I've seen a lot of talk of hue-shifting, but I'm curious as to what it is exactly, and how it's done. I've tried searching for it, but all I can find are side mentions of "this piece makes excellent use of hue shifting," or something along the lines, but never a solid tutorial on how it works.

My understanding is that you change the color's value and hue at the same time, but how do you decide how far each color shifts? Does anyone have or know of a solid tutorial/demonstration of this technique?