brains lying to us or have we not truly figured out the way that it works???? I think the latter. Yes the wavelengths are true and make sense but if this was the basis for purple being made up by our brains then the same would be for brown. Red Blue Yellow aren't the primary colours!!! Magenta, Cyan and Yellow are. When you mix Cyan and Magenta you get blue, add more magenta and you get purple, add more magenta and you get red. Same process with the other combinations. What is never said in these discussions is how the cones combine with the amount of light being reflected – giving us the tint of colours – purple vs lavender.

  15. So what was the first instance of this magenta color? If it's unattainable naturally, how did we discover it? This is poorly phrased, I hope someone understands what I'm going for here.

  16. Saying that we have red, green, and blue cones is a very simplistic model that does not fit with a significant portion of the data related to vision. However, it is a very useful model to understand vision, and to connect it to the visible spectrum and the additive color mixing in a cohesive paradigm where the same three colors are important in the three different models of it.
    Is it false that we have red, green, and blue cones? Yes, it is false in some sense to some degree. But guess what. All models are. All models are incomplete.
    Is it useful to classify our cones into red, green, and blue cones? It is useful to achieve a general understanding of the relation among vision, the visible spectrum, and the additive color mixing.
    Is this classification useful to achieve an in-depth understanding of human vision? No, it is not. There are other classifications that fit with more of the data.
    Different purposes require different models.

    By the way, purple is dark magenta. They share the same hue (300°). That is why he uses those names interchangeably.

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