you're right, I completely misread your post.

Picasa will work on some pictures but will not enhance all of them because some are different than others.

as for creating a better resolution I have not used a software that does that. My Fuji camera does something called interpolation which just means that the software of the camera guesses what the image looks like from the image that you give it.

a search of interpolation software gave me some choices that seemed to cover you original question
link