Magical Unicorns
Magenta is a magical unicorn. It is the color that really shouldn’t exist. First, let me explain about magenta. Colors, in light, are the visible to humans part of the electromagnetic spectrum.
Past red is infrared (on the chart above as IR), and past purple is ultraviolet (on the chart as UV). So…. where is magenta again?
Magenta is that magical color creature that takes the visible light spectrum and spins into a color wheel. Okay, that’s pretty neat. But, how???
It is important to establish that the color magenta is just an illusion created by our eyes. This purplish-red-crimson color, located between red and blue on the color wheel, is extra special as it is not found on the visible spectrum of light and there is no wavelength of light that corresponds to that particular color. Rather, it is physiologically and psychologically perceived as a mixture of red and blue. So technically, magenta doesn’t exist.
Arts on the Brain, Magenta Doesn’t Exist? by Rishika Nahata
https://scholarblogs.emory.edu/artsbrain/2020/12/02/magenta-doesnt-exist/
Ummm…pretty sure it exists. I mean, I can see it! And, printers everywhere use it as red. What is going on here?
The idea is that our brains are doing a lot of work on this one. If we take the blue light and the red light, it averages back out to a wavelength of green light. However, our brain is unhappy to have a green between the red and blue so they put in magenta. It is imaginary, like unicorns. However, we all believe it in. And, when it comes down to it all colors are in our imagination.
Colors and the Brain
Colors as we know them are the product of our eyes seeing the light bouncing into them and then sending those signals into our brain. Then our brain says, “Ah, yes, green.” And there is a LOT of green. (Maybe this is why I love staring at trees?) Back to our friend, magenta. Magenta is there. But she is a complicated color. She isn’t one wavelength. Our brain interrupts it that way. It knows blue, and it knows red. So when they get combined it says, yes, magenta. In light, it is really more a green color. But our brain says, Nope. MAGENTA.
Light Waves verses Pigment
In light, the three primaries are Red, Green, and Blue. And when you combine them all together you get white light. In pigments the three primaries are red, yellow, and blue. And when you combine them all together you get brown or black. Obviously some changes happen from light to materials such as paint. And we won’t be getting into the physics of that one today, but it is good to be aware of.
In color finders, common on computers, they are very limited to the visible color spectrum, plus magenta. And then the hues add values by going either lighter or darker from there. You will notice that the world has a lot more colors than those color finders. They aren’t great at combos. Like the difference between gray made from green + red, and the gray of orange + blue. As a painter you get more sensitive to these colors as you mix them and use them. The painting below is made of three tubes of paint: Cadmium Orange, Brilliant Blue, and Titanium White.
© Kristen O’Neill, Harris Beach, Acrylic on Unstretched Canvas, 8″ x 10″
Magenta as a Primary
In printing today the colors used in 4 color printing are CMYK. That is cyan, magenta, yellow, and black. Black is used to darken the value of a color. The white of a page is used to lighten a color. Yellow is a primary in pigment, so that one makes sense. Now, cyan is green + blue in light. And magenta is red + blue in light.
There are limits to CMYK It is a great formula for many things, but cannot reach them all. It is a limited palette just like anything else. Here is an overview of visible light to our eyes, verse RGB (used in light – like computer displays) and CMYK. 
Notice the blue numbers. These are the wavelengths of the colors. Magenta has no number because it is a mixture of 460 and 620. Yet that doesn’t let us stop ourselves from seeing, enjoying, and using our friend, the magical unicorn magenta.