I am curious how these work for people with common kinds of colorblindness. The author mentions at the end that they likely don't work for that case, but they don't seem to have spent much time thinking about it.
Would it be possible to generate ones that _would_ work for specific kinds of colorblindness? Or is the entire concept doomed due to the specific way(s) that colorblind eyes are messed up?
Didn't work for me. I notice that the color around the circle changes, but it's just a palish blue-something, not a new color, certainly not intense. Too much overlap, I guess. Perhaps it works when changing the background to blue?
I fail on the first page of the Ishihara (?) test. When using those colorblindness filters in photoshop/-like apps, the protanopia and deuteranopia filters do very little for me. No 'real' diagnosis. I can see red and green though, but the shape needs to be big, and the color should be quite saturated. Reading resistors is really hard.
It is incredible to see a concept going from 'optical table of sensitive equipment fraught with numerous safety concerns' to 'here is a 1 kB svg animation, stare at it for 1 minute' in 3 months.
> The idea for that animation is not new. It’s ~~plagiarized~~ based on Skytopia’s Eclipse of Titan optical illusion (h/t Steve Alexander), which dates back to at least 2010.
This is really cool. Tangentially, it's an example of an important life lesson, "work smarter not harder". To see the impossible color, you could build a super-expensive, super-complicated laser to directly stimulate the exact cells; or you could desensitize the other ones with an optical illusion that works on a personal device (effectively zero cost and minimal complexity since it uses existing technology).
Not to say the laser is a waste, despite the above I'd argue it's very useful. It lets us test how effectively the above actually works, and has other applications.
What is the animation supposed to be like? I see just a black bar on the left narrowing, but nothing else happens. The red circle and green background and white dot didn’t change. (iOS 26 beta, iPhone 15)
Using psychedelics, specifically 2C-B and LSD, you can also see very saturated colors you don't normally see in daily life. I see very saturated magentas.
Open the experiment animation and refresh the page multiple times to refresh the countdown while looking at the white pixel (from the same point of view) to get an even more impressive effect.
To me it looked like the circle outline had a shimmering aura, it felt very magical. This was a incredibly delightful experience so I just want to say thanks for posting it.
When the circle was around the halfway point of shrinking the color looked the most vivid for me, so be sure to wait the whole duration.
To me, it seemed to be a visual equivalent of that auditory trick where a note seems to descend or ascend in pitch indefinitely. The outer aura of color seemed to be shrinking constantly.
At the end, the green circle had a very intense grainy, hypersaturated quality for me. Not like the shimmering aura that shrinks with the red circle, but still there was something magical going on.
I looked away, and then back to the screen, and the effect was gone. It was only in my head. Wow.
The aura was a very brilliant green, which reminded me of an hallucinogenic experience I had. I was sat with friends in the city centre, my brain altered by chemical substances, and I spotted a guy 100m away with the most brilliant and beautiful green shoes. It was an amazing sight, standing out from everything else.
Sober, I later realised that they were normal green shoes, but in my no-brain-filter state, I was able to appreciate that we have many more green cones in our retina than red or blue, and normally the mix dial for green in our brain is kept pretty low not to overpower the other colours. The animation once again raised this dial to show how powerful is our raw perception of that colour.
(The evolutionary reason is that we spent a lot of time in vegetation or on trees, and it's very useful to be able to distinguish things and perceive small movements in a sea of green.)
The one with a red circle on a brown background had a really interesting effect; before the circle starts to shrink, the background becomes the same colour as the circle, then moving your eyes made a bright red or green circle appear, each on their opposite side.
I got that, as well as a seemingly random set of changes in apparent brightness. The Magenta one seemed to produce patches of bands in my vision as well, think like blown up versions of edge detection kernels.
As the circle was about to disappear, the blue-green was super saturated for me and persisted for a good minute if I kept locking onto the white dot. Another thing you can do, is at night time (lights off) look at the red circle like before, and when the timer runs out close your eyes and keep it dark. You will see blue-green glow very strongly.
Interesting colours coming out of it - a while back I suspected I have https://en.m.wikipedia.org/wiki/Tetrachromacy since I was able to describe colours more vividly that others, and certain plants for me like Verbena have a glow around them.
It's enough to stare at anything for a few minutes without moving eyes to get similar effects and hallucinations.
We see with good resolution only a small part of our visual field. Perhaps the brain starts to "invent" what's there it we don't give it information by constantly moving eyes.
As a more advanced version, they say that fire kasina practice may produce very interesting visual effects.
For whatever reason, evolution decided those wavelengths should be overlapping. For example, M cones are most sensitive to 535 nm light, while L cones are most sensitive to 560 nm light. But M cones are still stimulated quite a lot by 560 nm light—around 80% of maximum.
The reason is simple: genes coding the long wave opsins (light-sensitive proteins) in these cones have diverged from copies of the same original gene. The evolution of this is very interesting.
Mammals in general have only two types of cones: presumably they lost full color vision in the age of dinosaurs since they were primarily small nocturnal animals or lived in habitats with very limited light (subterranean, piles of leaves, etc.) Primates are the notable exception, and have evolved the third type of cone, enabling trichromatic color vision, as a result of their fruitarian specialization and co-evolution with the tropical fruit trees (same as birds, actually).
So, what's interesting is that New World and Old World primates evolved this cone independently. In Old World primates the third cone resulted from a gene duplication event on the X chromosome, giving rise to two distinct (but pretty similar) opsin genes, with sensitivity peaks at very close wavelengths. As a note, because these genes sit on the X chromosome, colorblindness (defects in one or both of these genes) is much more likely to happen in males.
New World primates have a single polymorphic opsin gene on the X chromosome, with different alleles coding for different sensitivities. So, only some (heterozygous) females in these species typically have full trichromatic vision, while males and the unlucky homozygous females remain dichromatic.
I'm pretty sure that line of the article didn't mean to imply that we don't know, or aren't sure, only that it goes beyond the scope of the article and isn't directly relevant to the topic at hand.
Is this just my device, or is there no way to use this roll-your-own SVG generator to actually roll your own? I can only pick from a tiny subset of preset colors, most of which seem super random and desaturated and not what I want. There's no FFFF00 yellow, for instance. Is there some way to enter an arbitrary RGB color that I am not seeing? If not, why on Earth write such an interesting article, advertise this custom SVG generator and then build the interface that way? :/
"If you’re colorblind, I don’t think these will work, though I’m not sure."
Should work for anomalous trichromats (by far the majority of people with color deficiencies) but probably with less intensity.
"Folks with deuteranomaly have M cones, but they’re shifted to respond more like L cones."
I don't think this is true.
What would the difference between deutan and protan then be?
"Why do you hallucinate that crazy color? I think the red circle saturates the hell out of your red-sensitive L cones. Ordinarily, the green frequencies in the background would stimulate both your green-sensitive M cones and your red-sensitive L cones, due to their overlapping spectra. But the red circle has desensitized your red cones, so you get to experience your M cones firing without your L cones firing as much, and voilà—insane color."
I think only people with missing L cone (Protanopia) or M cone (Deiteranopia) would not experience the phenomenon at all.
Maybe this could be used as a new type of color deficiency test?
A bit unrelated but I found this interesting: water is transparent only within a very narrow band of the electromagnetic spectrum, so living organisms evolved sensitivity to that band, and that's what we now call "visible light".
I like to joke that while nitrogen gas is the most common thing around us, we are blind to it. Of course, that's a feature, since it allows us to perceive everything else further away, instead of stumbling through a perpetual fog.
This location-dependent tradeoff is something to think about when it comes to "false color" images in astronomy. If some aliens described Earth as "a boring uniform nitrogen-colored ball", we'd probably be a little offended at their ophthalmo-centrism, and tell them that the fault lies in their eyes, not in our planet.
visible light is also the last octave before you hit ionizing radiation. it’s very energetic. good for harnessing in chemical processes. not so energetic that the electrons leave the party.
> If you refused to look at the animation, it’s just a bluish-green background with a red circle on top that slowly shrinks down to nothing. That’s all. But as it shrinks, you should hallucinate a very intense blue-green color around the rim.
I do not believe I have any kind or amount of colorblindness, so imagine my surprise when extremely confused I pulled the image into MS Paint, used the Color Picker tool, and found that indeed, the background has quite a bit of blue in it.
Anyhow, I cannot reproduce the illusion cited. For me the circle just blurs out and I start seeing orange.
Yeah, I don’t think I have any color blindness but that looked super green to me. I think I am fine at distinguishing two colors, but i am not the best at realizing the component colors I am seeing.
I believe they are simply describing the color components, just like you don’t “see red” in a soft orange color.
Did you wait for the black bar to finish, and the circle to start shrinking? Takes a very long time. The effect happens at the edges and disappears if you remove your focus from the center dot.
I have mild achromatopsia and can see the effect in all color variants I tried.
> I pulled the image into MS Paint, used the Color Picker tool
The RGB values used are also indicated in the filename.
What you are seeing (in the static image) is normal. Have you noticed that (0, 255, 0) looks way brighter than (0, 0, 255) regardless of your monitor calibration? For the same reason, non-red images can have quite a bit of blue in them while still subjectively registering as "green".
Just in case... Maybe you didn't wait long enough? I saw nothing so I came to the comments expecting a lot of others to day the animation is broken. However, it turns out it's a lot slower/longer than I thought. I saw the little bar on the left shrink to nothing and thought that was it and exited, but that's just the start. The full animation is the red circle shrinking all the way until it disappears. There is no illusion until the circle shrinks quite a bit.
I did a custom combination of yellow outer field, blue inner circle, and got a vibrant purple halo, which is not what I expected. I assumed it would be "yellow++", based on what I know about the human eye's colour sensitivity.
I didn't expect a strong effect, because the overlap between blue and red/green is so much less than the overlap between red and green, but bright purple is close to the opposite of what I expected. I'm genuinely puzzled.
That is interesting - I tried the setup you suggested and actually did see something that could be described as yellow++, with maybe a hint of gold/orange
It was also very intense, like staring into the sun. I observed this for both of the two default yellow tints that I could choose via the (Windows?) color picker
I have no idea why this would differ between individuals
Painters have been aware of this distinction for years. I encourage interested readers to get a good artist's book on color or just head for your local art store and explore the differences between pthalo and viridian greens (or any of many other surprisingly different tonal clashes).
The green I see around the red circle is exactly the color of a green traffic light bulb when lit, which has a hint of blue to it and is not actually pure green.
I don’t understand why you need the animation. If you point at the green background after staring the red one for a while, you can see a whole circle of the saturated color.
Incidentally, it’s also a demonstration that you shouldn’t use high contrast in typography. When you start the test you can clearly see the lines of text retained on your retina.
63 comments
[ 4.8 ms ] story [ 92.5 ms ] threadWould it be possible to generate ones that _would_ work for specific kinds of colorblindness? Or is the entire concept doomed due to the specific way(s) that colorblind eyes are messed up?
I fail on the first page of the Ishihara (?) test. When using those colorblindness filters in photoshop/-like apps, the protanopia and deuteranopia filters do very little for me. No 'real' diagnosis. I can see red and green though, but the shape needs to be big, and the color should be quite saturated. Reading resistors is really hard.
Enjoy your forbidden color, you earned it!
> The idea for that animation is not new. It’s ~~plagiarized~~ based on Skytopia’s Eclipse of Titan optical illusion (h/t Steve Alexander), which dates back to at least 2010.
Not to say the laser is a waste, despite the above I'd argue it's very useful. It lets us test how effectively the above actually works, and has other applications.
When the circle was around the halfway point of shrinking the color looked the most vivid for me, so be sure to wait the whole duration.
I looked away, and then back to the screen, and the effect was gone. It was only in my head. Wow.
A super fun, delightful experience indeed.
Sober, I later realised that they were normal green shoes, but in my no-brain-filter state, I was able to appreciate that we have many more green cones in our retina than red or blue, and normally the mix dial for green in our brain is kept pretty low not to overpower the other colours. The animation once again raised this dial to show how powerful is our raw perception of that colour.
(The evolutionary reason is that we spent a lot of time in vegetation or on trees, and it's very useful to be able to distinguish things and perceive small movements in a sea of green.)
We see with good resolution only a small part of our visual field. Perhaps the brain starts to "invent" what's there it we don't give it information by constantly moving eyes.
As a more advanced version, they say that fire kasina practice may produce very interesting visual effects.
The reason is simple: genes coding the long wave opsins (light-sensitive proteins) in these cones have diverged from copies of the same original gene. The evolution of this is very interesting.
Mammals in general have only two types of cones: presumably they lost full color vision in the age of dinosaurs since they were primarily small nocturnal animals or lived in habitats with very limited light (subterranean, piles of leaves, etc.) Primates are the notable exception, and have evolved the third type of cone, enabling trichromatic color vision, as a result of their fruitarian specialization and co-evolution with the tropical fruit trees (same as birds, actually).
So, what's interesting is that New World and Old World primates evolved this cone independently. In Old World primates the third cone resulted from a gene duplication event on the X chromosome, giving rise to two distinct (but pretty similar) opsin genes, with sensitivity peaks at very close wavelengths. As a note, because these genes sit on the X chromosome, colorblindness (defects in one or both of these genes) is much more likely to happen in males.
New World primates have a single polymorphic opsin gene on the X chromosome, with different alleles coding for different sensitivities. So, only some (heterozygous) females in these species typically have full trichromatic vision, while males and the unlucky homozygous females remain dichromatic.
Decent wikipedia article on the subject: https://en.wikipedia.org/wiki/Evolution_of_color_vision_in_p...
Types of opsins in vertebrates: https://en.wikipedia.org/wiki/Vertebrate_visual_opsin
Should work for anomalous trichromats (by far the majority of people with color deficiencies) but probably with less intensity.
"Folks with deuteranomaly have M cones, but they’re shifted to respond more like L cones."
I don't think this is true. What would the difference between deutan and protan then be?
"Why do you hallucinate that crazy color? I think the red circle saturates the hell out of your red-sensitive L cones. Ordinarily, the green frequencies in the background would stimulate both your green-sensitive M cones and your red-sensitive L cones, due to their overlapping spectra. But the red circle has desensitized your red cones, so you get to experience your M cones firing without your L cones firing as much, and voilà—insane color."
I think only people with missing L cone (Protanopia) or M cone (Deiteranopia) would not experience the phenomenon at all.
Maybe this could be used as a new type of color deficiency test?
http://hyperphysics.phy-astr.gsu.edu/hbase/Chemical/imgche/w...
But I guess it could be both.
This location-dependent tradeoff is something to think about when it comes to "false color" images in astronomy. If some aliens described Earth as "a boring uniform nitrogen-colored ball", we'd probably be a little offended at their ophthalmo-centrism, and tell them that the fault lies in their eyes, not in our planet.
I do not believe I have any kind or amount of colorblindness, so imagine my surprise when extremely confused I pulled the image into MS Paint, used the Color Picker tool, and found that indeed, the background has quite a bit of blue in it.
Anyhow, I cannot reproduce the illusion cited. For me the circle just blurs out and I start seeing orange.
https://www.colorblindnesstest.org/cambridge-color-test/
Did you wait for the black bar to finish, and the circle to start shrinking? Takes a very long time. The effect happens at the edges and disappears if you remove your focus from the center dot.
I have mild achromatopsia and can see the effect in all color variants I tried.
The RGB values used are also indicated in the filename.
What you are seeing (in the static image) is normal. Have you noticed that (0, 255, 0) looks way brighter than (0, 0, 255) regardless of your monitor calibration? For the same reason, non-red images can have quite a bit of blue in them while still subjectively registering as "green".
https://en.wikipedia.org/wiki/Luma_(video)
I didn't expect a strong effect, because the overlap between blue and red/green is so much less than the overlap between red and green, but bright purple is close to the opposite of what I expected. I'm genuinely puzzled.
It was also very intense, like staring into the sun. I observed this for both of the two default yellow tints that I could choose via the (Windows?) color picker
I have no idea why this would differ between individuals
Edit: link below with FFFF00 for yellow
https://dynomight.net/img/colors/generate.html?inside=0000ff...