Homography Matrix

 http://en.wikipedia.org/wiki/Homography

Homography is a concept in the mathematical science of geometry. A homography is an invertible transformation from a projective plane to a projective plane that maps straight lines to straight lines. Synonyms are collineation, projective transformation, and projectivity.^[1]

If the camera motion between two images is pure rotation, with no translation, then the two images are related by a homography (assuming a pinhole camera model).