Keystone correction for stereoscopic cinematography

Keystone distortion is a long-standing problem in stereoscopic cinematography. Keystone distortion occurs when a stereoscopic camera toes in to achieve a desirable disparity distribution. One particular problem from keystone distortion is vertical disparity, which often compromises stereoscopic 3D viewing experience. Keystone distortion can be corrected by applying a proper homography; however, this damages the desirable disparity distribution. This paper presents an approach to keystone correction for stereoscopic cinematography that both corrects keystone distortion and preserves the original disparity distribution. Our method formulates keystone correction as a spatially-varying warping problem. Our method eliminates the vertical disparities and preserves the original horizontal disparities by encoding them as data terms in the warping problem. The energy terms are designed to be quadratic and thus the keystone correction problem can be quickly solved using a sparse linear solver. Our experiment shows that our method can effectively solve the keystone problem while preserving desirable horizontal disparities.