In general, image effects plug-ins take zero or more input clips and produce an output clip. So far so simple, however there are many devils hiding in the details. Several supporting suites are required from the host and the plug-in needs to respond to a range of actions to work correctly. How an effect is intended to be used also complicates the issue, forcing sets of behaviours depending on the context of an effect.
Plug-ins that implement the image effect API set the
member of the
returned by the global
. The current version of the API is 1. This is enough to label the plug-in as an image effect plug-in.