Rotation and signal processing?

Hallo,

I am working on rotating a sprite in software.

What I am doing now is multiplying every pixel with a rotation matrix, which is slow.

I dont remember where I have this from, but I have been told/read that in order to speed up the rotation I can use some form of signal processing algorithm. It was something like rotating the first pixel, and the use the signal algorithm to find the rest.

Does anyone know anything about this? A link would be great. I tried google, but im not sure what to search for.

Regards,