At the moment we have examples in library and wiki showing how to show a real-time filtered preview - for example the Filter Explorer real time filter demo. However we don't have clear examples of how/where you would update the code to take a snapshot and save it.
This is not really complex as far as I know - in essence you shoot an image and apply the same filter/effect (with the same parameters) to it. Perhaps a good wiki article?
Maybe even an entry in the Nokia Imaging and Big UI Wiki Competition 2013Q4?