What is exactly neutral white ?

[brickbat]

Saying a color corresponds to a particular temperature, as what comes from a black-body radiation source as Aramid so kindly pointed out, is merely a different label for the psychological correlate of the physical stimulus. The stimulus itself is independent of our perception of it, but the label we associate with it, the concept we have of it, is not.

Agree with the above.

But color temperature is a non-subjective measure. It is expressed in Kelvins, a standard MKS unit. Would you also argue that a rock's measured mass of, say, 1 kg does not exist apart from the observer's perception?

 

[righttoown]

I think some people see color different.

 

[Watts Up!]

Then you got "High CRI" to add into the mix which I think looks the best...:twothumbs

 

[B0wz3r]

Agree with the above.

But color temperature is a non-subjective measure. It is expressed in Kelvins, a standard MKS unit. Would you also argue that a rock's measured mass of, say, 1 kg does not exist apart from the observer's perception?

The rock's mass is what it is. 1 Kg does not exist apart from our use of it. Again, there is a difference between the actual physical object, and our perception of it. This also extends to standardized measures such as grams, kilograms, etc. The substance of the rock itself that we refer to as mass exists separately and independently of us; the standard unit of measurement of "1 Kg" does not.

 

[wyager]

The rock's mass is what it is. 1 Kg does not exist apart from our use of it. Again, there is a difference between the actual physical object, and our perception of it. This also extends to standardized measures such as grams, kilograms, etc. The substance of the rock itself that we refer to as mass exists separately and independently of us; the standard unit of measurement of "1 Kg" does not.

OK-I'm not sure exactly what you're saying (I don't want to slog through all the comments), so I might be agreeing with you here-but color temperature is an empirically observable measurement. It is not based on perception any more than the frequency of a photon or the weight of a rock. There are equations used to find color temperature-it's not based on opinions or fallible perception.

 

[aramid]

the standard unit of measurement of "1 Kg" does not.

True, the unit of measurement referred to as a kilogram does not exist without humans to define it. However, the quantity of mass it describes exists no matter what. If there's a particular rock which happens to mass precisely one kilogram by human reckoning, it will continue to mass one kilogram even if every last human dies. It won't still be called a kilogram, but it won't have fundamentally changed, and will still contain the same mass.

It's the same with light waves and color temperature. We've described a "Neutral White" LED as one emitting a profile of radiation which is similar - at least between wavelengths of 400 and 750 nanometers (visible to humans) - to that emitted by a star with a surface temperature between 3700 and 5000 Kelvin. If all the humans die, the definitions of degrees Kelvin, nanometers, and the whole English language will cease to exist. That LED will still continue to emit the same radiation profile, and it will still share the same similarities with the same star.

The way I see it, you're basically arguing that if not for humans, a bunch of stuff wouldn't have names. It's true, but it's not really relevant to the original post in the thread. The only way perception ought to enter into this thread is to note that not all people feel that "Neutral White" is indeed neutral. Just because some people don't see it as pure white doesn't change its name, which is based on numbers and not directly on human opinion.

 

[red02]

"neutral white" is not close to sunlight. Visually everything looks different than it does with sunlight. Sunlight at midday is commonly taken as 6500K which is relatively further from NW than from CW.

 

[aramid]

"neutral white" is not close to sunlight. Visually everything looks different than it does with sunlight. Sunlight at midday is commonly taken as 6500K which is relatively further from NW than from CW.

According to NASA, the surface of the Sun is 5800K. This meshes reasonably well with the color temperature chart on Wikipedia, placing direct sunlight at 5500-6000K. You don't see 6500K unless it's an overcast day.

Of course, even 5500 is still pushing well into "cool" territory, but the majority of LED lights are cooler than that, and I've seen several which are even cooler than 6500. Since sunlight is ridiculously bright, it looks very white at 6500 thanks to the Kruithof curve. Since even the most powerful flashlights are generally dimmer than that, they'll look more blue to most people at the same color temperature. This is why a lot of users find "neutral" tints so pleasant - at typical flashlight intensities, it's entirely appropriate to use something warmer than sunlight.

 

[B0wz3r]

The way I see it, you're basically arguing that if not for humans, a bunch of stuff wouldn't have names. It's true, but it's not really relevant to the original post in the thread. The only way perception ought to enter into this thread is to note that not all people feel that "Neutral White" is indeed neutral. Just because some people don't see it as pure white doesn't change its name, which is based on numbers and not directly on human opinion.

To restate what I've already said;

Let me use a short analogy here... There are lots of different kinds of "hat"; baseball, sailor, beret, etc. They are all different but yet they're all hats, right? We ignore their differences in favor of a commonality they have so we have a way of talking about them that everyone understands. It's the same for "color temperature" and "mass", etc. People's perceptions vary just as there are different kinds of hats, that's why there has to be agreement on the units involved and what they mean, etc. Otherwise, we'd never be able to understand one another.

Further, there is a lawful relationship that exists in how the sensory systems work that determines whether or not we can tell if two similar stimuli yet when "objectively measured" they are found to be different. A light of 1000 lux is more intense than a light of 999 lux. But, is it brighter? No; we cannot perceptually tell the difference, no one can; that small a difference is beyond the ability of our visual system to detect. This is empirically verifiable and demonstrates that the characteristics of the stimulus and our perceptual experience of that stimulus are not the same thing. As I mentioned before, just do a quick Google search for "visual illusions" and you'll find LOTS of examples of how our perceptions do not match the actual physical stimulus in the world.

So, and let me be perfectly clear here; the psychological correlates (our conscious experience) of the objects we experience in the world are separate from those objects. They do indeed arise because of those objects but are in no way part of those objects themselves. Rather they are products of the functioning of the brain and visual system. You are misunderstanding that what exists in the world is separate from our knowledge of it, and that knowledge depends on our ability to perceive it.

Also, I am NOT saying that objects exist in the world only because of our perceptions; nowhere have I said that or even implied it.

Thus, once again, in short summary of what I've already said, people all have slightly different perceptions of the same physical stimulus, and there are times when two stimuli objectively measured as different cannot be perceived as different. As such, there is no agreement on standard units without perception, there are no definitions without perception, in fact there is no such thing as knowledge without perception of the thing to be known.

What I am trying to say here, regardless of all this stuff above, is that our knowledge, our definitions, our labels, terms, etc. ARE based on our perceptions. No matter what, even when using instruments to see which light is brighter, how do we know what the instruments are telling us if we don't perceive what their readings or output are? Even in this case, it comes down to perception; without perception you can't even read the display on a light-meter to find out what the "objective" measurement is.

I can't explain things any better than I already have here; but, I will write down some references for you to investigate on this so you can look into it yourself. I don't seem to be doing a very good job of explaining it to you, and for that I apologize.

So, let me shift the burden of explanation to you; please explain to me how it is that knowledge is possible WITHOUT perception, please explain to me how we can know one light is brighter than another without looking at the lights, or having to look at instruments that produce readings that indicate they are different, because that's what it seems you are arguing here. Please let me know how we can know anything at all without some way of perceiving it in the world.

I've made my case, now you make yours. I'll be happy to see what you have to say.

 

[mellowman]

According to NASA, the surface of the Sun is 5800K. This meshes reasonably well with the color temperature chart on Wikipedia, placing direct sunlight at 5500-6000K. You don't see 6500K unless it's an overcast day.

Of course, even 5500 is still pushing well into "cool" territory, but the majority of LED lights are cooler than that, and I've seen several which are even cooler than 6500. Since sunlight is ridiculously bright, it looks very white at 6500 thanks to the Kruithof curve. Since even the most powerful flashlights are generally dimmer than that, they'll look more blue to most people at the same color temperature. This is why a lot of users find "neutral" tints so pleasant - at typical flashlight intensities, it's entirely appropriate to use something warmer than sunlight.

+1. Best post in this thread.

 

[balloffthewall]

Neutral white- there is of course a standard definition. However, that doesn't mean that people won't argue over it. Personally, I have a malkoff m60w, which is supposedly warm- I think it's more neutral than warm. But that's my opinion- and I think color temperature is one of the more personal preferences with lights- so it will always be argued, regardless.

Ball

 

[red02]

According to NASA, the surface of the Sun is 5800K. This meshes reasonably well with the color temperature chart on Wikipedia, placing direct sunlight at 5500-6000K. You don't see 6500K unless it's an overcast day.

Of course, even 5500 is still pushing well into "cool" territory, but the majority of LED lights are cooler than that, and I've seen several which are even cooler than 6500. Since sunlight is ridiculously bright, it looks very white at 6500 thanks to the Kruithof curve. Since even the most powerful flashlights are generally dimmer than that, they'll look more blue to most people at the same color temperature. This is why a lot of users find "neutral" tints so pleasant - at typical flashlight intensities, it's entirely appropriate to use something warmer than sunlight.

NASA estimates that its closer to 5778K. That doesn't stop the Sun from appearing red when it sets. We do not live on the moon where there is no atmosphere to reflect, refract, diffuse and shift the color to what we experience everyday. What we experience everyday is closer to CW than it is to NW.

 

[aramid]

So, let me shift the burden of explanation to you; please explain to me how it is that knowledge is possible WITHOUT perception, please explain to me how we can know one light is brighter than another without looking at the lights, or having to look at instruments that produce readings that indicate they are different, because that's what it seems you are arguing here. Please let me know how we can know anything at all without some way of perceiving it in the world.

I have not at any point intended to claim that knowledge is possible without perception. Rather, my point all along has been that a discussion of human perception is out of place in a thread asking what it means when an LED is marketed as Neutral. Perception originally came into the discussion when a few people posted personal opinions, not about what a "Neutral White" LED means, but about how neutral that color appears to them.

There were then several responses essentially stating that just because someone doesn't think 4500K is actually neutral, doesn't mean the name Neutral should be applied to a different color. There's a science-based definition for Neutral, and personal opinion isn't used in binning them. There's not some guy at the Cree factory whose job is to look at each LED and throw it in the Neutral pile if he likes it; the process is computerized and based on math and numbers. Just because an individual doesn't find the color particularly neutral doesn't mean it's not Neutral, because the rating is not based on any one individual's perception.

I apologize that the claim "perception isn't involved" seems to have bothered you so much. Plainly, human perception is involved in all of science at some point. However, we're not trying to redefine science in this thread, we're trying to use it to answer an incredibly simple question. Perception is no more involved in the binning and naming of LED tints than it is in the measurement of brightness. Lumens are based on human perception in the same way tint is (else we'd use mW output to describe our lights, like we do laser pointers), but we don't generally argue with the results of a test in an integrating sphere with the claim that it's all based on human perception.

Basically, I don't think we've been having the same argument. I don't technically disagree with you, I just think it's a frustrating and unhelpful approach to the question we were originally discussing.

NASA estimates that its closer to 5778K. That doesn't stop the Sun from appearing red when it sets. We do not live on the moon where there is no atmosphere to reflect, refract, diffuse and shift the color to what we experience everyday. What we experience everyday is closer to CW than it is to NW.

I'm curious whether you actually read my whole post, or looked at any of the links in it.

If you look carefully at the temperature resource I linked (also NASA), you'd see that it agrees with your figure, saying the surface temperature is about 5500°C, which is 5773K. I think the use of the word "about" in their description covers them for the missing five degrees.

I chose to round further than that because I didn't really think anyone was going to complain about the 4% margin of error, particularly since it had me listing the Sun as cooler than it actually is, which works against my argument.

After that, I thought I'd made it very clear that yes, typical sunlight should be classified as Cool White, although not typically quite so cool as 6500K, and that even on the Moon with no atmosphere, sunlight is Cool. However, due to human physiology, the only way a flashlight should be cooler than the Sun is if it's brighter than the sun. Since this is generally not the case, flashlights should generally be tinted more warmly than sunlight. Sure, this won't fit 100% of humans, but I think it's a pretty good guideline - in use, for most people, Neutral tints will appear as white as sunlight, even though they're technically warmer.

 

[red02]

After that, I thought I'd made it very clear that yes, typical sunlight should be classified as Cool White, although not typically quite so cool as 6500K, and that even on the Moon with no atmosphere, sunlight is Cool. However, due to human physiology, the only way a flashlight should be cooler than the Sun is if it's brighter than the sun. Since this is generally not the case, flashlights should generally be tinted more warmly than sunlight. Sure, this won't fit 100% of humans, but I think it's a pretty good guideline - in use, for most people, Neutral tints will appear as white as sunlight, even though they're technically warmer.

While I understand that things will look whiter with higher lux. Its not really the case for relative "coolness" as blue lights will fall under a higher K and be considered cooler than the sun while not having as much luminous flux. If lights are corrected to 4000K - 5000K range they will appear dimmer. I think to give the appearance of being whiter they need to compensate by correcting the opposite way, to the cool side since Cree can't match the 10^24 watts that the sun puts out. But I guess thats just a personal preference.

I must be eating too many carrots then. NW appears very different from sunlight, pinker and much warmer. Things look more natural under a CW tint.

 

[aramid]

While I understand that things will look whiter with higher lux. Its not really the case for relative "coolness" as blue lights will fall under a higher K and be considered cooler than the sun while not having as much luminous flux. If lights are corrected to 4000K - 5000K range they will appear dimmer. I think to give the appearance of being whiter they need to compensate by correcting the opposite way, to the cool side since Cree can't match the 10^24 watts that the sun puts out. But I guess thats just a personal preference.

I think you're misunderstanding the Kruithof curve. It has nothing to do with a relationship between brightness and color temperature, which seems to be the interpretation you're working with. Remember, 'cooler' and 'warmer' refer to color temperature, which doesn't vary from person to person (although preferences certainly do).

What it actually describes is how visually appealing a certain tint is based on its intensity. A dim, yellowish light (think candle, not cheap incan) is more appealing than a dim bluish light (cheap LED), while a bright yellowish light is less appealing than a bright bluish light.

Look at the chart on the Wikipedia page. Pick a color temperature, and find it on the horizontal axis. Trace directly up from that until you hit the bottom of the shaded portion of the graph. From there, trace left to find the Lux value on the vertical axis. This value is the dimmest a light of that color temperature can get before an average person starts to find it unpleasant. Bear in mind the values aren't really exact; it looks like the study which produced that graph only used 80 random participants, so it's probably not perfect and at any rate definitely doesn't represent your personal opinion. The general shape and concept, though, should hold true for almost everybody, even if the lines are shifted slightly. Basically, the dimmer a light gets, the more yellow it should be to look good. Not necessarily white, I suppose, just pleasant.

I think a lot of people treat flashlights with a different set of criteria than they do most of the lighting in their lives. It might be interesting to compare with the light bulbs in your house, instead. Do you use incandescents or equivalent CFLs (2700K), or do you use 'daylight' CFLs (6500K)? I know a few people who really like cool LEDs, but they still use warm lighting in their houses. I've never met anyone who uses cool CFLs for general lighting of their house. Some people like them for work lights because they seem to help with concentration, but they're not common for area lighting. I'd be interested to see sales figures between the types, actually.

As far as seeing pink in a NW light, it's entirely possible that's an issue with CRI or the LED lottery, and not with color temperature.

 

[wyager]

I must be eating too many carrots then. NW appears very different from sunlight, pinker and much warmer. Things look more natural under a CW tint.

IMO this new R4 emitter I just got looks the most like sunlight. It's reportedly a 5B1 tint, much cooler than my quark neutral, but warmer than a cool white XP-E or XR-E. Cree does call it "daylight white". Cool is more of "depressing, overcast white" IMO.

Also, as a side note, I intend to do some experimentation with color perception in a while. If that goes through, I'll probably do a bunch of research on the subject of color perception shift later on.