tomfrh wrote:Well, the other "spectral" colours really do have corresponding physical reality, and even though we know the impression of "red" is in fact in our brains, we can at least take solace in the fact that there is a unique frequency out there in the REAL WORLD that it corresponds to.
but with these non spectral colour, e.g. magenta, our brain is totally misleading us, telling us there is a colour, but in fact there is no corresponding colour in the real world!
White/grey/black too! There's no such thing as "white".
This is perfectly valid of course, and the standard idea about it all, ie. that colours are just effects in our mind - but the philosophy I use these days is that the real world is an image (visual, sonic, tactile, etc), and that what goes on in our head is a reproduction or extension of that image, plus any theories we can entertain about that, eg. that red is an "impression in our brain" that otherwise corresponds to some unique frequency (or wavelength) of light out there in a "real world". Or alternatively (and no less theoretical) - that the concept of light and wavelengths, are a particularly useful way of describing colours such as red. In other words (according to this theory) it is red which belongs to the real world, and our description of red (by means of concepts such as light, etc) which belongs to what goes on in our head, or more so, within language (knowledge, etc). According to this approach we can therefore use the idea of a composite signal (prior to decomposition into more fundamental signals), to describe magenta. But the magenta itself is actually what is real, ie. not in our heads - or rather not just in our heads.
In simple terms: colours are real. And magenta is real. And we are not being misled at all. What we see is what is actually there. We're not imagining it. Or not just imagining it. Rather it becomes our descriptions of magenta that are a little less real. And our description of some reality behind magenta even less so. The so called "real world" behind what we see becomes the more "fictional" one (if often very useful one).
That's the theory I use anyway. And it makes sense to me. Why should light or colour be defined in terms of fundamental signals? Why should magenta be any less real than cyan or yellow, just because it doesn't correspond to a single wavelength of light? Why should single wavelengths of light be any more real than complex combinations of such? The only reason for reducing light into more simpler terms, it seems to me, is so that we might take advantage of that way of describing it. It is more economical. It is easier to describe light if we can simplify it that way. It's more to do with language and technological reasons than anything to do with that is how it is in reality. In reality, magenta would be there. It will only be for technological purposes that we assume it's not there, and assume that magenta (or more generally colour) is some sort of psychological effect in our heads.
The analogy I'd use would be a piano. One can decompose all the music that has been written (and yet to be written) into a set of key presses on a keyboard (into single notes) and suggest the keyboard is reality (or an analogous to what reality would be) and the music played on such a keyboard becomes an effect in our head. Or one can otherwise propose that music (in all it's complexity and simplicity) is that which is actually real, (outside of our head as much as in it) and the keyboard (and it's notes) are just a particularly nifty way of formalising a system of description for such music, because it allows for the reproduction of a whole range of different musical sounds, from complex compositions to single notes. Pursuing this idea it becomes a certain kind of domestication which treats the system of description as more real than that which is being described, and through such we can inadvertently come to assume that single notes are more real than the more complex "compositions" of those notes. For I doubt any musician actually composes music by simply rearranging individual notes. Although doing it that way is not out of the question (and not any less music). Rather I fully expect musicians start with music they can already hear (in some parallel universe) and decompose such into individual notes. They write it down as a score. It's then in the reproduction of that music (such as playing a piano) where the music is actually "composed" (from the notes). Or a better way of saying this is that during a performance they recompose the original music from the notes played on the keyboard. They put the music back together again. Reproduce or extend all the complexity and simplicity of the original reality.
But as mentioned, that's just the theory I use. Could be complete bollocks for all I know, but who cares? I certainly don't. I just find it very useful. Especially in creative work. But also very much in technical work.