Open Photo Booth is an application that takes a live webcam feed on your device as input, and allows you to easily add certain filters and text (in the form of name tags and word bubbles) to the image and save it to a file and a gallery on your connected Facebook profile. At least 8 different filters will be in the application, complete with their own mathematical/algorithmic implementation, including a filter that replaces the background with another image or video.
Filters are seen as an ordered list of image manipulations with settings for each, so it will also be technically very simple to create a user-made filter. A user interface will be provided for this, and filters can be shared to and loaded from files in a special format, making it possible for users to share filters with each other.