Digital correction of keystoning caused by image translation
David F. McAllister · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1994
Translating rectangular 2D images in planes perpendicular to the line of sight can create image distortion known as keystoning or projection warp. This can occur when viewing several images on a plane from a fixed position, when cross viewing, or when using non-parallel mirrors to view stereo pairs. In the latter case, vertical disparity can become a problem. The projection warp and its inverse are derived as functions of the viewing and translation parameters. It is shown that vertical disparity can be significant, even in small image translations. The inverse transformation applied to the original image corrects the keystoning caused by the translation. Rendering of the inverse image is also discussed.