a few things come to mind. Plug in wise, Re Vision inc makes a plug called smooth kit that would help that a lot. BUT - this should not be happening in the first place. If its just stills, resize them in photoshop first, thats what I generally do if I am not scaling it up much. Your image, to me, looks like its set at half resolution for the WHOLE image. Check your comp and render settings. It just looks like
your set at half rez.
You can email me a hi rez still and ill try it on my machine if it helps.
Animation & Visual Effects
Los Angeles Ca