an alternative would be to use something like the Gimp or Photoshop, and make the bubbles slightly transparent, and make them a separate layer over the original picture.

Smaller fonts might allow you to make smaller bubbles, but as with anything else, it's a compromise between legibility, and background...

I wish I'd said that.. The Staircase Wit

anahl nathrak uth vas betude doth yel dyenvey..;)