Anti-alias Plugin allows you to antialias an image.
Edit by : With this plugin, the result will be clear and Smooth, just like any other anti-aliased shapes.

Amount: pretty self explanatory. Slide it around to see different effects.
Strength: opaqueness of the feathering Default 980 for anti-aliasing. Turn it down for feathering.
Soft outline/None: Default is on. If turned on, it would darken the edge a Little bit to make it clearer. If the image has light colors, turn it off, or else there would be an ugly dark outline. you can free download Anti-alias Plugin 1.5.8.0 now.