Copywriting

What liability falls on us if we create an app for people to modify copyrighted images & violate the terms of the copyright?

We will release an application for iPhone for image editing. In this application the user can upload an image that does not own the copyright and modify it. The user can distribute the output image violating the copyright. I am concerned about the liability that this application can bring to us. If there is a lawsuit for copyright infringement, the final user will not have money and they lawsuit might leak to us (even if we make clear in the terms of use that this is responsibility of the user). How likely is this to happen? Can we do something to avoid it? Thanks