Nope.
You cannot clone or copy your current state of iphone into an ipsw and restore it with all your texts, contacts and other stuff for example.
You have to restore thru itunes to official firmware and then restore from backup.
And that will accomplish the same.
Yep, itunes is all you can use for iphone's.
You should have known that everything is done thru that program including transfering media, updates, restores, backups etc....