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A.K. Boomer
02-28-2017, 09:55 AM
Im perplexed about colors,
mainly because the way were supposedly perceiving them does not totally add up,

I grasp the concept of what we see of an object as yellow is actually every color but yellow and that's why the spectrum of yellow light is reflecting yellow back at us, same with what we think of a blue object is actually everything but blue, or a green one or red,

but what about brown?

here's the part that does not make sense to me, if seeing bright yellow or blue or red is actually an admission that the color brown is really in all of them and that's the very reason you cannot see it, then how come when you mix all of these other colors together you end up seeing it?, the color brown that is...

just drawing back on what happened when I was a kid and got all my different play-dough colors mixed together...

Puckdropper
02-28-2017, 10:41 AM
I'm far from an expert on color theory, so keep this in mind. However, colors are displayed as a result of two different methods: additive and subtractive. Additive colors are like those from light. If you took a flashlight that was perfectly red, one that was perfectly blue, and one perfectly green, and shone them on the same spot you'd have a white dot. Computer monitors are this kind of device. With subtractive colors, they're like paint. Take red and blue and yellow, and mix them and you'll get black.

As for brown, yeah that's still a bit of a mystery to me. Of the neutral colors, it was the one that I never knew how to make from the color wheel.

danlb
02-28-2017, 10:55 AM
A real poor explanation:

It's confusing be cause we have two ways that we mix "colors". We can mix pigments or we can mix lights. Either way, our eyes can only sense Red, Blue and Green LIGHT. The level of each of those lights are mixed by our brains to be interpreted as other colors.

There is mixing pigments, where white PAINT reflects all colors and Black reflects none. Then we have mixing light, where if you shine a red light and a blue light and a green light you get white light.

Pigments subtract light from what whatever light is shined on it. If you shine a red light at a blue dot, you only see a black dot because Blue does not reflect red. Shine a white light on that same blue dot and you will see the blue spectrum of the light reflected.

What you see as YELLOW is actually a mixture of green and red LIGHT. That means that a yellow dot has to absorb all blue light while reflecting red and green in roughly equal proportions. It also means that the light shining on the dot has to have a red and green spectrum in it. Yellow, orange and brown are all sensed as a combination of red and green LIGHT with little or no blue.

Like I said, a poor explanation.

Dan

kendall
02-28-2017, 10:57 AM
Think some of it has to do with the difference between RGB and CYM. red/green/blue when mixed produce white, cyan/yellow/magenta when mixed give black. RGB adds each color, with CYM each color cancels the other.


Edit:
with RGB, mixing red and blue gives purple
With cyb, you mix cyan and magenta (?) to cancel out the red in megenta and produce blue

J Tiers
02-28-2017, 11:02 AM
It's probably more useful to consider it a little differently.

A yellow object is not "all other colors", actually it is an object that REFLECTS YELLOW LIGHT. Because it does NOT reflect the other colors, it appears "yellow" because that is the only color (frequency) of light that remains. White paint reflects all colors, black paint reflects no colors (ideally). Clear material filters out no colors.

Paints, etc are a sort of "filter".

A colored glass is one that transmits only the one color. It filters out the others. Paint reflects only the one color. This is with single, not mixed, colors.

When you have mixed colors of paint, they have a mixed reflectivity. You have yellow, and blue, for instance. Your eye perceives this as being green.

danlb
02-28-2017, 11:49 AM
With the question of brown, specifically, I've noticed that you will never really see a bright brown. A bright blue, a bright red or a bright green, yes. Even a bright yellow. But brown is always a a dull color since most of the visible light spectrum is not reflected.

Dan_the_Chemist
02-28-2017, 12:22 PM
Additive - adding light

Take three adjustable lights - Red, Green, and Blue. Shine them on a spot. As you bring up the brightness of any two you get an intermediate color

(Red/Green mix) Red -> Orange -> Yellow -> Lime Green -> Green
(Red /Blue mix) Red -> Magenta -> Purple -> Indigo -> Blue
(Blue/Green mix) Blue -> Greenish Blue -> Turquoise -> Bluish Green -> Green

When you start adding three colors together you get more intermediate colors. If you add all three together in equal amounts you get white. If you add more red and a little green, you get something that is orange... around 590 on the periphery of this graph, or at about X = 0.53 and Y = 4.0.

https://upload.wikimedia.org/wikipedia/commons/b/b0/CIExy1931.png


Subtractive - removing light

Paint removes colors from light that hits it. If you have a paint that absorbs blue light, and you shine white light on it, then the reflection will be made up of a mixture of red and green light. The color will depend on just how much red is reflected and how much green is reflected (and if any blue is reflected). It might be a bright yellow if all of the red and green are reflected (X = 0.45, Y = 0.55). It might be a dull yellow if just a little red and green are reflected (still X= 0.45, Y = 0.55, but the brightness is reduced) And if a little more red is reflected than green, it will look orange (as above, X = 0.55, Y 0.4). If the overall reflectivity is reduced, it will go from orange to dull orange to brown... So brown is not only an orangish color, it is perceived because of low reflectivity compared to things around it. Take a scrap of dark orange construction paper and put it on a white background and then on a black background. Your perception of it's color name will shift (even though the spectrum of the reflected light doesn't change).

The color of randomly mixed paint tends towards brown because in general the mixtures are heavy on the colors that absorb blue light... If you look at the color triangle you will see that Red, Orange, Yellow and Green are actually all on one curved leg of the triangle. Mixing those four paint colors will absorb more color from the left lower corner, pushing the reflection (what is left) into the right upper middle... i.e., yellow/orange/brown. As the mixed pigments get more and more effective at removing light, it should go to black. However, cheap pigments are not very efficient, and so we end up with brown.

Of course, if the light hitting the paint isn't white light, then that changes things. Shining blue light on paint that absorbs blue light will reflect nothing - and it will look black. So something that looks yellow in white light may look almost black in blue light.

kendall
02-28-2017, 01:02 PM
Knew they were simple terms for coloring, additive subtractive.
So dosed up with cold meds couldn't think of em.

A.K. Boomer
02-28-2017, 02:05 PM
appreciate the explanations -

would be interesting to find an "anti color chart" one that shows what my favorite color actually really looks like, must be gawd awful im thinking...

Evan
02-28-2017, 02:26 PM
Here is a web page I put up some years ago when I was doing testing for JASC on Paint Shop Pro. It is about how to balance and calibrate colours on a computer to match a printer so it prints out properly. It also explains colours and how they work.

http://ixian.ca/color.htm

How we perceive colour is a very necessary part of the work I am now doing. Our eyes and brain are not at all linear and we do not all see colours the same. I even have a difference from my left and right eye that made it more difficult to get a pilot's licence.

Our eyes are very fast at detecting changes in luminosity (brightness) but are terrible at seeing changes in colour. With colours everything matters, how fast they change, how much they change and what the change in wavelength happens to be. We are far more sensitive to green light than red or blue. We are tricolour animals but the sensitivity of the cones in the retinal centralis area have a spectral overlap that stretches far into each of the other colours. The amount of overlap varies quite a lot so even if we see approximately the same colours in red, green and blue the overlapping in between areas can be a lot different. Brown is just dim yellow, not really a different hue (colour).

What you see also very much depends on your recent exposure to light, especially bright light. The afterimage effect can stay for quite a long time and it usually cause a reversal of the colour sensitivity. That is where I have had to compensate in my project by using changes in luminosity instead of just changes in colour. I am using exponential curves for the colour changes to compensate for afterimage effects. It doesn't help at all that computer monitors are also very non linear.

added: Also, it is know known that what we see and even afterimages are not just caused in the eye but also in the brain. One of the most amazing things I have learned is that the entire visual area for each eye is directly mapped into the occipital lobes at the back of the brain. The neural fibres connect in the same way that we actually see in our visual field. I would sure like to know when that mapping occurs. Is it before we first open our eyes the very first time or does it happen after that time and just how quickly does it happen? That would be a really nice research project in neurology. The main difficulty would be just how do you do it? We cannot play with a baby's vision so perhaps some sort of lab animal would work. But that would have to be some sort of primate.

danlb
02-28-2017, 07:40 PM
Evan, it appears to be learned, and even relearned. There was a study (that you probably know about) where the person wears glasses with prisms to invert their vision. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC311278/

The interesting thing is that the subjects quickly learned to see everything as right side up again. Even more fascinating was a later experiment that indicates that the subjects "reduce their motor errors under inverted vision" ( https://www.ncbi.nlm.nih.gov/pubmed/23700129 )

The mind is a marvelous thing.

Dan

elf
02-28-2017, 08:10 PM
But what does it taste like???

Evan
02-28-2017, 08:47 PM
The interesting thing is that the subjects quickly learned to see everything as right side up again.

We discussed that here a long time ago. From what I recall in some research I did, it was not at all easy for some to go back to normal vision. In particular the man that first tried it on himself had some very serious problems restoring his normal vision. It is very dependent on time as well as age. From birth to several years the brain is rapidly developing and undergoes a period of "pruning" excess neurons if they are not put into use for something. What this indicates is that right from birth a baby should be constantly kept busy with new things to see as well as new places, events, sights and sounds and that includes very early teaching in how to speak normal talk and early reading. My daughter was able to recite nursery rhymes from memory very well by the time she was 2 years old. She was reading long before she attended school. She now owns her own newspaper and is a national award winning photographer.

This sort of thing is now being seen in children that are treated for amblyopia by using an eye patch on the "good" eye to force the wandering eye to line up. Patching one eye for too long can cause serious problems that do not easily correct. "Too long" is not very long at all either.

The brain is indeed marvelous and I can testify to that. Mine is recovering far more than I thought possible and it is far faster than I ever thought could happen. It is a matter of pushing myself as hard as I can and not letting up. One thing I notice is what always happened in the past. When I work my brain hard I will start to sweat after an hour or two.

I have always liked my living space to be extra warm, most likely because I do not have much body fat. I normally keep it at around 24C (75F). But in the evening when I do my best work I let the heat drop and do not notice until it has fallen by about 3 degrees colder. That is a really big drop in room temperature, about 5.4 F colder. Also, when I work really hard it is like time slows down a lot. The clock speed must be accelerating some how.

Anyway, must go. I have a meeting at the University tomorrow and demonstration on Friday.

JoeLee
02-28-2017, 10:47 PM
I don't know if this relates to the OP's question but when I had my body shop every now and then I would have to paint something just for the sake of rust protection and or the customer didn't care what color it was as long as it was covered with paint...... so what I used to do was dump all my left over paint from previous jobs in a gallon can and stir it up. The results were, I always ended up with a dark blue gray color no matter what I mixed together.

JL..............

JRouche
03-01-2017, 12:44 AM
A yellow object is not "all other colors", actually it is an object that REFLECTS YELLOW LIGHT. Because it does NOT reflect the other colors, it appears "yellow" because that is the only color (frequency) of light that remains. White paint reflects all colors, black paint reflects no colors (ideally). Clear material filters out no colors.

That is how always thought of it. JR

Puckdropper
03-01-2017, 12:46 AM
I don't know if this relates to the OP's question but when I had my body shop every now and then I would have to paint something just for the sake of rust protection and or the customer didn't care what color it was as long as it was covered with paint...... so what I used to do was dump all my left over paint from previous jobs in a gallon can and stir it up. The results were, I always ended up with a dark blue gray color no matter what I mixed together.

JL..............

I was thinking about something similar when I wrote my initial response. I had some colored modeling clay that when mixed together gave a purpley-gray color. (It's probably close to the same color as your paint, just described differently.) Did you ever look at two different batches of mixed paint to see how close the two batches were in color?

JoeLee
03-01-2017, 09:15 AM
No, I never compared the two batches or any other batches that I mixed, simply because color match didn't matter.
There may have been some differences in the shades of blue / gray depending on the amounts of different color paints I threw into the mix, but it always ended being that blue gray.

JL..............

AD5MB
03-01-2017, 09:26 AM
clear window glass refracts green at a steep angle, which is why the edges of glass sheets appear green. green goes straight in and comes out the edges at a severe angle

if you have yellow shooting glasses, check out a construction site a little ways down the road. you will see vast clouds of dust not visible otherwise.
if you have blue blocker sunglasses, check out a city park. you will see trampled grass that looks as healthy as the grass around it, looks gray and lifeless.

A.K. Boomer
03-01-2017, 09:33 AM
No, I never compared the two batches or any other batches that I mixed, simply because color match didn't matter.
There may have been some differences in the shades of blue / gray depending on the amounts of different color paints I threw into the mix, but it always ended being that blue gray.

JL..............


this is a handy mixing tool and is super easy to use, my guess is you did not paint to many bright yellow+blue+red cars in the same era to save up those three colors and mix

try adding one of each in the mixer... I think they must have been some of the most popular colors in original play-dough and that's why I would come up with brown when all mixed together...

http://trycolors.com/

A.K. Boomer
03-01-2017, 09:38 AM
clear window glass refracts green at a steep angle, which is why the edges of glass sheets appear green. green goes straight in and comes out the edges at a severe angle



You can also place two mirrors facing each other to create a repetitive "infinite" tunnel of smaller reflections of the two mirrors, the tunnels borders will be green.

A.K. Boomer
03-01-2017, 09:55 AM
The simple overlapping circles in Evans link cover so much ground,

I understand the first additive example of basic colors coming together forming white in the center but the second example of all the subtractive colors (which appear to be actually lighter in pitch) when brought together forming black is a surprise to me.

danlb
03-01-2017, 09:57 AM
No, I never compared the two batches or any other batches that I mixed, simply because color match didn't matter.
There may have been some differences in the shades of blue / gray depending on the amounts of different color paints I threw into the mix, but it always ended being that blue gray.

JL..............

It makes sense if you think about it. Virtually all paints have pigments chosen from a small selection mixed into a white base. The proportion of the pigments determine the color. When you mix a bunch of paints you are mixing all the pigments. By the time you mix several colors of paint, you are likely to have added enough pigment to mute all three of the primary colors.

Slate is violet and green. Violet is actually red and blue. Green is actually blue and yellow. Throw in a bit of black and you have a nice blue grey .

But what if you did not throw any violet and green paint together. Look at the info below to see how many combinations eventually end up combining all three primary colors.

Stolen from /www.housepaintingtutorials.com (http://http://www.housepaintingtutorials.com/paint-color-mixing-chart.html)



Red, blue and yellow are called primary colors.
Unlike secondary, tertiary and quaternary colors, primary paint colors cannot be "made" by mixing

red + blue = violet
blue + yellow = green
yellow + red = orange
yellow + orange = yellow-orange
orange + red = red-orange
red + violet = violet-red
violet + blue = blue-violet
blue + green = green-blue
green + yellow = yellow-green
green + orange = brown
orange + violet = brick
violet + green = slate
If you add white to any color, that color becomes a tint
Another way to extend a color is to turn it into a shade, by adding black to it.
When you add gray to a color, you create a tone.

J Tiers
03-01-2017, 10:16 AM
T....
I understand the first additive example of basic colors coming together forming white in the center but the second example of all the subtractive colors (which appear to be actually lighter in pitch) when brought together forming black is a surprise to me.

Should not be a surprise..... if you consider that paint absorbs all colors except the actual color it is.

A.K. Boomer
03-01-2017, 10:37 AM
It's probably more useful to consider it a little differently.

A yellow object is not "all other colors", actually it is an object that REFLECTS YELLOW LIGHT. Because it does NOT reflect the other colors, it appears "yellow" because that is the only color (frequency) of light that remains. White paint reflects all colors, black paint reflects no colors (ideally). Clear material filters out no colors.

Paints, etc are a sort of "filter".

A colored glass is one that transmits only the one color. It filters out the others. Paint reflects only the one color. This is with single, not mixed, colors.

When you have mixed colors of paint, they have a mixed reflectivity. You have yellow, and blue, for instance. Your eye perceives this as being green.

This is well said and I guess the very reason why snow is so damn bright, it has three major wavelengths ganging up on your retina's

So I guess in theory it's impossible to have light without colors attached to it? if indeed we could create this what would things look like? just black and white no matter what?

clear materials (like water) are indeed clear given they have no other influence like the sky or whatever,,, although vaporize some and they give up the light spectrum's sequence of colors in the form of a rainbow,

Back to the snow, take these vapors and allow them to crystallize/collect and freeze and the once exposed prism mist goes back into hiding lights secrets and were left with a blinding white staring back at us, yet crystalline structures have prism capabilities also,
we see this when looking at snowflakes close up under magnification - yet the effect seems to be lost when all put together... ?

in theory snow on the ground should look like a bunch of psychedelic swirls should it not?

Weston Bye
03-01-2017, 12:58 PM
To further complicate:
Color can be derived from light wavelength interference.
All the samples in the picture were produced from the same material under identical conditions except temperature. Each sample was polished and then heated to induce the formation of a transparent colorless oxide layer, the thickness of the oxide being proportional to the temperature.

Part of the light striking the sample is reflected off the surface of the oxide but the rest of the light travels a little farther, passing through the oxide and is reflected off the surface of the steel. The two beams of light arrive at the eye or film or photosensor at different times or phases and interfere with each other, cancelling or reinforcing or otherwise altering the wavelength of the light.

http://img.photobucket.com/albums/0803/Weston/Heat%20Blue_zpshjrdgboh.jpg (http://smg.photobucket.com/user/Weston/media/Heat%20Blue_zpshjrdgboh.jpg.html)

Dan_the_Chemist
03-01-2017, 01:17 PM
Why doesn't snow look like psychadelic swirls? As the young kids say about their relationships... "It's complicated"

When you perceive yellow you can be responding to many different different inputs... all of them filtering down to "yellow". For example, if I put sodium into a nearly colorless flame you will see a yellow color (yellow orange to me). However, the light coming out is only two wavelengths, both very close to each other. The so-called Sodium D line. However, if a stage rigger puts up a green spot and a red spot and shines them on a white screen, you will see "yellow" even though there are all sorts of different wavelengths.

Compare and contrast to music. If a person plays a 440 A you hear a note you call "A".... If a pianist plays an A major chord, you don't hear "A", you hear an A major chord. The individual notes are still perceptible.

A visible spectrometer can tell the difference between the yellow of Sodium D and the yellow from mixed red and green. We can't. An audio spectrometer can tell the difference between A and A major. We can hear the difference, too.

Why the difference? It happens in the mechanics of the biology.

Our ears contains a gazillion little hairs that respond to different tiny bands of frequencies. If a sound comes in that is a mixture of 50 Hz, 95 Hz, 170 Hz and 333 Hz, we will get different hairs vibrating to each different frequency. There will be five signals going down the nerves to the brain... Our brain is wired so that it perceives 5 notes rather than combining them into one chord.

Our eyes have only three color receptors... They have their maximum response to blue light, green light, and orange-red light. However, they also have significant overlap in response. A monochromatic laser at 490 nm would tickle the three receptors about the same... The three signals (B, G, and R) travel down the nerves and hit the brain. HOWEVER... the brain doesn't perceive color like sound. We don't see "chords", we convert the three signals into one unified color signal. The retina sends equal signals for B, G and R, the nerves transmitt signals for all three signals, BUT our brains have learned to interperate that as a signle color - "blue green" . However, if we had monochromatic lasers at 440 nm (blue), 540 nm (green) and 600 nm (red), the three types of receptors would all fire and it would produce the same response as if we had seen a monochromatic 490 nm light.

In hearing we sort out different frequencies and keep those identities separate, so we hear chords.
In vision we sort of just three frequencies, and the ratios are combined to give a single result, so we see single colors in two different situations - single colors or multiple additive colors.

https://en.wikipedia.org/wiki/Color_vision

So the reason snow looks white is that we perceive all the various colors being reflected, and our brain processes that to the concept "white" before it hits our consciousness.

Dan_the_Chemist
03-01-2017, 01:31 PM
So I guess in theory it's impossible to have light without colors attached to it? if indeed we could create this what would things look like? just black and white no matter what?

"Colors" are the human names given to the thoughts that arise when eye-neurons are excited by different wavelengths of light and create a tri-stimulus that is processed by the brain.

I want to stress that ... the concept of "color" requires the mechanics of the eye and the brain.

The reason I wanted to stress that... Visible light is just one small part of what is known as electromagnetic radiation. One of the principle descriptors of EM is wavelength... EM radiation from 400 nm to 700 nm wavelength is absorbed by our retina cones and is perceived as colors.

Longer wavelengths in the 1000+ nm are Infra Red, and while we can't "see" them, they do affect us by being absorbed in skin and clothing and is perceived as radiant heat. Even longer wavelengths are radio waves. Normally we can't perceive them because they don't interact strongly with any processes in our body that fires off nerves.

EM radiation with wavlengths shorter than visible light include Ultra Violet, X-rays, and gamma rays. We can't see those either, but if you get enough of them you can feel the effect as your nerves are destroyed by the radiation.

Every EM wavelength is a form of "light". Every EM wavelength sorta has a color associated with it, but since we can't perceive those colors our brain doesn't recognize them and we don't have words for them. For example, a nice "FM" or a blitzy "AM". But a radio putting out FM or AM radio waves is a little light bulb glowing in the dark... Other radios can see it... Humans can't.

boslab
03-01-2017, 04:10 PM
If vibrations get into brains through ears we get sounds, vibrations through eyes at different frequency gets us seeing color, there are drugs that cause some interesting brain effects of seeing sounds and hearing colours, savant autistics even smell and see colours associated to numbers( primes smell of gasoline, lol)
The measuring instrument we use is sometimes out of calibration I think.
I liked Weston's thin film interference plates, we used to do that in the lab to get different oxide layers, as a guide to heat treatment, funny thing is blacksmiths and metalworkers, dare I say whitesmiths, an old term got it figured hundreds of years ago, I think finding out how to heat treat and temper steel is a fascinating subject.
Sounds are interesting too, acoustic transducers fixed to bolts under tension produce regular clicking as the dislocations pile up and move, creepy sound of steel.
Very interesting dialogue.
I remember my first encounter with additive and subtractive colour on an enlarger doing colour prints by C41 process, my mum came out like the Incredible Hulk
Mark

danlb
03-01-2017, 06:11 PM
Totally non scientific, but there is anecdotal evidence that women can differentiate more colors than the typical man. My brothers and I were comparing notes, and all three of our wives have shoes or clothes in different shades of brown or blue/green that only they can identify. They can actually identify the Alice blue shoes and the Aqua purse.

Dan

A.K. Boomer
03-01-2017, 06:56 PM
Does not surprise me at all --- they also can come up with about 50,000 different ways to arrange the furniture in any given room in comparison to our 2 or 3 max....

boslab
03-01-2017, 07:30 PM
Apparently the color we see best or most shades of is green, helps spot predators and mowers in the grass,
Funny story, my brother in law got on a training course to learn electrical or be an electrician, color blind electricians aren't in high demand.
Wasn't it Monet the artist who's paintings deterioration was due to cater acts, caused his blue period till he got fixed and was so disgusted with the paintings he destroyed or over painted most, to be honest I liked his blue phase myself.
There are people I've read about who have had artificial lense implants who are reporting seeing "new" colours, violets I think, although bees see UV quite well, flowers have landing lines for them to use, awesome.
How do flowers know what colour they are, they do it so well.
In the godless world I'm glad there's still some mystery left for us to think on.
Mark

Weston Bye
03-01-2017, 08:16 PM
In the godless world I'm glad there's still some mystery left for us to think on.

Mark, I love that line. Will save it for some future reference.

Evan
03-01-2017, 10:05 PM
How do flowers know what colour they are, they do it so well.

Accidental mutation(s) that resulted in pollination. It works both ways too. More flowers for more bees that can see it.

And yes, our green is sensitivity is much higher, most likely because it is things that are safe to eat. It has also been determined that most plants and trees in particular are green to avoid over exposure to hot sunlight. It is about how chlorophyll works, which, by the way, is now known to use quantum mechanics.

Paul Alciatore
03-01-2017, 11:56 PM
I guess you could say that I am an expert on colors, at least from a practical point of view. I spent decades of my life setting up and matching color video cameras in TV stations. In a major TV station and particularly at the networks the colors of the various cameras used for a show must match almost perfectly. With older cameras that used tube style image pick-up devices, that often was not an easy job.

Anyway, most of the theory behind colors and their perception has been given above. The first illustration in Evan's link shows the additive colors: these are what are used in TV cameras. The three image pick-up devices will be sensitive to the three additive primaries; red, green, and blue. It also shows the relative relationships of the three subtractive primaries; yellow, magenta, and cyan. This ties in to the way that I looked at colors and I will explain.

The color information in a video signal can be described in several ways called gamuts. These gamuts have one primary characteristic, they are three dimensional. When we see a two dimensional representation of the colors, often called a color wheel, we are not seeing the whole thing.

https://en.wikipedia.org/wiki/Gamut

In more traditional, analog TV/video work we look at the colors in terms of one of two gamuts. The first is the red, green, blue or additive primary gamut. By specifying a value, an intensity to these three primary colors, we can specify any color of any shade, intensity, and brightness. This is what comes from the image pick-ups in all color cameras: signals that represent the amount of those three additive primaries that are present at each point in the image.

But that required three different signals and they required three different wires or other means of transmission. NTSC encoding was a means of combining those three signals into one signal that could be transmitted over one wire or other transmission channel (TV channel). When they were combined they were done so using a different gamut that utilized the three values of luminance (black and white value), hue (color of the color), and saturation (intensity of the color). The luminance is exactly what was used for a black and white video signal. The hue and saturation were added for color video and they held the color information. We looked at the luminance signal on an oscilloscope that showed the signal with brighter values near the top and darker values closer to the bottom. It was easy to see the various shades of gray in such a display but, although the color information was also there, it was not possible to see what it meant. You can see such a display in the illustration here.

https://en.wikipedia.org/wiki/Waveform_monitor

The green blocks that arranged in a stairstep formation are displays of the six primary colors; red, green, blue, yellow, cyan, magenta. But all you can see from that image is the relative brightness of them; it is not possible to see which one is which. That oscilloscope in the illustration has a switch which would actually filter out the color information and show only the luminance values or black and white information.

So another way of viewing that same signal was developed. It was called the vectorscope. The method of encoding the color information into a black and white video signal used a subcarrier and the phase of that subcarrier was used to represent the hue while it's amplitude represented the saturation. Hence, the vectorscope shows the color information in a circle where the angle around the center represents the hue and the distance from the center the saturation.

http://img.photobucket.com/albums/v55/EPAIII/Web%20Post%20Photos/TV/ColorBarsNVectorscope_zpscs176nus.jpg (http://smg.photobucket.com/user/EPAIII/media/Web%20Post%20Photos/TV/ColorBarsNVectorscope_zpscs176nus.jpg.html)

This picture shows a standard video test signal called color bars, on the left. The top 2/3s of the screen shows the various combinations of the three additive primaries, red, green, and blue mixed in equal amounts in the seven ways that are possible. The first bar is white (actually a very light gray) and is made with equal parts of all three primaries. The second one is yellow and is made from equal amounts of red and green. Then cyan which is green and blue, then green by itself, then magenta which is red and blue, then red by itself, then blue by itself. These are the seven ways you can combine the additive primaries in equal amounts. This color bar test signal is what is shown on the illustration of a waveform monitor I referred to above and also on the vectorscope image below.

The right side of that illustration shows the reticule used on the face of the vectorscope. As I said, the angle around the center point shows the hue and the distance from the center shows the saturation of the color (it is labeled chroma which is a shortened form of chroma level and means the same thing). It does not show any information about the luminance of the color. This means that both black and white and all the shades of gray would be at the very center of the display as they do not have any hue or saturation. Also colors that are brighter and ones that are darker will fall at the same spots on the rest of the screen. The boxed areas are where the six primary colors should be and they are marked with abbreviations of their names.

This illustration shows that color bar test signal being displayed.

http://img.photobucket.com/albums/v55/EPAIII/Web%20Post%20Photos/TV/VectorscopeGraticule_zpsgjror2sl.jpg (http://smg.photobucket.com/user/EPAIII/media/Web%20Post%20Photos/TV/VectorscopeGraticule_zpsgjror2sl.jpg.html)

The important feature here is the bright spots in the small boxes. They represent the six primary colors. The lines between them are simply the transitions between them.

Now, for example, all shades of pure yellow would lie on a line between the center and the yellow box on the left. The more saturated the color is, the further from the center it will be. It was mentioned by someone above that brown is just a darker shade of yellow and a brown color would also be on this line. Brown really is a dark yellow. But that distinction does not show up on this display of the colors. The only way to distinguish between a yellow and a brown would be to look at the luminance value at that point in the picture. Most of the other colors are not that confusing. Pink would be on the line between the center and the red box and it would have a high luminance value. But so would a shade of slightly red black but it would have a very low luminance value. The point I am trying to make here is that any method of specifying a particular color requires that three different values must be measured. The familiar diagrams that are only two dimensional do not and can not tell the whole story.

I have mentioned only two color gamuts. There are many more that are possible and the advent of digital video has brought about the need for using several more of them. So you may see reference to others if you research this subject. It is always possible to develop a system of mathematical equations the will translate from any gamut's values to those of any other. In some cases these equations will be quite complicated.

On another level, colors are perceived by our eyes by the amount of stimulation that the color cells, the cone cells receive from it. There are only three types of these cone cells and they are sensitive to red, blue, and green light, respectively. Sound familiar?

https://en.wikipedia.org/wiki/Color_vision

The thing about this is, light is composed of not just three colors, but of a wide spectrum of wavelengths from infra red to ultra violet. So, there is an actual, single wavelength of light that is a pure color for any color, for instance yellow. It is like a primary all by itself. It is not composed of a mixture of red and green light, it is just yellow. This is the physical reality. And that light of a yellow wavelength will stimulate the red and the green cone cells in our eyes in an approximately equal manner because their response is over a broad range of colors, not just one wavelength. So we perceive that it is yellow. But if we also sent a combination of a pure red light and a pure green light, which would be two different wavelengths, to the eye, in approximately equal amounts, then the eye will see that SAME yellow color. The perception will be exactly the same. In the real world, an actual yellow color will probably consist of a broad, continuous spectrum of wavelengths of light from somewhere in the red portion of the spectrum to somewhere in the green part. The only requirement is that, on balance, it must stimulate the red and green cones equally. Our perception of all colors works in a similar manner but with different proportions of the three primary colors that the cones in our eyes actually see.

boslab
03-02-2017, 12:55 AM
Thanks Paul, quite a lengthy article to be sure, I'm on reading 5 of however many it takes at a retention rate of less than 1% lol, the word "gamut" was very common when I grew up, I suppose the old folks around me had a better command or bigger vocabulary than today seems to reqire, I've often been told to "bring the whole gamut", or get it, meaning to me everything, though the taming of the shrew I didn't read till quite a bit older, under protest as it was a standard in school( I wonder about English teachers as the Lord of the flies was next!).
I did watch a BBC documentary about quantum mechanics and the bits about plants and quanta was quite startling, as referred to by Evan
http://www.bbc.co.uk/programmes/b04v5vjz
The full thing isn't there anymore but there are some interesting clips.
Mark

AD5MB
03-02-2017, 08:58 AM
More flowers for more bees that can see it.

Do not wear a yellow T shirt near a flower bed in April. No, no, no, no, no.....

AD5MB
03-02-2017, 09:02 AM
http://img.photobucket.com/albums/v55/EPAIII/Web%20Post%20Photos/TV/ColorBarsNVectorscope_zpscs176nus.jpg

Old school pro grade glass CRT video monitors had a switch that turned off the red and green color guns. adjust the tint AKA hue control until bars 1,3,5 and 7 are equally bright and you had tint nailed on that monitor.

http://www.isaacbotkin.com/img/bluebars.gif

from http://isaacbotkin.com/2006/05/

Forrest Addy
03-02-2017, 11:52 AM
Objectifying color can be a nightmare. I've see paint department clerks of many years experience blanch when approached by a woman carrying upholstery, drape, and carpet swatches. For example: brown is merely a darker shade of yellow - until you talk to your girl friend who wants to paint her bathroom or something. I've had years of art and I still know nothing compared to a 16 year old girl matching shoes to a prom dress. Men can percieve no color ending in "e" that is not blue. Mauve, taupe, rose, beige, etc. Out of the question

Wizards have cooked up color gamuts and color wheels, computer matching, etc but still the objective realization iof what is subjective perception like color is still imperfect.

You guys work it out, let me know.

CalM
03-02-2017, 09:38 PM
Is strictly determined the quality of it's atomic structure and the quality of the objects illumination.
If a light source it's self, Color is strictly determined by atomic structure and temperature.

All color is a figment of your imagination, for light (EM radiation) has no color.

Back to "if a tree falls in the forest with no one to hear..."

Evan
03-03-2017, 02:48 AM
for light (EM radiation) has no color.

It has wavelength which is equivalent to "colour" until it is short enough to act like a particle with no rest mass. Our vision depends on the wavelength being short enough and energy high enough that the EMR will interact with molecules directly without destroying them (too quickly).

It most certainly is not a figment of anything. It is an interaction that changes molecular structure. That then creates electrical potentials that are transmitted in electrochemical "wiring". Our eyes are high quality, high resolution photometers that measure the incident radiation over an octave of frequency/wavelength.

ed_h
03-03-2017, 11:34 AM
Color is a perception. Without a consciousness to perceive it, color doesn't really have a meaning.

Ed

A.K. Boomer
03-03-2017, 11:37 AM
In effect can't you say that about everything then?

ed_h
03-03-2017, 12:05 PM
In effect can't you say that about everything then?

Not if you believe in objective reality. If you do, EM radiation exists whether we are here to observe it or not. The color of the radiation has no meaning without an observer.

Ed

A.K. Boomer
03-03-2017, 12:33 PM
The color of the radiation has no meaning without an observer.

Ed

Nor does the em radiation itself

ed_h
03-03-2017, 12:44 PM
Nor does the em radiation itself

Then it appears you are not an Objective Realist.

Ed

A.K. Boomer
03-03-2017, 12:48 PM
oh so now were going to start calling each other names? ----------- :p

ed_h
03-03-2017, 12:52 PM
oh so now were going to start calling each other names? ----------- :p

AK, I know a lot of really good people who are not Objective Realists. With some effort, they can lead pretty normal lives.

Ed

A.K. Boomer
03-03-2017, 01:06 PM
has it ever occurred to you that maybe we want to be this way? You OR's are all alike i'll tell ya...

(just waiting for someone to chime in and ask "uhhm - you guys still talking about colors?)


On a side note; of course were going to have different names for the different wavelengths that we can perceive with our specific sensors,,, get right down to it and it's just names but they are indeed names for something somewhat "tangible"

we also have names for certain textures on objects too, all that can appear somewhat different with different wavelengths they get hit by and from what angles, they exist as long as someone or something is able to recognize and distinguish between them I suppose...

Will the prism effect still exist with moisture in the air and form something that we call a "rainbow" yes, as it will still capture multiple wavelengths and expose them to certain sensors able to "see them" be it human or not or even machine...

the word "color" is just an inevitable description factor of the above,,, kinda like what we do with everything else...

jhe.1973
03-03-2017, 01:22 PM
Color is a perception. Without a consciousness to perceive it, color doesn't really have a meaning.

Ed

This reminds me of the quote, "If a man speaks in the forest and there is no woman to hear him is he still wrong?"

:D

A.K. Boomer
03-03-2017, 01:43 PM
This reminds me of the quote, "If a man speaks in the forest and there is no woman to hear him is he still wrong?"

:D

just because she doesn't hear him does not mean he's not going to get yelled at for it - so yeah he's still wrong because he's always wrong, just the way it works...

tomato coupe
03-03-2017, 02:13 PM
It has wavelength which is equivalent to "colour" until it is short enough to act like a particle with no rest mass.

All electromagnetic radiation, regardless of wavelength, can be described as a particle or a wave.

ed_h
03-03-2017, 02:31 PM
All electromagnetic radiation, regardless of wavelength, can be described as a particle or a wave.

Absolutely true, but at RF frequencies, with which I have some experience, I can't think of any practical situations where it exhibits it's particle nature. Certainly a well designed experiment could probably show it, though.

Ed

tomato coupe
03-03-2017, 02:51 PM
Absolutely true, but at RF frequencies, with which I have some experience, I can't think of any practical situations where it exhibits it's particle nature. Certainly a well designed experiment could probably show it, though.

How about Magnetic Resonance Imaging, aka Nuclear Magnetic Resonance? The absorption of a radio frequency photon causes a transition from one nuclear spin state to another inside an atom (or molecule).

A.K. Boomer
03-03-2017, 03:03 PM
How about Magnetic Resonance Imaging, aka Nuclear Magnetic Resonance? The absorption of a radio frequency photon causes a transition from one nuclear spin state to another inside an atom (or molecule).

that would take conscious thinking and it's not allowed in this discussion...

ed_h
03-03-2017, 03:26 PM
How about Magnetic Resonance Imaging, aka Nuclear Magnetic Resonance? The absorption of a radio frequency photon causes a transition from one nuclear spin state to another inside an atom (or molecule).

You're right, of course. I was inappropriately limiting my thinking to RF communications.

Thanks.

Ed

Evan
03-03-2017, 04:08 PM
Try exhibiting the particle nature at frequencies with kilometre wavelengths.

ed_h
03-03-2017, 04:21 PM
Try exhibiting the particle nature at frequencies with kilometre wavelengths.

I don't think there is anything fundamentally different at longer wavelengths. The same duality should still apply.

Ed

Evan
03-03-2017, 05:21 PM
In theory it may but in reality it would be essentially impossible to demonstrate it with something like ELF wavelengths of thousands of kilometers. That isn't even ionizing radiation. At the other end high energy gamma rays do not act like anything other than particles. They can and will pass through a lot of high density matter. Yes, they will interact but then so do particles with mass although the reasons are different.

ed_h
03-03-2017, 06:08 PM
Yes, I'm not sure how the particle nature could be demonstrated at such low frequencies. I calculated that at a 1 km wavelength (about 300 KHz), there would be something on the order of 10^12 photons in one period at a picowatt. So the quantum granularity is so fine it doesn't show up.

Maybe tomato knows if its ever been demonstrated.

Ed

tomato coupe
03-03-2017, 06:47 PM
Yes, I'm not sure how the particle nature could be demonstrated at such low frequencies. I calculated that at a 1 km wavelength (about 300 KHz), there would be something on the order of 10^12 photons in one period at a picowatt. So the quantum granularity is so fine it doesn't show up.

Maybe tomato knows if its ever been demonstrated.

Yeah, been there, done that.

We used to split the energy levels of a laser transition using a longitudinal dc magnetic field, and then drive transitions between the split energy levels with a transverse 100 kHz field (3 km wavelength). Because of spin conservation laws, this "prohibited" transition could only take place if each atom absorbed two photons, each with half the energy difference, simultaneously. (Transition was ∆m=2, photons have spin=1.)

You can, in principle, see the particle nature of electromagnetic waves by brute-force reducing the intensity to extremely low levels, however, it is often easier to see the particle nature by observing the interaction of electromagnetic waves with atoms or molecules.

CalM
03-03-2017, 09:37 PM
Ultimately, it's all momentum transfer.

Ask any blind person how it may manifest.
You might know that there have been "eyes" synthesized by placing sensors on the tongue, and also by "wiring" the optic nerve with photo emissive "chips".

The interaction of light with matter can be as simple or as convoluted as anyone's mind may make it.

aostling
03-04-2017, 03:58 AM
This photo of strawberries has no red pixels: https://www.dpreview.com/news/8615103660/this-photo-of-some-strawberries-with-no-red-pixels-is-the-new-the-dress.

Evan
03-04-2017, 11:55 AM
Thank you for that image Allan. I am educating the prof on how colour isn't what it looks like, especially when the actual colours available are so very limited. He is very impressed by my use of colours as is the lab team. He wants it to have statistical significance when he uses my charts in his published papers. I have been telling him about the very big difference between the additive gamut and the subtractive gamut in anything printed as well as the large difference just between computer monitors.

It amazes me how very specialized everybody is now. When I was at the lab yesterday we were chatting about a variety of things and I was able to contribute, including in medicine in general, the brain, astrophysics, AI and a few other areas, always with agreement. One guy turned to me and looked me hard in the face and then said "Is there anything you don't know?"

That pic is an excellent example of colour. It is just what I need.

Note: The statement that there are "no red pixels" isn't true but it does demonstrate the problems we can have with colours. The issue here is the much higher levels of the other primary colours and that is exactly what happens in my project depending on the distribution of the EEG signals.

This is also very interesting. I do not "do" social media so was not aware of this.

https://en.wikipedia.org/wiki/The_dress

Sigh... Just had reply from prof. "I mean to use colours to convey statistical information about the waveform." I have work to do I guess... Perhaps a legend will help. I already have one beside that chart but it is not calibrated in any way. Not sure what would be the best way to do that and it is very difficult to match it to the colour changing system. We can see colours reasonably well in a stable system that doesn't change quickly but when it changes all bets are off.

Because of all this I created a way to look at the graphs with a bar that shows the colour associated with the EEG value. It is full screen in 2D format, suitable for printing. The bar shows the legend colour in exactly the way the colour is used on the chart when you sweep the cursor along the chart.

michigan doug
03-04-2017, 01:20 PM
The color rabbit hole runs deeps. As an optometrist, I got a good grounding in color theory, color perception, additive, subtractive, etc.

Some years ago, the BBC reported on a fascinating study that suggested if your mother language didn't have two distinct words for blue and green, you either couldn't distinguish between the two, or you would be much slow and much more error prone than say, a european that had the words and concepts for "blue" and "green".

Later analysis suggests the effect is not so profound, or the BBC was hawking pseudoscience, but marketing it as settled science.

Read all about it if you want:

http://languagelog.ldc.upenn.edu/nll/?p=17970

And tetrachromacy is still controversial:

http://www.sciencealert.com/scientists-have-found-a-woman-whose-eyes-have-a-whole-new-type-of-colour-receptor

Some studies suggest that up to 12% of women may be tetrachromats.

Other analysis suggests it should be less than 1%.

Other studies suggest we have exactly one example where it has been demonstrated without question.



Yes, the rabbit hole runs deep...

Evan
03-04-2017, 02:13 PM
Now you have me very much wondering about my own vision. I am not colour blind in the slightest but my eyes are not the same. When working with colour the very limited number of hues available with the so called "16 million" 24 bit colour spectrum has always looked very coarse. It is trivial for me to match colours and especially grey scale values, even when they are not beside each other. I wonder if it has anything to do with my 20/5 vision? A few extra cones perhaps?

As usual, this now makes me wonder if they measured/compared the visual acuity of the test subject(s).

aostling
03-04-2017, 05:54 PM
... One guy turned to me and looked me hard in the face and then said "Is there anything you don't know?"



If it happens again, you can say "Sure, anything to do with social media."

That's better than "Not that I am aware of."

Evan
03-04-2017, 11:11 PM
I just told him I am a generalist, not a specialist. He seemed to be quite OK with that.

This is what the prof has to say about yesterday: "Great job today! The team was impressed and excited!"

Otherwise, I have been playing with the colour system and figured out a way to combine semi-transparent colours smoothly, which is not documented in SketchUp. That will make a nice difference in how it all looks.

Also, I have been playing with colours and how they affect the eye, my own anyway. It is surprising just how bad the afterimage effect can be. And, that is not with high brightness settings. If I do a quick run it then takes at least five seconds for the inverse colour to fade at the end of the run. That colour is related to high red back in the middle of the run of about five seconds, a cyan colour.

CalM
03-05-2017, 06:13 PM
clip

It is surprising just how bad the afterimage effect can be. And, that is not with high brightness settings. If I do a quick run it then takes at least five seconds for the inverse colour to fade at the end of the run. That colour is related to high red back in the middle of the run of about five seconds, a cyan colour.

Ample evidence that color is merely the product of a fertile imagination. Much like the images seen in dreams while sleeping.

Evan
03-05-2017, 06:53 PM
It most certainly isn't the "imagination". It is how electrochemical neural sensors work. This is precisely what neuropsychology is all about. The mind is not some sort of free floating separate entity from the brain. The mechanics of the brain must be considered in psychology. The professor is not just a professor of neurology, he is also a professor of psychology. Neuropsychology is considered the "latest and greatest" super-specialty of psychology and is throwing a big loop into psychiatry. It is also something that I have always had a big issue with since I was in school at Berkeley. One cannot somehow diagnose the function of the mind without taking into account the function of the brain. Finally, others are seeing it the way I have always seen it.


Much like the images seen in dreams while sleeping.

I don't dream the way most people do. I start to dream a few seconds after I close my eyes, while I am still fully aware. The dreams are extremely real looking and that is when I sometimes am able to fully visualize things in very nice 3D. It is one of the reasons I don't draw plans for most things I create.

CalM
03-05-2017, 11:40 PM
It most certainly isn't the "imagination". It is how electrochemical neural sensors work. This is precisely what neuropsychology is all about. The mind is not some sort of free floating separate entity from the brain. The mechanics of the brain must be considered in psychology. The professor is not just a professor of neurology, he is also a professor of psychology. Neuropsychology is considered the "latest and greatest" super-specialty of psychology and is throwing a big loop into psychiatry. It is also something that I have always had a big issue with since I was in school at Berkeley. One cannot somehow diagnose the function of the mind without taking into account the function of the brain. Finally, others are seeing it the way I have always seen it.



I don't dream the way most people do. I start to dream a few seconds after I close my eyes, while I am still fully aware. The dreams are extremely real looking and that is when I sometimes am able to fully visualize things in very nice 3D. It is one of the reasons I don't draw plans for most things I create.

Life is a dream

Reality is somewhat different. A persistent illusion... Even the "professor", as well as the "colors".

Get used to it.

You might watch the movie "What the Bleep do we Know" .

But then again, what do we know?

Evan
03-05-2017, 11:54 PM
That is one way of looking at it and it does have some merit. But that is going pretty deep into existential philosophy in general.


You only dream that you dream differently

No, there is a very real difference in my brain. The Orexin neurotransmitters are reduced due to my no-cataplexy narcolepsy. That causes a decoupling of my sleep cycle with other brain functions including dreaming.

CalM
03-06-2017, 01:19 AM
It must be tough to be exceptional, almost like being non-celiac intolerant.
https://www.ncbi.nlm.nih.gov/pubmed/24533607

J Tiers
03-06-2017, 01:23 AM
Life is a dream

Reality is somewhat different. A persistent illusion... Even the "professor", as well as the "colors".

Get used to it.

You might watch the movie "What the Bleep do we Know" .

But then again, what do we know?

There is always the possibility that it is a deliberate illusion, in which you are a willing participant....... THAT has quite a number of "ways to look at it"........

Evan
03-06-2017, 02:05 AM
Unfortunately, my celiac disease is very real. I am half Danish and the gene I must have can almost certainly be traced back to the area of Northwest Jutland in Denmark. In that area celiac disease is ten times more common than the average population. It is also more severe than usual. It is also clearly genetic since my son has it as does his son (my grandson) as well as the identical twins of my daughter. It also runs back on my Danish side. With my various genetic disorders I would never have had children but genetic counseling did not exist at the time.

Those without celiac disease have no idea just how much it limits those who do. First, if not treated is is often lethal. I was lucky I did not need to have much of my intestine removed after 40 years without diagnosis. But even with a nearly full recovery it totally limits my social life. Social events of nearly any sort usually involve food to some degree, even if it is just a visit to neighbors. Many of us with true celiac disease cannot afford to even have just a few crumbs of regular bread.



There is always the possibility that it is a deliberate illusion, in which you are a willing participant.

Heh. My work will be on his web site in the not too distant future. It may also show up in next seasons Quirks and Quarks TV show. It will also be in a public lecture on March 22 which I will be assisting. I am also considering submitting it to NASA in the medicine division of their yearly technology contest. It seems like something that could have some real value on the Space Station. It also just plain looks cool and is the sort of thing that people like even if they have no clue what it means.

I am also considering rewriting it so it can run stand-alone.

jhe.1973
03-06-2017, 02:06 AM
just because she doesn't hear him does not mean he's not going to get yelled at for it - so yeah he's still wrong because he's always wrong, just the way it works...

I don't know about 'always' wrong. I've noticed that when I say, "Yes dear/Of course dear/I'm sorry dear/Whatever you say dear etc. I'm never wrong.

;)

[QUOTE=Forrest Addy;................

You guys work it out, let me know.[/QUOTE]

Absolutely, couldn't have said it better!

dave_r
03-06-2017, 03:10 AM
I don't know about 'always' wrong. I've noticed that when I say, "Yes dear/Of course dear/I'm sorry dear/Whatever you say dear etc. I'm never wrong.

;)


You are still wrong unless you have the correct answer to "And just what are you apologizing for?"