How to get rotation of a bitmap?

I have bitmaps on the stage that are rotated, but when I publish a trace of myBitmap.rotation it always returns 0.
I did some research and it seems that flash somehow does rotation on bitmaps with a transformation matrix rather then using the displayObject.rotation property.
I need the rotation values in degrees. Is there some way I can get the rotation from the transformation matrix that flash is placing on the bitmap?
Thanks!