Smother pixels

at this link

you can see a graphic created in photoshop 7 and transferred to flash with a simple motion added to one leaf.

I have kept it basic to show the problem. The moving leaf pixels look very rough. I dont believe the issue is with Flash (the only thing I tried was the frame rate which makes no difference, i cant change the graphic) but with Photoshop.

So the graphics are photoshop saved as .png (after trimming) and imported into flash. In photoshop I created the graphics from a photograph (selected via quickmask) and contracted the result and feathered it.

Are there any ways to make it look smoother?

thanks in advance