Libgstsparrow is a Gstreamer plug-in that obliterates everything it sees, replacing it with images of sparrows.

It is designed to be used with a camera and projector pointed at the same wall. After a calibration phase, it will project a negative image of whatever is visible but not wanted on the wall. The combination of the original and negative images is a flat grey, and images of sparrows are superimposed on this by adding or subtracting from the projected negative. It works reasonably well for most images on flat surfaces.

The plug-in was made for an artwork first exhibited at the Dowse Art Gallery in Lower Hutt, NZ, in June 2010. It consists of two of these plugins, each with its own projector, competing for control of a single screen. Each projection works to cancel out the other, and the resultant complex feedback loops make for occasionally interesting video. People can disrupt the flow of the work by moving in front of the projectors and camera, the aftereffects of which can last for several seconds.