[Sophira]

That was incredibly well-explained. Kudos.

I do have a question that the article doesn't seem to attempt to answer, though. The article says (paraphrased in my new understanding) that any spectra which makes the cones in your eyes react the same way will result in seeing the same colour. Do we know of any examples of this?

(Colour-blindness seems like an obvious example; I'm curious though if there are any examples of two common scenarios where it can be demonstrated that there are different spectra in each, and yet most people will see them as the same colour.)

[grumbelbart2]

This is called metamerism. It can be a practical issue if two pigments have the same color under one light source, but a different one under another. You want your artificial teeth to have the same color as your real teeth in sunlight, led light, and a classic lightbulb for example.

[clort]

Well, now that you mention it, I'd just like to remind you that people are a lot weirder than you might think! Having incisors to be a different colour (say, a brilliant red) under artificial lights could definitely be a thing people desired..

[317070]

A flower, a picture of the flower in print and the picture shown on a screen will all have different spectra, but look the same.

See the first minutes of this video, where he has a spectrum analyser: https://youtu.be/-DyrBDsKA5s?si=mRJPT2ecy6NqpB4N

[Sophira]

That video was super interesting, thank you!

[frotaur]

Well, the most common example si precisely screens, no? A screen displaying the color yellow is actually a spectrum of red and green peaks, stimulating your red and green cones just like a spectrum containing a single frequency of the color yellow.

[Sophira]

Oh right. I feel silly for forgetting about that even though it's mentioned in the article. Thank you!

[addaon]

Everyone is pointing out examples around image reproduction, which are valid and interesting… but the case that comes up in nature is violet (beyond blue in spectrum) vs purple (mix of red and blue) pigments.

[somat]

Would not the definitive answer to this be a computer screen.

On one side you have an apple, illuminated by natural sunlight. it fills your eye with a rich texture of subtly mixed frequency's covering the whole gamut of visible and invisible light. On the other a picture of an apple composed of brutal pure frequencies only emitting at 430, 540, 570 Nm. Can you tell the difference?

[Sophira]

That makes sense. I feel a little silly that that's not something I considered despite the article saying exactly that. I think I got caught up in the details.

[subscribed]

No, no, the question was great. I read all the answers carefully and I feel a bit smarter now. Thanks for asking it!