Unreal claims concerning purple
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@HardwareGeek said in Unreal claims concerning purple:
@cvi said in Unreal claims concerning purple:
two distinct frequencies, 589nm ad 589.56nm
Those are wavelengths, not frequencies.They correspond to two distinct frequencies of 508.99 THz and 508.50 THz, respectively, but the values you stated are wavelengths.
It's like saying MPG isn't a fuel consumption unit.
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@cvi said in Unreal claims concerning purple:
@Flips said in Unreal claims concerning purple:
When it's produced, no.
No, when it's produced too. Black body radiation is (as mentioned) broad-spectrum. It's the number one source of light (mainly because the sun outshines everything else by unfunny amounts).
The black body would have multiple states in which different processes, create different wavelengths.
If you're talking about singular photons, the first part of your statements makes no sense. Singular photons have a single wavelength/frequency, so they will be single wavelength when they reach our eyes as well.
You are totally right. The photon still is monochromatic. I only tried to claim, that light we see in our lifes, is from multiple sources and as such it would be an exception when you can perceive a monochromatic color in it's true glory (without surrounding noise).
When we argue for a 100% isolated case (a LED on steroids), we maybe can conclude that for some power supply over x time, all energy went in the process exiting 1 or multiple electrons, and all energy came out in the form of light with the same amount of energy (hence, all light had the same frequency, regardless of empirical measurement-variances).
(b) There are always minor variations to everything in the real world. Even in a perfect system, you still have to deal with uncertainty. In a real-world system, you additionally have all sorts of noise (thermal, ...). This isn't a measurement variance; "imperfect" measurements just add on top.
Uncertainty already starts at power supply. If we can't input with deterministic accuracy, how can we conclude that the output does not correspond to the input, with deterministic accuracy? Not to mention we need to measure the complete state as well. For every planck's length and dT (preferably less).
Possible? No. Feasible? Yes. When you're a determinist.
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@Flips said in Unreal claims concerning purple:
When you see light, you can't determine the constituent frequencies based on how you perceive the color of that light. There seem to be multiple ways to 'construct light' which look the same but have different properties.
Thanks for clarifying your point! I think that everyone involved would mostly agree with this part.
And apparently this phenomenon is basis to discerning real (natural) colors, and that imaginary family of purples, as those fakey ones are not represented on the spectrum, only in our brain.
So the real (natural) colour space is "all possible spectral functions
P(λ)" and the colours we perceive (with our puny(X,Y,Z)tristimuli instead of infinite amounts of infinitely small buckets ofΔλ) are all fake, then? I hope I understand you correctly this time.
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@cvi Nice writeup! If someone reading it found it interesting, Digital show & tell by Monty Montgomery covers the video colour spaces and a lot of similarly exciting stuff.
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@Flips said in Unreal claims concerning purple:
Which (concrete) processes are there, and which are responsible for which frequency?
My turn for a writeup!
With a lamp, we're talking about emission spectrum. Given the energy level structure for a chemical substance and the conditions (e.g. temperature, particle and electron density), we can calculate how each energy level is populated ("for a big cloud of these particles, how many would be in this state?") and which transitions between states are likely. We usually know those well for individual atoms/ions and small molecules (like the CN particle, which is unstable, but responsible for bluish light of some gas flames). Not so much for bigger molecules, but those don't typically emit light in our lamps.
When a particle transitions from state A to state B with a different energy level, the difference in the energy has to be compensated. In a lamp, particles may be excited (from lower levels to upper levels) by collisions with other particles (there are other available excitation mechanisms) and then they release their energy as light (and go back to lower energy levels). The frequency of that light is proportional to the difference in the energy levels (so the wavelength is inversely proportional, then).
Light from a single transition between two energy levels is not exactly monochromatic (i.e. particles emit slightly different wavelengths when doing that over and over) and instead shows as a peak function with nonzero width. This is due to finite time of life for a given state of the particle; transition from a state with infinite lifetime would be exactly monochromatic, but then we wouldn't see its light because the transition would never happen. This is not the only or the most important line broadening mechanism. Particles travelling at different velocities, colliding with each other and interacting with other charged particles in other ways all broaden (and even shift) their emission lines. (So different particles doing the same transition may emit very noticeably different wavelengths, e.g. the most widely known hydrogen line shifts by tens of nm and broadens by hundreds of nm at 35000K and 1020 electrons/cm3.)
Lines resulting from different transitions start to overlap due to the broadening effects. Taken to their limits, various broadening mechanisms result in blackbody thermal emission spectrum, which is continuous and doesn't consist of lines (not even very broadened lines).
This may sound very chaotic, but processes resulting in these spectra may be modelled to fit the observed spectrum back to the conditions of the source that produced it, sometimes even elemental composition (e.g. if we are seeing plasma with discernible emission lines).
If we turn the lamp off and direct our attention at the polymers it's made of, there's a whole other theory that also gives verifiable predictions about ambient light it would scatter in that case, but I'm much less versed in it.
Apologies if you already knew that.
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Waiting for the FCC to start auctioning off the 509THz frequency band for 6G cell phone support, and demanding existing uses of visible light stop by 2027 or face multi-million dollar fines...
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@Flips said in Unreal claims concerning purple:
The black body would have multiple states in which different processes, create different wavelengths.
You should read up on black body radiation / thermal radiation. In short, it's generated by thermal motion, not from e.g. electron decay from discrete states.
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@aitap said in Unreal claims concerning purple:
So the real (natural) colour space is "all possible spectral functions
P(λ)" and the colours we perceive (with our puny(X,Y,Z)tristimuli instead of infinite amounts of infinitely small buckets ofΔλ) are all fake, then? I hope I understand you correctly this time.Our eyesight just has some purple-colory side-effects of fitting it's XYZ vector on a 1-dimensional function. And yes, apparently I believe that color-perception in itself is fake.
I could argue that stimuli and perceiving those, are by definition a translation (interpretation) of the actual experience (receiving the stimuli by photon). Or that by definition, light could be perceived in a non-visual way (like having a skin which tickles dependent on light perceived), which is coded without any notion of color.
Very useless to argue for so I won't.I argue that our eyes interpret signals in context of previous ones (cone-saturation) and interpret averages over timespans (gray-scaling), so our eyes in itself, interpret the same color, differently, depending on our state.
A human is just the worst measuring-stick, science can use.
@cvi said in Unreal claims concerning purple:
You should read up on black body radiation / thermal radiation. In short, it's generated by thermal motion, not from e.g. electron decay from discrete states.
I understand. I assume we can break that non-atomic operation down, to the point that 'every different wavelength is produced by a different internal state and/or process, and the complete spectrum we see consists of millions of these processes happening with millions of particles, at the same time'.
Don't get me wrong. I am way out of line here, if I compare my knowledge with some of you. Hell, I can't even define what I mean with a natural process, as it differs in many ways on many scales.
So as a request: I would love to see some kind of natural process in whichProcess(objects [2..inf]) -> [2..inf] photons + restproductswhere all photons are a result from the starting process, not from any sub-process, nor dependent on the others' creation.
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@cvi said in Unreal claims concerning purple:
YUV and YIQ are mainly used in video/image encoding/compression. Y is luminance, and somewhat similar to V or L in HS[VL]. UV and IQ are not very intuitive but encode color information. The main realization here is that humans perceive luminance/lightness at a much higher resolution than color.
Plus it means you can ignore the UV/IQ components and the remaining Y signal will still be useful on a monochrome display (YIQ and YUV derive respectively from NTSC and PAL broadcast standards).
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@cvi said in Unreal claims concerning purple:
@Flips said in Unreal claims concerning purple:
The black body would have multiple states in which different processes, create different wavelengths.
You should read up on black body radiation / thermal radiation. In short, it's generated by thermal motion, not from e.g. electron decay from discrete states.
Even black holes qualify as blackbodies (typically with a ridiculously low temperature), and it's not like they possess complex internal states (that we need to care about).
Counterintuitively, they have, if they're not spinning too fast, negative specific heat: the more they radiate, the hotter they get.
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@HardwareGeek said in Unreal claims concerning purple:
@cvi said in Unreal claims concerning purple:
two distinct frequencies, 589nm ad 589.56nm
Those are wavelengths, not frequencies.They correspond to two distinct frequencies of 508.99 THz and 508.50 THz in a vacuum, respectively, but the values you stated are wavelengths.
FTFY
Whn traversing substance, the wavelength-to-frequency formula changes a bit.
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@Flips said in Unreal claims concerning purple:
I argue that our eyes interpret signals in context of previous ones (cone-saturation) and interpret averages over timespans (gray-scaling), so our eyes in itself, interpret the same color, differently, depending on our state.
The receptors in our eyes work basically using a leaky-integrate-and-fire system. Receive enough stimulus (photons) in a short enough time and they fire off a signal. Different receptor types have different shapes of sensitivity curve and require different numbers of photons to fire. A photon being monochromatic is largely unimportant; we don't detect single photons without special equipment. When we see a colour, it's generally because many photons of many wavelengths were involved.
Of course, just because we're getting a particular stimulus from our eyes doesn't mean that we perceive the information in the same way. Perception doesn't work like that at all, as it tangles with memory and expectation, and is thus intensely personal even at a physical level (because brains are self-modifying hardware).
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@acrow said in Unreal claims concerning purple:
@HardwareGeek said in Unreal claims concerning purple:
@cvi said in Unreal claims concerning purple:
two distinct frequencies, 589nm ad 589.56nm
Those are wavelengths, not frequencies.They correspond to two distinct frequencies of 508.99 THz and 508.50 THz in a vacuum, respectively, but the values you stated are wavelengths.
FTFY
Whn traversing substance, the wavelength-to-frequency formula changes a bit.
True, but it is the wavelength that changes, not the frequency.
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@kazitor said in Unreal claims concerning purple:
On an entirely unrelated note, here’s an empirical approximation of the appearance of 420 nm light.
Why are you showing us a grey square with rounded corners?
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@Shoreline
Assuming this is a serious question about why the rounded square is even there to begin with…Spectral colours are beyond the sRGB gamut. They cannot be encoded by the colour space of that image and could certainly never be properly displayed by your screen. I won’t get into the maths here, not that it’s particularly involved, but it is easily doable to represent the colour of spectral light shining against a grey background within the sRGB gamut.
Although I made the purple circle dominate far too much of it for the proper effect to appear, I think.
This is one the most accurate renderings of the visible spectrum you’ll find on the internet. Most others distort the colours, have huge uniform bands where they shouldn’t be, etc.
Then the rounded corners are just to be more artsy or something.
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@Shoreline said in Unreal claims concerning purple:
@kazitor said in Unreal claims concerning purple:
On an entirely unrelated note, here’s an empirical approximation of the appearance of 420 nm light.
Why are you showing us a grey square with rounded corners?
...What rounded corners?
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@boomzilla said in Unreal claims concerning purple:
@kazitor said in Unreal claims concerning purple:
So things like “purple isn’t real” can take hold because you just throw a few simple, easy-to-grasp ideas around (“there’s no single wavelength, ooOOooOoOo, everyone knows the purpose of colour vision is to identify monochromatic lights that only exist in lasers!”) and it sounds convincing because nobody has the time to seek out and read a thorough treatment of the topic.
It's like those mathematical "proofs" that have a division by zero hiding somewhere.
Which may actually work if it's "0/0".
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@Karla said in Unreal claims concerning purple:
Pink is really just light red. We don't have a special color for light blue or light yellow.
But we do have a color for light brown: tan.
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@cvi said in Unreal claims concerning purple:
CIEL*U*V* and CIEL*A*B* (**** typing those asterisks)
Y*o*u* m*e*a*n* l*i*k*e* t*h*i*s*?
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@Zecc said in Unreal claims concerning purple:
@Karla said in Unreal claims concerning purple:
We don't have a special color for light blue
I'm pretty sure Russians disagree with you on that.
But are we Russians?
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@djls45 Y*e*s* :*-*(*
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@dkf said in Unreal claims concerning purple:
we don't detect single photons without special equipment
Jury might still be out on that one. I remember hearing that human eyes can detect single photons; a quick Google search yields a few relatively recent (definitively more recent than I remember) studies claiming that as well. Haven't read them, so wouldn't want to say either way.
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@cvi "Detect" and "perceive" may be an important distinction here.
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@cvi said in Unreal claims concerning purple:
I remember hearing that human eyes can detect single photons
Basically, the issue is that you need a signal to propagate along the optic nerve or you've not got anything. For a particular photon to trigger that, the photoreceptor needs to be in a state where it is already predisposed to fire. Normally, they aren't; it takes several photons to come in a relatively short time to trigger (each applies a bit of activation that decays over time, and there's cross-suppression from neighbouring photoreceptors; the various decay constants and so on depend on the exact cell type). In other words, while one photon might be able to trigger things, it's generally several photons in quick succession that actually triggers things, and in most situations where we are looking to see things there are plenty of photons about.
Detecting single photons reliably requires external equipment (or we wouldn't need night vision goggles and stuff like that).
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@djls45 said in Unreal claims concerning purple:
@Karla said in Unreal claims concerning purple:
Pink is really just light red. We don't have a special color for light blue or light yellow.
But we do have a color for light brown: tan.
Is that as universal as pink?
And what is brown when we are talking about primary colors making secondary colors? I don't know how to intentionally mix colors to make brown but I will end up with brown if I make a mess of mixing colors.
I actually use brown to describe other senses, e.g. so many smells mixed together into something less pleasant than the parts.
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@Karla said in Unreal claims concerning purple:
@djls45 said in Unreal claims concerning purple:
@Karla said in Unreal claims concerning purple:
Pink is really just light red. We don't have a special color for light blue or light yellow.
But we do have a color for light brown: tan.
Is that as universal as pink?
I have no idea.
And what is brown when we are talking about primary colors making secondary colors? I don't know how to intentionally mix colors to make brown but I will end up with brown if I make a mess of mixing colors.
I don't recall if it was mentioned earlier in this thread, but I was kinda (not-) referencing the factoid that brown is "really" just dark orange, so light brown (tan) should just be called orange.
I actually use brown to describe other senses, e.g. so many smells mixed together into something less pleasant than the parts.
Discordant aromas are one of the worst sensations to experience for several reasons: First, it's unpleasant. Second, it may cause unpleasant physiological reactions, like nausea. Third, it can cause mental confusion as the mind tries to separate and identify the scents as it tries to match memories of prior experiences/scents to the discordant mixture.
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@dkf said in Unreal claims concerning purple:
Detecting single photons reliably requires external equipment (or we wouldn't need night vision goggles and stuff like that).
I decided to skim one of the papers. It seems "reliable" is the keyword here. It seems that people can indeed detect and perceive single photons based on the tests there (albeit, as mentioned, not reliably).
The priming that you mention increases sensitivity (whether or not that is through the mechanism you describe I did not find in my quick skim), but from the sounds in the paper, it is not necessary.
As for needed night vision goggles ... that's solving a different problem. Detecting and perceiving a single photon is a far shot from having enough information to translate into a useful image.
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@aitap said in Unreal claims concerning purple:
I guess the problem boils down to whether "a real colour" is
A real color is something you can represent with RGB. There are also imaginary colors that need an i multiplier, where i^2 == -1
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@sockpuppet7 said in Unreal claims concerning purple:
@aitap said in Unreal claims concerning purple:
I guess the problem boils down to whether "a real colour" isA real color is something you can represent with RGB.
Fun fact: as far as your laptop is concerned, half of RGB doesn't exist.
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@Gąska
As far as I'm concerned half of the secondary colors don't exist.
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@Luhmann rounded up or down?
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@Gąska
I'm using metric colors you insensitive clod!
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@sockpuppet7 said in Unreal claims concerning purple:
@aitap said in Unreal claims concerning purple:
I guess the problem boils down to whether "a real colour" isA real color is something you can represent with RGB. There are also imaginary colors that need an i multiplier, where i^2 == -1
Since there are 3 colour channels, wouldn't a quaternion representation make more sense?
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@Karla said in Unreal claims concerning purple:
Is that as universal as pink?
That's not universal at all. The particular activation of photoreceptors might be largely common across all people, but the interpretation of that — the label, “pink”, in your mind — is very much not. That's far more culturally driven than most people like to admit.
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@dkf said in Unreal claims concerning purple:
That's far more culturally driven than most people like to admit.
The fact that the number of basic color names is not the same for every culture is interesting.
But what's even more fascinating is that the order colors are added to language is always the same, regardless of the culture. In other words, all cultures that have (for example) five color names use the same five groups.
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@Gąska said in Unreal claims concerning purple:
@sockpuppet7 said in Unreal claims concerning purple:
@aitap said in Unreal claims concerning purple:
I guess the problem boils down to whether "a real colour" isA real color is something you can represent with RGB.
Fun fact: as far as your laptop is concerned, half of RGB doesn't exist.
Status: wondering what @Gąska thinks “RGB” means
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Probably something in Polish that's completely unrelated to colors.
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fuck you all
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We love you too
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Guess I won’t be enlightened then.
Well for whatever it’s worth, people ought to stop referring to RGB as the sort of magic they tend to. It’s a broad set of models for producing a large range of colours with additive combinations of three primaries; it’s not an absolute descriptor of colours in any sense at all.
edit: to be more to the point… I can dream up an RGB space easily within the capabilities of any display. I can dream up an RGB space larger than typical displays can represent. I can dream up an RGB space that misses parts of a given display’s gamut while exceeding it in other areas. “RGB” is almost meaningless in this context.
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@kazitor said in Unreal claims concerning purple:
Well for whatever it’s worth, people ought to stop referring to RGB as the sort of magic they tend to. It’s a broad set of models for producing a large range of colours with additive combinations of three primaries; it’s not an absolute descriptor of colours in any sense at all.
It's worse. Kids these days use "RGB" to refer to blinkenlights.
Filed under: As far as some Razer devices are concerned, two-thirds of RGB don't exist.
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@kazitor said in Unreal claims concerning purple:
Well for whatever it’s worth, people ought to stop referring to RGB as the sort of magic they tend to. It’s a broad set of models for producing a large range of colours with additive combinations of three primaries; it’s not an absolute descriptor of colours in any sense at all.
That was kinda my point. @sockpuppet7 seems to have this simplistic idea that there exists one-to-one mapping between colors and RGB values. I meant to point out that most displays, especially ones in cheap and gaming laptops, aren't physically capable of displaying the difference between, say, #0204FB and #0303FC. That's before we even consider things like color accuracy and coverage, or human perception.
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@dkf said in Unreal claims concerning purple:
@Karla said in Unreal claims concerning purple:
Is that as universal as pink?
That's not universal at all.
Huh, that's interesting. Clearly my USain perspective.
The particular activation of photoreceptors might be largely common across all people, but the interpretation of that — the label, “pink”, in your mind — is very much not. That's far more culturally driven than most people like to admit.
Hhhmm, so why is it that out of 6 basic colors, we only have one (if it is) special name (and therefore consider it a different color)?
I do remembering hearing about an isolated culture that had many words for variations of blue. I apologize is this was brought up earlier in the thread and not looking up where it was
.WAG, a culture where life revolves around bodies of water. The different variations of blue may depend on season, animal migration, safe for traveling, etc.
I cannot think of why pink would become distinct in our culture.
I'd like to read something variations of color by culture and their likely cause
.
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@Karla said in Unreal claims concerning purple:
WAG, a culture where life revolves around bodies of water. The different variations of blue may depend on season, animal migration, safe for traveling, etc.
It says somewhere upthread (or maybe I heard it on YT?) that ancient Greeks didn't see water as blue. Poets have called the seas and the rivers all kinds of colors - yellow, green, black, red - but never blue.
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@Karla said in Unreal claims concerning purple:
WAG, a culture where life revolves around bodies of water. The different variations of blue may depend on season, animal migration, safe for traveling, etc.
Counterexample: Ancient Greece was a seafaring culture; inland areas might not have been, but even inland areas of Greece aren't far from the sea. Ancient Greek allegedly (my knowledge of Ancient Greek is too limited to personally confirm this) had only a single word for the range of colors we call blue and green.
BTW, that's definitely not true in Modern Greek. Not only is green (πράσονος, prasinos) different from blue, but sky blue (γαλάζιο, galazio) is different than other shades of blue (μπλε, ble).
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