Television etc and green, red, blue

[luckis11]

The antenna cable tranfers only the 3 frequencies of green, red and blue, yes or no?

 

[berkeman]

The antenna cable tranfers only the 3 frequencies of green, red and blue, yes or no?

Nope. When you search at HowStuffWorks.com for how televisions work, what other things do you see that are contained in the TV RF signal in?

 

[luckis11]

I see that: "Your search for "television" returned 3,468 articles".

link please?

 

[jtbell]

The antenna cable tranfers only the 3 frequencies of green, red and blue, yes or no?

I don't know where you are, but in the USA and many other countries, terrestrial broadcast TV that you receive with an antenna (aerial) is digital nowadays. The video is encoded as either MPEG-2 or MPEG-4 data, in which color is encoded not as separate red/green/blue (RGB) channels, but instead using chroma subsampling.

For analog television, the Wikipedia pages for NTSC, PAL and SECAM contain information about how color is encoded in those systems.

 

[berkeman]

I see that: "Your search for "television" returned 3,468 articles".

link please?

Yeah, their search engine results page has gotten really cluttered the last year or two. Yuck.

Turns out all you have to do at that results page is click on the word "Television" right above the picture of the Television. That gets you to the HowStuffWorks-specific results page:

http://electronics.howstuffworks.com/television-technology-channel.htm

There are the links for how TV works and the different related info.

 

[luckis11]

IF the screen radiates only the 3 frequencies of the red, green, blue, then the frequency of the yellow is formed before or after the eye? Please correct the previous "IF" (if false), and give me the correct answer.

(no links please, I've read a multitude, none of them explained it, I want your own answer).

 

[berkeman]

IF the screen radiates only the 3 frequencies of the red, green, blue, then the frequency of the yellow is formed before or after the eye? Please correct the previous "IF" (if false), and give me the correct answer.

(no links please, I've read a multitude, none of them explained it, I want your own answer).

This should help you answer your own question:

http://en.wikipedia.org/wiki/Color_gamut

Are you familiar with the differences between combining luminous colors versus combining pigment colors?

 

[luckis11]

I am asking what actually happens in the actual space between the tv and the eye, which has nothing to do with that triangle.

 

[berkeman]

I am asking what actually happens in the actual space between the tv and the eye, which has nothing to do with that triangle.

In the space between the TV and the eye, nothing special happens. Photons are photons -- they do not interact to make new "colors" of photons, if that's what you are asking.

 

[rcgldr]

The color receptors in your eyes each have different sensitivity versus frequency curves. Some colors will appear to be the same regardless if the source is a single frequency like yellow or a combination of frequencies like red plus green. Some perceived colors are only possible as a combination of frequencies (non-spectral colors).

http://en.wikipedia.org/wiki/Color

 

[D H]

For analog television, the Wikipedia pages for NTSC, PAL and SECAM contain information about how color is encoded in those systems.

To help with all those acronyms,
NTSC = National Television Systems Committee but also "not the same color",
PAL = Phase Alternating Line but also "pay and learn",
SECAM = Séquentiel couleur à mémoire but also "shows every color all murky".

Those alternative definitions hint at some of the issues with those analog formats.

 

[jtbell]

NTSC = National Television Systems Committee but also "not the same color",

The version I learned was "Never Twice the Same Color".

 

[Janus]

To help with all those acronyms,
NTSC = National Television Systems Committee but also "not the same color",
PAL = Phase Alternating Line but also "pay and learn",
SECAM = Séquentiel couleur à mémoire but also "shows every color all murky".

Those alternative definitions hint at some of the issues with those analog formats.

A great deal of those issues were the result of the insistence that older black and white sets be able to receive and decode color signals.

One of the reasons HDTV took as long as it did to come out was a similar battle over format. There were those that wanted to make HDTV signals so that they could be received by standard TVs (At the cost of degrading the quality for even HDTVs).

 

[NobodySpecial]

And PAL is perfection at last.

To answer the OPs questions, yes the TV screen only generates three colors red,green,blue - not exactly single wavelengths because the dyes used in the filters aren't perfectly monochromatic - but the theory is the same.
Our eyes have three color receptors and our brains can generate any color we can see from the relative brightness of these three

Although because our eyes color response and the TV standard RGB don't quite match up there are colors that we can see which you can't perfectly reproduce on a screen

 

[DaveC426913]

In the space between the TV and the eye, nothing special happens. Photons are photons -- they do not interact to make new "colors" of photons, if that's what you are asking.

In other words, yellow happens in the brain.

If you passed the light from the TV through a prism, it would show red, green and blue only.

 

[luckis11]

You mean that between the screen and the eye the green frequency and the red frequency have their own space and do not interfere resulting in the frequency of the yellow? (What's the proof for that?) Or what are you saying?

 

[DaveC426913]

You mean that between the screen and the eye the green frequency and the red frequency have their own space and do not interfere resulting in the frequency of the yellow? (What's the proof for that?)

This does not make sense. Colours do not interfere with each other.

Or what are you saying?

What I'm saying is this: there is no yellow light between the screen and eye.

Light coming from an RGB screen is exactly that, red green and blue. There is no yellow light (or orange or purple for all that matter) coming from the TV. The reason this is so is because TV is specifically built for human vision. Humans (most at least) have three receptors: red, green and blue. These are the peaks that the receptors are sensitive to, but they are also sensitive to adjacent colours to a lesser degree. Here's a cool graph that illustrates it:
[PLAIN]http://dvd-hq.info/dvdhq_images_2k8/human_vision_spectrum.png

The three peaks our where our three receptors are most sensitive, everything in between is where our receptors are stimulated by other (real-world) colours, such as yellow and purple.

So, though our red receptors and our green receptors are stimulated by yellow light in the real world (such as a lemon or a taxi), they are also stimulated by the red and green light that the TV image of a lemon or taxi is composed of.

In short, TVs simulate the colour yellow by displaying equal parts red and green. Our eyes cannot tell the difference between yellow and red-green.

 

[NobodySpecial]

DaveC's important point is that colors do not mix.
Whatever you where taught in school you do not make yellow light by mixing red and green light, your BRAIN interprets the red sensor and green sensor triggering together as yellow.

You can make a TV system by showing just the red image and then a fraction of a second later just the green image then the blue image. The three color photons never exist at the same time - but you see normal color. This is how most LCD projectors work.

 

[luckis11]

By "yellow frequency" I meant "the frequency of the yellow". Therefore according to you, you are wrong as much as I was, as you said my nonsense was that "the frequency IS yellow", whereas you also said "yellow light"<=>"the light IS yellow".

But you did not answer me: What's the proof that the R+G light does not become Y light because of intereference before it reaches the eyes? When you photograph the screen, the area on the photograph is again yellow.

 

[berkeman]

By "yellow frequency" I meant "the frequency of the yellow". Therefore according to you, you are wrong as much as I was, as you said my nonsense was that "the frequency IS yellow", whereas you also said "the light IS yellow".

But you did not answer me: What's the proof that the R+G light does not become Y light before the eyes. When you photograph the screen, the area is again yellow.

Please mellow your tone. We are trying to help you.

The proof is to use Dave's prism suggestion. Do you have a prism that you can use for the experiment?

 

[DaveC426913]

By "yellow frequency" I meant "the frequency of the yellow".

There is no yellow coming from the TV; there is no yellow reaching the eye. There is red, green and blue. Yellow occurs in the brain.

In the real world (not the TV), there really are things that are yellow, and really do have yellow as a frequency. Lemons. Taxis.

Therefore according to you, you are wrong as much as I was, as you said my nonsense was that "the frequency IS yellow", whereas you also said "yellow light"<=>"the light IS yellow".

I did not say nonsense; I said "does not make sense". Frequencies of light do not interfere to produce new frequencies. If you'd like to reword that, feel free.

Please, do not misquote me or put words in my mouth such as "yellow light"<=>"the light IS yellow"

But you did not answer me: What's the proof that the R+G light does not become Y light because of intereference before it reaches the eyes?

The onus is not on me to teach grade 9 physics; it is accepted knowledge. If you have learned enough about optics that you choose to reject it for an alternate theory, PF has a forum where you can submit your paper.

When you photograph the screen, the area on the photograph is again yellow.

Your eyes see yellow. That does not mean yellow is there.

A prism is not fooled. A prism will separate the TV light into r g and b.

Digital cameras have three receptors: red, green and blue. There is no yellow in digital pictures. There is no yellow in the computer monitor that projects the digital image to your eyes. Even then, yellow is still in your head.

If you want to talk about film cameras, we can do that too.

 

[NobodySpecial]

But you did not answer me: What's the proof that the R+G light does not become Y light because of intereference before it reaches the eyes?

Apart from the laws of physics - an LCD projector with a color wheel that shows separate R,G,B images at different times, the red and green photons don't exist at the same time.

 

[luckis11]

Actually you are putting words in my mouth, saying that I have an alternate theory. I just asked for the proof, I did not imply that the proof is wrong. How can I have an alternate theory since I just found out from you that the known theory claims the one thing instead of the other?

Then you say "it is accepted knowledge" whereas I asked for the proof for that knowledge.

And that "I should read the optic books". Why do you bother answering me at all and not say "This is so elementary optics, that you should find the answer yourself in the books". Well, I can't find it that's why I am asking.

From all you said, this sounds like a proof, so thanks for the hint:
"A prism is not fooled. A prism will separate the TV light into r g and b."

 

[DaveC426913]

Actually you are putting words in my mouth, saying that I have an alternate theory.

No, I am not telling you that you have a theory. I'm noting you challenging known basic physics. If you have a reason for challenging it, it would have to be because you have your own ideas on it.

Note the word "if", which I used in my original post. i.e. not putting words in your mouth (if you're going to try to copycat me, get it right).

I just asked for the proof.Then you say "it is accepted knowledge" whereas I asked for the proof for that knowledge.
And that "I should read the optic books". Why do you bother answering me at all and not say "This is so elementary optics, that you should find the answer yourself in the books". Well, I can't find it that's why I am asking.

I think you are misunderstanding the role of PF and its members. The onus is not on us to "prove" any challenge you happen to throw at us.

From all you said, this sounds like a proof, so thanks for the hint:
"A prism is not fooled. A prism will separate the TV light into r g and b."

Well great. Hope you don't tick off too many more people on your journey.

 

[berkeman]

I think we've done our best to help lukis understand. Thread closed.