How do I make a custom collision mask for a sprite?

is it possible to import and use an image with alpha channel as a collision mask?

object

transparent collision mask

EDIT

or any other way to use more than one collision polygon with a single sprite or achieve similar result?

thanks

I think you should separate those two sprites from the image. Why would you want them to be like that? It's a waste of memory.

yeah i know that's a waste of memory and of course i'm asking that just for learning purposes...

I am really courious to know if its possible to make something similar without having to create two sprites.

thanks for your reply anyway

No, it's not possible this way. You got to do two separate sprites.