Can you explain why you need this on a DVD?
DVDs are, by definition, limited to 640x720 @ 72"dpi" (they don't really have dpi but nevermind). So naturally photos don't look that great on them, particularly when they've been squished down to that. I've had much better luck with DVDs by PRE-preparing the photos to be that size ahead of time in something like Pixelmator or Photoshop.
If you NEED the photos to be as high-res as when they were shot, then you need to go with digital distribution (ie iPhoto, Aperture, Keynote, iMovies in HD formats, etc).