What is "White"

[EngrPaul]

I'm a little confused, when looking up the definition.

White is a color.

White is the abscence of color.

White is a color without color.

White is the sum of all colors.

Probably the best definition is that white stimulates all color perception equally. But this depends on light intensity and the person perceiving the light.

So, we don't really know what white is, or do we? :thinking:

 

[Marduke]

So, we don't really know what white is, or do we? :thinking:

By definition:

Main Entry: white light Function:noun : light that is composed of a wide range of electromagnetic frequencies and that appears colorless to the eye

 

[Muddquez]

Very good question
I've thought of this a lot.

Are you talking about light as our eyes see it or objects as our eyes see them? As I understand white light is the full spectrum of colors. so if you were to shine the three primary colored lights together you would see white.

When you look at an object you see the reflection of all the colors. so when you see a white object, that object is reflecting all colors.

 

[Beamhead]

Polar bears are white.........and transparent.
I await Marduke's reply......:laughing:

 

[Sgt. LED]

My father's legs.

 

[Search]

Easy one bro.

White is no color. It has no color and isn't a color.

When you shine a light with NO color, hence white, then you see the real color of what your lighting up.

I don't know, maybe the fact that white has no color means I'm wrong.

I do know that LEDs mix yellow, red, and blue or some crap like that to make a white beam and that's why you can't see the full color of some colors.

Someone will have to elaborate, I've forgotten.

 

[Zeruel]

Depends if you meant white LIGHT or white COLOR.

White light is the spectrum of all colors whereas white color is the absence of color pigments.

 

[Benson]

When you shine a light with NO color, hence white, then you see the real color of what your lighting up.

Not necessarily -- that's where CRI comes in. You can mix a pretty much flat spectrum, something like theoretical blackbody radiation, or a good hotwire, and there will be light at every wavelength, so you'll see things in their true colors. But you can also mix a white color from as few as two carefully selected narrowband sources, or 3 much less controlled sources, which will not show things in true colors, because whole swaths of spectrum are absent. White LEDs generally have one fairly narrowband blue peak (from the LED proper) and one rather broadband yellow peak (from the phosphor), giving a white color, but having only moderate CRI.

 

[chmsam]

When you are combing lights of different colors, if you combine red, green, and blue (the primary colors for additive colors), you get white. For subtractive color (think pigments like in paint, colored ink, or your good ol' box of Crayolas), white is the absence of color (no yellow, blue, or red primary colors or any combination of them).

Most of the time here on CPF, people talk about white, they mean white tint and that is when the light is absent of any tint. If you look at the beam or are smarter and just shine the beam against a white surface, you will only see a clear, white beam. It will be free of yellow, blue, or green tints.

The perception of color is based also on the reflective and refractive properties of the surface(s) the light hits or passes through and how the rods and cones in our eyes react to the light reflected to them.

Of course, depending on the task, sometimes you want tint and sometimes you don't.

And as the Amboy Dukes used to ask, "Why is a carrot more orange than an orange?"

 

[OceanView]

As far as flashlights are concerned, I would say that white is basically a color or tint. Only recently, with warm/neutral white tints or high CRI LED's has the actual composition taken on much importance. "White" sunlight has all colors while a white flashlight beam will be deficient in some. As Benson mentioned, you can create the illusion of white with limited colors, like those early office flourescent tubes that were very white looking but made flesh tones look awful.

 

[Owen]

Depends if you meant white LIGHT or white COLOR.

White light is the spectrum of all colors whereas white color is the absence of color pigments.

Thank you. Something I've said before regarding bin codes for LEDs is that tint is a variation from white. It doesn't matter what the tint is, it's a variation, and it isn't "white". A true white light source wouldn't add or take away from anything it illuminated color-wise. I doubt any of us have seen such a thing, or would recognize it if we did.
When I used to do spectrum analyses of color samples for powder coat manufacture(this was 12 years ago), the standard for calibration was a featureless white panel-though I've often wondered how we were supposed to know whether it was really perfect or not. We determined and adjusted for general and obvious variations in color and tint by eye part of the time, or based on an "ideal" color sample, but many customers also required printouts, sometimes multiple printouts of mutiple samples within a short run, documenting consistent and accurate color. Those were typically customers having small runs of custom colors that had to be perfect in color, impact and abrasion resistance characteristics, as well. A coating for a barbecue grill or fire extinguisher didn't require the same attention as something for parts for a custom car manufacturer. I only mention all that because of the correlation with much more sophisticated bin codes as LED technology has advanced over the last few years, and much like phosphor dispersion we could sometimes have a fairly wide disparity between product samples of the same batch, from the same mix of raw materials.
Imagine the variation in the early Luxeon codes, when we considered Q3J a premium bin, and the R2H seemed like the most incredible thing-even though their colors from sample to sample were all over the place.

 

[Empath]

Black is the absence of color.

Black results from the lack of light. Black pigmentation results from the inability to reflect any color that has been cast upon it. Black absorbs all colors that has been cast upon it.

 

[bluepilgrim]

White is a perception. It can't be objectively defined.

In painting we got lead white (or flake white), titanium white, chalk white, and a plethora of others. (In general, titanium white will look 'whiter' than other pigments.) Something which looks white can look gray or tinted next to some other white, and a tint will look white next to a darker shade or color with more hue.

One might say the ultimate white is intense enough ight that it completely overloads the eye -- for a moment, until you go blind from it -- but that's not a useful definition. Maybe the closest we can come is fresh snow in bright sunlight since it's harder to find anything which looks whiter in comparison, but it's more useful to say 'this' looks whiter than 'that' in a direct comparison -- but I expect that can vary depending on the individuals eyes and perception too.

White as a pigment will depend not only on the pigment but the light which is illuminating it -- and that holds for any other color as well. If you want to paint something that will render the colors as you want than you have to use the same light source as will be used by the person observing it, both in terms of spectrum and intensity.

If you want a diversion for a few years look up 'color theory' and note all the different schemes for trying to describe color. http://en.wikipedia.org/wiki/Color for instance, as a start. The bottom line is that vision is not objective, and takes place in the brain and mind, and is relative to what else we see or imagine, and as filtered by the eye and nervous system. We might even see things differently depending on what we are hearing or otherwise sensing (see synesthesia). We can't say what IS white, only what LOOKS white, at a given time.

 

[Marduke]

Both white light and white color is the presence of all colors.

 

[DM51]

White = R 255 + G 255 + B 255

 

[cave dave]

I like the description by Henry of HDS fame, I recommend reading the entire FAQ:

http://ralights.com/?id=LightFaq#Tint

just a snippet:

...The definition of white is the equal energy point that lies at x=0.333 y=0.333 on the CIE-1931 Chromaticity Diagram and corresponds to 5454°K...

 

[bluepilgrim]

"Both white light and white color is the presence of all colors."
And also "White = R 255 + G 255 + B 255"

Have problems as definitions. Look at an apple with a spectoscope and you will see all colors present -- just a predominance in the reds. The 255 scales is only the phosphors on the computer screen (with 0 to 255 derived from the levels stored in a byte).
We can say that in general white is a "balance" between the visible parts of the spectrum, but some frequencies of it can be missing and it would still look white: you can see this by looking at a 'white' fluorescent tube through a spectroscope. Low level incandescent may look yellowish, but it has most of the spectrum there continuously (falling off in level towards the high end blues, violets, and beyond). The eye can't do a spectral analysis -- it sees, and the brain interprets. There is even an optical illusion where spinning a wheel with only black and white can yield a perception of color. http://www.illusion-optical.com/Optical-Illusions/SpinningWheelBlack.php

 

[carrot]

#ffffff

 

[Liquidspaceman]

I love this thread. I think CPF needs more conversations along these lines...

Colors in general and eye perception is a fascinating topic and one that has interested me throughout the years. For example, black and white can produce colors if displayed in the right patterns. Old black and white TV shows tried to incorporate this black and white color wheel into their broadcasts with mild success. Basically our eyes (or brains) can interpret spinning patterns of 3 into various colors, depending on the black patterns against a spinning white wheel. When spun, these patterns are translated into colors in the eye.

 

[EngrPaul]

I didn't see any wrong answers yet...

In the computer world, R&G&B @ 100% is white. However, will the light coming from your screen be white?

If you have an object which is white, is the light coming from it white?

If it's white, are you sure it isn't gray?

Is a mix of monochromatic red, green, and blue light... white?