Dear Dar and Monte,
I should have specified more clearly what I need the conversion formula for. I am doing an optics/education stack. One of the substacks is on the physics of the rainbow. Actually that part is a little complicated. It involves a caustic formed by the light after it emerges from the drop after one internal reflection (for the primary bow)--a different caustic for each frequency. The light entering the drop is white--lots of frequencies. But since each frequency is refracted differently. It follows that the emergent light is composed of rays of pure frequency at each angle--if a ray at a given angle were composite, each component would refract at a different angle. A prism does the same thing.
So I need a formula that gives Frequency to RGB and not RGB to frequency. As you have pointed out quite correctly, RGB colors will be a mix of frequencies.
Although the *geometry* of the rays drawn by RunRev will be accurately represented on the screen since they are calculated using Snell's law given the index of refraction as a function of frequency. But the question is how give a reasonable *approximation* to the color of each ray and that is where the RGB values come in. I have done this in the stack that is posted on the RR education site for the seven conventional *discrete* colors (Roy G. Biv). (Aristotle said there were only three colors, but he has a thing about the number three.)
But I have had a thought about how to simulate a continuous variation in frequency of emerging light rays. So I would like a formula which allows for a continuous variation in color of the graphic lines. Actually I think the scheme I mentioned earlier might work. That is get an image with a smooth transition, left to right, from red to violet, use the imageData function to extract the RGB values and hope that something like a Switch--case wavelength > x and wavelength < y will yield a reasonably smooth, effective formula.
But I'll bet that someone has worked out a reasonable least squares fit (or whatever) of the tables you spoke of to reduce them to a nice simple algebraic formula.
Jim _______________________________________________ use-revolution mailing list [EMAIL PROTECTED] http://lists.runrev.com/mailman/listinfo/use-revolution
