Why is yellow so bright?

[LucyDuke]

This might be a dumb question and why I'm gonna ask it is gonna make me sound pretty silly.

How come yellow is so much brighter than the other colors? I mean, I understand the hue/saturation/brightness stuff, and the primary colors or light or pigment mixin', and the visible light spectrum and all that jazz. That doesn't explain why yellow out of all of 'em is the brightest! Yeah you can have a really bright blue that's still blue, or a really not-bright blue that's still blue, but if something's yellow, it's bright. If it's not bright, it's not really yellow! I don't think it's just because the category of colors we call yellow is limited to bright yellow, since if you look at the regular spectrum then yellow is the brightest one, not blue or something.

Spoiler rambly silly reason :

I'm asking 'cause I've been coloring. Like in a coloring book, you know? Only not pictures of ponies or whatever, but these geometric patterns. They're symmetric over three lines, so there are six identical pie-slices. There are ribbons that run over the different areas. I blacked out a lot of it, and now I've got a bunch of circular ribbons of twelve different colors going all over the place. The colors are the six rainbow colors and all the intermediaries (red, red-orange, orange, yellow-orange, yellow, yellow-green, green, blue-green, blue, blue-violet, violet, red-violet). I've got a whole chunk of it done and when I look at it from a distance the only color that's really easy to pick out of the bunch is the yellow because it's so bright!

What's up with this? Why is yellow so much brighter than the other basic colors?

 

[warpus]

Does it have anything to do with the fact that the sun appears yellow in the visible spectrum, and we've evolved to "notice" the sun?

 

[brennan]

The yellow pigment in paints etc is very weak. More light is reflecting off the white paper I assume you are using as a backing than for the other colours. Try using black paper and you'll see the difference.

Btw a 'weak' yellow is brown - both are mixtures of green and red light.

 

[Mise]

Yeah, probably to do with the way our eyes (rods or cones or whatever) are set up.

EDIT: Actually it's probably what Brennan said!

 

[Perfection]

I'd speculate it might have to do with the fact that yellow light stimulates both M and L cones to a high degree:

It seems that off all colors this one would produce the most stimulation.

 

[LucyDuke]

Brennan - that makes sense, but still what about a rainbow? Yellow is always brightest!

Perfy, I think that's what I was looking for. So it's 'cause the human eye only sees color in mixes of the primary colors of light?

I got a bunch more three-year-old-like questions. Hey, I was coloring.

Is there any particular reason those are the colors we can see? Can other animals see different primary colors? Like maybe some weird fish mixes orange, blue, and purple?

Also how come we see in those colors if colors are all different specific wavelengths? Do gadgets in our eyes break down a purple wavelength into blue and red ones somehow?

If our eyes are breaking down yellow into the red and green, is there just as much red as there was yellow and just as much green as there was yellow? 'Cause if it was breaking down into parts it should lose brightness.

 

[brennan]

Are you apologising for having fun? And for asking questions?

Apparently the different cones each respond to a range of wavelengths rather than a specific colour. So the colour you see depends upon the variation in the three responses.

I guess we talk about the primary colours being Red, Green and Blue because we can exploit the way the cone cells work to fool our eyes into seeing all the other colours based upon this mechanism. There is never any yellow, cyan or magenta light coming from your screen, only RGB, but your eyes can't tell the difference.

Good find Perf.

 

[LucyDuke]

Are you apologising for having fun? And for asking questions?

I don't see an apology! Just explainin' how come I got these questions. Three-year-olds ask some pretty good questions sometimes anyway!

Apparently the different cones each respond to a range of wavelengths rather than a specific colour. So the colour you see depends upon the variation in the three responses.

I guess we talk about the primary colours being Red, Green and Blue because we can exploit the way the cone cells work to fool our eyes into seeing all the other colours based upon this mechanism. There is never any yellow, cyan or magenta light coming from your screen, only RGB, but your eyes can't tell the difference.

Good find Perf.

So it's like a triangulation thing? I guess that means that we've got such a neat spectrum 'cause we have three different types of receptors... and a two-kinds-of-receptors animal would only be able to see a gradient from one color to another. Are there any creatures with four kinds of receptors?

If it's a range... that explains how it breaks 'em down, I guess? That's pretty cool. Based on Perfy's graph, though, it seems like it would be hard to distingush between reds through greens 'cause there's a lot of input from red and green!

How does colorblindness work? One of the receptors goes bad? Red-green colorblindness would happen if red or green receptors were no good, yeah?

 

[El_Machinae]

I'm just guessing here, but it look like yellow maximally stimulates the red cone (counter-intuitive, I know) without stimulating the blue cones very much at all. This sets up a near-maximum contrast between those two systems, and our system interprets that as 'really bright'. Our blue cones tend to be our brightness detectors.

But I'm not actually sure. It wouldn't be operating under the same system as why white light appears bright. I can't see colour, and so I can't use too much intuition on this question.

 

[raketooy]

[...] I can't see colour, and so I can't use too much intuition on this question.

Are you red-green colour-blind or don't you really see any colour (or some other rare variant)?

 

[brennan]

So it's like a triangulation thing? I guess that means that we've got such a neat spectrum 'cause we have three different types of receptors... and a two-kinds-of-receptors animal would only be able to see a gradient from one color to another. Are there any creatures with four kinds of receptors?

How does colorblindness work? One of the receptors goes bad? Red-green colorblindness would happen if red or green receptors were no good, yeah?

Now there's a couple of good questions! Colourblindness seems complicated. Wiki is your friend. It seems to relate in most cases to a lack of one or other set of cones.

Apparently there are creatures that are Tetrachromatic (they have four different types of cones). There seems to be a distinct possibility that this includes some humans with an unusual genetic heritage.

El'M: Are you Achromatopic?

 

[History_Buff]

Is there any particular reason those are the colors we can see? Can other animals see different primary colors? Like maybe some weird fish mixes orange, blue, and purple?

There is nothing unique about the primary colors. They're merely picked because they are common and distict. You can actually choose any three colors, and make any other color you want. For example, odds are your printer works in CYMB. This means it mixes Cyan, Yellow, Magenta and Black dyes to produce whatever color you need. It's close to RGB, but it is different, and works just as well.

Also how come we see in those colors if colors are all different specific wavelengths? Do gadgets in our eyes break down a purple wavelength into blue and red ones somehow?

Yes. The cones in our eyes see a certain wavelength with a certain bandwidth, and then the brain 'mixes' the signals together, forming the color spectrum you physically see.

 

[LucyDuke]

There is nothing unique about the primary colors. They're merely picked because they are common and distict. You can actually choose any three colors, and make any other color you want. For example, odds are your printer works in CYMB. This means it mixes Cyan, Yellow, Magenta and Black dyes to produce whatever color you need. It's close to RGB, but it is different, and works just as well.

I don't think that's true. RGB are the primary colors of light, RYB, or CYM, of pigment. I don't think you can choose just any three colors.

 

[warpus]

well, you guys totally blew my explanation out of the water

i'm going to the corner to sulk now

 

[History_Buff]

I don't think that's true. RGB are the primary colors of light, RYB, or CYM, of pigment. I don't think you can choose just any three colors.

I once got into this argument with both my Photogrametry and Remote Sensing profs. You can make any color out of just about any 3 colors (3 becuase of the 3 cones). Our Remote prof went so far as to bring cellophane in

RGB is what you use in computer monitors, CYMB is used for printers, RGY is what you tend to learn in grade school, older printing techniques used Orange-Green-Violet. The choice is entirely arbitrary.

 

[El_Machinae]

El'M: Are you Achromatopic?

Not really, but I tell people that for convenience. I have yet to find a test which specifies my condition. My suspicion is that I'm red/green colourblind but that my S-opsin (blue receptor) is a bit whacky. So I certainly see things rather differently from most people (and this causes me some trouble in figuring out the colour system)


Colour vision is mostly the differential firing between Red and Green cones, a lightwave will tend to activate one receptor more than another and then downstream neurons will judge the difference. Every receptor eventually will get stimulated by any specific wavelength, but the probably of firing will change based on the wavelength.

Our blue receptors then add an 'intensity' component to the colour, which then allows the colour to be identified. This 'intensity' component starts with our blue receptors, but they're actually (mostly) wired into our brain differently than our a red/green receptors. So, it's less a 'triangulation' and more of a 'bianglution' coupled with a flavour of intensity.

 

[LucyDuke]

I'm just guessing here, but it look like yellow maximally stimulates the red cone (counter-intuitive, I know) without stimulating the blue cones very much at all. This sets up a near-maximum contrast between those two systems, and our system interprets that as 'really bright'. Our blue cones tend to be our brightness detectors.

But I'm not actually sure. It wouldn't be operating under the same system as why white light appears bright. I can't see colour, and so I can't use too much intuition on this question.

So less input to the blue cone indicates brightness? That makes sense! Man, that makes a ton of sense.

But yeah, that doesn't explain white...

I once got into this argument with both my Photogrametry and Remote Sensing profs. You can make any color out of just about any 3 colors (3 becuase of the 3 cones). Our Remote prof went so far as to bring cellophane in

RGB is what you use in computer monitors, CYMB is used for printers, RGY is what you tend to learn in grade school, older printing techniques used Orange-Green-Violet. The choice is entirely arbitrary.

I'm not gonna let you off that easy. I'mma have to go get my own damn cellophane.

How could you print yellow with OGV? Or print red for that matter? The absorption/reflection thing has made so much sense to me, this is crazy! I'm not going to be able to mix paint anymore because of you, I'm gonna be questioning too much...


New question, which might be outside the realm of science. Why are the colors we see the way they are? Is there any particular reason, or is it just one of those "'cause that's the way it is" things?

Also, the "tetrachromatic" creatures... do they see extra colors? Or is there just better definition in the spectrum we're familiar with?

How far does the visible spectrum range for different animals? Does it vary much in humans?

 

[scy12]

Interesting thread. White is also a bright colour.(IMO)

 

[Mise]

It can't just be the (anti)stimulation blue receptors that dictate how bright something is, or else black (which doesn't stimulate the blue receptors at all) would appear bright.

Maybe it just goes back to what Brennan said -- white things reflect more light than, say, grey things, so appear brighter.

 

[scy12]

It can't just be the (anti)stimulation blue receptors that dictate how bright something is, or else black (which doesn't stimulate the blue receptors at all) would appear bright.

Maybe it just goes back to what Brennan said -- white things reflect more light than, say, grey things, so appear brighter.

But why does Yellow appear Brighter than White ?