alt.hn

4/20/2025 at 2:03:09 AM

Novel color via stimulation of individual photoreceptors at population scale

 https://www.science.org/doi/10.1126/sciadv.adu1052

by radeeyate

4/20/2025 at 10:00:03 AM

There are a bunch of "weird" colors that we don't see naturally. Wikipedia has a page on them: https://en.wikipedia.org/wiki/Impossible_color

Some can be created at home without any special equipment. For example, you can't mix red and green and create a "redgreen," but if you cross your eyes and have one eye see red and the other see green, you might see a new color you haven't seen before.

I also see weird colors in displays with a high frame rate that cycle between colors quickly. And at one point, I had a laser shot in my eye, which destroyed part of my vision. Initially, in that spot, I saw a weird iridescent silver-greenish color I had never seen before. Although that was pretty cool, I wouldn't recommend repeating this involuntary experiment just to see that color.

by InsideOutSanta

4/20/2025 at 2:17:19 PM

I tried really hard to see the "redgreen", but it just felt like an occlusion bug when two 3d objects have the exact same z layer and fight to render on top of the other.

by eddd-ddde

4/20/2025 at 1:58:35 PM

Stygian blue is my favorite. What an insane color.

by soulofmischief

4/20/2025 at 2:50:35 PM

I see it but it doesn't really feel like a new color? It just looks like blue on top of black. Maybe a new intensity, if I was being super generous, but not a new color.

by dataflow

4/20/2025 at 4:49:51 PM

To me, Stygian blue doesn't look like blue on top of black. It looks like black that glows blue, which doesn't make sense in the real world. I think it is fairly described as a new color—I would be quite unsettled if I encountered it in real life.

Of course, colors are a hallucination our brain produces, so perhaps different brains deal differently with an unusual experience like Stygian blue.

by InsideOutSanta

4/20/2025 at 5:41:55 PM

> It looks like black that glows blue

I could maybe buy that as a description, but...

> I think it is fairly described as a new color—I would be quite unsettled if I encountered it in real life.

I don't feel this follows. There are a lot of things that would unsettle me if I saw them, like if someone gave off a visible aura. Heck, I even found a "black flame" a bit unsettling, and I saw a literal video of it on YouTube (look it up if you don't know what I'm referring to). I'd feel similarly if I saw a transparent human too. The feeling you get - or the fact that you haven't seen something visually similar before - doesn't really imply it's a new color, I think!

by dataflow

4/20/2025 at 7:45:57 PM

I get more of a black in the middle and blue glow around the edges. Also not sure it qualifies as a new color. To me, it's more like an interesting illusion that combines black and blue.

by daveguy

4/21/2025 at 1:16:19 PM

Each person's qualia can be different from the next. It's definitely a new color, regardless, in that you won't encounter it in nature.

by soulofmischief

4/20/2025 at 2:56:04 PM

I think it qualifies as a new color. If we can't differentiate colors on saturation, hue or intensity then I don't know how there are supposed to be multiple colors at all. It seems like fair play by the scientists, if a bit shrewd in defining "new".

by bigyabai

4/20/2025 at 4:26:14 PM

> If we can't differentiate colors on saturation, hue or intensity

I don't think I follow. We can obviously distinguish all of these and do it on a daily basis... what do you mean we can't?

by dataflow

4/21/2025 at 6:46:28 AM

wait, crossing eyes to see color is a totally different thing than having pointing the receptor right ? The one in OP's article is a new weird signal that got sent to the brain, the other is the brain itself mixing 2 known signals.

by a124123

4/20/2025 at 5:12:05 AM

This story makes me remember that I had heard a fun fact a long time ago that many people have never actually seen the colour "violet" which is a single wavelength of visible light. Because there are very few things that reflect only this wavelength in reality. The purple colour we see is formed from a mixture of red and blue, whether it's something in nature, screen displaying or printing. I was so intrigued that I bought a 405nm laser torch and invited some friends to a home party to ‘See the real violet’. That single wavelength of purple really made a different experience, and with good friends, we had a great day.

The olo experiment was very interesting, and it told me that today we even have the technology to stimulate a single cone cell one by one in time. I know that we can't accurately display the olo on screen right now, which also prevents any of these articles from actually containing a picture of the olo. I think it's very close to #00FFEE, and I'm making it the colour of my Hacker News's top bar.

by tianqi

4/20/2025 at 8:36:51 AM

> many people have never actually seen the colour "violet" which is a single wavelength of visible light

The violet seen in a rainbow (in nature, not a photo) is legit single wavelength violet. Same with the rainbows created from shining white light through a prism.

It's true that you don't really get to see it in isolation very often though. Maybe some flowers, birds, or butterflies? Or maybe the purple glow you get from UV lights?

by erik

4/20/2025 at 10:57:27 AM

Why is violet in the rainbow not a very blue color? I would think it only activates the blue cones. 405nm is a nifty color.

by phkahler

4/20/2025 at 12:00:12 PM

Because the cone isn't really a "blue" cone, and neither is the "red" one. The curves overlap in complex ways. A pure violet photon also slightly stimulates the long wavelength cone.

That's why red+blue=purple feels a bit like violet. It creates a similar double firing.

(And why red plus green gives an even more accurate yellow. The long and medium cones have a lot of overlap.)

by jfengel

4/20/2025 at 4:19:50 PM

This is a common misconception, but the sensitivity of L cones ("red" cones) increases monotonically until about 570nm (monochromatic yellow), so violet light stimulates L cones the least out of all visible wavelengths of light. Magenta light, a mixture of red and blue wavelengths, stimulates L cones far more than violet light. See Wikipedia's LMS responsivity plot[1] or the cone fundamental tables from the Color & Vision Research Laboratory at [2].

I think the misconception comes from plots of XYZ color matching functions[3]. The X color matching function indeed has a local maximum in the short wavelengths, but X doesn't represent L cone stimulation; it's a mathematically derived curve used to define the XYZ color space, which is a linear transform of LMS color space selected for useful mathematical properties.

[1]: https://en.wikipedia.org/wiki/LMS_color_space#/media/File:Co...

[2]: http://www.cvrl.org/

[3]: https://en.wikipedia.org/wiki/CIE_1931_color_space#/media/Fi...

by GrantMoyer

4/20/2025 at 12:24:22 PM

It is technically the bluest color possible. What we perceive as true blue is different, and the brain has the weird imaginary magenta gradient between blue and red to confuse.

by carlosjobim

4/20/2025 at 2:21:54 PM

Meganta isn’t imaginary, it’s just non-spectral.

by _aavaa_

4/20/2025 at 3:07:53 PM

It's imagined only in our minds, it fits the definition better than anything else.

by carlosjobim

4/20/2025 at 7:03:24 PM

First of all, all colors are imagined only in our minds.

Second, the term imaginary color already exists, and it refers to a specific thing [0], and the colors on the line of purple are not one of them. What you are describing is a non-spectral color. They exist in day to day life and in nature, they simply do not have an associated wavelength.

[0] https://en.wikipedia.org/wiki/Impossible_color

by _aavaa_

4/20/2025 at 9:06:11 PM

What exactly are you trying to prove? The gradient between red and blue (magentas) are the only fully saturated colors that we can perceive, which aren't part of the electromagnetic spectrum. That's fantastic. Do you want to waste your life arguing about nothing instead of enjoying the miracles of nature?

by carlosjobim

4/20/2025 at 5:58:38 PM

Blue light looks different from violet light, because blue light activates M cones ("green" cones) more than violet light does.

by GrantMoyer

4/20/2025 at 7:22:04 AM

> The purple colour we see is formed from a mixture of red and blue, whether it's something in nature, screen displaying or printing.

Well if it’s on an RGB screen, or printed with CMYK inks then it’s not ‘real’ violet, but there must be plenty of natural and artificial pigments that are actually reflecting violet light and not blue + red light. I imagine any pure compound would be doing this. E.g cobalt phosphate (aka cobalt violet).

You could tell by illuminating a sample with different light sources. See metameric failure:

https://en.wikipedia.org/wiki/Metamerism_(color)#Metameric_f...

by perilunar

4/20/2025 at 5:28:47 AM

> Because there are very few things that reflect this wavelength in reality.

You mean few things that reflect only this wavelength? Because I would think anything white would reflect this wavelength just like any other.

by tines

4/20/2025 at 6:00:44 AM

Yes, I meant reflecting only this wavelength. Thanks.

by tianqi

4/20/2025 at 1:56:31 PM

Violet is a true wavelength, and does occur in nature.

Magenta, formed by mixing red and blue, does not exist in nature. For that reason, "magic pink" (full-brightness magenta, #ff00ff) is often used as a transparency color when the image format does not support an alpha channel (e.g., sprite sheets, Winamp skins).

by bitwize

4/20/2025 at 4:53:02 PM

It's not true to say that mixtures of red and blue 'do not exist in nature'. Fuchsia petals really are that color. All you need is a substance that preferentially absorbs green wavelengths but reflects reds and blues.

What 'does not exist in nature' is a single wavelength that produces the equivalent stimulation of your L, M and S cone cells as a mixture of red and blue light does.

But most of what we see in nature is not single wavelength light - it's broad spectrum white light reflecting off things with absorption spectra.

The reason stuff looks so weird under certain LED lights or pure sodium light is that the source light isn't broad spectrum - it's missing wavelengths already - so the way it interacts with absorption spectra is unintuitive. Something that looks blue under white light should still look blue under blue light - but a blue LED might just be emitting blue frequencies that the object absorbs, so it looks black instead.

by jameshart

4/20/2025 at 12:51:38 PM

You can make the difference between a single wavelength color and a composite color which looks the same, by looking at objects nearby.

If they are of one of the composite colors, they should appear in their natural hue

Else they will just appear darker

by Nesco

4/20/2025 at 6:56:36 AM

How did you spread laser light over larger area?

The idea I'm having right now is reflecting it off of the rough side of aluminum foil.

by scotty79

4/20/2025 at 7:48:36 AM

I remember we just simply shone at a white wall.

by tianqi

4/20/2025 at 6:10:27 AM

You did send a specific wavelength to your retina, but that wasn't violet. Because violet is a construct by your brain.

Color is not a property of wavelength. There's nothing special about photons wiggling in the 380 to 750nm range.

In general it's not necessary to be this pendatic, but given the topic here, I think it's important to realize this. It takes a while because we are so good at projecting our internal experience outward.

Remember the blue / black dress?

by subb

4/20/2025 at 6:47:59 AM

> did send a specific wavelength to your retina, but that wasn't violet.

It was, by definition

> Color is not a property of wavelength.

Sure, it's a label

> There's nothing special about photons wiggling in the 380 to 750nm range.

There is - they activate different receptors your brain relies on, hence leading to a distinct (from other wavelengths) sensation

by eviks

4/20/2025 at 2:59:06 PM

The waves aren't inherently special, your retina is.

What if we were sensitive to the 200 to 500nm range? What would be blue, violet and red then?

Our eyes and brain are the one constructing what we perceive as color. It doesn't exists outside of us.

Here's good article on the subject: https://anthonywaichulis.com/regarding-perception-photograph...

by subb

4/20/2025 at 6:18:52 AM

In my personal conception, violet is the kind of colour at the lower edge of the rainbow, which is a single wavelength. And purple is what the brain constructs. However, of course, the names of the colours are themselves vague.

by tianqi

4/21/2025 at 6:15:44 AM

Maybe that's a language issue, because purple and violet are color names around here.

And as such, they are both a construct of the brain, as any other colors, like... white.

What we label as "violet wavelength" is only a narrow projection of our experience outward. Case in point, we don't have such colorful (eh) names for other EM wavelength.

I say narrow because you could take this pure laser and change th surrounding and you will inevitably perceive it differently, even though the power and wavelength are the same.

by subb

4/20/2025 at 6:37:30 AM

Hmm if you talk to a colorist violet and purple are 2 different colors one more on the red and the other more on the blue. That’s still the construct of 2 wavelength colors. So a made up color of our brain that doesn’t exist.

by bdelmas

4/20/2025 at 8:36:38 AM

"Violet" is a spectral color, which means that it is a color formed by a single wavelength of light. And it is a member of the rainbow (the spectrum).

"Purple" is a mixture of red and blue.

by dleary

4/20/2025 at 12:26:42 PM

Violet is a real wavelength, below blue on the spectrum. Where it becomes invisible to the human eye, it starts getting called ultraviolet.

Magenta and purples are constructs by the brain, as you mention.

by carlosjobim

4/20/2025 at 3:15:15 PM

No, they are all constructed, including blue.

If I shine some wavelength to your eyeball and you say "it looks blue", but then I change the surrounding and now it looks white, I don't think you would conclude that the original wavelength is blue.

We have a many examples like this, which prescribe that vision is not at all an accurate wavelength measurement device.

by subb

4/20/2025 at 5:34:07 AM

This is really fascinating to me. I'm amazed they're able to image the cells of the eye with sufficient resolution and speed to achieve this. From the paper, "and targeting 10^5 visible-wavelength laser microdoses per second to each cone cell.".

If I understand correctly, they first use one type of spectroscopy (AO-OCT) to image the eye and build a map classifying the type of cells, and then use AO-SLO to find the positions of cells in real time. I assume that AO-OCT can't image at a sufficient rate for the second part (or they would just use one type?) so they need to first build this classification map, and then use it to match the position of cells to their type (e g., by overlaying the positions of cells with the classifications and making them line up).

by foota

4/20/2025 at 6:45:35 AM

The Guardian's article on this[1] includes a quote from an eminent colour expert at City:

> The claim left one expert bemused. “It is not a new colour,” said John Barbur, a vision scientist at City St George’s, University of London. “It’s a more saturated green that can only be produced in a subject with normal red-green chromatic mechanism when the only input comes from M cones.” The work, he said, had “limited value”.

[1] https://www.theguardian.com/science/2025/apr/18/scientists-c...

by ratatoskrt

4/20/2025 at 7:02:58 AM

identifying and shining light only on specific type of cells on retina through the iris is of limited value? I personally didn't know we even have that kind of precision.

by codesnik

4/20/2025 at 7:45:32 AM

It's just a typical response. What he means (in an admittedly unnecessary, snarky way) is that this is not going to revolutionise perceptual colour science. It's not going to be an out-of-this-world experience, nor will it change our understanding of how humans perceive colour. I personally think it's pretty cool, though.

by ratatoskrt

4/21/2025 at 3:43:16 AM

Agreed; that and the fact that it can be programmatic is either the major result or one of two. The title of the paper is,

Novel color via stimulation of individual photoreceptors at population scale

And they say, These results are proof-of-principle for programmable control over individual photoreceptors at population scale.

by mmooss

4/20/2025 at 3:21:57 AM

> Five subjects were recruited for this experiment ... Subjects 10001R, 10003L, and 20205R are coauthors on the paper and were blinded to the test conditions but were aware of the purposes of the study. The other two subjects were members of the participating lab at the University of Washington but were naive to the purposes of the study.

Is it normal for the authors to experiment on themselves and their colleagues like this? Or did they not like the idea of laser-stimulating the photoreceptors of random strangers?

by jonas21

4/20/2025 at 3:31:20 AM

That is the tradition.

I tooke a bodkin gh & put it betwixt my eye & the bone as neare to the Backside of my eye as I could: & pressing my eye with the end of it (soe as to make the curvature a, bcdef in my eye) there appeared severall white darke & coloured circles

https://www.newtonproject.ox.ac.uk/view/texts/normalized/NAT...

by pvg

4/20/2025 at 3:45:40 AM

Wow, I never knew that Newton risked retinal detachment to prove his theories.

by sebmellen

4/20/2025 at 4:30:21 AM

Also google “Giles Brindley” for another great self-experimentation tale

by parpfish

4/20/2025 at 5:23:37 AM

Also Albert Hofmann and Alexander Shulgin

by krispyfi

4/20/2025 at 4:28:55 AM

Self experimentation is pretty common in psychophysics experiments. I think a big part of it is that the experiments are long and boring, so the scientists themselves are the only people likely to pay attention and perform the task accurately the whole time.

by parpfish

4/20/2025 at 4:39:41 AM

Yes - many psychophysics experiments require a LOT of time and careful attention that would be tricky to get from random participants. It’s often not at all an issue of safety or risk and more just the length, tedium, and motivation.

by etrautmann

4/20/2025 at 4:34:20 AM

There is a theory that specific shades of colors are difficult to recognize or differentiate unless you name them. I wonder how unique these 100% saturated colors would look without context compared to other colors.

by robertclaus

4/20/2025 at 12:30:13 PM

Learning to see is a skill that we have to train. If you ever try to paint or draw a picture from a photographic reference, you will realize that you've spent your whole life blind. Even with the photo right in front of you, it can be extremely hard to paint certain details, because the brain simply refuses to accept the photographic reality when it has another idea of how an object should look.

As for colour, language does not help very much with being able to see and understand them. What helps more is playing with photographic software and getting a feel for the relations within a system like HSL, or RGB.

by carlosjobim

4/20/2025 at 6:36:54 AM

A great many languages don't differentiate between green and blue. There is simply one word for both.

by qingcharles

4/20/2025 at 10:14:34 AM

A great deal of languages only have one blue color

by Muromec

4/20/2025 at 2:30:46 AM

What is meant by population scale in this context?

by K0balt

4/20/2025 at 2:32:46 AM

It’s jargon for “a lot of cones.” 10^3 to be specific.

by turnsout

4/20/2025 at 2:50:06 AM

Cool, thanks. I skimmed the article on how to introduce new colors to entire populations, that seemed like a really promising capability! lol.

by K0balt

4/20/2025 at 3:18:26 AM

Very Snow Crash, maybe. If I recall, the cyberdecks in that story used lasers to draw on the user's retinas, rather than an HMD.

by throwanem

4/20/2025 at 5:39:29 AM

I swear I remember reading in the 80s about the Air Force having monochrome VR goggles consisting of a per-eye laser, magnetic oil lens for per-pixel depth focus, two perpendicular rotating mirrors for the raster scan and a curved glass lens to reflect and focus the raster scan on to the retina.

by corysama

4/20/2025 at 6:25:46 AM

Imagine walking through a shopping mall and suddenly having a Nike logo projected directly onto your retine, obscuring everything you see.

by fy20

4/20/2025 at 3:48:01 PM

Yeah, I mean I haven't been to Vegas myself, but I've had pillow talk with some people who went.

(All illuminated signage could be said to draw on one's retinas, after all. The major differences I see with this method beyond improved gamut are first that it rasters, and second that I think we have to worry what happens if it fails to raster...)

by throwanem

4/20/2025 at 1:18:27 PM

"Welp, time for terrorism I guess"

by Levitz

4/20/2025 at 4:44:36 AM

Microsoft Research had a project like this at one point, with "goggles" that used lasers on your retina instead of LCDs to project images. No idea what happened to the project, as I haven't heard anything recently.

by NitpickLawyer

4/20/2025 at 2:54:38 PM

Very cool!

It would be cooler still if this technique could be used for future VR technology, creating full immersion by targeting all photoreceptors individually. But unfortunately... the optics of the eye does not actually allow individual cones to be fully isolated, as the spot size would be below the diffraction limit. They discuss this in Fig. 2 and the first section of the results.

Even with a wide-open pupil and perfect adaptive optics, there would be 19% bleedover to nearby cells in high-density areas, while what they achieve in practice is 67% bleedover in a lower-density (off-center) area. This is enough to produce new effects in color perception, but not enough to draw crisp color images on the retina. :(

by mppm

4/20/2025 at 12:46:23 PM

There's another ongoing thread about this paper,

https://news.ycombinator.com/item?id=43736005 ("Scientists claim to have found colour no one has seen before (theguardian.com)" — 27 comments)

by perihelions

4/20/2025 at 3:24:58 PM

I wonder if hallucinogens or other altered mental states can produce this effect, by inducing these sorts of internal signals that can't be created by input through the normal channels.

by thenoblesunfish

4/20/2025 at 6:56:34 AM

As a colorblind person, I look forward to you normies arguing over whether a dress is green or “super green.”

by shermantanktop

4/20/2025 at 10:42:36 AM

Let’s just settle it with a spectrometer.

by nkrisc

4/20/2025 at 12:22:09 PM

Spectromers don't measure the subjective perception of color.

by fouronnes3

4/20/2025 at 2:28:46 PM

Of course, but trying to agree on the precise subjective perception of color is fruitless since no two people will perceive all wavelengths of visible light exactly the same.

by nkrisc

4/20/2025 at 11:13:51 AM

it should be called octarine, since it was brought forth by the magic of science!

by exe34

4/20/2025 at 5:29:50 AM

My shitpost is that they're lucky they didn't trigger a buffer overflow :-) but really, it doesn't seem completely out of question to me that it's possible that some unintended and serious consequence could occur from your brain receiving some stimulus that it doesn't naturally receive. I guess maybe there's no biological analog, but obviously bad things can happen in circuits, computers, etc., when this happens.

by foota

4/20/2025 at 5:49:18 AM

The brain is remarkably resilient to that type of issue… Temporary buffer overflow (if you like) can be easily induced and observed with chemicals that modify function at the receptor level; Psychedelics being a classic example. (Worth noting there are many such chemicals used in medicine and research that induce overflow in function besides perception.)

What I find fascinating is the neurological resilience that can be observed at cellular and behavioral levels to bounce back after an event like that.

Non-chemical interventions, like adaption wearing special glasses that flip vision(1), are quickly accounted for by a healthy brain.

1:https://www.npr.org/2012/12/14/167255705/a-view-from-the-fli...

by braingravy

4/20/2025 at 6:36:14 AM

An easy way to percieve an oversaturated colour like this is to stare at one colour for a long time, and then switch to its complementary colour. The superposition of the colour and the afterimage of the same colour produces a more intense effect.

by OscarCunningham

4/20/2025 at 5:33:36 AM

We can do this test on an ANN.

by ImHereToVote

4/20/2025 at 4:58:15 PM

This breakthrough in visual perception feels like a glimpse into a future where our senses are no longer limited by biology. It’s the kind of innovation that reminds me why we pursue science—not just for answers, but for the questions it raises.

by curtisszmania