As a weekend project I put together a little module that makes it easy to play with the filters in the G2 beta. It only has limited functionality, but you can apply multiple filters to an image, save the image, and some other things.
You need to have the Graphics 2.0 to use it. Your mileage may vary.
https://bitbucket.org/develephant/filter-helper-module-for-corona-g2
Enjoy.