Help with bitmapData

Hi everyone, I need some help

I’ve managed to texture a geosphere without mayor cpu usage and perforance loss, but tehre are still more ways to improve it

I need a good tutorial on Flash’s bitmapData from the basics, because masking duplicated movie clips is way slower than that

can anyone recommend me some related urls? I only found pixel transmition ones, but they are a bit complicated to start with when you are unfamiliar with bitmapData

thanks in advance