How School Buses Became Yellow (2019) | Hacker News Reader

How School Buses Became Yellow (2019)

smithsonianmag.com

46 pointsjelliclesfarm21 comments

The following is a very poor description of how color vision and paint color works. Almost nothing you’ll ever experience outside of lasers and LEDs have narrow light emission peaks around a single wavelength. Everything has a spectrum of color and trichromat vision splits these spectrums into three slightly overlapping bins with their own spectrum response. The colors you see do not map to frequency. They’re all synthetic based on the biology of your eyes.

Plus if the nonsense about activating two cones is right, why not activate three and paint them white? The yellow they picked is just bright and has a lot of contrast against more or less everything in the environment because there aren’t many big yellow things around… and they picked a color that is quite loud but also not very obnoxious like a neon yellow would be… just slightly muted while still standing out.

> “The yellow is not pure spectral yellow,” says Ivan Schwab, clinical spokesperson at the American Academy of Ophthalmology. “The best way to describe [the color] would be in wavelength,” says Schwab. The wavelength of the popular school-bus color is “right smack in the middle” of the peak wavelengths that stimulate the photoreceptor cells our eyes use to perceive red and green. The red and green photoreceptor cells, or “cones” as they are commonly known, are the two most predominant cones in our eyes. Schwab says, “If you get a pure wavelength of one color…and you hit just one cone with it, you’re going to have x amount of transmission of signal to the brain. But if that [wavelength] were to stimulate two cones, you’ll get double the amount of transmission to the brain.” Remarkably, “That color that we are calling school bus yellow hits both peaks equally.” So although they may not have fully comprehended the science behind it, the color Cyr and his colleagues chose at the 1939 conference makes it hard for other drivers to miss a school bus, even in their peripheral vision. “And it’s darned big,” Schwab adds.

>The best way to describe [the color] would be in wavelength,” says Schwab. The wavelength of the popular school-bus color is “right smack in the middle” of the peak wavelengths that stimulate the photoreceptor cells our eyes use to perceive red and green. The red and green photoreceptor cells, or “cones” as they are commonly known, are the two most predominant cones in our eyes. Schwab says, “If you get a pure wavelength of one color…and you hit just one cone with it, you’re going to have x amount of transmission of signal to the brain. But if that [wavelength] were to stimulate two cones, you’ll get double the amount of transmission to the brain.” Remarkably, “That color that we are calling school bus yellow hits both peaks equally.”

Curious, what is the color that would hit red and blue cones equally? What is the color that would hit green and blue cones equally?

There isn't much overlap with the blue cone. See picture at https://en.wikipedia.org/wiki/Cone_cell

Makes sense thanks.

Also the actually intersection of the green and red curves looks more like 3M Safety Green to me (the yellowish hi-vis vests). I wonder if that’s how they developed that color

Doesn't the fact that they are UV reactive help them glow and appear brighter? If they used the same color with a non-UV reactive material, would they still seem as bright?

This makes me wonder: how would the world look if we genetically engineered our eyes (and brains too I guess) to have cones more evenly-spaced in the spectrum, perhaps even with 4 cones instead of 3?

> perhaps even with 4 cones instead of 3?

You may enjoy reading https://en.wikipedia.org/wiki/Tetrachromacy#Humans

It seems that we've found one woman who is actually capable of using this (ctrl-f for subject cDa29)

This is how subtractive colour works.

Cyan = (White minus red) = (Green+Blue)

Magenta = (White minus green) = (Red+Blue)

Yellow = (White minus blue) = (Red+Green)

So if you lay perfect cyan, magenta and yellow pigments over each other you should get black (in theory).

EDIT: though, of course, there is no monochromatic "magenta wavelength". There is a cyan wavelength, though.

Yeah I get that I mean more specifically what shade of cyan or magenta. “Yellow” sure but according to the article, specifically National School Bus Yellow.

> according to the article, specifically National School Bus Yellow.

Yeah, no. I suggest skipping that paragraph. I read it first as demonstrating how rapidly quality of understanding can deteriorate as you move away from someone's areas of expertise. But on rereading, I could see how a non-science journalist might mangle someone's valid description that badly. And if the interviewee was Ivan (R) Schwab (of UCDavis), I'd lean towards a mangle.

Does this mean blue-orange movie posters are just trying to spam our cones?

I always thought neon green (not yellow) was the brightest color to the human eye.

https://www.mentalfloss.com/article/500751/most-visible-colo...

Fun read - I enjoy that it was just a guy in the 1930's who got a handful of people together to agree on something and they did. No dozens of working groups inundated by special interest groups.

I was curious what colors are used in other countries. Yellow seems to be the most common worldwide:

https://en.wikipedia.org/wiki/School_bus_by_country

The most common color would be color of family car since school buses are rarely used in most of the world and even in some of those countries in linked article like China seeing yellow school bus is rarity and in rural areas is much more common to see just some van of whatever color (grey, green, etc.) with bunch of benches in back and dozens of kids inside there travelling between villages.

Article also doesn't really touches why we keep using yellow color (certainly not just because bunch of people hundred years ago decided on it without any scientific basis), it is better explained here without lengthy article.

https://www.catrentalstore.com/en_US/blog/why-equipment-yell...

Similarly the Yellow brand of trucking company has orange trucks because they determined it was the most visible available color. And Yellow is the name of the guy, not the color.

The Sherwin-Williams paint company likes to take the following credit:

'1939 Sherwin-Williams color consultant Harry Scheid recommended the well-known “school-bus yellow” as the ideal color for buses for its high visibility.'

https://mb.cision.com/Public/4932/9915373/b6af8c5f4cd34662.p...

Semi related: it appears that rods are most sensitive to cyan-green light (498 nm), which makes me wonder if using such light would give you the best results in situations where seeing fine details is important, but color differentiation generally isn't.

This is a long standing argument in our family.

I say they're more orange than yellow.

Wife says they're more yellow than orange.

The battle continues.

Looking at the pantone color it appears more yellow to me. I have seen a lot of minor regional variation though, especially when weathering affects things, so they may be orangier in your area. You could always say they're yellange.

People differ in the sensitivity of their cones, I believe. I wonder if that explains such disagreements, or whether it’s merely linguistic.

To me it’s a warm yellow, by the way. It’s much closer in color to a banana than to an orange.

Huh, good point. I sorta wonder if nobody has "perfectly average color" who's vision matches the statistical average. Similar to how no pilot matches the statistically "average pilot size" as the air-force discovered when it first tried standardizing cockpits.

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