swarfrat said:
The spectrum may be continuous, but your eye's color sensitivity is not. It's analogous to RGB decomposition, interestingly, a small percentage of women posess genes for four color rather than three color vision.
ahh yes the color conversations.. these are usually interesting because you are incorrectly taught in school that there are 3 primary colors. red blue and yellow... they work nicely into a color "wheel" that makes the nature of colors seem cyclical. and in a way we may perceive it that way. but that's not how the spectrum works.
ok as a color blind person most people don't trust my input on this subject. then the philosophical types bring perceptions into question. it's tough to under stand because what color is and how the eye reads it are two different things.
the visible spectrum roughly breaks down to 6 or 7 identifiable "colors" from long wavelength to short we commonly name them roy g biv red orange yellow green blue indigo violet. but that confuses kids because "indigo" isn't on the color wheel and why not call violet purple? that and indigo isn't really a basic color, most would catagorize it under blue but maybe purple. obviously it breaks down infinitely but as humans we either identify a color as red, orange, whatever. i like to think of the colors named above as catagories more than actual colors. maybe a color is named fuscia but we would likely catagorize it under purple.
now on the end or our perception, or at least our ability to measure color biologically. our eyes pick up red GREEN and blue. notice there is no yellow. when light is in the "red" band of the spectrum we have rod cells that pick that up. if the wave length goes a little higher the red and the green rods will pick it up at the same time. this is when we see yellow and orange. it's interesting because we can see yellow light as yellow but we also see a mixture of red and green as yellow. mixing colors of light together doen't actually produce a new wave of light with an in between wave length, but as long as a combination of rods are able to pick it up our eye and thus our brains are incapable of telling the difference(unless for some reason you have an abnormality that allows you to see 4 colors). so to reproduce our world digital cameras and displays use only red green and blue. it's all that's needed. it's estimated we can distinguish 10 million colors with normal color vision. with 24 bit color a computer can produce over 16million combinations. that's 256 brighness levels for each of the red/green/blue. when you look at it that way it doesn't sound like alot. seems to me it could be useful to use some more bits to define the levels but i didn't create the standard.
so that kinda covers mixing pure light wavelengths to create the colors we see. notice nowhere in there did i ever mention brown! it's not on the spectrum but our brain clearly recognises it as a color. i'm not certain but i think brown is just a "noisy" color. soem weird balance of the 3 visible colors.
then it gets weirder when we try to mix pigments. the color wheel suggests we use red yellow and blue to create colors not the red green and blue we see. it gets kinda weird because pigments are filters and part of what they do is absorb light and only reflect or pass one color or perhaps a certain bandwidth of colors. so when we mix a red pigment with a green one we probably get brown instead of yellow as the red pigment absorbs the green and the green absorbs red. the result is a dark color rather than a bright yellow. purple is also a dark color when you mix it from rd and blue. that's also interestign because why do we see the same (more or less) color when we mix a low frequency long wave length (red) with a short one (blue) as a color we perceive that has an even shorter wavelength than either of the componants and not one that's in between? i think it's because the visible spectrum takes up about the equivlent of an octave. violet is somewhere around half the wave length as compared to red, so i think the red cells may pick up on it at a weak level. i think to combat the darkness of mixed colors printers tend to also substitute cyan in place of blue and magenta in place of red. i'd love to get into spectrography to see what's really going on with the whole yellow cyan and magenta thing. prisms are cool. also mapping by wavelength gives much more useful information than our eyes will let us see otherwise. if i had to guess i'd imagine these are "wide band width" pigments and mixing them narrows the the band with to the colors we can see.
so we can create colors with red green and blue light, or with yellow cyan and magenta pigments. after you take all that in it become crazy to think white is all 3 visible colors. and what the hell is brown anyway?
btw although i am color blind i can clearly see all the major colors and i doubt my world looks too different. i think my brain makes up for a lot of what my eye have trouble with, or maybe it's moy brain that's not quite right and my eyes are fine? ??? . i can see red and i can see green but sometimes if the object is small or dark my brain has a hard time choosing which color it really is. it gets even weirder when you put them near each other. then my brain starts going "i know i see red" and "i know i see green" but has a hard time drawing the line where they separate. i've seen object seem to snap from one color to the other, especially from my peripheral vision (stop lights can be weird if i don't look directly at them). which isn't that odd for peripheral vision because a person with normal vision can only see blue in the peripheral vision. the brain actually memorizes color and attaches it to objects outside of the red/green vision zone. this is just how the eye is constructed. but maybe some peoples brain does a better job of infering these things than mine.
fun vision facts...
http://xkcd.com/1080/