Colour and Gamma

[pne]

I must confess that I am a Bear of Very Little Brain when it comes to colour processing and, in particular, gamma.

I was looking for a way to create a "proper" rainbow and grepped for "color FAQ" to see whether there's any way to convert a wavelength of visible light to an R,G,B triple, and I found a colour FAQ and a companion gamma FAQ, but for the most part, they both read to me like "Blah blah blah highly technical blah blah equation blah blah" :(

I'm sure that there are people who can easily understand this and who'll say, "It's really quite simple," but it all seems very confusing to me (especially the bit about gamma, how it's used, when and when not to apply correction, etc.). So I ended up cheating and just saying "give me an image that transitions from 'red' over 'orange', 'yellow', 'green', 'blue', and 'indigo' to 'violet'" and trusting the colour name file to come up with suitable shades for those colour names.