What is the wavelength of pure yellow?

Yellow is a color where physiological differences can matter. There's a gene called Ser180 that has an allele, Ala180. 40% of Caucasians have it. Men with the Ser180 allele have red cones with a peak sensitivity 4 nm higher than people with Ala180. It doesn't have much effect on how people see red, but quite an effect on yellow. That's because yellow is seen when the red and green cones are equally stimulated.

bloompyle said:

Having seen 532, 543, 568, 589, and 593. I say 589 is the most "pure yellow" from that range.
Still though. These threads are very annoying...

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I agree, the threads are annoying as spectral colors and wavelengths are well known and have been established for a very long and are the wavelength definitions of colors based upon normal human trichromatic color vision of spectral wavelengths whether there is an observer or no observer. Lightexists and is a science of it's own independent of an observer.

Normal human vision sees at least seven pure spectral hues: red, orange, yellow, green, cyan, blue, and violet. The total number of discriminable, nonspectral, hues, ofcourse, is many more. It has been reported that Wool graders at the Gobelin Tapestryworks, in the 19th century, were known for being able to distinguishat least 20,000 different hues (Chevreul, 1839).
Newton in his Opticks(1704) named the seven colours of the spectrum red, orange, yellow, green, blue, indigo and violet. These names have stuck, although the choice of seven should be seen as conveniently sacred, rather than a precise description of the visible spectrum.
Color blindness was first remarked upon by John Dalton(1798) Extraordinary Facts Relating to the Vision of Colours, with Observations.
All very well known for a long time and well defined. No question about it at all.

Here is a tip of the iceberg article which discusses the wide range of differences in human perception of color and the basis for same---has an interesting section on yellow and how it appears to several types of vision defects see figure 1.11 on page 27
Title: Opsin genes, cone photopigments, color vision,and color blindness
See: http://www.cvrl.org/people/stockman/pubs/1999%20Genetics%20chapter%20SSJN.pdf

445nm
I voted for 585nm. It seems to be nearly equal between red and green.

Encap said:

I agree, especially as spectral colors and wavelengths are well known and have been established for a very long time.They are the definitions of the colors based upon normal human trichromatic color vision of spectral wavelengths whether there is an observer or no observer.
The oversimplifications, false questions, and false conclusions are also annoying.

Normal human vision sees at least seven pure spectral hues: red, orange, yellow, green, cyan, blue, and violet. The total number of discriminable, nonspectral, hues, ofcourse, is many more. It has been reported that Wool graders at the Gobelin Tapestryworks, in the 19th century, were known for being able to distinguishat least 20,000 different hues (Chevreul, 1839).
Newton in his Opticks(1704) named the seven colours of the spectrum red, orange, yellow, green, blue, indigo and violet. These names have stuck, although the choice of seven should be seen as conveniently sacred, rather than a precise description of the visible spectrum.
Color blindness was first remarked upon by John Dalton(1798) Extraordinary Facts Relating to the Vision of Colours, with Observations.
All very well known for a long time and well defined. No question about it at all.

Here is a tip of the iceberg article which discusses the wide range of differences in human perception of color and the basis for same---has an interesting section on yellow and how it appears to several types of vision defects see figure 1.11 on page 27
Title: Opsin genes, cone photopigments, color vision,and color blindness
See: http://www.cvrl.org/people/stockman/pubs/1999%20Genetics%20chapter%20SSJN.pdf

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A little knowledge is a dangerous thing. The Stockman paper is routinely assigned in community college to introduce the idea that people can see colors differently. Someone would need to read hundreds of other research papers to get some idea of what the rest of the iceberg looks like (very different from the tip).

There are people who's red and green cones are shifted so much that their peak sensitivities are within a few nanometers of each other (instead of the usual 30 or so). They suffer from a rare form of red-green color blindness. The are also people whose red and green cones are shifted to within 7 or 8 nm of each other. They score quite well on color vision tests. Some even score well when comparing pure spectral yellow with composite yellow made up of red and green light. Or not, depending on where things got shifted.

As for the seven spectral hues, why are you bringing up obsolete centuries-old research? Things have changed quite a lot since Dalton's time. Color requires an observer, otherwise you just have photons and wavelengths (or energy levels).

Newborn babies have the ability to recognize the difference between a smile and a frown and respond accordingly. People with halfway normal vision can see faces in floral wallpaper just by staring at it long enough. That's because our brains are hardwired to look for that sort of thing, even if it means building a face from false clues.

Similarly, certain colors are hard-wired into the brain. The spectral colors are red, green, blue, orange, and yellow. The non-spectral colors are brown, purple, pink, plus black-white-gray/light-dark-medium. Cyan is not on the list. People have absolutely no inborn sense of cyan, but can be trained to see it when they know what to look for. Violet is not on the list. People have a natural tendency to mistake violet for purple. Telling the difference is learned, not innate.

My reason for conducting these polls is to find out how laser pointer hobbyists see the spectrum. The exact wording of the questions was borrowed from another LPF member who had previously been conducting these polls. Laser pointer hobbyists are among the few people who have access to a variety of pure wavelengths, can view them under a variety of conditions, have some idea of what the wavelength actually is, and in some cases have access to digital spectrometers.

I was always impression that 577nm was "pure yellow"

@zyxwv99: +1 to reputation from me. Really like this thread!

zyxwv99 said:

My reason for conducting these polls is to find out how laser pointer hobbyists see the spectrum. .

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All the BS aside, my point is what colors are called is beyond well established as are the visable spectral colors, although eveyone's vision/perception is individual and slightly different.

You are not even close finding out "how laser pointer hobbyists see the spectrum" at any level of which many are mixed and matched here. Be real. Many voters have indicate they have never seen a laser of the individual wavelength they are voting on so even open eyes/vision is not a factor in your "wavelength of pure" color votes and answers, except indirectly. Do lasers even exist that output all the wavelenghts you list for someone to be able to view--no.

Intereting and/or ntertaining? Yes, to a degree. White noise about your question? Yes mostly and for many reasons which makes the threads annoying to some people.

Reportedly, a person in their 20's with "normal" trichromatic color perception can discern about 150 different spectral wavelengths apparent discreteness of "colors" being an artefact of human perception the spectrum being continous and the exact number of colors is a somewhat arbitrary choice.

If you are looking for the key to the universe, I have good news and bad news.
The bad news is, there is no key ton the universe. The good news is that it has been left unlocked.

lazerman121 said:

I was always impression that 577nm was "pure yellow"

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The research papers I've been reading match the results of this poll pretty closely. Yellow cannot be an exact wavelength because there are too many variables. Eliminating yellows with even the slightest hint of green really helps. Eliminating amber and golden yellow narrows it down even more. I've tried to narrow it down one step further by eliminating "happy, cheerful" yellow and just focusing on "plain, boring yellow" (which lies perilously close to slightly greenish yellow). However, even taking all those precautions, the most you can say is that the center of gravity lies in the 580s for most people, although mainly under the ideal laboratory conditions of vision experiments.

I suspect that under many conditions and for many people 577 can look pure yellow, just as for others 589 is the purest yellow. That's only a 12nm spread.

Yea, 577 is lemony yellow. But still, these threads are frickin annoying. Please stop making them, people....

Why would cyan not be "hardwired" while orange is? To me they both look like "mixes" - one of blue and green the other of yellow and red.

Violet might be explainable by it being an uncommon color. AFAIK the only "proper" sources one encounters are black lights and 405nm lasers (which are rare to non-laserists).

Pure yellow is the colour of your wee after drinking a pint of lemon juice - science fact ;-)

Multimode said:

Pure yellow is the colour of your wee after drinking a pint of lemon juice - science fact ;-)

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No no no.... It is the color of your wee after eating asparagus. Strange but true. :>)

Atomicrox said:

Why would cyan not be "hardwired" while orange is? To me they both look like "mixes" - one of blue and green the other of yellow and red.

Violet might be explainable by it being an uncommon color. AFAIK the only "proper" sources one encounters are black lights and 405nm lasers (which are rare to non-laserists).

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Researchers spend a lot of time trying to figure what sort of stuff is hard-wired into the brains of humans and other animals. Sometimes they don't have an explanation for why it's there. Other times they have conflicting theories. With spectral colors, our instinct for distinguishing blue from green is relatively weak. In some cultures blue and green are a single color anthropologists call "grue." In other cases, as in Japan, the dividing line between blue and green is so far away from "normal" that the words blue and green may not even be properly translatable into their language. A weak instinct can easily be overridden by culture, or may require a certain kind of culture to develop more fully.

On the other hand, most cultures and languages do have separate concepts of blue and green, and most of them strongly agree with each other on which Munsell color chips represent their ideas of those colors. Orange can possibly be explained by the fact that one of our neural subsystems, the yellow-blue opponent process, treats yellow as a primary color, which would elevate orange from a tertiary to a secondary color.

Basic Color Terms: Their Universality and Evolution by Brent Berlin and Paul Kay

Interesting! One of these days I'll need to save som free time to read all those color perception books/papers.

Atomicrox said:

Interesting! One of these days I'll need to save som free time to read all those color perception books/papers.

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...and threads!:eg:

From what I can tell, calibrating a Mantis Shrimp to respond to colors might be your best bet, as they have the best color vision of all known animals on the planet.

After that, it appears that, due to the way we perceive color, there will simply be a range of wavelengths that people will perceive as "yellow", as we don't all perceive it exactly the same due to genetic and other factors that produce our interpretations.

There may BE no exact "True Yellow in nm" for humans...it may simply always be a range, which is what the data supports thus far.