Pictures are not saved in iTunes. All photos transferred from your computer via the iTunes sync/transfer process should remain on your computer.
Photos/videos captured by the iPad or saved on the iPad from a received email, from an iMessage, from a website, or imported from a digital camera or from an iPhone with the Camera Connection Kit can and should be imported by your computer as with any other digital camera - especially before restoring the iPad.
All iTunes content on your iPad - music, movies, tv shows, tones, audio and print books, and 3rd party apps should be in your iTunes library on your computer.