Tagged Questions
2
votes
1answer
48 views
Is there a one-to-one relationship between colour theories and our trichromatic vision?
This has started to bug me more and more… it involves:
colour theory
the trichromatic properties of our eyes through cone cells
and light.
Is there a one-to-one relationship between colour ...
0
votes
0answers
9 views
Why are trichromat cone cells unable to sense ultraviolet and infrared radiation? [migrated]
I understand that cone cells vary in the color they sense, is this because of wavelength, frequency, something else, or a combination of the previous? I also understand that tetrachromats can see an ...
4
votes
2answers
183 views
How photons represent colors that you see?
Right now, my understanding is that, a mixture of photons of many different frequencies is perceived as white by your eye. While no photons at all, is perceived as black. And photons with the blue ...
3
votes
4answers
235 views
Eye sensitivity & Danger signal
Why are danger signal in red, when the eye is most sensitive to yellow-green?
You can check luminosity function for more details...
0
votes
1answer
76 views
The color purple in a rainbow
In a rainbow the colors order is red then orange (made from red and yellow, thus making sense that it appears in between them) the yellow followed by green after which comes blue (again green formed ...
2
votes
1answer
131 views
Can an invisible light source cast shadows?
Let's assume that we have a mechanism for producing EM radiation suspended in the air, and that that mechanism itself is invisible to the naked eye (e.g. a microscopic light bulb on a microscopic wire ...
0
votes
2answers
110 views
Can I see the light from 10 million km away?
If light is switched ON, only for a second, and the distance between the observer and the light source is 10 million kilometers, can I still see the light spark?
For example, let's assume that the ...
6
votes
1answer
171 views
Why both yellow and purple light could be made by a mix of red, green and blue?
We see the mix of red light and green light as yellow light (#FFFF00). The wavelength of yellow light lies between red and green.
But the wavelength of purple light lies outside of red and blue. ...
-1
votes
1answer
178 views
How can you test what color different people perceive? [closed]
If I would show someone a yellow object and ask them, "is this object yellow?"
That person would say "yes".
But I could never know if my perception of the color yellow is the same as that other ...
40
votes
10answers
4k views
Is it possible that there is a color our human eye can't see?
Is it possible that there's a color that our eye couldn't see? Like all of us are color blind to it.
If there is, is it possible to detect/identify it?
6
votes
2answers
179 views
Blue-shifting as opposed to violet-shifting
A recent XKCD comic implies that the sky is blue as opposed to violet due to human physiology, and that animals more sensitive to shorter wavelengths will perceive the Earth's sky as the shortest ...
6
votes
2answers
479 views
Why do green lasers appear brighter and stronger than red and blue lasers?
This is mostly for my own personal illumination, and isn't directly related to any school or work projects. I just picked up a trio of laser pointers (red, green, and blue), and I notice that when I ...
3
votes
2answers
272 views
Why does light of high frequency appear violet?
When people are asked to match monchromatic violet light with an additive mix of basic colours, they (paradoxically) mix in red. In fact, the CIE 1931 color space chromaticity diagram shows this ...
6
votes
5answers
780 views
Why is Light invisible?
Why can't we see light? The thing which makes everything visible is itself invisible. Why is it so?
0
votes
3answers
377 views
What colour is nothing?
To me this is very confusing, but I hope we can discuss it and find a solid answer to the question.
If you were somewhere where there was absolutely nothing, what colour would your eyes see?
0
votes
1answer
69 views
What is the new distance for resolution of the images? [closed]
The taillights of an automobile are $1.25\:\rm{m}$ apart. Assume the pupil of a person's eye has a diameter of $5\:\rm{mm}$ and the light has an average wavelength of $604\:\rm{mm}$. At night, on a ...
1
vote
4answers
2k views
Why is there a difference between additive and subtractive trichromatic color theories?
Helmholtz distinguished between additive and subtractive trichromatic color theories.
Additive theories concern optical combinations of colored light sources and are usually modelled on RGB while ...
1
vote
4answers
578 views
Explanation about black color, and hence color
I'm bit confused about 'black' as a color. As per my knowledge, it is not given in visible color spectra like other colors for example red, violet etc. Also I'm confused with definition of color--does ...
3
votes
1answer
572 views
How do we see different colours?
Why do different wave lengths cause electrons to behave(?) differently, causing us to see different colors?
What is happening at the quantum level which causes the colour black to absorb all of the ...
3
votes
1answer
820 views
Purple doesn't occur in rainbow - or does it?
Usually, when asked whether the purple color exists rainbows, an answer similar to this is given:
The purple color is perceived by human eyes via the activation of both red-sensitive and ...
2
votes
6answers
2k views
Limit of human eye flicker perception?
I am designing a LED dimmer using software-controlled Pulse Width Modulation, and want to know the minimum PWM frequency that I must reach to make that LED dimming method indistinguishable from ...
2
votes
4answers
1k views
Is it only red, green and blue that can make up any color through additive mixture?
I'm reading about color vision and have some trouble understanding the motivation for why the trichromatic theory was suggested in the first place. The book I'm reading ("Psychgology: The science of ...
6
votes
4answers
2k views
Can someone explain the color Pink to me?
I just finished watching this interesting video:
http://youtu.be/S9dqJRyk0YM
It does a very quick explanation of how pink light doesn't exist, and that the concept of pink is our brain's attempt at ...
2
votes
1answer
506 views
Effects of high frequency lighting on human vision?
I have a couple of different LED flashlights. One of them has three different "modes" of brightness, and the way it controls it is via pulse width modulation (PWM). Here is a picture that illustrates ...
2
votes
4answers
469 views
Why are color values stored as Red, Green, Blue?
I learned in elementary school that you could get green by mixing blue with yellow.
...
6
votes
1answer
30 views
Refraction and scattered light for NLCs
For helping with judging NLC candidates (are they NLC or not) I have a set of formulas to calculate the minimum altitude (in km) of the candidate given an observed altitude (in degrees) of the ...
12
votes
3answers
13k views
Why does the moon sometimes appear giant and a orange red color near the horizon?
I've read various ideas about why the moon looks larger on the horizon. The most reasonable one in my opinion is that it is due to how our brain calculates (perceives) distance, with objects high ...
