Yellow light is as much light as red or green or blue or violet. It even comes between red and green, which are both quite easy to see.
Draw on a white piece of paper with any color of the rainbow–except yellow–and you will have no trouble seeing/reading what you wrote.
Yellow? Nope. What makes it seem like a “lighter” color than others?
Thanks!
I believe it has more to do with human physiology than anything else. It just so happens to be one of the colors with very little contrast against white.
If you can’t give us the full story, what hope does anyone else have? 
Serious possibility - according to the chart herehttp://hyperphysics.phy-astr.gsu.edu/hbase/vision/colcon.html#c1, yellow light triggers both the green and red cones in your eyes quite strongly. If you also take into account that the greatest number of cones are “red” followed by “green”, and hardly any blue, it seems likely that yellow is causing the greatest amount of cone activity of any of the colours.
Seconding Apadistra on this. When you’re looking at yellow text on a white background, what you are trying to see are the regions where your blue photoreceptors aren’t activated as much- but the white from the background is always activating them at least a little.
It doesn’t help that most yellows we use tend towards lighter tones of it, dark yellow is fairly uncommon. Flourescent, translucent yellow like most markers, pencils or crayons is going to be the worst possible comparison. Use a dark yellow opaque paint, and you should still be able to read it fairly well.
Our eyes have very poor resolution in the blue channel. Hence, it is difficult to distinguish shapes between two colors that differ only in the blue. This would apply to, for instance, yellow on white, or blue on black, or magenta on red, or cyan on green. You can still see that the color is there, but it’s hard to do things like reading text.
Of the three cone types in human retina, only two (“red” and “green”) contribute to perceived luminance. “Blue” cones contribute only to perceived chromaticity.
Meanwhile, we are quite used to converting yellow to white mentally, in order to cancel the yellow tint to orange from sun , fire and artificial lighting …
You don’t have to “convert” lighting from the sun. As we’ve remarked before, although people think of the sun as yellow, sunlight is literally our definition of white light. If it weren’t, clouds would be yellow.
Sunlight does look yellow when the sun is low in the sky, and Rayleigh scattering removes significant amounts of blue from it. And the fact that you can see this is an indication that neither your eye or brain is “converting” the colors – the physiology of color is complex, and there are afterimage effects, but for the most part we don’t do “color correcting” in our heads – we just know how different things appear under different lighting conditions.
Yes, and it is a common trick in painting to use yellow instead of white to make things look brighter. If you do it right, the brain will interpret it as a vivid white.
Thanks for all the answers, but this seems to make the most sense to me!
Hence the fnords.
Yeh, I get that a lot.
What I meant, and Chronos did a good job of explaining, was that it’s all in the way our eyes/brain deal with luminance and contrast of specific colors. And it’s hard to see the difference between their closest companions between the additive & subtractive color models. Like Chronos mentions Red/Magenta, Green/Cyan, Blue/Black, Yellow/White.
So in that it’s all physiological, that is to say there’s no inherent physical property about the yellow wavelength of the EM spectrum that makes the contrast between yellow and white hard to distinguish. It’s just how our eyes/brain evolved to perceive colors.
But bluish white is normally perceived as “bright white” isn’t it? A color that’s labelled “Arctic white,” for example, will almost always contain some pale blue in it.
I think people have covered the physiological aspect but I want to return to the fact that yellow is a very light color compared to the others.
If you take your standard kindergarten color wheel (like this), yellow is far brighter than any other color. As a very quick example, when you look at RGB color tables and see what they call “Yellow” the code is FFFF00. Which is essentially 100% red, 100% green and 0% blue. In terms of total light, we’re at 66% of white. But the RGB code for “Blue” is 0000FF and Red is FF0000, only 33% of the brightness of white. If you lightened up red that much, you’d have to call it Pink. Blue would still be blue, but most people would be calling it “Sky Blue” or “Light Blue” We don’t have a word for “Dark Yellow” and most people would look at you funny for saying that.
So it is also a linguistic phenomenon. Yellow simply refers to a brighter color than most of our other words.
…and eventually changes name to brown.
Blackbody radiation of the sun plotted against the visible spectrum. The peak radiation is yellow, but as CalMeacham pointed out, there’s enough radiation in all the visible frequencies to render the sun as white.
I thought brown was dark orange?
You’re right that yellow is lighter than other colors–in fact, you’re underestimating its lightness.
When you convert RGB to luminance, the typical formula is 21% red, 72% green, and 7% blue. Removing the blue leaves you with 93% of the original luminance.
That’s not quite true, although practically speaking it ends up being the case sometimes.
Display devices are actually pretty shitty overall. They are designed to be just barely bright enough when all three (RGB) color elements are fully on, and to display a relatively pure white in this state.
Unfortunately, as a side effect of this is that individual colors are always going to be dimmer than white. For instance, white already has the blue component at full brightness, so if you’re displaying just blue, it’s guaranteed to be much dimmer than the white alone.
You can sort of fake an increased brightness by decreasing the saturation. “Bright” blue will have the red and green components scaled up, which does make the color brighter but then looks like baby blue instead of a true bright blue.
This could be fixed by having very bright displays, but which typically run at much less than full brightness. If your standard white level was only 5% of the possible total brightness, then you could run blue at 71% brightness and it would look as bright as white.
This is essentially the whole point behind HDR (High Dynamic Range) displays. They’re coming, but it remains to be seen if they really take off or fizzle like 3D. I’ve seen prototypes in action and they’re amazing, but they are more expensive and there is the content problem.
Here is the same text in other colors at the same level of brightness as yellow is usually shown:
Now in Color!
Now in Color!
Now in Color!
Now in Color!
Now in Color!
Now in Color!
Now in Color!
