Virtual Bellows: Constructing High Quality Stills from Video

Cameras with bellows give photographers exibil-ity for controlling perspective, but once the picture is taken, its perspective is set. We introducèvir-tual bellows' to provide control over perspective after a picture has been taken. Virtual bellows can be used to align images taken from diierent viewpoints, an important initial step in applications such as creating a high-resolution still image from video. We show how the virtual bellows, which implements the projective group, is an exact model t to both pan and tilt. Speciically, we identify two important classes of image sequences accomodated by the virtual bellows. Examples of constructing high-quality stills are shown for the two cases: multiple frames taken of a at object, and multiple frames taken from a xed point.