Ask HN: Where to start to learn 2D raster graphics development?

I'm curious where one would go to learn how to create 2D graphics like Photoshop, tools where the important subtleties like creating antialiased drawing brushes and blending modes, alpha compositing, etc, are explained to a newbie. There's a myriad of stuff scattered on blogs and stackoverflow but none that seem to really address a good learning path like so many other areas in CS.