How do humans perceive color? Is it just the way we see it or is color actually there?
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In our eyes, we have four types of light sensitive cells. There are rods, which can detect a wide range of wavelengths of light and can detect it even when it’s dim. And there are three types of cones, which detect narrower ranges of wavelengths. The three types of cone cell are called Short, Medium and Long based on the size of the wavelength they detect. They’re also called Blue, Green and Red, based on what we perceive when they’re activated. When your L cones are activated most strongly, you perceive red. When your M cones are activated most strongly, you perceive green. When both your L and M cones are activated then you perceive yellow.
In regard to your second question, the wavelength of light is an objective physical property that exists independently of humans. The way we perceive that spectrum as a rainbow is a result of the way our cone cells work.
Edit: Though, actually, the way we perceive color is actually much more complicated than just the raw inputs our eyes provide. It also depends on context. An object that reflects all wavelengths equally will look white in normal light, but if you shine a red light on it, it will reflect that red light and appear red. But if everything looks red, then your brain concludes that the light must be red (like at sunset) and automatically adjusts. That’s how the [checker shadow illusion](https://en.wikipedia.org/wiki/Checker_shadow_illusion) works. The light square in shadow is the same shade as the dark square out of the shadow, but because you can see the shadow, your brain adjusts and the square in shadow looks lighter.
Well, it’s kind of both. When you look at a lemon and see that it’s yellow, that’s because pigmentation works subtractively. White light, which is a combination of all colors within the spectrum is absorbed by the leaf, well almost all of it is absorbed. The pigments reflects light that is 570nm in wavelength but it absorbers everything else. Humans detect light of that wavelength as being green.
Now human have three types of color receptors in our eyes: red, green, and blue. These receptors don’t absorb a single wavelength, but rather have a spectrum they can detect. At the ends of that spectrum they have a weaker response, and in the middle the response gets stronger. What that means is when you see purple yellow light, you don’t have a distinct receptor specifically for yellow, but yellow light does activate both the green and red receptors. This combination of cross activation we then perceive as yellow!
The really cool thing is tvs, and most LED displays, don’t make subtractive color the way the lemon does. The lemon reflects only 570nm light which weakly activates both your green and red receptors. Your TV, however, only produces Red, Blue, and Green light (rbg display). How does your TV show you an image of a lemon? By combining red and green light together at the same relative intensity that your two receptors detect yellow light, tricking your brain into seeing yellow
Color is our Brain interpreting wavelengths of light.
So yes, the light entering your eye has specific wavelengths that we can measure for each color that we see.
But, that actual “color” that we see, red, blue, green, etc etc, that is something that our brain in creating based on the wavelengths of light hitting our eyeballs. Our brain interprets that information and then makes what we “see”.
So, there’s actually no real way to know that what you see as “red” and what I see as “red” are actually the same thing, or if our brains are interpreting that wavelength of light two different ways.
We just assume that we see it the same way because we have the same kinds of cells in our eyes that detect light and have the same kinds of brain cells, so, why would it be any different?
Just wanted to add on to what everyone said
Receptors. We have 3 for red green and blue. But if you see green, it’s not that you’re seeing GREEN, it’s bc you’re seeing “not red and blue” if you see yellow it’s bc you’re seeing “not blue.” I know this sounds backwards but everything everyone here said was right, but we don’t see combos OF colors, we see combos of what lightwaves there “aren’t” which I always thought was just weird enough to be cool lol
We don’t see color.
We see the light bounced off the surface.
And as it turn out, whats bounced off is light NOT absorbed by the material.
so really, the actual color of the object is every spectrum of light MINUS w/e color your observe.
Objects reflect and absorb light at different wavelengths. Every object has its own “signature” of the types of wavelengths of light that are bouncing off of it. That’s all that really exists, for the purposes of this conversation. Light is bouncing off of things and has different wavelengths depending on what it has bounced off of.
Now, this is useful information for us because it lets us identify things based on what kind of wavelengths are being emitted by different objects around us. Is that food? Is that an animal? Is that good or bad? Knowing how to identify those different wavelengths can help us identify what we are seeing around us.
But how can our brain show us that information? By putting floating numbers over every object telling us the wavelength? Of course not. So what it does is “color” the image we are decoding in our brains. It overlays this wavelength information onto the image by causing us to “see” them through different colors in our minds. These colors do not exist physically, they are just applications of the wavelengths that are being detected.
Now we can see if something is an apple or a rock because we can sense the wavelengths coming off of it.
Color does not exist in the physical world. It only exists in our minds. Color is the way our brains classify frequencies of light, but the light waves are all qualitatively the same. There’s no physical reason one would be blue and another red. Consider sound waves. We can hear and differentiate between a range of sound frequencies, but sound doesn’t suddenly change completely when we go from one frequency to another the way light does. It varies continuously. There aren’t different bands of sound.
Cold-hearted orb that rules the night
Removes the colours from our sight
Red is grey is yellow white
But we decide which is right
And which *is* an illusion
It’s just the way we see it, birds have additional color cones in their retina so they are able to perceive colors that we humans can’t.
Light isnt one thing. It comes in a lot of different sizes. Even when it seems completely dark there is a lot of light going through you. Your phone uses light to talk to other phones and everything around us is always glowing a little bit with light we cant see.
Each color is just a specific size of light that our eyes can see.
These arent the real sizes but if all marble sized light was blue, then we would see golf ball sized light as blue and we would see pebble sized light as blue because they are close together in size. If basketball sized light was red, then we would see soccer ball sized light as red and football sized light as red because those ones are closer together.
The light is just the different sizes of balls. The colors are how your brain puts them together.
The balls are not actually red or blue. But your brain imagines them as red or blue. And that is what you see.
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