When the world turns purple
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- Опубликовано: 17 сен 2024
- Trace Dominguez, Nahre Sol and Jordan Harrod discuss a question about an unusual visual effect.
LATERAL is a weekly podcast about interesting questions and even more interesting answers, hosted by Tom Scott. For business enquiries, contestant appearances or question submissions, visit www.lateralcas...
GUESTS:
Trace Dominguez: @TraceDominguez, / tracedominguez
Nahre Sol: @NahreSol, / nahresol
Jordan Harrod: @JordanHarrod, / jordanbharrod
HOST: Tom Scott.
QUESTION PRODUCER: David Bodycombe.
RECORDED AT & EDITED BY: The Podcast Studios, Dublin.
EDITOR: Julie Hassett.
GRAPHICS SYSTEM & DESIGN: Chris Hanel at Support Class.
GRAPHICS ASSISTANCE: Dillon Pentz.
MUSIC: Karl-Ola Kjellholm ('Private Detective'/'Agrumes', courtesy of epidemicsound.com).
ADDITIONAL QUESTIONS: Josh Halbur, Ben Justice, Lewis Tough, Arun Uttamchandani, Eglė Vaškevičiūtė.
FORMAT: Pad 26 Limited/Labyrinth Games Ltd.
EXECUTIVE PRODUCERS: David Bodycombe and Tom Scott.
© Pad 26 Limited (www.pad26.com) / Labyrinth Games Ltd. 2023.
We run a greenscreen studio. One more factor is that greenscreens tend to be a very saturated, pure green. This depends on the material or paint used. In our studio, we actually changed the paint to a slightly less saturated one, partly because the almost neon-green paint we originally had was nauseating to work in for extended periods.
After spending some time on the green, it starts to look much less saturated, and what first looked like a green void starts to show its imperfections clearly. The seams, the accumulated dirt, and even the brush strokes of paint start to show. This is the point where our eyes have completed the white balance adjustment and everything outside the green will look purple.
About our eyes adjusting, part two: It is my understanding that human perception will adjust for the brightest thing we see as pure white, as long as there is no reference telling us otherwise. So if you have a completely black room with only one lit piece of paper in the darkness (or similar), it will always look white - regardless of the actual color it is. Haven't tried this in practice though, and i assume there are limits on the saturation we can balance for.
Part three: As a personal anecdote, the first time I experienced the tinted world effect was way back as a young lad when camping. I had an orange tent, and one morning I spent a few wake hours in it before going out. Everything looked bright turquoise for quite some while.
Part four: Yet one more way to run into this is to wear the old-school blue-red 3D glasses. It's actually even weirder, as one eye will have a blue tint, the other a red tint when you take the glasses off.
I think I need more of an explanation of how this works. It makes sense to me that behind and maybe to the sides is green. But why would in front of the presenter where the camera, and probably a composite scene monitor be have to be green as well?
@@Tahgtahv The "camera side" of the studio is usually not green. It's normally a neutral colour, most often black or white. In some cases, the green is extended to up to three walls (back, left, right), in order to allow more camera angles from the side.
The effect occurs when one works for an extended time facing the green backdrop. In a presenter's case, this may happen e.g. before the shoot, when preparing for a take, reading the script turned away from the camera. In the case of technical workers, the people behind the camera, this is the direction they face most of the time.
When they keyed in on green, my first thought was Night Vision Goggles. The older ones were very green to look through. But it's kind of hard to notice everything has gone purple without another light source.
I was wondering if that might have something to do with staring at a particular colour for a long time. I used to work as a swimming pool maintenance technician (which was just a fancy title for a pool cleaner) and spent 3 hours every day sweeping and vacuuming the bottom of the bright blue pools, and whenever I'd finish, the world would look slightly tinted in false colours, especially freakily so in case of the now deep dark blue sky.
I've never felt so smart- got this one instantly.
I think I can give a better explanation of this. Your eye has 3 types of color sensing cones, one for red, one for green, and one for blue. If one gets over exposed for a long time, it becomes temporarily less effective compared to the other ones. So if you look at green for a long time, the green cone becomes dull, so whn you leave the room and look at something white, it expresses all 3 cones, but because the green cone is duller, your brain precieves that you are only getting red and blue light, so everything looks purple.
This does sound very sensible, thanks! I was confused about green being the opposite of purple, because if you assume that the base colors are red, blue and yellow, then surely the opposite of purple=red+blue would be yellow. But the explanation with the cones makes perfect sense.
Yellow is the opposite from purple on the color wheel (~RGB~ edit: red blue yellow), but with vision, often blue/green tinted glasses will cause a pink-purple cast after prolonged use.
The opposite (negative) of yellow is blue. "Purple" is a broad range (from violet to red), but its mid point (magenta) is directly opposite to green.
probably depends on how you define purple, green, and yellow
@@MrUhlus - Well, Humpty Dumpty did say "when I use a word it means what I choose it to mean". And you're also free to draw a colour wheel with the colours in whichever order you want (there are some really crazy ones in books from the Renaissance, though they may have looked more accurate before the pigments faded).
But for the meanings used and assumed by the majority of English-speaking humans with an understanding of the physical properties of light, and using a regular distribution along the spectrum in a standard RGB model, the negative of yellow is blue, and the negative of green is magenta.
@@RFC-3514 It appears there are quite a few deceptive color wheels on Google. Half of them (or more) have red opposite green, and yellow opposite purple...
@@RFC-3514magenta is yea. Meaning that if the studio lights were not on it might appear pink. Interesting
Cool to see Nahre on here! We need more classical musicians on the show!
I love how I can spend the entire episode being completely wrong (i thought something to do with neon sign making) and absolutely love it.
In the US "GP" would be the type of doctor, but "PCP" is more like their relationship to you. Not neccesarily, but that's the usage I am familiar with. "My PCP is a GP" would make sense, albeit be mostly redundant.
In Britain, at least from my experience (born and raised), we just say our GP, so we would say "I'm going to see my GP", in my experience when we need to see our GP we always see the same one (unless their off for some reason) so there is no need for other terms
For americans, PCPs might be GPs but might also be Family Doctors or Pediatricians (for children). Each of the three is distinct. I'm inclined to say "I'm going to see my GP" is probably the way someone in the US would describe their own visit (if their PCP is a GP) more often, but the instruction to "go see your PCP" makes more sense to another person because it leaves it unspecified. Although, even more likely would be "I'm going to see my doctor", or as is ubiquitous in medical advertising "ask your doctor", because when healthcare is absurdly inaccessible, the nuances of which doctor is which is much less apparent to most of the public.
I guess, also, some states have independent practice for Nurse Practitioners and Physician Assistants, who aren't MDs/DOs, but might be PCPs.
A more accessible example of this effect is known as the lilac chaser. For anyone not familiar, I highly encourage you to Google a gif of it yourself, or the corresponding Wikipedia page
I was thinking welding, oxy-acetylene to be precise. Because those goggles are not as tinted as arc welding masks are, so it allows more light to come through meaning you sometimes keep them on when you're not welding since you can still see somewhat through them. And since you're wearing them usually for quite a while, the goggles green tint will make everything in a pink-purple hue when you take them off. In my experience that is.
That's exactly what I was thinking too!
I thought yellow was the opposite of purple. Green is opposite of red, right? Have I been tought wrong?
For something like painting, a subtractive model like RYB will have yellow opposite purple as you say. However, for light, you use an additive model like RGB, and there green is opposite purple.
I think what you are describing is closer to the “paint” model of colour (i.e. subtractive model).
Ink and paint absorb light, so the typical primary colours used are anti-red, anti-green and anti-blue; which are cyan, magenta and yellow.
You can find it as “CMYK” colour model (Key for rich black) used in printing.
These colours are close to more common red, yellow and blue.
"Purple" can describe a lot of different colors - I imagine in this case the more proper word would be "magenta".
Anyway, the color inverse of red is cyan/turquoise. Whenever you invert a primary color (red/green/blue) it becomes a CMYK color (cyan/magenta/yellow) and vice versa.
At a middle/high school for the arts I attended the art teacher taught us that red is opposite green and purple is opposite orange when painting. This was more than 20 years ago though so hopefully my memory still serves
Purple isn’t a singe wavelength of light like colors of the rainbow (think red, or green, or yellow, or blue) but rather the color we perceive when seeing red and blue light together.
I find it kinda poetic that journalist have a daily reminder that perception might be easily altered and you should only stick to facts
my first thought was "she reveals photos"
which kinda makes sense in my head
you're only seeing a red light and all of the sudden you can see all the other colors
Similar effect, though the color would be turquoise or cyan, not purple.
I once spent too many hours (10+) in a cleanroom in Tokyo. Because they were doing lithography for semiconductor writing, the lighting was a thick amber color. I ended up leaving, shortly after sunrise. The sky had never seemed so blue! Across the street, and a parking lot, there was actually a beach. My interpreter and I went into a little seafood and sushi shack, and had breakfast. Occasionally, an ice chest full of fresh seafood would slide under the half-door behind the counter. Just one of those memories.
That color isn't purple, it would be Magenta.
Which is a shade of purple.
Reminds me of Jasper Fforde's book Shades of Gray and the concept "chasing the green".
My guess was mocap performer, but that fits under the larger umbrella.
I was thinking she was a welder. Welding masks have those green filters.
I get Greenvision from time to time. Programming industrial controls, some of them have red LED displays, and from there all reflective surfaces have a green hue. The effect can last up to 30 minutes.
I guess Prince (or TAFKAP) was in a green-screen studio for some time.
When he walked home in the rain he must have thought.. "Hey, there's a song here."
Annual physicals 😂 Ahh Americans. I am not a car.
Yellow is opposite Purple on the color wheel, Green is opposite Red. This is why people with color blindness usually have issue distinguishing between red/green and/or yellow/purple. The same colors that usually pop for the rest of us.
Your colour wheel is broken. The three monochromatic colours corresponding to the peak reception of the cones in the retina are red, green, blue. Those should be at 120 degrees from each other.
@@petertaylor4980 no, that is the colour wheel - green opposite red, orange opposite blue, and purple opposite yellow.
@@adam.f89You're talking about subtractive color models like painting or printing. In which case, the primaries are Cyan, Magenta and Yellow.
Eyesight is an additive color model, though. Primaries are Red, Green and Blue.
So the other guy is correct. And OP is so off on color blindness, I'm not even gonna get started. Just read a wiki article on human color perception if you are genuinely interested. (It is a really cool topic!)
I got the green idea really early but haven't thought of a profession for it
In inside grow rooms for nighttime cycles you use green lights to not mess with the plants cycles. Being in the room for awhile and walking out has this effect.
I was going "Helen is a welder!" the entire time
I was so confused since yellow is technically the opposit of purple so I was trying to think of a yellow thing someone would be staring at all day
That's in subtractive color models, like printing (primaries are cyan, magenta, yellow). Light is an additive color model (primaries are red, green, blue)
One time my friend got a concussion & everything he saw was green for about ~15 minutes afterwards
I used to see this effect when I had a green tent when I first stepped out.
Initial thoughts: it's negative visual stimulii after a long constant exposure to the opposite lightwaves. Like if you focus on a negative colour image for a while, and then look at a blank white wall, you will "see the real colour" image, until your vision adapts back to neutral.
So purple... I would understand that purple is meant for indigo/UV. And the opposite would be green. A QA tester/user for glow-in-the-dark phosphorescence or nightvision light enhancement green-hue (not thermal/IR) products would see a lot of bright green during work. As such, she would afterwards "see purple" until the effect dissipates.
If it was back in the days of monochrome computer monitors, she could be working with a green coloured one (orange and grey/white ones also commonly used), producing the same effect.
Results: I had all the right ideas, but not the, now obvious, use-case: green-screens.
first time I went to the lego store tent at downtown Disney I had the exact same thing after leaving. so very much yellow and the world went somewhat blue
The opposite of purple on a color wheel is yellow
Just to explain, this is based on first-hand experience from a friend who is a TV presenter (though not called Helen). Also, the cyclorama colour they use is more greenish-yellow, so that would account for the purplish colour she sees. - David (Producer)
It's green for light
On a color wheel for paint, yes. But when your eyes are exposed to green, other things look purple.
I remember being inside a yellow slide for a while as a kid, and afterwards everything looked blue.
@@lateralcast Sorry I wasn't trying to say the eye thing isn't true. I've experienced the same thing wearing purple sunglasses or waking up in an orange tent.
No, it isn't. Yellow is the negative of blue. Purple is a broad term (covering colours from violet to red), but its mid point is magenta, and the negative of magenta is pure green. Chroma green is actually slightly _bluer_ than pure green, to avoid getting too close to yellow (since human skin has more yellow than blue), so the afterimage will generally be slightly _redder_ than pure magenta (but still something an average person could call "purple").
Green CRT screens did that to my eyes too
From elsewhere in this episode - did any other fans of TechDif and Citation Needed find themselves yelling the answer to the most kissed woman question?
Absolutely, as soon as Tom read the question I remembered that episode!
I instantly knew but couldn't remember where I had heard it. Also, is the midroll ad for sports betting in Ohio for everyone, or is it customized? Cause I honestly got weirded out when it said Ohio.
Wren would have had to sit this one out :P
I'd guessed that she worked in a polaroid developing room with the red light they have, if only I hadn't guessed the wrong colour.
4:12- You just mean the strong studio lighting makes the green background more vivid, right? Not that the lighting itself is green (that would make the presenter look green, and harder to separate from the background).
Correct, the effect is stronger the more brighter the monochromatic light you have been looking at is as it depletes the cones even more at higher brightness levels.
@@seraphina985 - I'm not sure what you're saying is "correct". Studio lights aren't monochormatic.
@@RFC-3514 No neither would the wall be I suppose as it's not a laser but I meant in the sense of being in the range of largely or exclusively a single cone type. Wrong word choice I guess.
@@seraphina985 - Green is very much *not* "in the range of a single cone type". Both L and M cones peak in the green part of the spectrum, rods peak just slightly above it (and cover greens quite thoroughly), and even S cones are still somewhat sensitive to green.
And a material doesn't have to be "a laser" to reflect a single wavelength (or a very small range of wavelengths). But there would be no advantage in making chroma green backdrops reflect a single wavelength because it would create problems with narrow-spectrum lighting (like LEDs). It should reflect all wavelengths within a defined range (typically centred just above pure green).
In most cases, the lighting is white, and the greenness just comes from the color of the studio walls and floor.
But there actually are some interesting alternatives. There are studios where the backdrop is lit with green-gelled lights or green LEDs to get a purer green color. In this case, the performer is placed far enough from the wall not to get a green cast from these lights, and he/she is lit with normal white light.
In some setups, the backdrop is retro-reflective material, and there is a *very* low-intensity green led ring light placed around the camera lens - so low, that even though this light also illuminates the performer, it's not visible.
Finally, it's also possible to use a video/LED wall showing a pure green image as the backdrop. This is often a fallback in situations where the plan was to shoot a final image "live" using the backdrop video wall as-is, but for some reason, this didn't give good enough results, so the problem is delegated to post-production.
This concludes the infomercial ;-)
my first through immediately is
when you look at a green thing for a long time it makes things go purple because your brain is compensating for what you're seeing
maybe she's a camera operator for a film that's using a lot of green screen?
Close!!
This is one of those times when something I thought “everyone” knows, turns out to be fairly specialized knowledge. Purple isn’t a single color of the rainbow like red or green or yellow or blue (or infrared or ultraviolet) but rather purple is what the human brain perceives when looking at blue and red light combined. The human eye has three different kinds of color receptor cells in the retina, they are most sensitive to light frequencies corresponding to what we call “red”, “green”, and “blue” but the frequency response overlaps between all three, so, for example, even a “pure” green right in the sweet spot for the frequency green cells respond to, will also stimulate red and blue cells to a degree. Colors in between red green and blue, for example yellow, are perceived based on the ratio of red, green, and blue. We see yellow when green and blue are more-or-less equally stimulated, so that can come from a single frequency of light that is “yellow” or from green and blue light that happens to stimulate the eye in the same way as yellow light would.
As the cells in the eye are exposed to a bright light of a single frequency the cells most sensitive to that frequency will get fatigued (basically, the cis-to-trans transition of the rhodopsin molecules (that is the basis for color vision) slows down because they all end up at a lower potential energy state) so when the green cells get fatigued from constant exposure to bright green light, then the blue and red give a signal that is ‘too loud’ in comparison. The brain compensates for this via a mechanism called “color constancy” but that is relatively slow, taking many seconds to even a few minutes.
TL;dr: lots of exposure to green makes red and blue over-compensate, when green stops the result is blue-red which we call purple.
Just to elaborate on that, the human visual system can't distinguish discrete wavelength peaks, so we average all of them into a single hue for each location. For example, red + green gets averaged and seen as yellow, even if there's no actual "yellow" light. The "physical" average of red and blue wavelengths would be green, but since we're trichromats we can figure out that sometimes we're getting red and blue light but *no* green. So, instead of averaging it as green, our brain maps it into an imaginary "loop-around" part of the spectrum. So purple is how we perceive red and blue light combined _in the relative absence of green._
Also, our cones aren't really specifically sensitive to red, green and blue (the "green" and "red" cones actually have very close spectral peaks), so it's generally preferable to refer to them as "L", "M" and "S" cones (long, medium & short wavelength). The separation between our cones' sensitivity peaks doesn't match the separation of mutually complementary colours on a colour wheel (i.e., 1/3rd, or 120 degrees). But it doesn't really need to, because the brain does (or tries to do) the rest.
@@RFC-3514 thanks for that elaboration, that’s a very clear explanation of why the cones are designated S, M, and L and how the differences and averages are what matter.
3D glasses are red and cyan specifically because they are opposite colors. They are not blue.
My first thought was someone working with dermatology lasers and stuff like it
You would wear a certain color laser safety glasses that after some time would color your vision
I thought she was a model who gets her photo taken all day. Every time the camera flashes, it would distort her vision as if she were staring at the sun.
Anyone else bothered by the fact that the opposite of Purple on the color wheel is actually Yellow, not Green?
Additive (Light, Vision) vs Subtractive (Painting, Printing) color models.
wELDER?
I was in the right area immediately because I have several shelves of those 'blurple' plant lights, and when I turn away after watering everything looks a sickly yellow-green for a minute.
And I don't get that in my bedroom because I've got both green and purple walls. 😆👍
??? the opposite colour of purple isn't green ??? Purple is red and blue, what's left is yellow. The opposite colour of purple is yellow. I got this instantly i just couldnt think of a job that needs you to looks at something yellow all day. The opposite colour of green is red, how do you guys get this wrong?
That's pigments, not light. If your green cones in the eye get tired, the red and blue cones take over = purple.
@@lateralcast thanks for the explaination! This has to do with human biology though and not with what colour is the opposite of purple. The fact that the human eye lacks yellow cones doesn't change the opposite of purple. I guess it depends on the model though, i guess purple is opposite yellow and magenta is opposite green
Four seconds in: "she works in a semiconductor processing facility, somewhere in the patterning department". Let's see...
Oops, green, not yellow. She's an inspector for/with optical flats.
Possible spoiler:
My guess is It’s either plants that need green light, lens shaping with a green light, or green screen.
One of the old green tents have the same effect when you leave it after a long time inside during daylight
My first though was that it had something to do with maybe going into a booth with a black-light or UV light to kill of bacteria after working in a lab.
Perhaps this question was too easy? Even though I have never worked with green-screens, I got this within 10 seconds because indeed purple is opposite green, and if you spend time looking at a bright coloured light your brain compensates that out, and when you look away you then see the opposite colour more clearly, then you know green and who spends loads of time looking at bright green things and you're there. Not really a lateral though in there? Or I just stare too much at bright colours :P
Purple is opposite yellow, though
There's been plenty where I get it before the repeat of the question is finished, but the panel spends 5-10 minutes mulling it over and working on it, so it depends on your frame of reference and whatever knowledge you may have. My proudest "Got it in one" was the Putney Bridge two churches question, because despite having only been to London twice, never to Putney Bridge and not interested in churches, I knew exactly what the answer was before Tom finished the second reading of the question. Still took the panel a long time cause I happened to know the history of bridges in London for some reason
"After Helen finishes work, everything turns purple for a few minutes"...
🤔 Well, I bet Helen's got a good pair of safety goggles on while everything is purple. Specifically goggles that block UV-C light while she's in the sterilization/ decontamination chamber.
Maybe the purple is from Potassium Permanganate? Helen is working in a full-body suit, that's for sure!
But then again, "no one around her is affected the same way", so Helen is a volunteer in an experiment?
Helen's a scientist/experiment volunteer who deals with possibly dangerous medical/biochemical stuff is what I guess?
Now I'm really curious! Tell me the answer already!
EDIT: Oh Noes, I got it completely wrong... Green Screen and Colour After-Images! 😄
Your vision goes red after staring at green.
To see purple you'd have to stare at yellow.
That's pigment, not light. Staring at green tires out those cones, and the red and blue ones take over.
I used to work in a school that was painted entirely light purple.
Most of those studios aren't 360° so most likely she is staring at a non-green scenery where the film crew is seated. The filmcrew though has to look in her direction and is presented with way more green.