2D pixel perfect collision detection

Hi all,
I'm struggling with implementing pixel perfect 2D collision detection for my simple 2D game. I'm also using Allegro, if that helps.

I know what the basic algorithm is, but... is there a way for me to use allegro to simplify this?

Notes:
I have sprites loaded from bitmaps, but I rotate them according to the way they're facing (360 degrees are possible) I've also created a parallel list of mask bitmaps with black for where there's background and white for where that pixel is part of my character.