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Comment by c3534l | Hacker News Reader

Fuchsia is not a combination of pink and purple. It is the color your brain comes up with when it sees contradictory color signals (such as very high and very low wavelengths without the appropriate middle stimulation). It's the only color not in the rainbow. As you can see from this additive color program (http://trycolors.com/?try=1&ffb5d9=0&c31cff=0), pink and purple create a lavender color. Whereas fuscia is what happens when you combine colors in an unusual way (http://www.exploratorium.edu/sites/default/files/ColoredShad...). Normally I wouldn't be this pedantic, but this is hackernews after all.

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To be clear on its origin its from the fuchsia flower which was made into the fuchsine dye which has these properties. See for its relationship to the visual spectrum [1] noting that the visual spectrum is ~400-700nm. The plant absorbs only the middle of the visual spectrum not the ends. This is the kind of stuff neither RGB monitors nor CMYK prints can capture well.

Note this isnt the complete story either as your eye may percieve it very similarly to purple anyway due to the way we see light (through our rods and cones which clump the spectra again anyway and are subtlety different for everyone).

[1] https://www.researchgate.net/profile/Bo_Hu12/publication/231...

To be yet more pedantic, it's the only fully-saturated color that's not present in the rainbow.

Colors are perceptual phenomena- the interpretation of a spectrum of light impinging on a patch of retina that almost invariably contains more than one frequency at a time. Colors include white, black, gray, pink, tan, beige, baby blue- none of which are in the rainbow.

How do I read more about this "not being in the rainbow" aspect of this color ?

Wikipedia[1] has nothing to say about it ... in fact, the wiki definition of "fuchsia and magenta are exactly the same color, made by mixing blue and red light at full and equal intensity" makes it seem not that interesting at all ...

[1] https://en.wikipedia.org/wiki/Fuchsia_(color)

>How do I read more about this "not being in the rainbow" aspect of this color ?

By a color "not being in the rainbow" we mean that if you take light and spatially separate its different frequencies (like what happens in a prism or droplet of water), none of those individual frequencies will produce that given color response. And no, it's not that interesting. Almost all color perception experiences involve stimulating a patch of retina with multiple frequencies; we've given names to many of those experiences.

A way that I have had the idea of this explained is this. There are two ways to experience most colours.

Take yellow. You could experience yellow by seeing pure yellow light which is at the yellow wavelength. The other way to experience yellow is by seeing a mixture of red and green wavelength light.

Your eye can't tell the difference between these two types of yellow. The yellow as reflected off a banana is "real" yellow. The yellow you see coming out of your computer monitor is actually just a mix of red and green.

Magenta is interesting because the only way to experience it is by a combinations blue and red. There is no "real" magenta.

This video explains this concept very well:

https://www.youtube.com/watch?v=R3unPcJDbCc

Actually, lutein in banana absorbs blue and violet, reflecting the lower wavelengths. http://jn.nutrition.org/content/132/3/540S/F2.large.jpg

I don't understand why a single wavelength would be considered the "real" stimulus that results in a color perception while other metamers for that perception are somehow less "real".

That's why I put "real" in quotes. There isn't really another single word I can think of that gets the idea across.

"Pure"?

"Simplest"?

If you're really into colors, I suggest to read the xkcd: https://blog.xkcd.com/2010/05/03/color-survey-results/

Have fun!

I forgot about this, Randall Munroe sometimes does things I'd like to do. And, I also "weep for my gender".

Some more background on the 'line of purples', of which fuchsia is a part: http://hyperphysics.phy-astr.gsu.edu/HBASE/vision/colper.htm...

From your reference: "The 'line of purples' across the bottom represents colors that cannot be produced by any single wavelength of light." The GP is suggesting that fuchsia is special, but surely what he/she said applies to all the purples?

A rainbow starts at red and ends a violet. In your brain, the rainbow wraps around in a circle, connecting red and violet. This is not the reality of the wavelengths, so your brain makes up a color that fits between red and violet.

It's also almost an octave of color---I cut my brain some slack

Do you mean a cylinder?

> It's the only color not in the rainbow.

Wrong.

I hate this argument about pink/fuchsia being "special".

most colors are not in the rainbow. most colors are what our brain comes up with when it gets contradictory signals. However, most colors are "close enough" to a color that's in the rainbow. Pink isn't. But this is very subjective and depends on the culture you originate from -- for example, in Japan green and blue are often regarded to be shades of the same color. I'm sure that similar things can happen with pink and red. If you've grown up with the same word for pink and red, thought of them as the same color, and only later learned names for the individuals shades, you'd probably say that pink is in the rainbow (and perhaps some subdivision of blue is not)

No you're wrong.

Pink is the only colour that doesn't correspond to a colour on the rainbow (a "real" colour if you like). Rainbow colours are single-frequency, i.e. they can be generated by a laser. You can have a red laser, a blue laser, a yellow laser, etc. But you can't have a pink laser.

But also, that doesn't mean that fuschia isn't a combination of pink and purple. OP is being super-pedantic to the point of being wrong.

You haven't refuted my point. I agree that rainbow colors are single-frequency. I'm asserting that most colors we see are not.

Rainbow red is single-frequency. Most shades of red which we see are not. Rainbow blue is single-frequency. Most shades of blue which we see are not. Etc. You can have a red laser, but not a laser for most shades of red. You can't have things like a maroon laser.

The only reason pink is special is because we do not consider it to be a shade of a rainbow color, which is a cultural thing.

I think you are conflating purple with (spectral) violet here. All purples are created from the mixing of high and low wavelength and are not present in the rainbow.

Violet, which is present in the rainbow, is not available for addition in the links provided since it can't be represented on computers using blue as their lowest wavelength primary.

yes and from !wen:

"In the RGB color model, used to create colors on computers and television screens, and in web colors, fuchsia and magenta are exactly the same color, made by mixing blue and red light at full and equal intensity."

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