Colors

Primary Colors:

Red Green Blue

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Regards
Ahmed

Interesting point.

However, red, green, and blue are considered the primary colors of light only because the cones in human eyes are most sensitive to them. Light is actually composed of a spectrum of frequencies and none is inherently more primary than the others. I recently learned that the primary colors of pigment I was taught were blue, red, and yellow, are essentially random choices. Printers use cyan, magenta, and yellow (plus black) and can still mix up any color they want. File that away with "milk is a food group", "Pluto is a planet", "glass is a liquid", "lactic acid buildup is what makes your muscles tired and sore", etc. as lies we learned in school.

I am not sure of whether the primary colors (RGB) are in context of Light only.

What I could say that, these three colors are usually stand base for all the other colors by means of integration and mixup.

File that away with "milk is a food group", "Pluto is a planet", "glass is a liquid", "lactic acid buildup is what makes your muscles tired and sore", etc. as lies we learned in school.

Partially agree, as lies we learned in school like I can mention e.g.
Sun is static(not moving), and Moon and Earth are rotating(moving)

While the fact is, Sun and Moon are moving and Earth is static.

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Regards; Ahmed
I argue with a principled person and always win.
I argue with the unprincipled ignorant person and I always lose. - 1 of the Scholar of Islam

Greg Charles wrote:File that away with... "Pluto is a planet"

But when I was in school, Pluto WAS a planet. The Astronomers got together recently (in astronomy time where things last for trillions of years) and re-defined the word "planet". So Pluto was demoted.

It wasn't a lie when it was taught to me, any more than when they told me Jimmy Carter was the current President. It was true at the time.

primary colors: cyan magenta yellow

fred rosenberger wrote:

Greg Charles wrote:File that away with... "Pluto is a planet"

But when I was in school, Pluto WAS a planet. The Astronomers got together recently (in astronomy time where things last for trillions of years) and re-defined the word "planet". So Pluto was demoted.

Phil Plait the Bad Astronomer has a good explanation:

Phil Plait wrote:My feelings about this are on record: the word "planet" is not and can not be defined; it's a concept, not a definition. It's like the word "continent": it's more of an idea than something you can rigidly define. There is no sharp border that you can use to divide objects into planet and not planet.

Baseet Ahmed wrote:
I am not sure of whether the primary colors (RGB) are in context of Light only.

What I could say that, these three colors are usually stand base for all the other colors by means of integration and mixup.

File that away with "milk is a food group", "Pluto is a planet", "glass is a liquid", "lactic acid buildup is what makes your muscles tired and sore", etc. as lies we learned in school.

Partially agree, as lies we learned in school like I can mention e.g.
Sun is static(not moving), and Moon and Earth are rotating(moving)

While the fact is, Sun and Moon are moving and Earth is static.

Actually, everything is moving. You can use any arbitrary point in space as a reference point and make your maths so you consider the reference point as stationary. The basic math doesn't change. The formulas change. However if you consider Earth as stationary, the formulas get a lot more complicated. The motion of planets is mostly influenced by the gravitional force that the Sun exerts on them. So, the formulas are much simpler if you consider Sun as stationary.

Primary Colors:
Red, Green, Blue - when I watch television, monitor, or any other screen
Red, Yellow, Blue - when I make some paintings, or deal with colors
Cyan, Magneta, Yellow - when I deal with digital image processing software

Jesper de Jong wrote:

fred rosenberger wrote:

Greg Charles wrote:File that away with... "Pluto is a planet"

But when I was in school, Pluto WAS a planet. The Astronomers got together recently (in astronomy time where things last for trillions of years) and re-defined the word "planet". So Pluto was demoted.

Phil Plait the Bad Astronomer has a good explanation:

Phil Plait wrote:My feelings about this are on record: the word "planet" is not and can not be defined; it's a concept, not a definition. It's like the word "continent": it's more of an idea than something you can rigidly define. There is no sharp border that you can use to divide objects into planet and not planet.

In my opinion, the astronomers painted themselves into a corner. There were too many pluto like bodies in the kuiper belt. Either they accepted Pluto as a planet, and accept five more planets, with possibily 100 more when the counting is done. Or they lose one planet.

Heck, when I first heard of the "clear the neighborhood of it orbit" rule, I thought it was a rule with a goal in mind.

Henry

Greg Charles wrote:I recently learned that the primary colors of pigment I was taught were blue, red, and yellow, are essentially random choices. Printers use cyan, magenta, and yellow (plus black) and can still mix up any color they want.

They're not random at all, and they're not choices at all. The fact that they can be mixed to produce any other hue is what makes them primary.

No, cyan yellow and magenta are the secondary colours. As stated earlier, the three primary colours red green and blue correspond to the sensitivity of the eye. If our eyes had different sensitivities, we would have chosen different combinations of primary colours.
You can make white by mixing the three primary colours, i.e. shining red green and blue light together.
The three secondary colours are chosen because they transmit pairs of the primary colours, and the primary colours can be reconstructed by superimposing pairs of secondary colours. Red yellow blue are what people say to small children because they think they wouldn’t understand magenta yellow cyan

.

And on a tangent: Why do people talk about blood being crimson, or saying magenta is blood‑red? The two colours look totally different to me.

Jayesh A Lalwani wrote:Actually, everything is moving. You can use any arbitrary point in space as a reference point

doesn't that mean that your arbitrary point is not moving? So therefore, it should be "everything is moving but the arbitrary point in space you select as your reference point"?

Campbell Ritchie wrote:You can make white by mixing the three primary colours, i.e. shining red green and blue light together.

This is true for ADDITIVE things, like light.

For SUBTRACTIVE things, like pigments, you use a different set of primary colors. There is no combination of paints you can mix together to get white. And there is no combination of lights you can mix together and get black.

Campbell Ritchie wrote:Red yellow blue are what people say to small children because they think they wouldn’t understand magenta yellow cyan .

People (that is, people who care) say to small children what they deem will be useful and relevant to them. Until very recently, familiarity with the terms magenta yellow and cyan would have been useless to someone who was not in some way involved in (or at least had a deep fascination with) printing. And unless small children no longer paint in school, the traditional blue-red-yellow color wheel is substantially more useful and relevant to them.

Henry Wong wrote:In my opinion, the astronomers painted themselves into a corner. There were too many pluto like bodies in the kuiper belt. Either they accepted Pluto as a planet, and accept five more planets, with possibily 100 more when the counting is done. Or they lose one planet.

It was pretty much an exact repeat of what happened in the 19th century. In 1801 they found the first asteroid (Ceres) and so that got added to the list of planets. Then they found another one the same year, so that got added to the list. And then they continued finding more asteroids. When the list of planets reached 23, the astronomers (who were a much smaller group back then) said "This is stupid" and excluded the asteroids from the list of planets.

Paul Clapham wrote:

Henry Wong wrote:In my opinion, the astronomers painted themselves into a corner. There were too many pluto like bodies in the kuiper belt. Either they accepted Pluto as a planet, and accept five more planets, with possibily 100 more when the counting is done. Or they lose one planet.

It was pretty much an exact repeat of what happened in the 19th century. In 1801 they found the first asteroid (Ceres) and so that got added to the list of planets. Then they found another one the same year, so that got added to the list. And then they continued finding more asteroids. When the list of planets reached 23, the astronomers (who were a much smaller group back then) said "This is stupid" and excluded the asteroids from the list of planets.

As an FYI, I was actually hoping Pluto remained a planet. Why? The trigger for the latest Pluto debate was the finding of a 10th planet -- a planet that was larger than Pluto. It didn't have a name yet, but it was nicknamed Xena, with its moon nicknamed Gabrielle (as Gabrielle is always circling Xena). Of course, Pluto lost its planet status. And now that Xena got the official name of Eris, I don't care anymore either....

Henry

Pluto's 5th moon has been discovered.

I agree with Neil deGrasse Tyson; including Pluto (and other plutoids) as planets makes no sense. As with the asteroids, if we continued to classify Pluto as a planet, we'd need to also include the many objects continuing to be discovered in the Kuiper belt, and eventually the Oort cloud.

Good points about Pluto and planethood. I figured people would make that point, although I expected "glass is a liquid" to be brought up too. It's not that glass or our understanding of it has changed. We just classify it as an amorphous solid now. To quibble on the Pluto quibble, I think there always some debate on whether Pluto deserved to be called a planet dating back to its discovery. Meanwhile, I like the name Eris. She was the troublemaker goddess ... the one who started the Trojan war, and so is an appropriate namesake for the cause of Pluto's demotion. The Greek myths have proven their staying power, but 100 years from now will people remember a campy TV series?

@Dennis -- yes, blue, red, and yellow allow you to mix to any color (always assuming you're allowed to add white). The "lie" was that there is something special about those particular three, when actually there are any number of sets of "primary" colors that would have that same property. I also sort of remember being told that it would be impossible to mix other colors to produce red, yellow, or blue, which is not true.

But all of the colours discussed so far are human-centric, i.e. they are colours that humans can see and no others. What about, say, some birds which can distinguish colours in the ultra-violet range? What are their three primary colours? Or are there even three?

fred rosenberger wrote:

Jayesh A Lalwani wrote:Actually, everything is moving. You can use any arbitrary point in space as a reference point

doesn't that mean that your arbitrary point is not moving? So therefore, it should be "everything is moving but the arbitrary point in space you select as your reference point"?

You have reality, and then you have the model of reality that you express mathematically. In Reality, everything is moving. But to model reality mathematically, you have to pick a reference point, and consider that to be the center of your universe (and fixed) and build your model accordingly. It's a limitation of our models (actually the very way we understand the world) that requires us to consider a point in space as fixed.

Bear Bibeault wrote:Pluto's 5th moon has been discovered.

And of course, having a moon isn't a requirement of being a planet. If it was, we would lose two more planets.

Henry

Jayesh A Lalwani wrote:

fred rosenberger wrote:

Jayesh A Lalwani wrote:Actually, everything is moving. You can use any arbitrary point in space as a reference point

doesn't that mean that your arbitrary point is not moving? So therefore, it should be "everything is moving but the arbitrary point in space you select as your reference point"?

You have reality, and then you have the model of reality that you express mathematically. In Reality, everything is moving. But to model reality mathematically, you have to pick a reference point, and consider that to be the center of your universe (and fixed) and build your model accordingly. It's a limitation of our models (actually the very way we understand the world) that requires us to consider a point in space as fixed.

The problem with choosing earth as a reference point, is that it is not only moving, but it is also has (circular) acceleration. This makes the math, while possible, much more difficult than it needs to be..... Why would anyone purposely develop a mathematical model to be more difficult to envision?

Henry

Because the Pope will imprison you otherwise. Oh wait... that was over 400 ago.

Henry Wong wrote:The problem with choosing earth as a reference point, is that it is not only moving, but it is also has (circular) acceleration. This makes the math, while possible, much more difficult than it needs to be..... Why would anyone purposely develop a mathematical model to be more difficult to envision.

This is beginning to remind me of my all-time favourite XKCD cartoon.

http://xkcd.com/123/

Henry Wong wrote:The problem with choosing earth as a reference point, is that it is not only moving, but it is also has (circular) acceleration. This makes the math, while possible, much more difficult than it needs to be..... Why would anyone purposely develop a mathematical model to be more difficult to envision?

Because it's one of the questions at the end of Chapter 4 in your physics textbook?

Henry Wong wrote:

The problem with choosing earth as a reference point, is that it is not only moving, but it is also has (circular) acceleration. This makes the math, while possible, much more difficult than it needs to be..... Why would anyone purposely develop a mathematical model to be more difficult to envision?

Henry

Yeah well, depends on what part of universe you are modeling. If all you are concerned about is predicting moon-rise and moon-sets, an eartho-centric model is simpler. A solar-centric model makes modeling the motion of the moon much more complicated

Matthew Brown wrote: . . . This is beginning to remind me of my all-time favourite XKCD cartoon.

http://xkcd.com/123/

And XKCD is right all along. See, red green and blue. Even though, as . . .

I, earlier wrote:The three primary colours red green and blue correspond to the sensitivity of the eye.

There is no more an absolute primary colour than there is an absolute static point in space, but we have to work with what we have, our eyes.

Birds which can see UV would work with four primary colours.

Campbell Ritchie wrote:Birds which can see UV would work with four primary colours.

Interestingly, the Wikipedia article about Bird vision says

Wikipedia wrote:Most birds are tetrachromatic.... Pigeons have an additional pigment and are therefore pentachromatic.

Paul Clapham wrote:But all of the colours discussed so far are human-centric, i.e. they are colours that humans can see and no others. What about, say, some birds which can distinguish colours in the ultra-violet range? What are their three primary colours? Or are there even three?

Many birds, some frogs, etc. have sensors to recognize four or more primary colors.

But most of this discussion is based on a false premise. Its not that RGB or CMY are "the primary colors" but rather than they are a basis set to allow the full gamut of what we think of as color space. When you have a basis set and an operator or two, you can do anything.

If two or more basis sets contain different elements and still are complete, then they are isomorphic.

All anyone needs to know about colors:

Bear Bibeault wrote:All anyone needs to know about colors:

Does it still have "flesh" as a color?

Not since 1962.

Bear Bibeault wrote:Not since 1962.

Guess that dates me, eh?

And me, I remember "flesh". Now renamed "peach".

OK, take a piece of dark paper and @bear's box of crayons.

Combine them to make white.

When you fail, the box of crayons is not a basis set.

Bear Bibeault wrote:And me, I remember "flesh". Now renamed "peach".

Perhaps you even remember "flesh-colored" Band-Aids?

Natural examples of Primary Colours: Red, Green, Blue

1. RED as Blood
2. GREEN as Tree
3. Blue as Sky

Lalwani wrote:
Actually, everything is moving.

How?

Agree with Sun and Moon as the Day and Night repeats.

Bottom line: When Earth was created it was shaking, then Mountains has been kept on it. Then it gets stopped shaking.

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Regards
Ahmed

There's an interesting show about colors from the RadioLab podcast - very interesting and entertaining to listen to.

One of the subjects they talked about was how different people, or people in different cultures, seem to perceive colors differently. One thing that's curious for example is that many ancient cultures, for example the ancient Greeks, didn't have a word for "blue". You'd say that the blue sky should be obvious to them, but it seems that for some reason they weren't very aware of the color blue.

Baseet Ahmed wrote:

Lalwani wrote:
Actually, everything is moving.

How?

Galilean transformation - you can use any inertial (non-accelerating) point as a reference point and the laws of physics are identical. There's no natural fixed point, though there's often a convenient one for any particular problem.