The OFX Image Effect Plug-in API is designed for image effect plug-ins for 2D visual effects. This includes such host applications as compositors, editors, rotoscoping tools and colour grading sytems.

At heart the image effect API allows a host to send a plug-in a set of images, state the value of a set of parameters and get a resulting image back. However how it does this is somewhat complicated, as the plug-in and host have to negotiate what kind of images are handled, how they can be processed and much more.