Red, green, and blue are the primary colors of light—they can be combined in different proportions to make all other colors. For example, red light and green light added together are seen as yellow light. This additive color system is used by light sources, such as televisions and computer monitors, to create a wide range of colors. When different proportions of red, green, and blue light enter your eye, your brain is able to interpret the different combinations as different colors.   My question is can the eye distinguish between light of the pure wavelength corresponding to yellow(monochromatically yellow) and a mixture of red and green light that also produces the sensation of yellow in our eyes?  The question is related to the question asked here:   But my specific question is whether the eye can distinguish between the mixture and a pure wavelength of purple.
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In music, when two or more pitches are played together at the same time, they form a chord. If each pitch has a corresponding wave frequency (a pure, or fundamental, tone), the pitches played together make a , which is obtained by simple addition. This wave is no longer a pure sinusoidal wave.  For example, when you play a low note and a high note on a piano, the resulting sound has a wave that is the mathematical sum of the waves of each note. The same is true for light: when you shine a 500nm wavelength (green light) and a 700nm wavelength (red light) at the same spot on a white surface, the reflection will be a superposition waveform that is the sum of green and red.  My question is about our perception of these combinations. When we hear a chord on a piano, we’re able to discern the pitches that comprise that chord. We’re able to “pick out” that there are two (or three, etc) notes in the chord, and some of us who are musically inclined are even able to sing back each note, and even name it. It could be said that we’re able to decompose a Fourier Series of sound.  But it seems we cannot do this with light. When you shine green and red light together, the reflection appears to be yellow, a “pure hue” of 600nm, rather than an overlay of red and green. We can’t “pick out” the individual colors that were combined. Why is this?  Why can’t we see two hues of light in the same way we’re able to hear two pitches of sound? Is this a characteristic of human psychology? Animal physiology? Or is this due to a fundamental characteristic of electromagnetism?
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How to make the single color in a photography to be color and other parts changed to B&amp;W?.  Don't know exactly the name of the effect, to be more clear in the following photo I want the green part to be green and other parts( leg and sandal) in B&amp;W..    How to achieve that effect in Photoshop?
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I want a green for "correct answer" and a red for "wrong answer". My current choice is rgb(144, 238, 144) for the green and rgb(250, 128, 114) for the red. (See wikilearner.net/wiki for the colours in action.)  I have been told that these colors are very close in contrast, making it difficult for a person with red-green color-blindness. What would be a better choice?
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What determines the color of light -- is it the wavelength of the light or the frequency?  (i.e. If you put light through a medium other than air, in order to keep its color the same, which one would you need to keep constant: the wavelength or the frequency?)
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Both options affect colors in a similar way, but I can't figure out the difference.
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I'm designing a chart right now, that will slowly have more items added to it. I'd like to create an list/order of colors for the items, that will be most usable for the color blind to differentiate between each item. Any ideas how/where to start?
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I am trying to design an infographic that is colorful and informative. At the same time, people who are colorblind should be able to view it.   allows you to view images with normal vision and different type of color-blindness.  When I my computer program's default "colorblind safe" colors, the image is visible to people with some types of color blindness and not others.  Please tell me where I can find a palette of all colors that are visible to those with normal vision and all different types of color blindness.  Thank you
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\documentclass{article}  \usepackage{xcolor}  \begin{document}  \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue  from here, something is wrong?  \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue \color{red}red  \color{green}green  \color{blue}blue  \end{document}
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The book I'm reading about optics says at some point that "each color (wavelength) contained in the white light interferes only with itself". But why is this so?  Edit: I moved the rest of the question .
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I have learnt that depending on the various gases those are involved in the reaction that produces fire, different colors (yellow, red or blue) of flames become visible.  I have a question .. what are the possible colors that fire can possess? and do they (how, if yes) relate to the intensity? like I know blue is more intense than red, etc..
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What is the difference between color and colour?
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I realise the question of why this sky is blue is considered reasonably often here, one way or another.  You can take that knowledge as given.  What I'm wondering is, given that the spectrum of Rayleigh scattering goes like $\omega^4$, why is the sky not purple, rather than blue?    I think this is a reasonable question because  (or, strictly, violet or indigo) in rainbows, so why not across the whole sky if that's the strongest part of the spectrum?  There are two possible lines of argument I've  and I'm not sure which (if not both) is correct.  Firstly, the Sun's thermal emission peaks in the visible range, so we do actually receive less purple than blue. Secondly, the receptor's in our eye are balanced so that we are most sensitive to (roughly) .  Our eyes are simply less sensitive to the purple light than to the blue.
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My understanding of colour is that atoms in a particular object will absorb certain wavelengths of electromagnetic radiation, and the scattered wavelengths give the object its colour. The absorbed wavelengths contribute to lattice vibrations, increasing the kinetic energy and raising the objects temperature. Is this correct?  What is the sequence of events when a solution of particular atoms is sprayed through a Bunsen burner? I don't understand this. In this case is the colour seen a result of electrons moving up and then back down energy levels?
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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 person's. Because he or she could actually be seeing, what I know to be the color green. But then tells me that its the color yellow because that has been taught to him or her from young age.  So how can you test if people are really seeing the same color?  Question closed and can now be found @
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I was taught that something which reflects all the colors of light is white. The function of a mirror is the same, it also reflects all light. What's the difference?  Update: But what if the white object is purely plain and does not scatter light? Will it be a mirror?
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We have seen the Newton disc, when it is rotated it produces white color. So I want to know whether white exists as a single color or is that a combination of multiple colors?
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This is a question thats been bothering me a while. I don't even know if it makes sense or not (like if it is a physics question or becoming a philosophical one). But here it goes. The crux of my question basically is that we all know that we can't see light (like in its photon or electromagnetic wave form) directly when it is traveling past us. However, we also know that the way we see objects is by light reflecting off them. This then means that we are "seeing" the light reflecting from the object which then sends the signal to our brain saying that we are seeing a particular object. We know that both light traveling past us and light reflected from objects are made of photons (so they are the same kind)? So then my question is that what is happening to the photon of a light after it is reflected from the objects, that causes us to see it or the object, but on the other hand we can't see light as it is directly traveling past us.