Novel color via stimulation of individual photoreceptors at population scale

There are a bunch of &quot;weird&quot; colors that we don&#x27;t see naturally. Wikipedia has a page on them: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Impossible_color" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Impossible_color</a><p>Some can be created at home without any special equipment. For example, you can&#x27;t mix red and green and create a &quot;redgreen,&quot; 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&#x27;t seen before.<p>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&#x27;t recommend repeating this involuntary experiment just to see that color.

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 &quot;violet&quot; 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&#x27;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.<p>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&#x27;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&#x27;s very close to #00FFEE, and I&#x27;m making it the colour of my Hacker News&#x27;s top bar.

This is really fascinating to me. I&#x27;m amazed they&#x27;re able to image the cells of the eye with sufficient resolution and speed to achieve this. From the paper, &quot;and targeting 10^5 visible-wavelength laser microdoses per second to each cone cell.&quot;.<p>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&#x27;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).

The Guardian&#x27;s article on this[1] includes a quote from an eminent colour expert at City:<p>&gt; 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”.<p>[1] <a href="https:&#x2F;&#x2F;www.theguardian.com&#x2F;science&#x2F;2025&#x2F;apr&#x2F;18&#x2F;scientists-claim-to-have-found-colour-no-one-has-seen-before?CMP=Share_iOSApp_Other" rel="nofollow">https:&#x2F;&#x2F;www.theguardian.com&#x2F;science&#x2F;2025&#x2F;apr&#x2F;18&#x2F;scientists-c...</a>

&gt; <i>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.</i><p>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?

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.

What is meant by population scale in this context?

Very <i>Snow Crash,</i> maybe. If I recall, the cyberdecks in that story used lasers to draw on the user&#x27;s retinas, rather than an HMD.

Very cool!<p>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.<p>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. :(

There&#x27;s another ongoing thread about this paper,<p><a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=43736005">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=43736005</a> (<i>&quot;Scientists claim to have found colour no one has seen before (theguardian.com)&quot;</i> — 27 comments)

I wonder if hallucinogens or other altered mental states can produce this effect, by inducing these sorts of internal signals that can&#x27;t be created by input through the normal channels.

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

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

My shitpost is that they&#x27;re lucky they didn&#x27;t trigger a buffer overflow :-) but really, it doesn&#x27;t seem completely out of question to me that it&#x27;s possible that some unintended and serious consequence could occur from your brain receiving some stimulus that it doesn&#x27;t naturally receive. I guess maybe there&#x27;s no biological analog, but obviously bad things can happen in circuits, computers, etc., when this happens.

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.