I don't believe the blurred images at the end have anything to do with eye focus, as the author suggests.
After all, chromatic aberration is blurring of only a very, very small amount.
The demonstrated seemingly negligible perceptual effect of blurring blue to a huge degree in a multicolor image doesn't seem to have anything to do with that, but rather the fact that we perceive primary blue as a much darker color than primary red or green, and we perceive differences in lighter colors much more easily.
If the author were correct that we have big problems focusing on blue, then we'd see that blue text against a black background would be massively blurry -- but it's simply not. It's comparatively low-contrast (because blue is a dark color), but it's nearly indistinguishably as sharp as red and green.
Right, I picked the "blurred blue" and "blurred green" pictures, converted them to grayscale using luminance and "blurred blue" still looks sharp and "blurred green" still looks blurry.
If it really was the effect of blue light, the effect should have disappeared by converting to grayscale.
It is well known that luminance matters much more than color when it comes to perceived sharpness. Digital and analog video exploit that by encoding color at a lower resolution (chroma subsampling). And blue only accounts for less that 10% of luminance while green is around 70%. You may find different values because color spaces are a mess but that's the general idea.
See the very low coefficients for the blue channel when converting (gamma-compressed) RGB to luma. E.g. the common Rec. 709 standard assigns only 0.0722 weight to blue.
It also matters a bit that the blue channel is only 2% of all color-sensitive cones in the retina. That has a lot more to do with poor spatial resolution int the blue channel than the optics.
Chromatic aberration may be a contributing factor, but I am surprised the author didn’t mention that S cones (which we use to perceive blue) are only 2% of the cones in the retina [1]. Additionally S cones are distributed randomly when compared the regular lattice of M and L cones. The distribution of the different cone types alone may be sufficient to explain why our acuity for blues is impoverished relative to reds and greens.
I'm not sure you're right. At night both I and my wife have reported difficulty reading glowing blue signs compared to glowing red/green signs at the same font size, brightness, and distance.
I'm also not sure that the author is correct; the wrong-focal-distance explanation seems rather weak simply because our focal length is adjustable.
I mostly agree with you, but would add that blurring the blue is affecting the sharpness of the ocean, which has little detail in that image; blurring red or green affects details on the land, which are very noticeable. One might think the cloud-ocean edges would be blurred by the blurring of blue, but the clouds are so much brighter than the ocean (red & green channels), that you can barely notice any difference.
I think that the title is a massive oversimplification because chromatic aberration by itself is not enough for us to be blind to the color blue. We do have cones that can detect blue for one.
We are however, less sensitive to it so maybe the eye doesn't focus based on that channel(?).
Exactly. In the real life I find very difficult to focus on violet signs against the black night background, but it’s a completely different effect from the one in this article and it’s exacerbated by the bigger pupil diameter in the night that increases the aberration.
I agree, in that it was pretty easy to dismiss effects on the example image. Doing this with shapes and a variety of hues and luminances would be a better way to prove the point if it bears out.
I'm sure you could find an image where blurring blue ruins it, and blurring red and green have no impact. This feels like cherrypicking especially given how trivial it would be to just show a bunch of examples.
One of my favourite series in art is Yves Klein's blue work. For anyone unfamiliar, he found a blue that he considered the bluest possible blue [1], and went on a journey painting everything in that blue. I loved that he did this, and then eventually managed to get to an exhibition of his work at the Tate Modern and was absolutely blown away by it - it really needs to be seen in the flesh to appreciate it. There's something about his blue, that when painted on to a sculpture, almost makes the 3D disappear and the sculpture looks 2 dimensional. Extremely beautiful.
As a side note, some (many?) cultures around the world have no word for blue, blue is just other shades of green.
1. All languages contain terms for black and white.
2. If a language contains three terms, then it contains a term for red.
3. If a language contains four terms, then it contains a term for either green or yellow (but not both).
4. If a language contains five terms, then it contains terms for both green and yellow.
5. If a language contains six terms, then it contains a term for blue.
6. If a language contains seven terms, then it contains a term for brown.
7. If a language contains eight or more terms, then it contains terms for purple, pink, orange or gray.
The opposite of the grue phenomenon exists too, i.e. languages which subdivide the "blue" part of the spectrum into separate lexemes. In Russian, for instance, goluboy = light blue, whereas siniy = blue to dark blue. This morning I was reading the Wikipedia entry for color revolution, and there's a quote from Belarusian President Lukashenko, "They [the West] think that Belarus is ready for some 'orange' or, what is a rather frightening option, 'blue' or 'cornflower blue' revolution." I had to chuckle about that - it sounds so goofy in the English translation, but that's only because we don't have a lexical distinction there. (Now I would have personally translated it to light blue, but that's another matter.)
As someone who hasn't seen it in the flesh yet, and doesn't "get" modern art unless someone explicitly spells it out for me, could you elaborate more on why it's so spectacular?
For example, Blue Monochrome [1] seems to my uneducated eye to be just a layer of pure blue that every wall painter recreates every time they paint a wall blue. Why is the Blue Monochrome piece more than just a wall painted blue?
I saw some of the same things you'd have seen in the MoMA (not actually called that) in Nice, France. Walking into the room of these insanely blue paintings and sculptures was almost a religious experience. It's the first time I experienced Stendhal Syndrome[0]. I just had to stand there and stare for a while.
Yves Klein's "Leap into the Void"[1] is another one of his works that really grabbed me when I first saw it. Can't quite explain it. Those are the best types of art experiences in my book.
There's an optometry place in my neighborhood with a back-lit sign with big, blue block letters. And every time I walk by at night I note how fuzzy it looks.
I'm convinced this is an intentional troll. This optometrist knowingly picked a sign to make people momentarily question their vision.
The author is wrong, that experiment doesn’t show anything about focusing. The blue channel in RGB is simply much less bright than the green, which means it has much less contrast, which means that manipulating it in various ways has less of a noticeable effect on the image as a whole. This happens to be true for blurring it, but also adjusting the contrast, inverting it, pixelating it, offsetting it, averaging it completely, whatever manipulation you can think of.
> 2 reasons: 1) You don't have the nearly as many short wavelength detecting blue cones as you do red and green in your fovea. 2) The angle of refraction is dependent on wavelength and short wavelengths get refracted more than relatively longer ones by your eye and therefore focus in front of your retina if you are myopic (nearsighted). The black lights are throwing off a ton of very short wavelength light and when coupled with the larger pupil you have in the dark it sets your eye up for a bunch of chromatic aberration. They should look clearer if you are hyperope or overcorrected in your myopic prescription, or if you view them at a closer distance.
Interesting demo, but I think the retina resolution has more effect on this.
Also note that blue neurons are also much less dense, and our eye blue channel has natively much lower resolution.
This is why in old Windows installers, blue color was used for gradient, when colors were 16 or 256 -- blue and black dots were blurred in the eyes, while the same combo of green dots was very visible.
I would guess the deeper reason is that the sky is blue. That makes it more useful to have good vision in red and green.
If we needed good resolution everywhere, we might have had eyes optimizing for different colors, four eyes, etc.
Also, it isn’t as simple as this article describes. The human eye can vary its focal distance (https://en.wikipedia.org/wiki/Accommodation_(eye)) over a larger range than the effect of color aberration, so the eye _could_ optimize for having optimal focus for blue light or vary that over time.
One theory I've heard is that hunting for fruit was probably a major driving factor in human color vision, as well as that of other primates. Good red/green vision would've helped our ancestors search for ripe fruit (usually red) by being able to easily distinguish it from foliage and unripe fruit (usually green).
What's funny is that most mammals can't distinguish between red & green.
For example: the reason why tigers have red camouflage is that their prey cannot distinguish them from the background green of the forest, combined with the fact that mammals cannot create green pigment for their fur (yet).
i guess with red you get a similar effect. The green channel is the one that affects most the perceived intensity. If you blur the green everything becomes blurred.
I always wondered how the focusing actually works. It happens „automatically“, but what is involved? Are all cone types used for the focusing, or mostly the green-type ones? Or are there even special, dedicated cells for the focusing only? Does the control ober the muscle controlling the lens shape goes via the brain, or is there a more direct mechanism?
Is there an expert around to explain or give some links to explanations?
(as a side comment: as a teenager I learned to control the focus point to a certain degree. There were these pattern-3D images, „Magic Eye“, and since the perceived depth does not correspond to the actual distance of the image, they eye needs to correct. I guess the same applies to 3D cinema, and may well cause the eye strain reported by many)
This is amazing to see. We should use this for image optimization. When we compress channels, we should compress the blue channel to like 30% while keeping others at fairly large 80% and it might appear better than a 60% compressed image.
As triclops200 says, lossy image compression algorithms have long taken advantage of this. You might be interested in this page, Your Eyes Suck at Blue, which shows an image with the blue channel increasingly compressed:
I'd like to see what happens when the red channel is blurred. Digital images like JPGs seem to blur the red channel more than the blue and green channels.
The Himba tribe of Namibia cannot see the color blue (same tribe that Nike studied about running long distances). They are an isolated tribe that can't see blue ... The study included presenting a chart with 10 boxes where 9 boxes were green and 1 was blue but all boxes had the same hue (reasonable value that we can easily differentiate); and the entire village couldn't identify 'the one box that was different from the others'. They relocated an orphan newborn to another tribe and the child easily identified the color blue proving it wasn't genetic. It's weird how all the videos about it have been deleted. It was presented on a TED Talk and an unrelated National Geographic episode. A linguist on TED Talks did a whole talk on how vocabulary defines what we see. I wonder if this was a correction and hence, the removal.
>This is one of many examples of our brains being much more powerful than our eyes. Too often we think of our eyes as perfect cameras. However, it is the brain that is able to accomodate [sic] for all of the optical shortcomings in order to resolve the world.
While this is a description of the human brain and human eye it's interesting to me that it is a very accurate description of the progression of camera technology in the last few years as we shift from the supremacy of Big Glass to the amazing results from computational photography being applied to cell-phone sized lenses
I'm surprised the author doesn't mention the fact that only 2%-5% of the cone cells in our eyes can perceive blue. That's a huge factor in how well we process colors with blue light.
First, personal. I always thought something was wrong with my eyes because I couldn't focus on blue LEDs at night. I always thought either the LEDs have done irreversible damage to my eyes since some are so bright or that my eye is damaged some other way.
Second. This means we're missing so much about the world that we're not seeing. To be exact 33% or maybe even more if Earth has more blue than red and green, which I suspect it does last time I looked up.
Lots of doubt in the discussion here. I found this, and it’s not quite as elegant an explanation, but it seems to agree that it is due to chromatic aberration and the eye being tuned to focus on red and green light.
This would seem to explain why when you go to the optician, he's got a lot of red/green tests but never blue one as far as I can tell. The critical graph is the one with the blue peak to the left and the red and green near each other on the right.
Also it seems to hint that there's a fourth receptor that humans don't have in the gap region. Tetra-chromatic creatures do exist IIRC.
That was my first thought when reading this. On numerous times I've been watching a stage show and can see everything great. Then the lights turn blue and it's just a blue blur.
[+] [-] crazygringo|4 years ago|reply
After all, chromatic aberration is blurring of only a very, very small amount.
The demonstrated seemingly negligible perceptual effect of blurring blue to a huge degree in a multicolor image doesn't seem to have anything to do with that, but rather the fact that we perceive primary blue as a much darker color than primary red or green, and we perceive differences in lighter colors much more easily.
If the author were correct that we have big problems focusing on blue, then we'd see that blue text against a black background would be massively blurry -- but it's simply not. It's comparatively low-contrast (because blue is a dark color), but it's nearly indistinguishably as sharp as red and green.
[+] [-] GuB-42|4 years ago|reply
If it really was the effect of blue light, the effect should have disappeared by converting to grayscale.
It is well known that luminance matters much more than color when it comes to perceived sharpness. Digital and analog video exploit that by encoding color at a lower resolution (chroma subsampling). And blue only accounts for less that 10% of luminance while green is around 70%. You may find different values because color spaces are a mess but that's the general idea.
[+] [-] bacan|4 years ago|reply
Here are my results, with a 22px Gaussian Blur on the Channels
https://imgur.com/a/AS0LAyk
IMO The only reason the blue appears a little less blurry is that most of that color is in the water & clouds.
Not in the land masses, with the sharp borders
[+] [-] mrob|4 years ago|reply
[+] [-] sgtnoodle|4 years ago|reply
[+] [-] rst|4 years ago|reply
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.ht...
[+] [-] gisely|4 years ago|reply
[1] https://en.m.wikipedia.org/wiki/Cone_cell
[+] [-] crdrost|4 years ago|reply
I'm also not sure that the author is correct; the wrong-focal-distance explanation seems rather weak simply because our focal length is adjustable.
[+] [-] nickff|4 years ago|reply
[+] [-] jcoq|4 years ago|reply
[+] [-] isatty|4 years ago|reply
We are however, less sensitive to it so maybe the eye doesn't focus based on that channel(?).
[+] [-] gcanyon|4 years ago|reply
[+] [-] tigershark|4 years ago|reply
[+] [-] phnofive|4 years ago|reply
[+] [-] stkdump|4 years ago|reply
[+] [-] ddingus|4 years ago|reply
[+] [-] thehappypm|4 years ago|reply
[+] [-] TheOtherHobbes|4 years ago|reply
That description doesn't do it justice - you have to experience it to appreciate it. It's very striking and slightly surreal.
[+] [-] drcongo|4 years ago|reply
As a side note, some (many?) cultures around the world have no word for blue, blue is just other shades of green.
[1] https://en.wikipedia.org/wiki/International_Klein_Blue
[+] [-] archduck|4 years ago|reply
Paul and Kay (1969) argue for a linguistic universal which posits that the set of which colors a language has is a function of how many colors it has. (Stealing from https://en.wikipedia.org/wiki/Linguistic_relativity_and_the_...):
1. All languages contain terms for black and white. 2. If a language contains three terms, then it contains a term for red. 3. If a language contains four terms, then it contains a term for either green or yellow (but not both). 4. If a language contains five terms, then it contains terms for both green and yellow. 5. If a language contains six terms, then it contains a term for blue. 6. If a language contains seven terms, then it contains a term for brown. 7. If a language contains eight or more terms, then it contains terms for purple, pink, orange or gray.
The opposite of the grue phenomenon exists too, i.e. languages which subdivide the "blue" part of the spectrum into separate lexemes. In Russian, for instance, goluboy = light blue, whereas siniy = blue to dark blue. This morning I was reading the Wikipedia entry for color revolution, and there's a quote from Belarusian President Lukashenko, "They [the West] think that Belarus is ready for some 'orange' or, what is a rather frightening option, 'blue' or 'cornflower blue' revolution." I had to chuckle about that - it sounds so goofy in the English translation, but that's only because we don't have a lexical distinction there. (Now I would have personally translated it to light blue, but that's another matter.)
[+] [-] selestify|4 years ago|reply
For example, Blue Monochrome [1] seems to my uneducated eye to be just a layer of pure blue that every wall painter recreates every time they paint a wall blue. Why is the Blue Monochrome piece more than just a wall painted blue?
[1] https://www.moma.org/collection/works/80103
[+] [-] pier25|4 years ago|reply
Reminded me of the short story Zima Blue by Alastair Reynolds (which was adapted into an animation short on Netlifx's "Love, Death and Robots").
[+] [-] herbstein|4 years ago|reply
Yves Klein's "Leap into the Void"[1] is another one of his works that really grabbed me when I first saw it. Can't quite explain it. Those are the best types of art experiences in my book.
[0]: https://en.wikipedia.org/wiki/Stendhal_syndrome
[1]: https://www.metmuseum.org/art/collection/search/266750
[+] [-] Qub3d|4 years ago|reply
https://en.wikipedia.org/wiki/YInMn_Blue
[+] [-] mmaunder|4 years ago|reply
I’ve seen blue man group live and they have an otherworldly look in person, and I suspect it’s related to this phenomenon.
I really like his combination of blue and grey images.
[+] [-] agumonkey|4 years ago|reply
also how no art teacher ever told us about Klein's blue the way you did.. they simply used it as an authority figure
[+] [-] abeppu|4 years ago|reply
I'm convinced this is an intentional troll. This optometrist knowingly picked a sign to make people momentarily question their vision.
[+] [-] tobr|4 years ago|reply
[+] [-] mdeck_|4 years ago|reply
> 2 reasons: 1) You don't have the nearly as many short wavelength detecting blue cones as you do red and green in your fovea. 2) The angle of refraction is dependent on wavelength and short wavelengths get refracted more than relatively longer ones by your eye and therefore focus in front of your retina if you are myopic (nearsighted). The black lights are throwing off a ton of very short wavelength light and when coupled with the larger pupil you have in the dark it sets your eye up for a bunch of chromatic aberration. They should look clearer if you are hyperope or overcorrected in your myopic prescription, or if you view them at a closer distance.
[+] [-] culebron21|4 years ago|reply
Also note that blue neurons are also much less dense, and our eye blue channel has natively much lower resolution.
This is why in old Windows installers, blue color was used for gradient, when colors were 16 or 256 -- blue and black dots were blurred in the eyes, while the same combo of green dots was very visible.
A windows setup with blue background: https://guidebookgallery.org/pics/gui/installation/copying/w... (Don't have a green one, but one may try photoshopping this one.)
[+] [-] Someone|4 years ago|reply
If we needed good resolution everywhere, we might have had eyes optimizing for different colors, four eyes, etc.
Also, it isn’t as simple as this article describes. The human eye can vary its focal distance (https://en.wikipedia.org/wiki/Accommodation_(eye)) over a larger range than the effect of color aberration, so the eye _could_ optimize for having optimal focus for blue light or vary that over time.
(https://www.osapublishing.org/josa/abstract.cfm?uri=josa-68-... indicates humans can learn to do that in the lab)
[+] [-] throwaway8582|4 years ago|reply
[+] [-] crowbahr|4 years ago|reply
For example: the reason why tigers have red camouflage is that their prey cannot distinguish them from the background green of the forest, combined with the fact that mammals cannot create green pigment for their fur (yet).
[+] [-] briefcomment|4 years ago|reply
[+] [-] enriquto|4 years ago|reply
[+] [-] cgufus|4 years ago|reply
I always wondered how the focusing actually works. It happens „automatically“, but what is involved? Are all cone types used for the focusing, or mostly the green-type ones? Or are there even special, dedicated cells for the focusing only? Does the control ober the muscle controlling the lens shape goes via the brain, or is there a more direct mechanism?
Is there an expert around to explain or give some links to explanations?
(as a side comment: as a teenager I learned to control the focus point to a certain degree. There were these pattern-3D images, „Magic Eye“, and since the perceived depth does not correspond to the actual distance of the image, they eye needs to correct. I guess the same applies to 3D cinema, and may well cause the eye strain reported by many)
[+] [-] atishay811|4 years ago|reply
[+] [-] MaxBarraclough|4 years ago|reply
https://gamesx.com/misctech/visual.htm
edit See also this counterpoint: https://news.ycombinator.com/item?id=573593
[+] [-] uj8efdjkfdshf|4 years ago|reply
[0] http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.ht...
[+] [-] seunosewa|4 years ago|reply
[+] [-] parm22|4 years ago|reply
[+] [-] JacobDotVI|4 years ago|reply
While this is a description of the human brain and human eye it's interesting to me that it is a very accurate description of the progression of camera technology in the last few years as we shift from the supremacy of Big Glass to the amazing results from computational photography being applied to cell-phone sized lenses
[+] [-] seanalltogether|4 years ago|reply
[+] [-] ars|4 years ago|reply
[+] [-] soheil|4 years ago|reply
First, personal. I always thought something was wrong with my eyes because I couldn't focus on blue LEDs at night. I always thought either the LEDs have done irreversible damage to my eyes since some are so bright or that my eye is damaged some other way.
Second. This means we're missing so much about the world that we're not seeing. To be exact 33% or maybe even more if Earth has more blue than red and green, which I suspect it does last time I looked up.
[+] [-] mmaunder|4 years ago|reply
https://www.thenakedscientists.com/articles/questions/why-ar...
[+] [-] lordnacho|4 years ago|reply
Also it seems to hint that there's a fourth receptor that humans don't have in the gap region. Tetra-chromatic creatures do exist IIRC.
[+] [-] seba_dos1|4 years ago|reply
[+] [-] ulrikrasmussen|4 years ago|reply
[+] [-] obloid|4 years ago|reply