Limits of the Visible Spectrum

[@Chromaphobe]

FOOTNOTE 1: Some people believe this harmful light doesn’t stop at 400nm and extends into the visible spectrum in a phenomenon called blue light hazard. These same people are happy to fear monger you into buying mostly useless blue-light blocking glasses. The truth is, your lens is already taking care of the worst of those wavelengths by blocking out the UV light, and if the blue light was really bad for our retina, we probably would have evolved a lens that blocks out the blue light too. I’ll definitely have another episode on blue-blocking lenses soon though. FOOTNOTE 2: No, seriously! It is a convenient explanation to say that green is all light between 490-550nm, but almost none of the green you see consists of a single wavelength, and some colors cannot be reproduced by a single wavelength or continuous range of wavelengths. Light does not have a color until it interacts with your visual system, and depending on the parameters of your vision, the same light spectrum will evoke a different color. We only label 530nm as green, because it evokes green to the “standard observer”. Fish, birds, dogs and even myself have visual systems that differ from the standard observer, so 530nm does not evoke green for us. A better definition of color is to describe it in LMS color space, or the relative excitation of the three cone types, but even this is not perfect. Color models that seek to define color just keep getting more complex as we learn more about the human visual system. FOOTNOTE 3: If we really space the cones out evenly along the visible spectrum, we may be able to see a few more hyper-greens (where the green cone is excited in absence of the other cones) that were not perceptible before, but we would lose color resolution in other parts of our gamut. Overall, we wouldn’t notice “new” colors, just some different colors. FOOTNOTE 4: The pressure that led primates to very recently evolve separate green and red opsins is very contentious. There is a whole wiki page on it. Why our ancestors 400 million years ago originally evolved the blue cone (SWS opsin), and why we have retained it, or even why primates SWS more recently shifted to shorter wavelengths is… really anybody’s guess. FOOTNOTE 5: When opsin proteins bind to normal retinal (11-cis-retinal; A1), the red cone can reach a maximum peak wavelength (lambda max) of about 570nm, a bit longer than the human max. However, some animals use the same opsins with a different form of retinal (11-cis-3,4-dehydroretinal; A2) to achieve a peak wavelength of up to 620nm. Opsins with this retinal need less energy to trigger the phototransduction cascade, and therefore the IR limit is extended, but the tradeoff is lower sensitivity and noisier vision (Corbo 2021). Certain fish and amphibians that use the A2 retinal (see porphyropsin) may be able to see a bit deeper into the infrared than the rest of us. FOOTNOTE 6: Pit vipers and vampire bats have heat “vision” that is essentially IR perception. This works completely differently to normal vision and does not use the eyes or anything similar to opsin proteinss. Whether images are actually formed by this “vision” is contentious, so I’ve not included it here as IR vision, but maybe another good topic for a future video.

[@AllYourMemeAreBelongToUs]

"primates SWS more recently shifted to shorter wavelengths" Primates SWS is shifted to _longer_ wavelengths.

[@Chromaphobe]

Good catch! 100% right. Glad that's in the footnote and not the video. 😅

[@AllYourMemeAreBelongToUs]

@@Chromaphobe It’s easy to mix up. Light is often spoken about in terms of wavelength _and_ frequency two inversely proportional attributes. It’s all too easy to accidentally think in terms of one and speak in terms of the other. The magnitude of light either increases or decreases depending on what attribute you’re talking about. It’s easy to flub and say longer wavelength when you mean higher frequency. It happens to the best of us.

[@klikkolee]

Regarding footnote one: I don't think I have ever seen claims of physical damage from blue light in the marketing for those products. I have exclusively seen claims about effect on circadian rhythm, and especially claiming to prevent monitors and phones from interfering with the circadian rhythm

[@Chromaphobe]

After a few fines and lawsuits, most retailers have cleaned up their advertising. It was a lot different 3 or 4 years ago. en.wikipedia.org/wiki/Biological_effects_of_high-energy_visible_light

[@Travelin2Wit]

Interesting thing happened to me when I had both lenses replaced with prosthetic lenses. Blues were much more intense than previous. I researched it, the particular brand of lenses I had gotten allowed more UV light to be visible to me. Further research revealed that the famed Impressionist painter Monet, had cataract surgery and they knew back then - even though they had no prosthetic lenses that he would see into UV and because it might affect his paintings he was unwilling to have his other eye done. Instead of prosthetic lenses, thick lenses in glasses had to be worn. Monet continued to paint and his blues are more intense. There are some articles on this. I, on the other hand, got into 'All Spectrum' photography which uses modified equipment where the filters placed by manufacturers into cameras to block UV and IR are removed. I get very interesting photos without having to wait the long exposure times required in IR photograph. I just found your channel, can you do a video on the 'Retinex' algorithm, invented by Edwin Land and now the patent is held by NASA? It's used in image processing to make the hard to see more visible. Another interesting algorithm is 'Edge Detection.' Thank you for an interesting video.

[@Chromaphobe]

Monet is the best example. His vision immortalized in his paintings. Even with UV blocking artificial lenses, they will tend to let more blue in than the previous yellowed lenses, so cyanopsia is almost always a side effect of cataract surgery. We see that in Monet, and also as you describe your vision. I understand the foundation of retinex, but don't know the algorithm. I can look into that. Edge detection is cool, I actually am taking a machine vision course this semester and edge detection is pretty much the foundation of everything in the course.

[@raulcheva]

Very interesting. I just visited a Monet's exhibition and saw his corrective glasses were yellow(one eye yellower than the other).

[@Chromaphobe]

@raulcheva Ooh, those glasses look neat, where was that exhibit?

[@zimluura]

I've been geeking out on the electromagnetic spectrum for a few years now. Thanks for making this video. Tight editing! Good voice! Chill music. Subscribed.

[@Chromaphobe]

Glad you enjoyed it!

[@alexherrington9142]

Not sure how I got here, but awesome video. That back drop is insanely cool.

[@brianlivingston4753]

holy crap man I love youtube presenting more small channels recently. Excellent video cant wait to check out the rest😊

[@clawsoon]

Interesting video, thanks for making it! I was watching a video about military night vision goggles the other day, and the blackbody glow that everything gives off - and that warm things like food or predators give off more than cool things - seems like a potential evolutionary advantage for an animal that could develop effective IR vision. I guess the three possibilities are a) there's some animal that already does it that I don't know about, b) there's an evolutionary constraint that has made it too difficult to develop so far, or c) it's not as big of an advantage as I think it would be.

[@Chromaphobe]

Thermal vision definitely would be advantageous, but there are several factors that make it very hard to effectively "implement". As far as we know, thermal "vision" is in vampire bats and pit vipers and that's about it. That's definitely a future video topic.

[@clawsoon]

@@Chromaphobe Interesting! Do we know if the vampire bats and pit vipers have any sort of focusing/image formation ability, or is it more "there's something warm in that general direction"?

[@Chromaphobe]

Great question. The viper pits can't focus, but they are cupped, which can lead to some image formation similar to a mediocre pinhole camera. Furthermore, the nerves from the pits join the optical nerve very early on before they enter the brain, so their vision may be a very abstract mixture of normal vision and IR vision. There is also one study that shows that pit vipers cannot only see a mouse in pitch darkness, but can also strike it AND strike it at vulnerable spots (like the neck), so it supports them having IR image forming. Vampire bats on the other hand looks like no. As I understand, they will use their "thermal detector" to detect a big vein as they travel over the back of a cow for example, then no image is necessary. They just stop when they detect something warm and dig in.

[@clawsoon]

@@Chromaphobe Very informative, thanks!

[@AllYourMemeAreBelongToUs]

7:49 "There is so much conflation in pop sci between wavelength and color. Wavelength does not actually define color, seriously and seeing more spectrum does not equal seeing more colors." This is so true. And it's the source of my biggest vision misconception pet peeve, the erroneous idea that purple isn't a real color. (dichromats notwithstanding) I can't tell you how many times I've tried to convince people that purple is not less real than any other color even if there is no single wavelength associated with it only to fail. Another great episode Chromaphobe keep up the good work! Looking forward to the next installment in the evolution series.

[@Chromaphobe]

Just yesterday I watched another [6 year old] video from an educational youtuber I've gotten into recently, on the topic of tetrachromacy. The thesis was that tetrachromacy is not a superpower, and I was in, since I also believe human tetrachromacy is wholly overblown. Then he continued on with the whole "purple is an illusion" nonsense (i've got an older video on the topic) and elaborated that human tetrachomacy doesn't improve color vision because it doesn't expand the spectrum, and just makes "two colors easier to differentiate". My eyes went wide. I managed to not waste 20 minutes writing a nasty comment to the void, but I was close... I don't care if my friends have color misconceptions, but to promote this crap as an educational content creator... ugh.

[@ooqui]

@@Chromaphobe I think I know which video you're talking about. Apart from some scientific papers the infromation online about tetrachromacy is most often misinformed and misleading, or non-existent. Most often short articles and KZbin videos that just want to snatch some views by using the keywords "tetrachromat" and "tetrachromacy" are the worst. Tetrachromacy, depending on the use case of course, is definitely a "superpower". Not a (fictional) superpower like being able to fly, or reading minds, but definitely "super" in the sense that you'll be able to do things others can't. Being able to differentiate the visible color spectrum approximately two times better than normally by adding twice as many colors in between, where each color becomes a lot more unique due to the addition of a 4th (e.g. yellow) cone, doesn't "just make[...] 'two colors easier to differentiate'", it reshapes how we see colors entirely. Just like when the colors change drastically when we go from dichromacy to trichromacy, the colors will change drastically going from trichromacy to tetrachromacy (if the 4th cone is placed well, that is). Understanding human tetrachromacy takes time, and explaining it takes even more time. At this point I've spent about 2 years trying to understand tetrachromacy, pentachromacy, color vision, etc., and I'm still learning new things about these topics every day.

[@Hoellenmann]

"just be glad if you are not colorblind" 😰😥😭 I'm now gonna go shine some lasers into my eyes But seriously tho, nice video. As always

[@Chromaphobe]

😊 thank you

[@anothersquid]

My parrots use UV vision to seek out and destroy day-glo towels.

[@Chromaphobe]

Valid hypothesis. That must have been their evolutionary pressure. 😂

[@somnvm37]

08:20 wouls be very fun to see this using some professional cameras use UV camera and map its results to blue infrared camera for red and for normal camera its just green

[@Chromaphobe]

Ooh, this kind of wide-spectrum multispectral imaging would be sweet. I would love to shoot a whole video that does this, but I don't think I've got the cash for that... even cameras that shoot NIR-RGB are costly, let alone the UV...

[@somnvm37]

​@@Chromaphobewell, yeah thats bad but one of the options is (im case you really want) find someone on the internet whod either be willing to make a shoot with/for you or just send you full video/photo files or, maybr ig just find such stuff online. i know the man from "man who did thing"(dont remmember the name, smth like that) did that with a (boston dynamics style) dog robot . That could make for a really fun video, as there is barely any content on this topic, and a lot of people would be interested in alternative vision. Also you can use regular rgb in interesting ways. Like shoot a small clip, then swich and change colours in few ways, and show like: tritan vision for people with protanopia (ofc it wouldnt be the same mental image and so on), but what if what is red for tritans was shown with yellow/green pixels, and what is cyan/blue/green? for tritans will become blue/cyan. So now things that were destinct for 1 type of cvd are now destinct for another type of cvd. (i chose tritanopia because for me as a colournormal it looks the most forgiving, and also you once said it is at least kind of so). hopefully none of that sounded stupud or silly and i was polite. Sorry if it looked different.

[@fernandocacciola126]

A related question would be, why don't we have cones for 4, 10, 64 wavelengths, all within the same visible range? That might be interesting. Some people have Tetrachromacy (an additional cone), out of which they can distinguish millions of colors, and they often describe the color experience as overwhelming. So, I guess that if we could get a lot more color detail we might focus less on the other aspects of vision such as borders, shape, depth, etc...

[@Chromaphobe]

So this a controversial point... But... Your brain has got to process all that information. I don't think it's so much the dimensionality, but the number of total colors you can see that's important. Humans as trichromats see 1 million colors. It's often said as 100 colors per dimension, so 100*100*100. Pop sci often says that tetrachromats would therefore see 100 million. Unlikely. That just wouldn't fit in our brain, so to speak. We could have 6 cones, giving hexachromacy and see in 6 dimensions of color, but we'd probably just see 10 gradations in each dimension, giving still only 1 million colors, because that's all our brain can handle. And is 10x10x10x10x10x10 vision really that much better than 100x100x100 vision? Debatable.

[@fernandocacciola126]

@@Chromaphobe ah right this is a very good point.... I recall when computers had just one color, then a dozen, then 256, then the so-called True Color of today. And the deciding factor was always the required resources to handle it. In fact, a color depth higher than the standard 256 levels per channel is reserved to specific applications because of it. So right, it most probably is a matter of optimization, like basically everything else in our biological design.

[@Reluxthelegend]

"Don't shine lasers into your eyes" ~ Chromaphobe, 2023

[@Chromaphobe]

You're making my non-existant lawyers happy.

[@somnvm37]

they cant tell us what to do

[@brendan714]

Wow, I had an epiphany moment around 8:15 when you mentioned the widening of the visible range. It makes sense when you explain it, but my mind wants to imagine that being equivalent to some kind of super vision. So if you did want to genetically engineer "super colour vision", what would you do? Widen the excitation range but also add additional cones?

[@Chromaphobe]

I'd say the superness of color vision has very little to do with the breadth of the spectrum and mostly to do with the dimensionality, i.e. how many cones someone has. A hypothetical trichromat with a 200nm wide visible range would have much richer vision than me, a dichromat with a 270nm visible range. This is why tetrachromats are considered - and rightfully so - to have super color vision, regardless of the width of their visible range.

[@Chromaphobe]

But to get a bit more technical, its also important to note that there becomes a data processing bottleneck as you increase in dimensionality. Lots of tradeoffs must be made to have pentachromacy, for example. Also, there becomes a point where the spectral resolution of your cones is higher than necessary to resolve the spectral elements in the light spectrum (like Mantis shrimp), since most natural emission/reflectance spectra do not have sharp peaks that need to be chromatically resolved by high spectral resolution.

[@VariantAEC]

1:40 I resent that... even if ALVS doesn't rely on, might be enhanced by or maybe even adversely affected (though I don't know how yet) by the existence of lightning. Secondary electroreception has got some uses, like... well, accurately predicting lightning fall!

[@kiwipomegranate]

5:48 damn my lenses must’ve been protecting me from so much UV light in the womb, I guess my dad was being literal when he said my mom was like sunshine

[@ooqui]

My original comment is bugged, because of KZbin reasons I guess. Or because it's too long. So I'll post it here again in multiple comments. If you've already read my original comment and it's only bugged for me, please feel free to delete this one. (At least I don't see my original comment under this video with my other channel logged in.) My original comment: This is the reason why I've focussed my personal research on perceiving new (and/or more) colors within the visible range. It would be cool to see ultra-violet and infrared, but realisticly there's most often just not enough of that light, so it's perception is rendered almost useless. What exites me a lot more is adding a new cone type into our eyes and into the visible range. Just like when you get a lot more colors going from deuteranopia/protanopia to trichromacy, you'll be able to distinguish a lot more colors going from trichromacy to tetrachromacy. Of course we're still far away from (safely) adding such a new cone type to the human eyes, but there are other ways to achieve a similar thing. Though not by addition, but rather by subtraction. Color filters, especially band pass filters, can help people (I've tested this only on trichromats so far) distinguish more colors. There's a company called "Infitec", which makes glasses ("Triple Band Pass Glasses", short: TBP) with two lenses which together split the 3 trichromatic cones into 6 virtual cones with special band pass filters. You won't see "new" colors with these glasses, but because the colors are shifted differently for each eye you'll be able to notice more colors in everyday things, and you'll see new impossible color combinations which can look and feel like new colors (but technically aren't).

[@ooqui]

Especially human made unnatural light is sometimes very stunning to look at. Some (but not all) "yellow" lights, for instance, split perfectly into red for one eye, and green for the other eye. The resulting color is an impossible color combination of a very strong red and very vivid green. If this "yellow" light shone before on a reddish wall you wouldn't have noticed much of a color change. But because the TBP glasses change the "yellow" of one eye into a green you'll be able to see a lot more color changes. Some colors split more evenly, like some whites split into a very strong magenta and a very vivid green, which results in a color combination normally impossible (like the red-green) that is indescribably more different and unique from its original color. The company "Infitec" has made other special glasses, too, like the "Dualcolor 3D" glasses, which have double band pass filters, where one band pass filter in each lens is a lot broader than the other. Combining the right lens of the Dualcolor 3D glasses with the right lens of the TBP glasses makes you a little bit color blind in the green to blue range, because the band pass filters of the two lenses don't even out anymore, but you'll be able to see sooooooo much more colors in between green and red. Normal yellow looking flowers will then shimmer in a gradient of red to yellow with this special lens arrangement. Red becomes strinkigly more different from green. The beauty of not just seeing more color in, for example, flowers, but also seeing new impossible color combinations, like yellow-orange, yellow-red, orange-green, etc., made this past summer an otherworldy color experience for me. The downside of this method is that it doesn't work well in the dark or dim. If you subtract color (= light) instead of adding it there will admittedly be color changes and shifts, but you'll also see less light overall, even if the band pass filters of your two lenses even out perfectly. Also, because the world is made for neurotypical trichromats you sometimes have to search for colors that work well with the special glasses I've talked about. But when it works, then it works really well.

[@ooqui]

Furthermore, color is not the only property of light (at least as light is seen and distinguish by us humans). There are also other properties of light, like polarization and polarized light, which humans can normally not distinguish from normal light. But with linear polarization glasses where the polarization filter rotations of the two lenses are either 0/90 or 45/135 you'll be able to distinguish polarized from normal light (in the visible range). This polarization is encoded into the value (lightness/darkness) of color, because one lens dims one type of polarized light, while the other lens dims another type of polarized light. Together a 45/135 linear polarization lens combination (left eye 45°, right eye 135°) will help you distinguish objects and light by their polarization alone. From personal experience I can say that water polarizes light really well, a lot of plants polarize light very differently, the sky polarizes light to such an extent that you can sometimes tell the time of day and the sun's position by the polarization of the sky alone. Stones, skin, etc., and almost everything polarizes light very uniquely. Combine the 45/135 linear polarization glasses with Infitec's TBP glasses and you'll even be able to see the polarized light, which looked white/grayish before, in a dichromatic gradient. It's difficult describe how cool the world looks with this lens combination using only words. The visible range that humans can perceive, ever so small it may seem in comparison to the full electromagnetic light spectrum, packs already more than enough infromation about the everyday world. We just need to design technology that allows our eyes to better distinguish the differences we can already make. Also, I really liked this video! :D

[@Chromaphobe]

You're describing BINOCULAR DISPARITY, which has been used in colorblind aids before, namely the Monocular lenses like Chromagen or X-Chrom. I hadn't heard of the ones you describe and they sound way more sophisticated. I'll look into them, thanks! But I HAVE gone an hour on a lake wearing cross polarized filters as you describe. Interesting experience, but I guess not enough time for my brain to react and take advantage of the binocular disparity.

[@suditichaurasiya1902]

Can you please make a detailed video on the actual process or functioning of the opsin proteins, their composition and how they actually trigger electric signals deeply? And the deep biological concept about the errors in the gene that make you colourblind. I am actually looking for some deep scientific study into it. If not a video, then can you please just help with some links or websites where I can get better knowledge? I have been giggling my head with multiple places for my research without much results. Though your channel has been a huge- huge aid for my knowledge.

[@Chromaphobe]

I am hesitant to make a deeply technical video, as they do quite poorly, at least on this channel. I started the following wikipiedia article and made the graphics for the mechanism section: en.wikipedia.org/wiki/Congenital_red%E2%80%93green_color_blindness For my favourite journal papers on the relation of opsins and colorblindness, you can check out Sharpe 1999 or Neitz 2011: www.cvrl.org/people/stockman/pubs/1999%20Genetics%20chapter%20SSJN.pdf www.sciencedirect.com/science/article/pii/S0042698910005699

[@suditichaurasiya1902]

​@@ChromaphobeI understand your reluctance. Thankyou so much for the help!

[@arseniov.7809]

I’m curious, are there any eyeglasses to simulate a color blindness??? I know there are phone apps, but it’s not the same

[@Chromaphobe]

Variantor glasses can simulate protanopia, but they're 400 bucks.

[@SandeepKumar-fx6zg]

have you find some treatment about colorblindness

[@Chromaphobe]

Brother, there is none.

[@SandeepKumar-fx6zg]

@@Chromaphobe i want to be a pilot what should i do? OR shold i go for cabin crew with ishihara bypass method ? can you please explain completely for me ..... and i like your videos these are fantastic....

[@tirebiter1680]

Are there TV cameras that are sensitive to infra red or ultra VIOLET?

[@Chromaphobe]

There are video cameras that are used for machine vision, like in quality control in a factory, that have 5 color pixels, so the typical RGB plus UV and IR. You could absolutely use that camera and replace the R with IR and B with UV to get an image that simulates the broadened visual spectrum. A bit too expensive for this small channel though!

[@user-zn4pw5nk2v]

@@Chromaphobe if you use lorence transformation you can see all the em spectrum with the naked eye. You would just need the object emitting the light you want to see to be traveling in a circle forward and back near the speed of light relative to you.

[@Chromaphobe]

Ah yes, want to see infrared? Just travel towards it's source at 50% the speed of light! There's the real jackass genie solution.

[@tirebiter1680]

If there are cameras like this, snipers could have a powerful lamp on their guns that could be used to look at targets with invisable light. The sniper could watch them in the dark, by looking at something similar to a TV set. Don't try this using visable light, you willm make it easy for the target to see you.

[@user-zn4pw5nk2v]

@@Chromaphobe glad i could deliver. On (nobody's)your request. Cheers.

[@fredlllll]

"how come we can only see in the visible spectrum?" well cause its visible, duh XD

[@208467]

what about parrots?

[@Chromaphobe]

According to the figure below, budgies (dichromatic) and Keas (maybe tetrachromatic) both have the SWS1 opsin, which is what generally enables uv vision in birds. So we can extrapolate that most parrots have UV vision. www.researchgate.net/figure/The-presence-absence-patterns-of-avian-opsins-Green-circles-indicate-the-presence-of-a_fig4_282651548

[@Veraconah]

It's not junk.

[@merkdirwas]

groce, cant aphakia people see sperm and skin residue on beds , hotelrooms etc.

[@Chromaphobe]

Oh damn, that's a good question. Without the blacklight, there isn't enough uv illumination for the stains to really appear different to aphakics, I would guess.