I'm trying to understand mipmapping.
It makes sense that you would have many pictures of your textures at different resolutions, and use the closest ones in size to what you need in order to avoid moiré patterns--that's logical. But a lot of the diagrams I've seen split out the R, G, and B channels: for example splitting a square into quarters, in which the top left is the red component of an image, the top right is green, the bottom left is blue, and the bottom right recursively splits the image up again, at a lower resolution.
So what's the point of splitting up the RGB? Why not just have a bunch of different-sized images of your texture? It seems that splitting them up is wasted work, since you'll ultimately just have to put them together again.
(There is an example of this phenomenon on the Wikipedia page for mipmapping, under the "Mechanism" heading.)