Just thinking out loud here (with admittedly little expertise working with graphics in Java) maybe something like this would work?:
ImageView iv = (ImageView)findViewById(R.id.imageview);
Bitmap bitmap = Bitmap.createBitmap(iv.getWidth(), iv.getHeight(), Bitmap.Config.RGB_565);
Canvas canvas = new Canvas(bitmap);
iv.draw(canvas);
Out of curiosity, what are you trying to accomplish? There may be a better way to achieve your goal than what you have in mind.