Representing RGB colour in 3-space

[MDJH]

Ok, so supposedly white light is a combination of red, green, and blue light... but programs like MS Paint treat it like the amount of light goes from 0 to 255; in theory, could brightness of light be infinite? If so, would that imply that brightness of the components would be infinite?

 

If so, then, would a better representation of light be a 3-dimensional graph, wherein one axis represents the intensity of red light, another the intensity of green light, another the intensity of blue light... and based on the intensity values for these three component colours, a position in 3-space on the graph would represent a particular colour, so as for colour to be seen as a linear combination of red, green, and blue light?

[Sisyphus]

Light is not really made up of red, green, and blue light. It is made up of all wavelengths. How we perceive color is the ratio of how stimulated our red, blue, and green color receptors are. There is such thing as yellow light, and that is not the same as a combination of red and green light. We just can't tell the difference, because of how our eyes work. Hence a computer display can trick your eyes into "seeing" all visible colors when it's really only capable of producing red, green, and blue.

[Mr Skeptic]

Yes, light intensity has no reasonable upper limit. I think at some extreme intensity it would start turning into particle-antiparticle pairs which would limit the intensity. But you won't ever see anything that bright, nor accidentally make anything that bright, so for all intents and purposes you might as well consider there to be no limit to brightness.

[alan2here]

Fantastic explanations btw.

 

If you like you can think of full brightness of for example 255 per channel as being 1, so for example if your color has 128 green at a color depth that gives 255 as being the full brightness you could think of it as half green or 0.5. Some OpenGL\DirectX things work like this. A perfect black keeps it's same number of 0. You could then immagine 2 as being twice as much green light as your monitor is capable of, if you wanted to imagine the ammount of green required to be between 0 of 255 and 1 of 255 (a verry dark green that appears as good as black), it would be roughly 0.001953125 in this model reguardless of color depth.

 

If you got a bright monitor and sat in a dark room you could make full brightness unpleasent and turn the brightness of your interface down giving everything more muted colors. Then it would be easyer to reprent verry bright things but harder to differentiate subtle differences in dark things. HDR photography plays with ideas like thease often to great effect.

Edited September 4, 2010 by alan2here