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Octarine?
May 10, 2010 9:01 PM   Subscribe

The average human eye has three types of cone cells, each of which is sensitive to a different wavelength range of visible light. The difference in the relative signal from the three cones allows us to distinguish colors. Unfortunately, since these sensitivity ranges overlap, there are some combinations of signals from the cones that can't be created by light emitted from a real object. These are the so-called "imaginary colors". However, by selectively overstimulating one or more types of cone, we can still perceive these colors; this is the principle behind the Eclipse of Titan, an optical illusion which produces both a green and a cyan that don't otherwise appear in nature. (Similar effects can be seen in the Eclipses of Mars, Neptune, and Triton.)

For more on the correlation between wavelength and perception, you might check out Giordano Beretta's Understanding Color, a very readable introductory short course. Skytopia on Metafilter previously. For naming rights, be sure to check your prior art first.
posted by Upton O'Good (64 comments total) 184 users marked this as a favorite

 
The colors out of space.
posted by eccnineten at 9:04 PM on May 10, 2010 [12 favorites]


Wow, this is amazing. But can't people with some sorts of color blindness (e.g., protanopia) see these colors?
posted by Joe in Australia at 9:26 PM on May 10, 2010


Trippy.
posted by carter at 9:34 PM on May 10, 2010


This gave me a headache, BUT IT WAS WORTH IT!
posted by mek at 9:35 PM on May 10, 2010 [1 favorite]


Love it.
posted by Durn Bronzefist at 9:38 PM on May 10, 2010


This...this is awesome.

Funnily enough, just the other day I was reading about Lab color's relevancy to imaginary colors. Really impresses upon you just how subjective our perception of the universe really is...
posted by Sticherbeast at 9:42 PM on May 10, 2010


After trying this, it's hard to come back to my professional white page and see anything. It's like the Eclipse of MetaFilter.
posted by tellurian at 9:46 PM on May 10, 2010 [1 favorite]


Is there a MeFi word for the experience of beginning to type what one thinks is a very witty and or insightful comment, only to realize that the very same observation has already been hidden in the title of the post? No? Well, in that case...

Hey, it's octarine!
posted by Rock Steady at 9:54 PM on May 10, 2010 [8 favorites]


I covet the visual system of the mantis shrimp. Being a member of a clade that only recently has reevolved color vision sucks.
posted by oonh at 9:57 PM on May 10, 2010 [9 favorites]


I covet the visual system of the mantis shrimp

Even though they can perceive a lot of different types of light, they only have about 10x individual sensors, whereas humans have 120 million rods, and several million cones, so human eyesight has far better resolution.
posted by delmoi at 10:13 PM on May 10, 2010


CANNOT UNSEE.

Ow, my eyes.

But beautiful. Thanks OP!
posted by Malice at 10:55 PM on May 10, 2010


Damn it, I've now seen colors more beautiful than any I think I've ever witnessed and I will never get to see them in real life. Thanks.
posted by bfootdav at 10:57 PM on May 10, 2010


Someone needs to update the Squant plug-in to support Windows 7, Mac OS X, and Ubuntu.
posted by infinitewindow at 11:06 PM on May 10, 2010 [1 favorite]


The possible existence of these colors had occurred to me, but not the method of getting at them by fatiguing one set of the cones with overlapping sensitivities.

Certain untoward neurological events such as seizures and strokes could produce them by direct stimulation of involved regions of the brain, I'd imagine, the latter perhaps even on a permanent basis, if you lost a part of the brain essential for processing the output of one set of cones but not the others. I bet some synaesthetes might see them, too.

Oliver Sacks reports the perception of an ethereal and elusive indigo on only a couple of occasions in his life:

Sacks: Hume wondered whether one can imagine a color that one has never encountered. One day in 1964, I constructed a sort of pharmacological mountain, and at its peak, I said, "I want to see indigo, now!" As if thrown by a paintbrush, a huge, trembling drop of purest indigo appeared on the wall — the color of heaven. For months after that, I kept looking for that color. It was like the lost chord.

Then I went to a concert at the Metropolitan Museum of Art. In the first half, they played the Monteverdi Vespers, and I was transported. I felt a river of music 400 years long running from Monteverdi's mind into mine. Wandering around during the interval, I saw some lapis lazuli snuffboxes that were that same wonderful indigo, and I thought, "Good, the color exists in the external world." But in the second half I got restless, and when I saw the snuffboxes again, they were no longer indigo — they were blue, mauve, pink. I've never seen that color since.


I wonder if his indigo is to be found among these. (Interview and article from our own digaman, by the way.)
posted by jamjam at 11:06 PM on May 10, 2010 [5 favorites]


Vision science? "Science?" Everyone knows that the only science is Newtonian mechanics. This involves perception, is thus subjective, and not at all scientific.

Furthermore, oh? Shit, seriously?

Uh, sorry. Wrong thread, wrong side.

On the level: this is an awesome post. Thanks very much.
posted by solipsophistocracy at 11:08 PM on May 10, 2010 [5 favorites]


I didn't think there was anything on Earth that could actually make MetaFilter look dull. But also cool as shit.
posted by iamkimiam at 11:11 PM on May 10, 2010


This is awesome, and I'm going to keep my scarred and overstimulated-by-default retinas away from all of these links, if no one minds terribly.
posted by fairytale of los angeles at 11:12 PM on May 10, 2010


Man, how symbolic is that.
posted by Rinku at 11:45 PM on May 10, 2010 [1 favorite]


Nice!
posted by fonso at 12:00 AM on May 11, 2010


Cool! From the "selectively overstimulating" link: At Walt Disney World, Kodak engineered Epcot's pavement to be a certain hue of pink so that the grass would look greener through the reverse of this effect.

I'm going to start wearing these colors together. If somebody looks at my shirt for a while and then gazes at my pants they'll go "Whoa".
posted by twoleftfeet at 12:09 AM on May 11, 2010 [1 favorite]


If somebody looks at my shirt for a while and then gazes at my pants they'll go "Whoa".
Fixed that for me.
posted by lumensimus at 12:12 AM on May 11, 2010 [1 favorite]


OK that's the coolest thing I've seen all day.

And as a bonus, I can still see it when I go away and look at other things! :)
posted by Sutekh at 12:27 AM on May 11, 2010


Okay, now I'm curious. Is there a link for the Eclipse of Titan illusion that is not blocked by Websense for ostensibly being "Games"?
posted by goodnewsfortheinsane at 12:41 AM on May 11, 2010


Okay, now I'm curious. Is there a link for the Eclipse of Titan illusion that is not blocked by Websense for ostensibly being "Games"?
posted by goodnewsfortheinsane at 8:41 AM on May 11 [+] [!]


It's just an image with some instructions, so here:

"The idea is to stare at the white dot in the centre of the red circle for at least a minute (the longer the better - say 2 minutes!). You may blink, but don't move your head, and never take your eyes off the white dot. As you begin staring, you'll begin to already notice a strange glowing effect as if the surface of Titan is melting from the heat. Don't stop now though! Keep staring away, then finally, after a minute.... SLOWLY.... begin to move your head backwards.

Witness the Eclipse of Titan!!


...and then curse our television and monitors for being unable to reproduce this depth of saturation exactly. Also curse your vision which, also, will never otherwise be able to experience the true Cyan quale, due to colour pollution from the other colour cones in our eyes.

The blue gradient bit to the right is not part of the illusion, but just there to show you that the colour you have just witnessed is not anywhere in the colour palette of your PC/monitor.

Out of all the shades a monitor (CRT or LCD) can reproduce, cyan happens to be the worst in terms of sheer colour saturation, with green following close behind. The amount of red pollution is clearly evident if you take the shiny side of a CD, turn the light off to make the room dark, and fill the screen in bright cyan or #00ffff. On the CD, you should see a great deal of red, aswell as the green and blue. This shouldn't be there, since the only light coming from the monitor should be blue and green! If you were to fill the screen with bright green #00ff00, you'll also see some blue pollution and a massive amount of red pollution."

posted by rollick at 1:53 AM on May 11, 2010 [2 favorites]


Are these colours real or artefactual, and does that question make any sense?
posted by Phanx at 2:45 AM on May 11, 2010


I am a changed man.
posted by goodnewsfortheinsane at 2:56 AM on May 11, 2010


I have a new favorite color.
posted by Kattullus at 3:13 AM on May 11, 2010 [1 favorite]


Even though they can perceive a lot of different types of light, they only have about 10x individual sensors, whereas humans have 120 million rods, and several million cones, so human eyesight has far better resolution.

I've had it up to here with you high-definition size queens. It's how you use what you got that counts.
posted by obiwanwasabi at 3:25 AM on May 11, 2010


Why are the icons in the launcher on the left on fucking square buttons? It looks like a 1996 Geocities page with borders around all the image elements.
posted by obiwanwasabi at 3:37 AM on May 11, 2010


Argh - wrong thread. I blame just having my retinas seared off.
posted by obiwanwasabi at 3:37 AM on May 11, 2010 [4 favorites]


Kattulus: I have a new favorite color.

It's totally the blue one, right? The Eclipse of Mars?

'Cause... me too.

(Amazing post, Upton O'Good! Thank you!)
posted by Rumpled at 4:01 AM on May 11, 2010


One of my favorite scientific images comes from vision scientist Dave Williams at my university, showing that people with normal color vision can have widely varying ratios of the three cone types within the retina.
posted by knile at 4:47 AM on May 11, 2010 [1 favorite]


What's really amazing is that the white dot in the center of the red Titan is totally invisible! How'd they do that?
posted by hexatron at 4:48 AM on May 11, 2010


I think my eyes must be broken. When I move back, I see a kind of halo around Titan but no imaginary colors.
posted by DU at 5:14 AM on May 11, 2010


Wow, this is amazing. But can't people with some sorts of color blindness (e.g., protanopia) see these colors?

Guess so. I have protanopia and don't see any unusual colors in the squares or the circles of the Eclipse of Titan pieces.
posted by zarq at 5:21 AM on May 11, 2010


This article by Paul Churchland is good reading if you're interested in these sorts of color perception phenomena.
posted by Wolfdog at 5:42 AM on May 11, 2010 [2 favorites]


I can only see the "eclipse" through my left eye and the combined effect [via both eyes] just looks like a 3D image from a comic book, a flat disk floating in front of the monitor... neat but I'm not sure if that was what was being sought.
posted by NiteMayr at 5:53 AM on May 11, 2010


I tried this last week when it was linked somewhere else. After ten minutes, I hadn't seen any colors other than muddy-mud. And I had a headache.

I left a broken, sad person, and today I wake up and MeFi has to throw my failure back in my face?

I know it's a fucking sailboat, okay? That doesn't mean I can see it!
posted by rokusan at 7:28 AM on May 11, 2010 [1 favorite]


The fucking Moody Blues had this nailed a generation ago, man.
posted by Danf at 7:33 AM on May 11, 2010


A few years ago I was visiting the National Gallery of Canada in Ottawa, and was spending some time with Barnett Newman's Voice of Fire. I knew it from the huge controversy that erupted when the NGC purchased the piece in 1989 for $1.8M, and it's been given a very prominent place in the gallery, so I was viewing it for quite a while. One of the guards noticed me and approached to tell me how to view the piece. "Stare at a spot on the rightmost edge of the red stripe" he said, "and hold your gaze there for a while". I did.
"Now switch to the left edge"
When I did the "red" stripe immediately exploded into a reddish-orange colour I've never seen before, or since. The after-image from the blue on top of the existing red created this beautiful, pulsating burst of pure awesomeness.
"That", he said as my mouth hung open in awe, "is the Voice of Fire"
posted by rocket88 at 7:34 AM on May 11, 2010 [19 favorites]


Here's how it works for me:

- I get my head close the monitor and stare at the white dot in the middle of the red circle.
- After a while, the red circle gets fuzzier and it's harder to see the gradient in it.
- If my eyes move slightly I see the bluish/greenish edges around the circle become brighter.
- I pull my head farther away from the monitor, still keeping my vision centered on the white dot.
- Now the bluish/greenish area of my vision that used to be on the red circle but is now outside of the red circle is much brighter and more saturated. These are apparently the colors that I'm not able to see under normal circumstances.
- For a while afterward, if I look at something white, I see a red circle where my vision has been overstimulated.
posted by burnmp3s at 7:47 AM on May 11, 2010


Phanx: Are these colours real or artefactual, and does that question make any sense?

Sure, they're real -- at least as real as any other colors you see. Which also means they're artefacts of your imperfect brain.

A "color," outside a human brain, is the combination of the amount of light an object emits at each wavelength. X light at 400 nanometers, Y light at 401 nm, Z light at 402 nm, etc. So a true color is the combination of a huge (infinite?) number of measurements.

A color inside your brain is way simpler -- it's three measurements. X light between 400 and 550 nm (blue cones); Y light between 400 and 650 nm (green cones); Z light between 425 and 700 nm (red cones). (See the graph at the top of this article for a more complete picture.)

So when you look at the blue-green gradient in the Titan image, you're seeing some combination of X+Y+Z. There's no red light, so there shouldn't really be any Z, but there's actually a lot, because the three kinds of cones overlap so much.

What happens when you stare at the red dot for a couple of minutes is that the Z cones get overstimulated and shut down. So (maybe for the first time in your life) you're seeing X+Y, with no Z. In some ways it's *more* real than what you're used to, because your brain isn't lying to you and telling you there's red light, where really there should only be green and blue.

It's like painting with red and blue and yellow paint all mixed together for your whole life, and then finding some paint with just yellow and blue -- you'd see green for the first time, instead of brownish-green.

Awesome!

(Disclaimer: I am not a color scientist, but I read Wikipedia.)
posted by jhc at 7:49 AM on May 11, 2010 [6 favorites]


Should we be expecting the return of the Great Old Ones, now that this has been created?

Seriously, though, nice post.
posted by Meep! Eek! at 8:35 AM on May 11, 2010


I'm going to start wearing these colors together. If somebody looks at my shirt for a while and then gazes at my pants they'll go "Whoa".

Once, in a public park, I saw this trash can. (Bear with me!) It had once been bright blue, but someone had painted it a kind of weird shade of red. Over time the red paint had flaked off, exposing little bits of the blue underneath. When I saw it, I realized that the blue was glowing and vibrating. I thought I was just seeing it out of the corner of my eye, but staring right at it, squinting, etc made no difference. I was entranced. I called my whole family over and we all stood staring at this magical trash can for several minutes, until we realized... that we were standing there staring at a trash can. Then we left.

That trash can should have been in a freakin museum. It was the coolest shit ever. And now I know why!
posted by showbiz_liz at 8:35 AM on May 11, 2010 [8 favorites]


Mmm. I totally need to figure out how to use this in a piece of art. I already like playing with colors created in the mind rather than on the canvas; I've done one piece in nothing but B&W that's alive with swirling color and have a couple similar pieces abandoned on my hard drive.

Now how do I coax people into staring at the saturated colors and manipulate the afterimages into what I want? Hmmm.
posted by egypturnash at 9:22 AM on May 11, 2010


I had the same experience as DU. I stared at the white dot for at least 2 minutes. It was difficult to do, but I did it.

As my eyes moved slightly, I could see flashes of bright color at the edge of the circle, but I did my best to keep my gaze steady. The circle itself seemed to become sort of muddy. As I moved backwards, a vivid halo of color appeared around the muddy circle.

Interesting, but not amazing, and I didn't see any new colors that I could tell. It was a nifty effect, but similar to lots of others that rely on staring-at-a-dot effects.

I have been tested many times for color blindness, my eyes are fine. Could it be that my jaded, cynical self is more than just a mental worldview, but extends to the physical perception of my environment?
posted by Xoebe at 9:36 AM on May 11, 2010 [2 favorites]


Somewhere buried in a pile of stuff at my parents' house is this strategy guide. You can't tell from the picture on that page, but the color of the "SUPER NES" text against the background seems to hover and wiggle to an alarming degree when you move the guide or your eyes. For a while (as a kid) I was convinced that it was actually physically separated somehow, like googly eyes.
posted by NMcCoy at 9:37 AM on May 11, 2010 [1 favorite]


Interesting, but not amazing, and I didn't see any new colors that I could tell
You are not good at judging whether you have seen a particular color before. That's why the reference square is provided. By moving your gaze around the reference square, you can verify that the afterimage color is different from any colors generated by your monitor (in that region of its color space).
posted by Wolfdog at 9:52 AM on May 11, 2010 [1 favorite]


In a way, this is sort of like binaural frequencies for the eyes, then?
posted by symbioid at 9:53 AM on May 11, 2010


binoptic frequencies?
posted by symbioid at 9:53 AM on May 11, 2010


That first sentence sounds ruder than I intended. I simply mean that nobody has the ability to take a particular color sensation and determine from memory whether it is or is not represented by the part of color space represented by, say, 24-bit rgb triples.
posted by Wolfdog at 9:54 AM on May 11, 2010 [1 favorite]


To steal a line from someone else: it's a pigment of your own imagination.
posted by alby at 10:36 AM on May 11, 2010 [1 favorite]


Awesome! That was the most intensely beautiful blue I've ever seen! Thanks for a nifty post!

I've now used up all the exclamation marks on my computer, so I'll recommend a visit to the Exploratorium for anyone who
likes this kind of stuff, next time you're in SF. They have lots of exhibits about the visual system, with trippy optical illusions and vibrating colors and stuff.
posted by Quietgal at 10:47 AM on May 11, 2010


It's not as pretty as squant but it's nice.
posted by ErikaB at 11:32 AM on May 11, 2010


But does it add anything to the movie? Don't let Ebert near this site.
posted by mouthnoize at 11:35 AM on May 11, 2010 [1 favorite]


Octarines are tasty, if you're lucky enough to find them ripe.
posted by Goofyy at 11:48 AM on May 11, 2010 [1 favorite]


This reminds me of pushing your fingers into your eyes. With your eyelids closed, of course. The intensity of the color, and the way it flashes.

When I used to get high as a teenager, sometimes I'd trigger a camera flash right into my vision at close range. (Probably a "don't try this at home" kind of idea.) I'd never get any cool hallucinations from just drugs, but with the camera flash, I could close my eyes and explore a vivid, abstract, dimensional image. The colors were similar, and it makes sense; it's the same principle, fatiguing the cones.
posted by nathan v at 11:59 AM on May 11, 2010


You are not good at judging whether you have seen a particular color before. That's why the reference square is provided.

That reminds me. I had a dream (well, a series of dreams with a common theme -- alien invasion) many years back, and one of the odd aspects of it was "seeing a colour I've never seen before". Now, as pointed out, we're terrible at those kinds of determinations without a reference handy, and dream-logic in any case knows no bounds. But would it have been possible for it to be one of these sorts of colours, or was this just dream nonsense, I wonder.
posted by Durn Bronzefist at 2:05 PM on May 11, 2010


I covet the visual system of the mantis shrimp

Even though they can perceive a lot of different types of light, they only have about 10x individual sensors, whereas humans have 120 million rods, and several million cones, so human eyesight has far better resolution.


Are you sure that's really right? They have at least 12 kinds of color-sensors whereas humans have three types of color-sensing cones, which is why their vision is better across all spectra. Unless you meant 10k which is the number of ommatidia (ommatidium — an optical unit composed of photoreceptor cells, a cornea, and an axon to transmit information to the brain) in each eye.

Now, you're right that that doesn't add up to our millions of cones, but there's some other factors to bear in mind. For a start, for a Mantis Shrimp eye to work - it actually *has* to be moving - this is a limitation on the type of compound eye it posesses - so judging resolution in megapixels per lightphoton is maybe missing the point

Human eyes do this too, to a smaller degree - when you're reading a page, for example, your eyes are constantly scanning to create a seamless whole. Now imagine that each eye was able to operate independently and near instananeously on an eyestalk for a much wider field of view while utilising a couple of extra senses (tri-nocular vision in each eye, optimal polarisation vision - analogous to the improvement afforded by stereo over mono vision in terms of increased information capacity) AND had its own GPU to process all this and create coherent vistas to transmit while the underpowered shrimpbrain was doing all the walking, feeling hungry and stuff, and you can see that with such completely different machinery, resolution is a bit of an anthroconcept.
posted by Sparx at 3:07 PM on May 11, 2010


Those were beauticiously awesome. And I can go back to see them whenever I want! Yay!

jamjam mentions strokes and seizures can stimulate this effect. Now I understand something better - I have a type of epileptic seizure that triggers hallucinations, often with colors that seem like the TRUE version of colors I see in daily life. (I also experience synesthesia*.) I can quit being so disappointed in the colors available to my feeble human eyes now.


* Once you stop being frightened, left temporal lobe epilepsy is quite the kick, better than LSD and not criminalized ATM.
posted by _paegan_ at 3:50 PM on May 11, 2010 [1 favorite]


So wait, Nigel Tufnel was wrong all that time? The humour of his tautological statement has now collapsed, WTF?
posted by Meatbomb at 3:41 AM on May 12, 2010


I am confused...sure, these are beautiful, intense colors, and the illusion is cool, but "imaginary colors you've never seen the like of before"? They don't seem much more unusual/intense than the bright reddish color of Titan in the picture before it turns into an illusion. As a matter of fact, the blue is almost exactly the same shade as a huge, weird, soundless, pure blue explosion I saw once in the night sky in Monroeville, PA...I never figured out what it was, maybe a meteor landing? It was almost the same color/shade as a beautiful bowl we have, made of some kind of ceramic I guess. Anyhow, again, I've seen colors this intense before, with no illusion going on that I was aware of. And these are not new colors...simply new shades.
posted by serena15221 at 6:29 AM on May 12, 2010


When I used to get high as a teenager, sometimes I'd trigger a camera flash right into my vision at close range.

When I was even younger, maybe five or six, and lying in bed at night unable to sleep for hours (yes, it's been a lifetime insomnia), I would entertain myself* by squishing my closed eyelids and watching the kaleidoscope patterns**, which are now so burned into my memory that I can recall them in detail without even trying.

Maybe I damaged my imaginary-color receptors.

* I also had a fabulous game known as "throw the balled up socks up in the air and try to catch them in the dark before they land on your nose" that I'd do a few thousand times. Great fun.

** They're yellowish and fractal-y, sorta like this but softer and a bit more herringbone.

posted by rokusan at 7:54 AM on May 12, 2010


I can't see it. I just get a little halo effect. I assume my red-green colorblindness is hijacking the effect.
posted by chairface at 4:17 PM on May 12, 2010


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