While it is true that some saturated blue-green colors will never be reproducible with only 3 primary colors, the CIE 1931 chromaticity diagram used in TFA overemphasizes their importance, because human vision cannot distinguish many colors in that area of the diagram.
In reality, the greatest defect of the sRGB color space, which is still too frequently the default color space, is that it is not able to reproduce many saturated orange/red/purple colors, which are very frequently encountered around us, e.g. in flowers, fruits and clothes.
The missing orange-red-purple corner appears small in the diagram in comparison with the missing blue-green corner, but in reality humans perceive much more different colors in the orange/red/purple corner, so the relation between those areas would be opposite in a uniform color space.
The Display P3 color space is much better than sRGB for reproducing orange/red/purple colors and now it is available even in many cheap monitors. However many monitors that can reproduce Display P3 come configured by default to use just sRGB. Such monitors should always be reconfigured to use Display P3.
Monitors that can reproduce an even greater part of the Rec. 2020 color space are obviously better than those that can do only Display P3, but such monitors with a higher color gamut are usually more expensive. The full Rec. 2020 color space can be reproduced only with laser projectors, because it uses monochromatic primary colors.
> The full Rec. 2020 color space can be reproduced only with laser projectors, because it uses monochromatic primary colors.
All of the non-commercial triple laser projectors I'm aware of are single-chip DLP, so they suffer rainbow artifacts and have poor black levels. They're also liable to laser speckle[^1] if you're not careful on your screen selection.
The JVC (LCoS), Sony (LcoS) and Epson (LCD) laser projectors all use a single blue LED laser and phosphor wheel to make white light, then use prisms and filters to split it to RGB and can only get 87-98% of DCI P3. They have better blacks and no rainbow artifacts, but the color reproduction is not as complete.
As I understand it, JPEG cuts out a lot of detail in the blue range, because we don't see it as well. Is that due to the same thing as you're saying here?
That has more to do with RGB -> YCbCr conversion, and how much blue contributes to Y (brightness). If you quantize YCbCr down to 8-bit range (0-255 range), you'll get RGB colors that can't survive a round trip back between RGB and YCbCr, but I don't think blue is particularly worse there.
JPEG is a different thing, first it does RGB -> YCbCr conversion, then it splits the image into blocks. Wikipedia article shows a good diagram of the 64 possible DCT blocks. Each image block becomes a linear combination of the DCT blocks. You did that for the Luma channel, then you do the same thing for the Chroma channels. It's even common to reduce the resolution of the chroma channels (chroma subsampling).
Then JPEG means that you are deleting information that is less popular after you've made your blocks. Often throwing out more information in the chroma channels than the luma channel. You're left with ringing (high frequency noise to fill the block), and blocking (differences between edges of adjacent blocks). Better compression codecs have ways of mitigating blocking and ringing.
> the relation between those areas would be opposite in a uniform color space.
If I understand correctly fig. 3 in [1] should be perceptually uniform. The bluegreens missing from sRGB, but present in BT.2020 comprise a sizeable chunk comparable to redyellows.
Indeed, "Figure 3" from that article should be a realistic depiction of the differences between sRGB, Display P3 and BT.2020.
It is true that both the red and green primary colors of sRGB are bad (because they correspond with obsolete CRT phosphors that have not been used for decades), but in practice the defects of the green primary color are much less important, because the objects with saturated green colors are more rarely encountered.
Like I have said, objects with saturated orange/red/purple colors are very frequently encountered, even in most homes, e.g. flowers, fruits, clothes, blood.
Photographs or movies showing such objects that have been recorded using a wider color gamut look extremely differently on an sRGB monitor vs. a monitor supporting Display P3 or an even wider color gamut.
Only very rarely I have seen examples with obvious differences between monitors when showing green objects, e.g. some documentaries with certain vividly colored animals, like some insects, birds, frogs or lizards.
> Only very rarely I have seen examples with obvious differences between monitors when showing green objects, e.g. some documentaries with certain vividly colored animals, like some insects, birds, frogs or lizards.
According to the article you get purified greens from transmittance through foliage, ie backlight in eg a maple forest. This makes me suspect that it may be more important than just exotic animals, and maybe we are more sensitive to ”greens” than we think? For instance, a lot of my photography of trees/forests tend to feel much more ”green brown mess” and loses structure when going from reality to screen. (Another explanation is that my photos are bad, but I like that one less)
> According to the article you get purified greens from transmittance through foliage, ie backlight in eg a maple forest.
This sounds plausible. I think that in general for content that you record yourself, where you would record whatever is interesting, e.g. the more unusual things, especially outdoors, it is more likely for all the parts of the color space to be important.
My point was that for the content most frequently watched on a monitor, like commercial movies, it is much more likely that the main effect of using the obsolete sRGB color space is to see a lot of objects whose color is in the orange/red/purple area and which appear to have washed-out colors.
In almost any commercial movie, if I switch at almost any point between a Rec. 709 copy on an sRGB monitor and a Rec. 2020 copy on a Display P3 monitor I immediately notice some reddish objects that have become more vivid, looking like in real life, while on sRGB they look abnormally dull.
Until a dozen of years ago, I had used for many years sRGB monitors and I was content with them, but immediately after I used for the first time a Display P3 monitor I could no longer enjoy sRGB photographs or movies, because now their limitations had become obvious.
I think the lack of depth perception in a 2D photo is another big factor in why the magic of a forest can’t be captured. There are so many different layers that all get flattened!
There is so much going on in a modern digital camera between what the sensor captures and what is stored on the flash card that you might be a perfectly fine photographer and it’s the software in the camera that just doesn’t get your style.
Not to mention the Color Rendering Index (CRI) metric Ra does not weigh the R9 (deep red) so many forms of lighting don't try to render it correctly to save costs.
This is truly an (accidental?) setback of color reproduction as it has progressed over time. For LED lights R9 is also crucial for skin tones which makes it so bad to just leave that out. Now, the mass produced LEDs are even optimized for CRI at all are virtually all excluding R9, which may be one of the main quality issues that many people perceive with LEDs vs eg incandescent. There’s of course more to it but R9 probably has a disproportionate effect for being a ”minor detail”.
It is not reported often by the manufacturer, but SSI and TLCI numbers can be a better metric if available. They are used by the Broadcast/Photography community to match the spectrum's similarity to Sunlight.
There's color space and there's color depth. You may be using D-P3 with 8 bit, which is worse (less accurate?) than sRGB with 8 bit. And there's bandwidth. Your monitor may not be able to handle 4k 240fps 16 bit.
You are right that I have not mentioned this, but indeed wide color gamut monitors should also support 10 bit or better resolution per color component.
Software that does color processing should convert all input pixel formats into BT.2020 linear FP16 color components, do whatever processing is desired and convert from linear FP16 to whatever pixel format is sent directly to the monitor through DisplayPort/HDMI, as the last step.
I have not looked on the market to see how widespread are different kinds of monitor specifications nowadays.
I am using relatively cheap monitors, but not the cheapest, e.g. some common types of Dell monitors. There are more than ten years since my minimal requirements for a monitor have been 4k resolution, 10-bit color components and Display P3 color gamut and 60 Hz at 4k and 10-bit.
So I believe that, especially after a decade, it is easy to satisfy these minimal requirements or better, except that not everybody checks the monitor specifications when they buy one.
> Your monitor may not be able to handle 4k 240fps 16 bit.
10 bits per channel is the common target for higher color depth. The formats with 16 bits per channel are generally for image storage and allowing more bits for downstream transforms to avoid quantization. I don’t even know if there are video cards that would output 16 bits per channel, let alone panels for it.
These days cheaper monitors with only 8bpc support advertising higher color support use FRC to flicker between different 8-bit colors at a high enough rate to trick the vision receptors to seeing a mix between the two.
Separately, sorry to nitpick, but while wide gamut colors with only eight bits of data have lower resolution than sRGB, that doesn’t make them an inferior option. You might not be able to specify the exact shade but a) your effective accuracy is still greater and b) you trade that for greater range.
Just as an example, assume you have buckets of granularity 1 (sRGB) and 0.5 granularity (wide gamut). With only eight bits you can precisely select any individual bucket of granularity 1, whereas with only eight bits you sometimes miss the intended wide gamut 0.5 precision bucket and hit its neighbor instead (as if you had a granularity of 1 in this specific worst case). That doesn’t make it worse; you just aren’t taking full advantage. On top of that, your range with granularity one is, say, 200 to 800 while your “range” with the wide bucket is 0 to 1000 (just as an example).
There’s a reason photos or graphics saved as eight-bit png or jpeg still manage to look ten times better in a wide gamut profile than in sRGB (on a better-than-sRGB display).
I took up acrylics painting a few years back and I've been surprised by how much is lost in photos and videos. The two colors with which I've noticed this the most are ultramarine blue and prussian blue. I don't think it's just the color though, part of it comes down to how light is reflected off the painting and where you're standing, as well as the texture and the brush strokes. I have a few paintings hanging in my room and occasionally I'll look at them for a while and it'll reveal a new perspective to me that I had previously missed, despite being the one who made it.
This post is making me feel a bit inspired to go outside and immerse myself in the forest to take in the greens. Thanks for sharing.
Thanks mentioning acrylics. Now I'm wondering if new technology will eventually improve our printing to allow better colors in news media, and even in prints in art exhibits?
Does anyone have any comments on the future of printed media?
The phosphor screen of a B&O MX8000 TV (a Philips tube) was unlike any I’ve ever seen in terms of cyan intensity. That was in 2020 while the tv is from the 1980’s. Playing Donkey Kong on it was totally different than any other screen. It was like a Morpho butterfly, but in the article it is pointed out that phosphor screens have limited color range.
Triangles between screens may differ with tuning, but I suppose they all are limited in range. I’ve yet to experiment if this experience was a “brand experience” because I liked the TV or that the colors are indeed more intense than even some HDR/DV flat screen from the past few years.
This article was so well written that it gives a lot of energy to make this comparison for real. Absolutely masterful writing and all of the plenty examples make me want to look for colors I’ve missed out on while watching so many screens.
What the article does very well is vibrantly describe what you are missing and then post an image of it, such as a beach. Looking at that image, it falls absolutely flat compared to memories and the imagination of those places. This makes it tangible how limited screens really are.
I’m not sure it’s possible to truthfully describe what we are missing in reality with a photo.
You can publish a photo with default automatic JPEG processing, say by a phone, and it will certainly look flat. You could also present a masterful interpretation of raw sensor data that uses the most out of the available display space, and the impression might be different.
There is no objectively correct way to represent reality in a photo; even the concept of neutral grey is not a real thing as soon as perception is concerned. A default camera interpretation of light is baseline and safe to maximally avoid awkward edge cases. We all know that time we photograph a bright pink sunset but our phone renders it as pale yellow or orange. However, give the same shot human attention, and even though it may never be as pink as what you have perceived in reality it will pop enough that the viewer will have a similar response.
It is photographer’s job to work raw data in specific ways and make what impressed you stand out to your audience, arranging colours both relative to each other and in absolute display space, however limited it is. Human eyes are incredibly adaptive: we lower our relevant thresholds, adjust our idea of neutral grey—in short, we adapt to given display medium, to given photographic style, etc., and in the end perceive a true lush lagoon in a photo even if our eyes only receive a truly minuscule amount of colour range present in the scene.
The original 1953 NTSC standard specified phosphors with a way bigger gamut than sRGB, that were chosen to approximate the gamut of film projectors.
Original NTSC cyans are more saturated than even DCI-P3 cyans.
Typical CRTs use the cheaper, brighter phosphors specified by SMPTE C (the basis for the sRGB gamut) and a circuit that pumps the saturation to compensate.
It's likely your screen uses the better phosphors instead of a colour correction circuit.
What I missed in the article: the curves of the three “cone kinds” overlap. What if you could stimulate kinds of cones individually to see entirely new colors? Some people shoot layers at them into eyes. But you can also try this website: https://dynomight.net/colors/ (previously on HN but search fails me).
Through the magic of liner algebra it turns out that you can stimulate cones independently even with normal displays. Search for 'silent substitution'!
Somewhat related, but TIL the macOS Screenshot.app utility (and the system wide keyboard shortcuts) in Sonoma got HDR capability to help re-convey just a bit more fidelity. Even in PNG, it keeps the display profile, just not HDR.
Open Utilities->Screenshot.app Options->Capture/Capture Format->HEIC.
Note, it changes the system screenshot default away from PNG too.
Really nice article, I'll look closer to green lights next time I see one.
The most striking experience I had was working with a blue laser (430nm). The best way I found to describe its color is that it was screaming "blue" at me. Since then, I'm always disappointed when looking at a screen displaying #0000FF.
"This is a good time to spare a thought for our red-green colorblind brethren. [...] it is to them that we owe the beautiful color of green traffic lights. The spectral requirements that make the green signals distinguishable from red in their eyes make them beautiful in ours."
Really enjoyed the article, even though it's not a new topic to me, but still it was very interesting, very nicely written and I still managed to pick up a couple of new details.
To be fair to Jurassic Park, though, at least in the book the quirks of T-Rex's vision were explained by the details of genetic engineering (the base DNA used was some kind of amphibian, that allegedly had this problem — still not very scientifically plausible, but not quite as silly as in the movie). It goes a long way to emphasize that in the end these are not real dinosaurs, these are human-made abominations.
Doesnt Dr Grant scare a kid in the beginning with the Velociraptor and say there that T Rex vision was movement based? I wonder if Chrichton made that up or if it was a real theory by paleaologists?
Incredible article.
I used to work as a light designer and therefore spent lot of time thinking about colors and training my eyes to see them more precisely.
I lost some of this competency surprisingly quickly, but this article brought many great feelings/souvenirs back.
ACES AP0 is the only color space I know that is designed to represent all possible visible colors. It's a purely theoretical color space, though. The widest color space designed for actual implementation, Rec. 2020, still can't faithfully show most of the natural greens and cyans, like your green laser pointer.
Its unclear to me why the color space is 2-dimensional. Why wouldn't it be a 3-dimensional space, indexed by how much each of the 3-cones is activated ? Not clear to me from the article!
It is 3 dimensional. That commonly repeated CIE diagram is a 2d slice of the color volume. Since 1931 that diagram is obsolete, misleading, and fails at a lot of modern color science, and has been replaced many times, but is what many people go to. The most recent replacement (well, by CIE), is CIE 2015. Comment on it [1]
Modern color modeling is much richer then 3 parameters, because human vision is much more complex than simply color frequencies. CIE 1931 was low brightness, 2 degree field of vision, center of vision derived. As brightness increases, color perception shifts. Colors are NOT linear; sRGB and CIE 1931 chose such a small section of human vision that they approximate that section with a linear assumption. Modern CIECAM models are not linear, are not 3 parameter, because color is not linear (CIECAM02 is 6 parameter [2], there are several after that one). A century of experiments, wide color gamuts, HDR, have thrown out CIE 1931 as a good model. It’s only momentum now, and slowly higher end things are replacing it.
A good introduction is Color Appearance Models, by Mark Fairchild, also any of his technical papers give a starting point into the science.
It is, inasmuch as we have 3 types of cone, which is an inherent orthogonality. It is also not, inasmuch as each cone is a wavelength in the same spectrum.
Either way, you can project a volume onto a plane, which is great for communicating visual data on paper or screen.
The interesting question is "why that arc in particular"; my ignorance will shine through if I speculate.
I assume that the projection encodes something about our relative perception of each cone's band, hence the big green corner.
It is 3 dimensional, because in our perception we see the third dimension of magentas and purples, which do not exist in physical reality on the spectrum.
There are three cones, but there is an additional constraint that we plot the colors at maximum summed luminosity. So for one cone you would just have a point; two would show a line from 0% cone A+100% cone B -> 100% cone A; three is a plane
>indexed by how much each of the 3-cones is activated
This will actually differ from person to person. If you look at a pure yellow wavelength light next to a red/green light mixed such that they create the exact same perceived yellow to you, it will look different to another person.
Aside from that, not really sure what a 3d view with the dimensions being r,g,b would actually offer
If we had a display with n (n>3) pixel colours, say (red, green, cyan, blue) for example, we could display more of the colour space. Shopping list: 4 colour channel display, 4 channel GPU, 4 channel software. Why isn't this a thing already?
5) You'd need image formats that record those channels, and that in turn would cause problems for raw bitmaps with alpha (they either get twice as big or the pixels are no longer aligned).
> Nearly every species of scorpion intensely fluoresces under UV light. […] Scorpions have photoreceptors in their tails, separate from their eyes. […] It is hypothesized that a scorpion uses this fluorescence to tell whether any bit of its body is left exposed from its hiding place. Its tail “looks” down at its body, and if it sees its own fluorescence, it knows it is exposed to light, and in danger.
And a special call-out to the “Andean Cock-on-a-Rock” :), see a photo in the article.
My debatable factoid is that all vision is movement-dependent, including human vision, and so the bigness and wonderfulness of the tyrannosaur's eyes is beside the point of whether it needed its prey to move around in order to perceive it.
I do have a question that the article doesn't seem to attempt to answer, though. The article says (paraphrased in my new understanding) that any spectra which makes the cones in your eyes react the same way will result in seeing the same colour. Do we know of any examples of this?
(Colour-blindness seems like an obvious example; I'm curious though if there are any examples of two common scenarios where it can be demonstrated that there are different spectra in each, and yet most people will see them as the same colour.)
This is called metamerism. It can be a practical issue if two pigments have the same color under one light source, but a different one under another. You want your artificial teeth to have the same color as your real teeth in sunlight, led light, and a classic lightbulb for example.
Well, now that you mention it, I'd just like to remind you that people are a lot weirder than you might think! Having incisors to be a different colour (say, a brilliant red) under artificial lights could definitely be a thing people desired..
Well, the most common example si precisely screens, no? A screen displaying the color yellow is actually a spectrum of red and green peaks, stimulating your red and green cones just like a spectrum containing a single frequency of the color yellow.
Would not the definitive answer to this be a computer screen.
On one side you have an apple, illuminated by natural sunlight. it fills your eye with a rich texture of subtly mixed frequency's covering the whole gamut of visible and invisible light. On the other a picture of an apple composed of brutal pure frequencies only emitting at 430, 540, 570 Nm. Can you tell the difference?
That makes sense. I feel a little silly that that's not something I considered despite the article saying exactly that. I think I got caught up in the details.
Very well written, super interesting topic. I never understood all these natural reasons why real life colors feel so much more vivid. I guess when I look outside of the rgb triangle in the graphic, the cyans/blues/greens shown (since I'm seeing this on a screen) are sort of shadow colors? Approximations without the full vibrancy?
Reading this made me realize how much of my day is spent looking at screens. It's weird to think there are colors in the world that I've technically seen before, but have never actually been able to capture or reproduce digitally.
Impressionist paintings used a lot of synthetic ultramarine, they look very different IRL. There is a whole room in the Orsay museum where paintings seem to glow from the inside in the dark.
Great article. Small nitpick though: while I understand that P3 deserves specific mention because it’s so ubiquitous now, it’s not like Apple invented the idea of wide-gamut displays. Adobe RGB, commonly used by wide-gamut computer monitors, in particular is noteworthy in the context of this article because it extends further into the blue-cyan-green than P3,
My favorite color in all the world is the green of a mineral called dioptase. It's a deep, dark green, richer than an emerald. It looks amazing in real life and utterly boring on an RGB display. The Houston Museum of Natural Science has a large sample; every time I'm there I go stare at it for a while.
This reminds me of a video [1] going over the use of structural color photography, where theoretically what you see in real life is what you get in your final image. It cover some of the same topics, but goes more in depth about the process of structural color and some animal examples, like the butterfly mentioned in the article. If you have an interest in chemistry or film photography it is a great watch! This process was also, to my knowledge, the stepping stone for holograms, which we can now see structural colors everyday on IDs and licenses.
I hate that type of diagrams. Why sRGB-encoded image, pretends to show any color outside of sRGB region? It doesn't make any sense! (and when these diagrams attempt to illustrate sRGB, often actual colors encoded are narrower than full sRGB)
Ultramarine pigment is too blue for your screen to replicate properly, for example. I don't know if there's a pigment that reflects only 520nm light, though.
For printing there was PANTONE's Hexachrome which used 6 ink colours to greatly extend the possible colour range --- but the only printer I know of who made great use of, and profited by doing so, used it only for its increased range's covering of additional spot colours --- so they basically persuaded every printer w/in driving distance to sub-contract spot colour work to them (for those colours which fit in the Hexachrome gamut), then used fancy software to gang up jobs onto a plate, run as many copies as were necessary, cut and stack, and then send out the jobs and run the next plate, no need to wash down the press and change inks.
I tried to sell the idea of implementing it for high-end photo pieces at a printer I worked at, but no real interest because it was difficult for sales to communicate, and no one wanted to spend money printing a sample/researching images which benefited from it.
Many colours outside of the electric screen spectrum can be made with ink or paint. You probably have a bunch of objects in your own house with colours that can't be shown as full on your screen.
I once abseiled into a crevasse while in Antarctica. The colours I saw in there were utterly breathtaking and I never knew why. Now I do, and this also tells mewhy the photos don't even remotely do it justice (aside from not being as big and three dimensional!)
Thanks for such a beautiful article about not looking at a screen: I'm off outside... :)
What an truly incredible article, particularly the way the color space diagrams are used to gradually tell the story (and the prose is great too). I actually want to read it again tomorrow morning in more depth.
I'm having an amazing time seeing colors now because I just had cataract surgery on my right eye (left eye next month) and have a clear lens again. If I compare my new right eye to my old left eye, I'm seeing colors I haven't seen in decades. Skies look blue with my right eye, gray with my left.
It's odd he noted Apple monitiers were "better". Maybe but marginally. Many options for other platforms, like Asus Pro Arte, beat it handily. And profressional color graders use Sony BVM series (Trimaster HX / OLED) for HDR or Flanders Scientific (FSI) DM/XM series or Eizo ColorEdge CG series. You won't see a single Mac at a movie studio for movie editing or color grading.
Colors on the screen are like symbols. Like words. they aren't the actual experience. They evoke the experience. Your mind connects the color to a memory and then it's the memory that you experience.
That's screen reality. 1% evocative symbols and 99% in your head.
While it is true that some saturated blue-green colors will never be reproducible with only 3 primary colors, the CIE 1931 chromaticity diagram used in TFA overemphasizes their importance, because human vision cannot distinguish many colors in that area of the diagram.
In reality, the greatest defect of the sRGB color space, which is still too frequently the default color space, is that it is not able to reproduce many saturated orange/red/purple colors, which are very frequently encountered around us, e.g. in flowers, fruits and clothes.
The missing orange-red-purple corner appears small in the diagram in comparison with the missing blue-green corner, but in reality humans perceive much more different colors in the orange/red/purple corner, so the relation between those areas would be opposite in a uniform color space.
The Display P3 color space is much better than sRGB for reproducing orange/red/purple colors and now it is available even in many cheap monitors. However many monitors that can reproduce Display P3 come configured by default to use just sRGB. Such monitors should always be reconfigured to use Display P3.
Monitors that can reproduce an even greater part of the Rec. 2020 color space are obviously better than those that can do only Display P3, but such monitors with a higher color gamut are usually more expensive. The full Rec. 2020 color space can be reproduced only with laser projectors, because it uses monochromatic primary colors.
> The full Rec. 2020 color space can be reproduced only with laser projectors, because it uses monochromatic primary colors.
All of the non-commercial triple laser projectors I'm aware of are single-chip DLP, so they suffer rainbow artifacts and have poor black levels. They're also liable to laser speckle[^1] if you're not careful on your screen selection.
The JVC (LCoS), Sony (LcoS) and Epson (LCD) laser projectors all use a single blue LED laser and phosphor wheel to make white light, then use prisms and filters to split it to RGB and can only get 87-98% of DCI P3. They have better blacks and no rainbow artifacts, but the color reproduction is not as complete.
Which is to say, it's still a compromise in projector land, unless you've got $400K for a https://www.christiedigital.com/products/projectors/all-proj...
[^1]: https://www.valerion.com/blog/triple-laser-speckle
As I understand it, JPEG cuts out a lot of detail in the blue range, because we don't see it as well. Is that due to the same thing as you're saying here?
That has more to do with RGB -> YCbCr conversion, and how much blue contributes to Y (brightness). If you quantize YCbCr down to 8-bit range (0-255 range), you'll get RGB colors that can't survive a round trip back between RGB and YCbCr, but I don't think blue is particularly worse there.
JPEG is a different thing, first it does RGB -> YCbCr conversion, then it splits the image into blocks. Wikipedia article shows a good diagram of the 64 possible DCT blocks. Each image block becomes a linear combination of the DCT blocks. You did that for the Luma channel, then you do the same thing for the Chroma channels. It's even common to reduce the resolution of the chroma channels (chroma subsampling).
Then JPEG means that you are deleting information that is less popular after you've made your blocks. Often throwing out more information in the chroma channels than the luma channel. You're left with ringing (high frequency noise to fill the block), and blocking (differences between edges of adjacent blocks). Better compression codecs have ways of mitigating blocking and ringing.
> the relation between those areas would be opposite in a uniform color space.
If I understand correctly fig. 3 in [1] should be perceptually uniform. The bluegreens missing from sRGB, but present in BT.2020 comprise a sizeable chunk comparable to redyellows.
[1] https://www.researchgate.net/publication/345252499_Evaluatin...
Indeed, "Figure 3" from that article should be a realistic depiction of the differences between sRGB, Display P3 and BT.2020.
It is true that both the red and green primary colors of sRGB are bad (because they correspond with obsolete CRT phosphors that have not been used for decades), but in practice the defects of the green primary color are much less important, because the objects with saturated green colors are more rarely encountered.
Like I have said, objects with saturated orange/red/purple colors are very frequently encountered, even in most homes, e.g. flowers, fruits, clothes, blood.
Photographs or movies showing such objects that have been recorded using a wider color gamut look extremely differently on an sRGB monitor vs. a monitor supporting Display P3 or an even wider color gamut.
Only very rarely I have seen examples with obvious differences between monitors when showing green objects, e.g. some documentaries with certain vividly colored animals, like some insects, birds, frogs or lizards.
> Only very rarely I have seen examples with obvious differences between monitors when showing green objects, e.g. some documentaries with certain vividly colored animals, like some insects, birds, frogs or lizards.
According to the article you get purified greens from transmittance through foliage, ie backlight in eg a maple forest. This makes me suspect that it may be more important than just exotic animals, and maybe we are more sensitive to ”greens” than we think? For instance, a lot of my photography of trees/forests tend to feel much more ”green brown mess” and loses structure when going from reality to screen. (Another explanation is that my photos are bad, but I like that one less)
> According to the article you get purified greens from transmittance through foliage, ie backlight in eg a maple forest.
This sounds plausible. I think that in general for content that you record yourself, where you would record whatever is interesting, e.g. the more unusual things, especially outdoors, it is more likely for all the parts of the color space to be important.
My point was that for the content most frequently watched on a monitor, like commercial movies, it is much more likely that the main effect of using the obsolete sRGB color space is to see a lot of objects whose color is in the orange/red/purple area and which appear to have washed-out colors.
In almost any commercial movie, if I switch at almost any point between a Rec. 709 copy on an sRGB monitor and a Rec. 2020 copy on a Display P3 monitor I immediately notice some reddish objects that have become more vivid, looking like in real life, while on sRGB they look abnormally dull.
Until a dozen of years ago, I had used for many years sRGB monitors and I was content with them, but immediately after I used for the first time a Display P3 monitor I could no longer enjoy sRGB photographs or movies, because now their limitations had become obvious.
I think the lack of depth perception in a 2D photo is another big factor in why the magic of a forest can’t be captured. There are so many different layers that all get flattened!
There is so much going on in a modern digital camera between what the sensor captures and what is stored on the flash card that you might be a perfectly fine photographer and it’s the software in the camera that just doesn’t get your style.
Not to mention the Color Rendering Index (CRI) metric Ra does not weigh the R9 (deep red) so many forms of lighting don't try to render it correctly to save costs.
This is truly an (accidental?) setback of color reproduction as it has progressed over time. For LED lights R9 is also crucial for skin tones which makes it so bad to just leave that out. Now, the mass produced LEDs are even optimized for CRI at all are virtually all excluding R9, which may be one of the main quality issues that many people perceive with LEDs vs eg incandescent. There’s of course more to it but R9 probably has a disproportionate effect for being a ”minor detail”.
what's the alternative metric to look for as a consumer?
It is not reported often by the manufacturer, but SSI and TLCI numbers can be a better metric if available. They are used by the Broadcast/Photography community to match the spectrum's similarity to Sunlight.
There's color space and there's color depth. You may be using D-P3 with 8 bit, which is worse (less accurate?) than sRGB with 8 bit. And there's bandwidth. Your monitor may not be able to handle 4k 240fps 16 bit.
You are right that I have not mentioned this, but indeed wide color gamut monitors should also support 10 bit or better resolution per color component.
Software that does color processing should convert all input pixel formats into BT.2020 linear FP16 color components, do whatever processing is desired and convert from linear FP16 to whatever pixel format is sent directly to the monitor through DisplayPort/HDMI, as the last step.
I have not looked on the market to see how widespread are different kinds of monitor specifications nowadays.
I am using relatively cheap monitors, but not the cheapest, e.g. some common types of Dell monitors. There are more than ten years since my minimal requirements for a monitor have been 4k resolution, 10-bit color components and Display P3 color gamut and 60 Hz at 4k and 10-bit.
So I believe that, especially after a decade, it is easy to satisfy these minimal requirements or better, except that not everybody checks the monitor specifications when they buy one.
> Your monitor may not be able to handle 4k 240fps 16 bit.
10 bits per channel is the common target for higher color depth. The formats with 16 bits per channel are generally for image storage and allowing more bits for downstream transforms to avoid quantization. I don’t even know if there are video cards that would output 16 bits per channel, let alone panels for it.
I don’t think 16 bpc is supported in the standard consumer workflow but I believe 12 bpc is?
> 4k 240fps
As a cinema enthusiast, I say 24 fps ought to be enough for anyone.
These days cheaper monitors with only 8bpc support advertising higher color support use FRC to flicker between different 8-bit colors at a high enough rate to trick the vision receptors to seeing a mix between the two.
Separately, sorry to nitpick, but while wide gamut colors with only eight bits of data have lower resolution than sRGB, that doesn’t make them an inferior option. You might not be able to specify the exact shade but a) your effective accuracy is still greater and b) you trade that for greater range.
Just as an example, assume you have buckets of granularity 1 (sRGB) and 0.5 granularity (wide gamut). With only eight bits you can precisely select any individual bucket of granularity 1, whereas with only eight bits you sometimes miss the intended wide gamut 0.5 precision bucket and hit its neighbor instead (as if you had a granularity of 1 in this specific worst case). That doesn’t make it worse; you just aren’t taking full advantage. On top of that, your range with granularity one is, say, 200 to 800 while your “range” with the wide bucket is 0 to 1000 (just as an example).
There’s a reason photos or graphics saved as eight-bit png or jpeg still manage to look ten times better in a wide gamut profile than in sRGB (on a better-than-sRGB display).
I took up acrylics painting a few years back and I've been surprised by how much is lost in photos and videos. The two colors with which I've noticed this the most are ultramarine blue and prussian blue. I don't think it's just the color though, part of it comes down to how light is reflected off the painting and where you're standing, as well as the texture and the brush strokes. I have a few paintings hanging in my room and occasionally I'll look at them for a while and it'll reveal a new perspective to me that I had previously missed, despite being the one who made it.
This post is making me feel a bit inspired to go outside and immerse myself in the forest to take in the greens. Thanks for sharing.
Thanks mentioning acrylics. Now I'm wondering if new technology will eventually improve our printing to allow better colors in news media, and even in prints in art exhibits?
Does anyone have any comments on the future of printed media?
The phosphor screen of a B&O MX8000 TV (a Philips tube) was unlike any I’ve ever seen in terms of cyan intensity. That was in 2020 while the tv is from the 1980’s. Playing Donkey Kong on it was totally different than any other screen. It was like a Morpho butterfly, but in the article it is pointed out that phosphor screens have limited color range.
Triangles between screens may differ with tuning, but I suppose they all are limited in range. I’ve yet to experiment if this experience was a “brand experience” because I liked the TV or that the colors are indeed more intense than even some HDR/DV flat screen from the past few years.
This article was so well written that it gives a lot of energy to make this comparison for real. Absolutely masterful writing and all of the plenty examples make me want to look for colors I’ve missed out on while watching so many screens.
What the article does very well is vibrantly describe what you are missing and then post an image of it, such as a beach. Looking at that image, it falls absolutely flat compared to memories and the imagination of those places. This makes it tangible how limited screens really are.
Edit: added last paragraph
I’m not sure it’s possible to truthfully describe what we are missing in reality with a photo.
You can publish a photo with default automatic JPEG processing, say by a phone, and it will certainly look flat. You could also present a masterful interpretation of raw sensor data that uses the most out of the available display space, and the impression might be different.
There is no objectively correct way to represent reality in a photo; even the concept of neutral grey is not a real thing as soon as perception is concerned. A default camera interpretation of light is baseline and safe to maximally avoid awkward edge cases. We all know that time we photograph a bright pink sunset but our phone renders it as pale yellow or orange. However, give the same shot human attention, and even though it may never be as pink as what you have perceived in reality it will pop enough that the viewer will have a similar response.
It is photographer’s job to work raw data in specific ways and make what impressed you stand out to your audience, arranging colours both relative to each other and in absolute display space, however limited it is. Human eyes are incredibly adaptive: we lower our relevant thresholds, adjust our idea of neutral grey—in short, we adapt to given display medium, to given photographic style, etc., and in the end perceive a true lush lagoon in a photo even if our eyes only receive a truly minuscule amount of colour range present in the scene.
The original 1953 NTSC standard specified phosphors with a way bigger gamut than sRGB, that were chosen to approximate the gamut of film projectors.
Original NTSC cyans are more saturated than even DCI-P3 cyans.
Typical CRTs use the cheaper, brighter phosphors specified by SMPTE C (the basis for the sRGB gamut) and a circuit that pumps the saturation to compensate.
It's likely your screen uses the better phosphors instead of a colour correction circuit.
What I missed in the article: the curves of the three “cone kinds” overlap. What if you could stimulate kinds of cones individually to see entirely new colors? Some people shoot layers at them into eyes. But you can also try this website: https://dynomight.net/colors/ (previously on HN but search fails me).
Last year a research group managed to do just that, see https://www.science.org/doi/10.1126/sciadv.adu1052 for details.
https://en.wikipedia.org/wiki/Tetrachromacy
Through the magic of liner algebra it turns out that you can stimulate cones independently even with normal displays. Search for 'silent substitution'!
Also search for "impossible chimerical colors"
<https://en.wikipedia.org/wiki/Impossible_color#Chimerical_co...>
Somewhat related, but TIL the macOS Screenshot.app utility (and the system wide keyboard shortcuts) in Sonoma got HDR capability to help re-convey just a bit more fidelity. Even in PNG, it keeps the display profile, just not HDR.
Open Utilities->Screenshot.app Options->Capture/Capture Format->HEIC. Note, it changes the system screenshot default away from PNG too.
Really nice article, I'll look closer to green lights next time I see one.
The most striking experience I had was working with a blue laser (430nm). The best way I found to describe its color is that it was screaming "blue" at me. Since then, I'm always disappointed when looking at a screen displaying #0000FF.
Sounds like we need the next VR glasses to shine colorful lasers into our eyes instead of screens.
"Destroy them with lasers!" https://youtu.be/u6-U-apEUZI
it'll be awesome, once
"This is a good time to spare a thought for our red-green colorblind brethren. [...] it is to them that we owe the beautiful color of green traffic lights. The spectral requirements that make the green signals distinguishable from red in their eyes make them beautiful in ours."
Really enjoyed the article, even though it's not a new topic to me, but still it was very interesting, very nicely written and I still managed to pick up a couple of new details.
To be fair to Jurassic Park, though, at least in the book the quirks of T-Rex's vision were explained by the details of genetic engineering (the base DNA used was some kind of amphibian, that allegedly had this problem — still not very scientifically plausible, but not quite as silly as in the movie). It goes a long way to emphasize that in the end these are not real dinosaurs, these are human-made abominations.
Doesnt Dr Grant scare a kid in the beginning with the Velociraptor and say there that T Rex vision was movement based? I wonder if Chrichton made that up or if it was a real theory by paleaologists?
Incredible article. I used to work as a light designer and therefore spent lot of time thinking about colors and training my eyes to see them more precisely. I lost some of this competency surprisingly quickly, but this article brought many great feelings/souvenirs back.
Thanks to the author
> Today, on your way home, look at the “green” light on a traffic signal. It’s not green.
Independently from this, the names for colors are culturally determined.
The Japanese call green traffic lights as 青 "ao", blue.
Russians have different terms for different shades of blue.
This is a good point. Here's the article on the weirdness of blue/green in different cultures:
https://en.wikipedia.org/wiki/Blue%E2%80%93green_distinction...
Off topic, but the other articles are well made too. I enjoyed this one: https://moultano.wordpress.com/2025/02/24/you-should-make-cr...
Many modern triple-laser projectors can reproduce or exceed the Rec. 2020 color space. It's still not full coverage but much larger than P3.
Couldn't we capture more of it by just using a slightly bluer green phosphor?
ACES AP0 is the only color space I know that is designed to represent all possible visible colors. It's a purely theoretical color space, though. The widest color space designed for actual implementation, Rec. 2020, still can't faithfully show most of the natural greens and cyans, like your green laser pointer.
Its unclear to me why the color space is 2-dimensional. Why wouldn't it be a 3-dimensional space, indexed by how much each of the 3-cones is activated ? Not clear to me from the article!
It is 3 dimensional. That commonly repeated CIE diagram is a 2d slice of the color volume. Since 1931 that diagram is obsolete, misleading, and fails at a lot of modern color science, and has been replaced many times, but is what many people go to. The most recent replacement (well, by CIE), is CIE 2015. Comment on it [1]
Modern color modeling is much richer then 3 parameters, because human vision is much more complex than simply color frequencies. CIE 1931 was low brightness, 2 degree field of vision, center of vision derived. As brightness increases, color perception shifts. Colors are NOT linear; sRGB and CIE 1931 chose such a small section of human vision that they approximate that section with a linear assumption. Modern CIECAM models are not linear, are not 3 parameter, because color is not linear (CIECAM02 is 6 parameter [2], there are several after that one). A century of experiments, wide color gamuts, HDR, have thrown out CIE 1931 as a good model. It’s only momentum now, and slowly higher end things are replacing it.
A good introduction is Color Appearance Models, by Mark Fairchild, also any of his technical papers give a starting point into the science.
[1] https://community.acescentral.com/t/cie-2015-cmfs-what-would...
[2] https://en.wikipedia.org/wiki/CIECAM02
> CIE 2015
Does that look like 3d?
It is, inasmuch as we have 3 types of cone, which is an inherent orthogonality. It is also not, inasmuch as each cone is a wavelength in the same spectrum.
Either way, you can project a volume onto a plane, which is great for communicating visual data on paper or screen.
The interesting question is "why that arc in particular"; my ignorance will shine through if I speculate.
I assume that the projection encodes something about our relative perception of each cone's band, hence the big green corner.
It is 3 dimensional, because in our perception we see the third dimension of magentas and purples, which do not exist in physical reality on the spectrum.
There are three cones, but there is an additional constraint that we plot the colors at maximum summed luminosity. So for one cone you would just have a point; two would show a line from 0% cone A+100% cone B -> 100% cone A; three is a plane
>indexed by how much each of the 3-cones is activated
This will actually differ from person to person. If you look at a pure yellow wavelength light next to a red/green light mixed such that they create the exact same perceived yellow to you, it will look different to another person.
Aside from that, not really sure what a 3d view with the dimensions being r,g,b would actually offer
I guess it is the 2-dimensional section such that it have constant total brightness. You can then multiply later by your desired brightness.
If we had a display with n (n>3) pixel colours, say (red, green, cyan, blue) for example, we could display more of the colour space. Shopping list: 4 colour channel display, 4 channel GPU, 4 channel software. Why isn't this a thing already?
More than 3 channel displays have been attempted by several companies, but I suspect they fail due to:
1) trying to convince content makers to use new custom high-gamut hardware to capture the new spot colors
2) you'd need a full video content production pipeline that can render to that color space
3) finding enough people to care enough to pay the (substantial) premium for niche production numbers.
4) Most content just doesn't warrant high gamut unless it's narrated by David Attenborough.
So, you have both a chicken and egg problem, and not that big of a TAM to warrant the struggle.
5) You'd need image formats that record those channels, and that in turn would cause problems for raw bitmaps with alpha (they either get twice as big or the pixels are no longer aligned).
Such a cool article chock-full of cool facts!
> Nearly every species of scorpion intensely fluoresces under UV light. […] Scorpions have photoreceptors in their tails, separate from their eyes. […] It is hypothesized that a scorpion uses this fluorescence to tell whether any bit of its body is left exposed from its hiding place. Its tail “looks” down at its body, and if it sees its own fluorescence, it knows it is exposed to light, and in danger.
And a special call-out to the “Andean Cock-on-a-Rock” :), see a photo in the article.
My debatable factoid is that all vision is movement-dependent, including human vision, and so the bigness and wonderfulness of the tyrannosaur's eyes is beside the point of whether it needed its prey to move around in order to perceive it.
https://en.wikipedia.org/wiki/Stabilized_images , https://en.wikipedia.org/wiki/Fixation_(visual) , https://en.wikipedia.org/wiki/Microsaccade
We fake the movement of anything we're staring at, by means of tiny automatic eye movements, in order to remain able to see the thing at all.
Very well-written!
I wonder if the inaccurate representation of colors by screens, etc, in any way underlies the distinctive color palette of many AI image generators?
That was incredibly well-explained. Kudos.
I do have a question that the article doesn't seem to attempt to answer, though. The article says (paraphrased in my new understanding) that any spectra which makes the cones in your eyes react the same way will result in seeing the same colour. Do we know of any examples of this?
(Colour-blindness seems like an obvious example; I'm curious though if there are any examples of two common scenarios where it can be demonstrated that there are different spectra in each, and yet most people will see them as the same colour.)
This is called metamerism. It can be a practical issue if two pigments have the same color under one light source, but a different one under another. You want your artificial teeth to have the same color as your real teeth in sunlight, led light, and a classic lightbulb for example.
Well, now that you mention it, I'd just like to remind you that people are a lot weirder than you might think! Having incisors to be a different colour (say, a brilliant red) under artificial lights could definitely be a thing people desired..
A flower, a picture of the flower in print and the picture shown on a screen will all have different spectra, but look the same.
See the first minutes of this video, where he has a spectrum analyser: https://youtu.be/-DyrBDsKA5s?si=mRJPT2ecy6NqpB4N
That video was super interesting, thank you!
Well, the most common example si precisely screens, no? A screen displaying the color yellow is actually a spectrum of red and green peaks, stimulating your red and green cones just like a spectrum containing a single frequency of the color yellow.
Oh right. I feel silly for forgetting about that even though it's mentioned in the article. Thank you!
Would not the definitive answer to this be a computer screen.
On one side you have an apple, illuminated by natural sunlight. it fills your eye with a rich texture of subtly mixed frequency's covering the whole gamut of visible and invisible light. On the other a picture of an apple composed of brutal pure frequencies only emitting at 430, 540, 570 Nm. Can you tell the difference?
That makes sense. I feel a little silly that that's not something I considered despite the article saying exactly that. I think I got caught up in the details.
No, no, the question was great. I read all the answers carefully and I feel a bit smarter now. Thanks for asking it!
Very well written, super interesting topic. I never understood all these natural reasons why real life colors feel so much more vivid. I guess when I look outside of the rgb triangle in the graphic, the cyans/blues/greens shown (since I'm seeing this on a screen) are sort of shadow colors? Approximations without the full vibrancy?
Reading this made me realize how much of my day is spent looking at screens. It's weird to think there are colors in the world that I've technically seen before, but have never actually been able to capture or reproduce digitally.
When reading the article, 520nm light is closest in color reproduction to the "yellowgreen" Crayola color, as seen within their 64-pack.
Impressionist paintings used a lot of synthetic ultramarine, they look very different IRL. There is a whole room in the Orsay museum where paintings seem to glow from the inside in the dark.
Great article. Small nitpick though: while I understand that P3 deserves specific mention because it’s so ubiquitous now, it’s not like Apple invented the idea of wide-gamut displays. Adobe RGB, commonly used by wide-gamut computer monitors, in particular is noteworthy in the context of this article because it extends further into the blue-cyan-green than P3,
My favorite color in all the world is the green of a mineral called dioptase. It's a deep, dark green, richer than an emerald. It looks amazing in real life and utterly boring on an RGB display. The Houston Museum of Natural Science has a large sample; every time I'm there I go stare at it for a while.
"The eyespots on a peacock’s train are super cyan, so when the peacock spreads its train feathers it is going super saiyan super cyan." Haha.
This reminds me of a video [1] going over the use of structural color photography, where theoretically what you see in real life is what you get in your final image. It cover some of the same topics, but goes more in depth about the process of structural color and some animal examples, like the butterfly mentioned in the article. If you have an interest in chemistry or film photography it is a great watch! This process was also, to my knowledge, the stepping stone for holograms, which we can now see structural colors everyday on IDs and licenses.
[1] (18 minutes) https://youtu.be/-DyrBDsKA5s
I hate that type of diagrams. Why sRGB-encoded image, pretends to show any color outside of sRGB region? It doesn't make any sense! (and when these diagrams attempt to illustrate sRGB, often actual colors encoded are narrower than full sRGB)
interesting, nicely written article. if you want to replicate the colors, you can use wider gamut end to end:
- use raw format on the camera
- edit raw eg pro photo rgb
- send this to a wide gamut printer with a large set of inks to view the image
the printer would replicate the color outside the srgb space
there are such inks as cyan, light cyan, orange
Can these colours be replicated or captured using ink, paint or traditional film photography?
Ultramarine pigment is too blue for your screen to replicate properly, for example. I don't know if there's a pigment that reflects only 520nm light, though.
Should be.
For printing there was PANTONE's Hexachrome which used 6 ink colours to greatly extend the possible colour range --- but the only printer I know of who made great use of, and profited by doing so, used it only for its increased range's covering of additional spot colours --- so they basically persuaded every printer w/in driving distance to sub-contract spot colour work to them (for those colours which fit in the Hexachrome gamut), then used fancy software to gang up jobs onto a plate, run as many copies as were necessary, cut and stack, and then send out the jobs and run the next plate, no need to wash down the press and change inks.
I tried to sell the idea of implementing it for high-end photo pieces at a printer I worked at, but no real interest because it was difficult for sales to communicate, and no one wanted to spend money printing a sample/researching images which benefited from it.
yes, using a photo printer. with varying levels of price and gamut.
Many colours outside of the electric screen spectrum can be made with ink or paint. You probably have a bunch of objects in your own house with colours that can't be shown as full on your screen.
I once abseiled into a crevasse while in Antarctica. The colours I saw in there were utterly breathtaking and I never knew why. Now I do, and this also tells mewhy the photos don't even remotely do it justice (aside from not being as big and three dimensional!)
Thanks for such a beautiful article about not looking at a screen: I'm off outside... :)
What an truly incredible article, particularly the way the color space diagrams are used to gradually tell the story (and the prose is great too). I actually want to read it again tomorrow morning in more depth.
I'm having an amazing time seeing colors now because I just had cataract surgery on my right eye (left eye next month) and have a clear lens again. If I compare my new right eye to my old left eye, I'm seeing colors I haven't seen in decades. Skies look blue with my right eye, gray with my left.
It's odd he noted Apple monitiers were "better". Maybe but marginally. Many options for other platforms, like Asus Pro Arte, beat it handily. And profressional color graders use Sony BVM series (Trimaster HX / OLED) for HDR or Flanders Scientific (FSI) DM/XM series or Eizo ColorEdge CG series. You won't see a single Mac at a movie studio for movie editing or color grading.
Colors on the screen are like symbols. Like words. they aren't the actual experience. They evoke the experience. Your mind connects the color to a memory and then it's the memory that you experience.
That's screen reality. 1% evocative symbols and 99% in your head.
what a beautiful article, thoroughly enjoyed reading it.
Tl;dr.... It's LSD.